This PDF file contains the front matter associated with SPIE Proceedings Volume 6837, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

We report on approaches of pulsed digital holographic recording and its relevant digital reconstruction based on Fourier optics for measurements of high resolution in time domain or in space domain, in which angular division multiplexing system is respectively employed to record multiple images in a single frame of a CCD. This new approach can be used to record either a series of images in an ultra-fast process with high resolution in time domain, or to record a transparent object with super-resolution in space domain. In the digital reconstruction process, Fourier transformation and frequency filtering in the Fourier plane will be employed to separate the spatial spectra of the multiple recordings, and each of the reconstructed images can be displayed individually with a time resolution of the femto-second order or fused into an image of the object with a synthetic aperture.

A known-plaintext attack on the double phase encryption scheme implemented with parallel hardware is presented. The double random phase encoding (DRPE) is one of the most representative optical cryptosystems developed in mid of 90's and derives quite a few variants since then. Although the DRPE encryption system has a strong power resisting to a brute-force attack, the inherent architecture of DRPE leaves a hidden trouble due to its linearity nature. Recently the real security strength of this opto-cryptosystem has been doubted and analyzed from the cryptanalysis point of view. In this presentation, we demonstrate that the optical cryptosystems based on DRPE architecture are vulnerable to known-plain text attack. With this attack the two encryption keys in the DRPE can be accessed with the help of the phase retrieval technique. In our approach, we adopt hybrid input-output algorithm (HIO) to recover the random phase key in the object domain and then infer the key in frequency domain. Only a plaintext-ciphertext pair is sufficient to create vulnerability. Moreover this attack does not need to select particular plaintext. The phase retrieval technique based on HIO is an iterative process performing Fourier transforms, so it fits very much into the hardware implementation of the digital signal processor (DSP). We make use of the high performance DSP to accomplish the known-plaintext attack. Compared with the software implementation, the speed of the hardware implementation is much fast. The performance of this DSP-based cryptanalysis system is also evaluated.

A method of digital image measurement of specimen deformation based on CCD cameras and Image J software was developed. This method was used to measure the biomechanics behavior of human pelvis. Six cadaveric specimens from the third lumbar vertebra to the proximal 1/3 part of femur were tested. The specimens without any structural abnormalities were dissected of all soft tissue, sparing the hip joint capsules and the ligaments of the pelvic ring and floor. Markers with black dot on white background were affixed to the key regions of the pelvis. Axial loading from the proximal lumbar was applied by MTS in the gradient of 0N to 500N, which simulated the double feet standing stance. The anterior and lateral images of the specimen were obtained through two CCD cameras. Based on Image J software, digital image processing software, which can be freely downloaded from the National Institutes of Health, digital 8-bit images were processed. The procedure includes the recognition of digital marker, image invert, sub-pixel reconstruction, image segmentation, center of mass algorithm based on weighted average of pixel gray values. Vertical displacements of S1 (the first sacral vertebrae) in front view and micro-angular rotation of sacroiliac joint in lateral view were calculated according to the marker movement. The results of digital image measurement showed as following: marker image correlation before and after deformation was excellent. The average correlation coefficient was about 0.983. According to the 768 × 576 pixels image (pixel size 0.68mm × 0.68mm), the precision of the displacement detected in our experiment was about 0.018 pixels and the comparatively error could achieve 1.11&perthou;. The average vertical displacement of S1 of the pelvis was 0.8356±0.2830mm under vertical load of 500 Newtons and the average micro-angular rotation of sacroiliac joint in lateral view was 0.584±0.221°. The load-displacement curves obtained from our optical measure system matched the clinical results. Digital image measurement of specimen deformation based on CCD cameras and Image J software has good perspective for application in biomechanical research, which has the advantage of simple optical setup, no-contact, high precision, and no special requirement of test environment.

We review applications of 1D Fourier transform to Fourier transform spectroscopy, optical coherence tomography, and fiber distributed sensor.

In this paper, a new system of multi-channel single-output rotation-invariant joint fractional Fourier transform correlator (JFRTC) for color pattern recognition is proposed. Due to the shift-variant property of fractional Fourier transform (FRT), we can obtain three correlation peaks at the output plane which show a pair of cross-correlation peaks that is desired and one autocorrelation peak, so the noise is greatly reduced. The Synthetic discriminate function (SDF) is quoted at the input plane to store the reference images to realize rotation-invariant recognition. To optimize the correlation peaks, the joint power spectrum is binarized to perform Fourier transform. The theoretical analysis and optical experiments are discussed in detail. Experimental results are presented to demonstrate the ability of this system.

Traditional matched filter-based correlator needs to make matched filter in advance, which has many disadvantages, such as large calculation and slow speed. The more important thing is that it is not suitable for real-time processing and recognition precision is also very low. In this paper, the method of optical joint transform correlation (JTC) is presented, which can recognize targets in real time with higher precision. In JTC, Electricity Addressed Liquid Crystal Display (EALCD) is adopted as spatial light modulator, which has the feature of high resolution. It can record not only objects and images of optical system, but also joint image of target and template stored in computer beforehand. In the experimental system, EALCD is the key device to realize optical correlation. Two area array CCD are used to record the joint transform spectrum (JTS) and correlation peaks image respectively. By the coordinate of correlation peaks, the position of the target can be determined. Comparatively, stationary targets can be detected and recognized easily by JTC. When targets get moving, the intensity of the correlation peaks of joint image turns weak. Sometimes we even can't get them. Thus, an effective method is needed to solve the problem. In this paper, dynamic templates are applied to realize tracking the targets. Temporal state of targets will be used as new templates. According to the experiments, good tracking results are achieved.

Based on the extended fractional Fourier transform, we propose a zone-processing joint extended fractional Fourier transform correlator. With the zone-processing technique, first, the high- and low-frequency zone can be obtained from high- and low-brightness joint extended fractional Fourier transform power spectra, respectively. Second, they are combined into new power spectra, so it can preferably include high- and low-frequency information simultaneously. The experiment results demonstrate that this processing technique can largely improve correlation performance.

We have proposed photonic DNA computing as a new parallel computing paradigm, in which optical techniques are used to manipulate information-coded DNA. In this paper, we present a parallel transportation of multiple beads bound with hairpin-structure DNA using a dynamic optical tweezers system which combines a spatial light modulator (SLM) with a diffractive optical element (DOE). This system provides and effective method for parallel manipulations of DNA-bound beads at multiple positions. In the experiments, three 2.8-μm-diameter beads bound with hairpin DNA were trapped and transported in 1 μm of step by switching of the SLM patterns. The results demonstrate that the dynamic holographic optical tweezers system with combination of the DOE and the SLM is useful in spatially parallel processing required for photonic DNA computing.

Optical digital processor is the core of some future optical parallel computing systems. A novel optical discrete correlation processor using a high-speed digital micromirror device is proposed, which mainly consists of a VanderLugt correlator. In the processor, the computer generated hologram filters which are inputted by the digital micromirror device will determine the specific logical operations. With properties of high reflectivity, high resolution and short response time, the digital micromirror device can control the wave-front of the light beams with high optical efficiency, large contrast ratio and high rate. An experimental prototype is constructed to demonstrate some specific logical operations. The experiment results indicate that, the novel optical digital processor based on digital micromirror device can perform some specific logical operations properly, and the digital micromirror device can remarkably improve the performance of the optical digital processor.

A new method that the equivalent mode field radius can be acquired according to the equivalent matching efficiency method is presented and the equation of the equivalent mode field radius, which is based on the core layer radius, the normalized standing wave parameter and the normalized evanescent wave parameter, is given. Moreover, adopted computer numerical simulation, a mathematical modeling between the equivalent mode field radius and the normalized frequency of fiber is established. Based on this, the equation between the equivalent mode field radius and the normalized frequency is introduced by curve fitting method. The numerical calculation indicates that it has a higher precision. As for weakly guiding optical fiber, referred to the characteristic of the beam propagation factor of diffractive beam of LP₀₁ mode from its end surface, it was illuminated that the Gaussian approximation for the mode field distribution of LP₀₁ mode is rational. The characteristic of the field of the Gaussian approximation, which is based on the equivalent mode field radius, is analyzed. The difference between the eigen mode field of LP₀₁ mode and the field of its Gaussian approximation is discussed. From that, we can draw the conclusion that it is relatively accurate to adopt the equivalent matching efficiency method to obtain the equivalent mode field radius.

We propose a novel scheme for simultaneously realizing optical mm-wave generation and remote photonic down-conversion by using optical phase modulator along with sidebands separation technique. In the central office, optical double sideband (DSB) signal is generated by using an optical phase modulator. One sideband of the generated optical DSB signal is filtered out to carry downstream data signal. In the base station, the sideband carried with downstream data beats with part of the optical carrier, thereby generates mm-wave signal. Another sideband along with part of the optical carrier is injected into the second phase modulator to implement photonic frequency down-conversion for uplink signal transmission. We also theoretically show the principle of photonic frequency down-conversion based on the optical phase modulator. By using the scheme, no additional optical local oscillator signal or RF signal is needed because the full advantage of sidebands of the optical DSB signal has been taken.

Diffraction of optical field by subwavelength metallic hole is analyzed with the rigorous coupled wave analysis. The surface plasmon polaritons generated in this diffraction process can be coupled to directional beam-like radiation modes by circular surface grating structures. A simple holographic grating design equation is proposed for realizing various beaming of surface plasmon polaritons. The designed grating structures for on-axis beaming and Bessel-like beaming are demonstrated with three-dimensional electromagnetic field visualization. We discuss several interesting physical features in the diffractive beaming of surface plasmon polaritons by circular surface grating structures.

In the measurement of aspheric surfaces, spatial phase modulation technology is always combined. With a tilt, the linear spatial carrier is introduced to enhance the signal noise ratio (SNR). Then using DFT on the interferogram, after spectrum shifting, the first order spectrum filter and IDFT, the wavefront phase of aspheric surface is obtained. In this paper, the traditional way to introduce spatial carrier, namely that the center of the first order spectrum is positioned on the x axis, is analyzed. This method exist a limitation which may influence the testing result. Thus a new method is put forward here. Make sure the slope of spatial carrier is unvaried, and transfer the first order spectrum to the bisector of x axis and y axis. This change can not only reserve the low frequency components of the first order spectrum, but also keep the high frequency components at a large extent. So in some circumstance, the wavefront phase of aspheric surface with a large PV value can't be recovered accurately by the traditional spatial carrier way, but it can be recovered accurately by the new way. This greatly expands the testing range of wavefront of aspheric surface.

Many experiments of optical sampling based on the second-order optical nonlinear interactions in periodically poled LiNbO₃ (PPLN) quasi-phase-matched (QPM) waveguides have already been demonstrated during the last few years. There are several processes in PPLN that may be used for sampling optical signals, including sum-frequency generation (SFG), difference-frequency generation (DFG), cascaded second harmonic generation and difference-frequency generation (cSHG/DFG), and cascaded sum-frequency generation and difference-frequency generation (cSFG/DFG). The comparisons are carried out, which are necessary for designing the optical sampling system that satisfies the requirements of optical performance monitoring (OPM) of the optical networks. The SFG and cSFG/DFG based conversions are much more suitable for constructing OPM systems. The SFG of either two pulsed waves or one pulsed wave and one continuous wave is the basic nonlinear process for sampling optical signals using PPLN waveguide. Theoretical analyses based on coupled-wave equations are carried out for the pulsed-SFG process.

After concluding the application of under-water optics, the development of under-water laser imaging technology is reviewed. The main types of laser imaging technology are introduced, such as laser scanning imaging, distance selected imaging, and three-dimensional technology. The respective imaging principle, characteristics and update status are presented. Furthermore, the newest detecting technology, such as fiber optic hydrophone, under-water holograph and under-water spectrum detecting technology are described in detail. The recent researching status and new application are included.

We propose a novel scheme to generate duobinary RZ and dark RZ signals. It needs only one differential Mach-Zehnder modulator (DMZM), which can adjust the operating point of the modulator to generate duobinary RZ and dark RZ signals easily. It is more cost-effective compared to conventional schemes due to its simple configuration.

In this paper, a scheme of optical millimeter (mm)-wave generation by using only one phase modulator has been investigated experimentally. To generate a mixing signal, the baseband signal is mixed with the radio frequency (RF) signal using an electric mixer. And the double-sideband (DSB) signal generated from phase modulator driven by the mixing signal is transmitted to base station via a single mode fiber. The central carrier and the first-order sideband are separated by an optical interleaver at base station. The two peak modes of the first-order sideband will beat to generate an mm-wave with a double repetitive frequency of the RF signal when they are detected by an optical receiver. The transmission performance of the optical mm-wave is analyzed. According to our research, the different delay of two first sidebands due to the fiber dispersion will lead to power loss of the mm-wave. And the duty cycle of the code is reduced. It limits the largest transmission distance of the mm-wave. In the experiment, the 20GHz RF signal generates 40GHz mm-wave and 2.5Gbps NRZ is carried by the mm-wave. For downlink connection, the power penalty is 0.2 dB after transmission over 20-km.

A nonlinear optical loop mirror (NOLM) based on photonic crystal fiber (PCF) is used for optical pulse shaping. The transmission of optical pulses in the fiber loop can be described by the nonlinear Schrödinger equations. The crossing phase modulation (XPM) effect which happens between signal pulse and control pulse in NOLM is used for pulse shaping. The theory of XPM effect in NOLM is analyzed theoretically and the process of pulse shaping is simulated. For the input Super-Gaussian signal pulses, it can be found that the pulse can be shaped from flat to sharp by the compression effect. For the input Hyperbolic-Secant signal pulses, it can be found that the pedestal from the compressed pulse can be suppressed by the NOLM. Due to the characteristics of PCF, especially high nonlinear properties, the high quality shaped pulses can be got. Compare with the self phase modulation (SPM) effect for optical pulse shaping, it is shown that the input pulse with low power itself can be shaped and the shaping of the input pulse can be controlled by the control pulse. Based on the analysis of the result, proper parameters and the crystal fiber of the NOLM will be selected.

Traditional free-space optical (FSO) communications use a single transmitting antenna (laser/VCSEL/LED) and a receiving antenna (a photo-detector) for single channel communication between two nodes. In this paper we study two transmitting antenna one receiving antenna M-FSO (mobile FSO) communication system. In the process of single transmitting antenna moving, the optical beam broadens to make receive power smaller with the divergence angle larger and the power is difficult to be detected when long-distance communication. When short-distance communication, the divergence angle is so small that it makes a narrow beam which is hard to be aimed at receive aperture, even more serious when the beam is out of target caused by vibration. We take advantage of space diversity technology to reduce BER caused by atmospheric turbulence and mobile vibration. Through the multi-transmitter, the best choice of multi-divergence angle reduces BER, thus the receiver accurately recovers information.

Optical label switching (OLS) has been regarded as an efficient technique to route and forward IP packets transparently in the optical layer. In label switching system, orthogonal modulation has shown some advantages, such as its high spectral efficiency. One example is the combination of amplitude-shift-keying (ASK) label and differential phase-shift-keying (DPSK) payload. However, differential quadrature phase-shift-keying (DQPSK) payload has not been used in optical label switching system yet. In this letter, we propose and demonstrate a novel optical label switching scheme by the combination modified return zero (MD-RZ) and DQPSK for the first time. The transmitter is set up by cascading two phase modulators (PM) and one dual-arm LiNbO3 modulator (LN-MOD). The signal is first phase modulated by two PMs. The MD-RZ label is then impressed by the subsequent LN-MOD. Duty cycle and extinction ratio of the MD-RZ labels are tunable. The DQPSK payload can be used in a 20Gbit/s optical label switching system, with 2-bit per symbol modulation/demodulation. Within the network, the label information is read, processed and updated, a process known as label switching, until the burst reaches the desired egress edge node. The use of balanced detection is expected to improve performance for the payload. The transmission performance of 20Gbit/s DQPSK payload with 2.5Gb/s MD-RZ-ASK label is also analysed. MD-RZ labeling of a DQPSK payload has been shown to be a promising candidate for the implementation of OLS system.

When used at oblique angles of incidence, the reflectance and transmittance of thin films exhibit strong polarization effects, particularly for the films inside a glass cube. However, the polarization effects are undesirable in many applications. Novel non-polarizing beam splitter designs are shown, non-polarizing beam splitters with unique optical thin films are achieved through combination of interference and frustrated total internal reflection, the non-polarizing condition expressions based on frustrated total internal reflection is derived, and applied examples of the non-polarizing beam splitters are also presented with the optimization technique and the results of Rp=(50±0.4)% and Rs=(50±0.4)% in the wavelength range of 500-600nm are obtained.

The image feature extract method of image pattern recognition algorithm is studied in the paper. A high speed and real-time method of image locating and feature extract is presented. And the method mainly consists of two key technologies, one is to locate the target area of measured object using mask matrix method, the other is to extract the edge feature based on the template matching method. The experiment results show that the method of image feature extracting is a high speed and high precision image recognition algorithm, and it can be satisfied the high-speed and real-time requests of on-line detection.

In this paper, we have proposed a novel compact sub-terahertz wave modulator based on silicon photonic crystals. In our proposed structure, the photonic crystals are made up of p-i-n silicon. As the free carriers are injected, the photonic band gap of p-i-n silicon photonic crystals shifts. The light modulation mechanism of the novel sub-terahertz wave modulator is based on a dynamic shift of the photonic band gap (PBG). The finite-difference time-domain (FDTD) method is used to investigate the performances of the designed sub-terahertz wave modulator. The simulation results show the sub-terahertz wave modulator with a high extinction ratio (-40 dB), low insertion loss (-1dB), rapid response time, and small size can be obtained. Being its small size, the novel sub-terahertz wave modulator can be used in future sub-terahertz wave integrated circuits.

A wave-meter based on Michelson interferometer consists of a reference and a measurement channel. The voice-coiled motor using PID means can realize to move in stable motion. The wavelength of a measurement laser can be obtained by counting interference fringes of reference and measurement laser. Reference laser with frequency stabilization creates a cosine interferogram signal whose frequency is proportional to velocity of the moving motor. The interferogram of the reference laser is converted to pulse signal, and it is subdivided into 16 times. In order to get optical spectrum, the analog signal of measurement channel should be collected. The Analog-to-Digital Converter (ADC) for measurement channel is triggered by the 16-times pulse signal of reference laser. So the sampling rate is constant only depending on frequency of reference laser and irrelative to the motor velocity. This means the sampling rate of measurement channel signals is on a uniform time-scale. The optical spectrum of measurement channel can be processed with Fast Fourier Transform (FFT) method by DSP and displayed on LCD.

The multiphoton ultraviolet and visible upconversion luminescence of Tm³⁺Yb³⁺ codoped ZBLAN fluoride glass as excited by a 975nm diode laser was studied. Two typical ultraviolet 290.6nm ¹I₆ → ³H₆ and 362.0nm ¹D₂ → ³H₆ upconversion luminescence lines were found. The careful measurement of the variation of upconversion luminescence intensity F as a function of the 975nm pumping laser power P has proven that the 290.6nm ¹I₆ → ³H₆ and 362.0nm ¹D₂ → ³H₆ upconversion luminescences are a six-photon and a five-photon upconversion luminescence respectively. Several visible upconversion luminescence lines at 450.5nm, 473.9nm, 648.5nm, (687.3nm, 696.2nm) and (793.5nm, 800.7nm) were found also, which result from the fluorescence transitions of ¹D₂ → ³F₄, ¹G₄ → ³H6, ¹G₄ → ³F₄, ³F₃ → ³H₆ and ³H₄ → ³H₆ of Tm³⁺ ion respectively. It has been proved that the upconversion luminescence of ¹G₄ state is a three-photon upconversion process, while that of ³F₃ or ³H₄ state is a two-photon upconversion process. The theoretical analysis suggests that the upconversion mechanism of the 362.0nm ¹D₂ → Tm³⁺ upconversion luminescence is the cross energy transfer of {³H₄(Tm³⁺) → ³F₄(Tm³⁺), ¹G₄(Tm³⁺) → 1D₂(Tm³⁺)} and {¹G₄(Tm³⁺) → ³F₄(Tm³⁺), ³H₄(Tm³⁺) → ¹D₂(Tm³⁺)} between Tm³⁺ ions, whereas the mechanism of the 290.6nm ¹I₆ → ³H₆ upconversion luminescence is the sequential energy transfer of {²F₅/2(Yb³⁺) → ²F₇/2(Yb₃₊), ¹D₂(Tm³⁺) → ³P₁(Tm³⁺)} and {²F_5/2(Yb3+) → ²F_7/2(Yb³⁺), ¹D₂(Tm³⁺) → ³P₂(Tm³⁺)} from Yb³⁺ ions to Tm³⁺ ions. In addition, the upconversion luminescence of G₄ and ³H₄ state also results from the sequential energy transfer {²F_5/2(Yb³⁺) → ²F_7/2(Yb³⁺), ³H₄(Tm³⁺) → ¹G₄(Tm³⁺)} and {²F_5/2(Yb³⁺) → ²F_7/2(Yb³⁺), ³F₄(Tm³⁺) → ³F₂(Tm₃₊)} from Yb³⁺ ions to Tm³⁺ ions respectively.

The depth of field for optical imaging system is restricted according to its structure parameters. It is obviously when optical microscopy is used, which depth of field is very small and it is lesser with larger amplification ratio. In the paper, three main methods to extend the depth of field will be shown, and their merits and shortcomings will be analyzed. The first method is to use optical mask. It is easy to achieve satisfied results with calculation simulation, but it is difficult to produce this mask if it is complicated. The second method is to use image processing. Many images can be obtained with scanning of imaging system in the direction of depth. Using image processing method, the information of each image will be extracted, then to compose a new image with them. It is a hard work to capture these scanning images. And it is difficult to achieve real time image. The last method is to combine the method of optical mask and image processing. The larger depth of field for optical imaging methods can extend the image range that can be used in the field of optical microscopy and scanning image system.

Introduces a Fourier transform spectrometric method for the precise characterization of dispersion of chirped FBGs(fiber Bragg grating). The measurement system is a fiber Michelson interferometer composed of a broadband EDFA (Erium doped fiber amplifier) light source, a 3db 2×2 fiber coupler, a pair of polarization controllers, a optical attenuator, a fiber filter, an O/E converter, A/D converter, computer and a optical path difference (OPD) scanning system. The digital interferogram of the system is acquired by recording the electric signal produced by the O/E converter through the A/D converter and by computer during the scanning of OPD. The recorded interferogram is then manipulated through a process involving low-pass filtering, fast Fourier transformation, phase unwrapping and computation of the numerical differentials of the unwrapped phase to the wavelength so as to obtain the relative group delay of the chirped FBG under test. It is proved by practical experiments that the repeatability of the system is up to Ps(picosecond) magnitude order.

This letter bases on the researches of LSB (least significant bit, i.e. the last bit of a binary pixel value) matching steganographic method and the steganalytic method which aims at histograms of cover images, and proposes a modification to LSB matching. In the LSB matching, if the LSB of the next cover pixel matches the next bit of secret data, do nothing; otherwise, choose to add or subtract one from the cover pixel value at random. In our improved method, a steganographic information table is defined and records the changes which embedded secrete bits introduce in. Through the table, the next LSB which has the same pixel value will be judged to add or subtract one dynamically in order to ensure the histogram's change of cover image is minimized. Therefore, the modified method allows embedding the same payload as the LSB matching but with improved steganographic security and less vulnerability to attacks compared with LSB matching. The experimental results of the new method show that the histograms maintain their attributes, such as peak values and alternative trends, in an acceptable degree and have better performance than LSB matching in the respects of histogram distortion and resistance against existing steganalysis.

In this paper, we propose a new technique in direct sequence code division multiple access system using on-off key and modified prime sequence code, the scheme of this technique dubbed successive interference cancellation (SIC). The basic principle of SIC scheme is to subtract the strongest received signals from the original signal one by one till all users have been detected, and demodulated. In this analysis we take in account the possibilities of errors in previous cancellation. It has been shown that the proposal IC scheme with (-20dBm) effective power can suppress multiple-access interference (MAI), and improve the system performance significantly.

A quantitative numerical modeling of laser-induced Lamb waves in thin unidirectional fiber-reinforced composite plate, transversely isotropic, is established by using finite element method (FEM). Taking into account the effects of thermal conduction, optical penetration as well as the finite width and duration of laser source, the transient temperature distributions are calculated. Applying the temperature distributions induced by the absorbed laser energy to structure analyses as thermal loading, the stress fields, the deformations of plate and the laser-induced Lamb waveforms are obtained. The mechanical generation process of Lamb wave is presented intuitively by analyzing the stress field propagation and the deformations of plate. The characteristics of Lamb waveforms caused by the anisotropic nature of specimen material, including amplitude and dispersive nature, are analyzed. This method provides insight to the generation and propagation of the laser-induced Lamb waves in thin unidirectional fiber-reinforced composite plate and establishes the quantitative relationship between the laser-induced Lamb waveforms and the laser input as well as the specimen parameters.

Using 2-dimensional (2D) photonic crystal with hexagonal lattice to extract guided waves inside slab waveguides is investigated in the paper. Since 2D hexagonal lattice structure is circularly symmetrical, the effect of light extraction can be regarded as the same for guided waves propagating toward different directions on the plane of the slab. Theoretical analysis was carried out under the assumption that a hexagonal lattice consists of many groups of gratings with different periods and orientations. Based on the assumption, the simulations of the extracted light-spot distributions on the waveguides for the guided waves with different reflection angles inside the slab were obtained. The simulations are consistent with the experimental result, verifying that the observed spot array above the slab surface, where 2D hexagonal lattice was fabricated, was generated by the diffraction of the lattice. The light extraction method can be used to separate a laser beam into many distributed beams for optical network interconnection applications and to extract trapped light inside LEDs. Theoretical analysis indicates that to obtain efficient light extraction via hexagonal lattice, lattice constant should be properly chosen. Method for choosing desired lattice constant is provided.

Wavefront coding (WFC) used in 2D barcode scanners can extend the depth of field into a great extent with simpler structure compared to the autofocus microscope system. With a cubic phase mask (CPM) employed in the STOP, blurred images will be obtained in charge coupled device (CCD), which can be restored by digital filters. Direct methods are used widely in real-time restoration with good computational efficiency but with details smoothed. Here, the results of direct method are firstly filtered by hard-threshold function. The positions of the steps can be detected by simple differential operators. With the positions corrected by projection algorithm, the exact barcode information is restored. A wavefront coding system with 7mm effective focal length and 6 F-number is designed as an example. Although with the different magnification, images of different object distances can be restored by one point spread function (PSF) with 200mm object distance. A QR code (Quickly Response Code) of 31mm X 27mm is used as a target object. The simulation results showed that the sharp imaging objective distance is from 80mm to 355mm. The 2D barcode scanner with wavefront coding extends field depth with simple structure, low cost and large manufacture tolerance. This combination of the direct filter and projection algorithm proposed here could get the exact 2D barcode information with good computational efficiency.

In this paper, we propose a new encoding method to make a binary amplitude-based phase-only-encoded barcode in a security system based on the conventional random phase encoding technique. In this method, the values of the phase distribution in the system are quantified with a high phase level, and afterwards the result is encoded into a binary matrix based on the rule of decimal-binary conversion. The binary matrix is arranged specially and printed as the 2-D anti-counterfeit label which can be printed by standard halftoning technology and read by optical scanning device. It is obvious that the higher phase level could be chosen to obtain the better reconstruction image in the improved method and the fabrication is also very convenient. In additions, computer simulations and optical scanning experiments are illustrated in detail. The tolerance to data loss of the encoded barcode is also studied particularly. The results show that the presented encoding method has advantage of robustness and high security, and very convenient to be popularized in practice.

In this paper, a universal description of the optical coherence is represented, where the quasi-monochromatic optical field and the corresponding coherence are expressed by Dirac state vector and the coherence operator, respectively. The spatial coherence, the temporal coherence, and the partial polarization state are described by the abstract operator i. e. coherence operator. With the operator method, the description of the optical coherence becomes simple and flexible, and reveals the essence of the optical coherence.

A simple architecture of all-optical wavelength conversion in a highly nonlinear bismuth oxide-based photonic crystal fiber (PCF) is proposed, which consists of an erbium-doped fiber amplifier, a polarization controller, a nonlinear medium PCF, two tunable fiber Fabry-Perot filters and an optical isolator. Self-phase modulation is utilized to induce spectral broadening for all-optical wavelength conversion. The desired dispersion properties can be tailored by the parameters of bismuth oxide-based PCF microstructure. The propagation loss at 1550nm is about 0.8dB/m. The nonlinear coefficient is expected to be 1100W^-1km^-1 by using bismuth oxide-based glass and reducing the effective core area. The mode-field diameter of PCF is estimated to be 1.98μm and the predicted effective core area is 3.3μm². The intermediate high numerical aperture fibers between bismuth oxide-based PCF and single-mode fibers are considered to reduce the splicing loss. The obtained results show that the all-optical wavelength converter has a potential of high conversion efficiency, wide conversion bandwidth, ultrafast response time, compact configuration and low insertion loss etc.

In this paper, we demonstrated the tunable 1.5-μ m-band wavelength conversion based on cascaded second order nonlinear processes "SHG+DFG" by fan-out grating in lithium niobate waveguide for the first time. We fabricated the waveguide by annealed proton exchange in periodically poled LiNbO₃ (PPLN). The device used in this experiment is 4 cm long, has a QPM period from 14.8μm to 15.2μm, waveguide width of 12μm, proton exchange depth of 0.7μm, and was annealed for 32h at 350°C. After proton exchange in pure benzoic acid using a SiO₂ mask, the substrate was annealed in an oxygen atmosphere. The wavelength of signal light was set at 1551.3nm. The wavelengths of tunable pump lights we used in experiment were 1543.2 and 1556.2 nm, and the corresponding grating periods were 14.87μm and 15.03μm, respectively. The temperature was set at 100.5°C to avoid photo refractive damage and to match the QPM peaks to the pump wavelengths. The conversion efficiency was about 10dB to be expected with the pump power 175mW in a similar device with a slightly different QPM period and operated at 125°C.

Grating is well known for its dispersion characteristic. A new characteristic that we call spectral combination has been studied in this paper. It is a reverse phenomenon of grating dispersion. Light incident on a grating is dispersed into a spectrum. The same order diffracted lights of different wavelengths come from different places of the first grating converged on the second grating and outgoing beam at the same diffraction angle is spectral combination. Both using dispersion and spectral combination characteristic of grating, two gratings consist of an imaging system and a novel grating imaging phenomenon will occur. In this case, a virtual objective image can be formed after the object waves are diffracted by two gratings. This new grating imaging effect has close relation to spectral combination characteristic of grating. The characteristic is studied by theoretical analysis and numerical simulation. A relationship between the two gratings' spatial frequencies and diffraction orders that reflecting the spectral combination quality on certain condition is given. The spectral combination property of Grating on general condition is discussed by numerical calculation. To recognize the new property of grating deeply is very helpful for its application.

Through a two laser beams interference method, holographic gratings were successfully fabricated in Polyacrylic Acid binder photopolymer (PAA). The real-time dynamic fabrication process of the grating was monitored by a He-Ne laser which was used as the probe light. During the heat treatment process of grating, the refractive index modulation and hence the diffraction efficiency will change. Firstly, the gratings were fabricated under different temperature; secondly, the dynamic change of diffraction efficiency of holographic grating with temperature was investigated just after fabricating it at room temperature. The change range of temperature in experiments was from 25°C to 100°C. We found there was one optimal temperature value for each kind of photopolymer. The surface topographical change of Photopolymer film was also investigated by atomic force microscope(AFM). The results and concerned discussion will help to design and synthesize the highly functional Photopolymer that can show better environmental stability.

We have proposed an improved optic-electronic hybrid encoding technique for certificate validation based on works of Junji Ohtsubo and Ayano Fujimoto. Corresponding experiment was carried out for substantiating our proposed method. Our approach enhances the level of security by importing another key image, largely increasing the cipher space and inducing a better resistance to brutal attacks. Optical experiment exhibits while the encrypted results offered is a correct one and another licit one but contaminated by an Additive Gaussian Noise with a Standard Deviation of 0.4, the PSNR of decrypted image is 6.87 and 6.54, respectively. Experimental results indicate the effectiveness and robustness of this method. This paper conducts a beneficial exploration in the practical application of optical authentication technique.

This paper improved the traditional experiment system detecting Brillouin shift in pure water to educe an experimental equation. We calculate Brillouin shifts and the sound speed in pure water not only by the spectroscopic method, but also by the improved method and then deducing an experiential equation at our specific experimental conditions. Comparing the two results, we learn that the experiential equation we deduced is better than the traditional spectroscopic method, smaller error and more close to the theoretical value.

The MMI optical power splitters which are based on the self-imaging effect (SIE) have been analyzed in the paper, and 1×4 MMI power splitter is designed. The designed device is simulated and optimized by Beamprop software, the simulation results are basically agreement with the designed effect, the excess loss induced by multimode interference is less than 0.04dB, uniformity is about 0.01dB.The low loss and fine uniformity MMI power splitter has been made by Lithium Niobate annealed proton exchange technology, and the experiment sample measurement results are achieved.

Rotating scan is a common 360-degrees measurement method in 3D measure system which based on line-structure light. In this system, the calibration for rotary axis of the rotary platform is an important section. It will be affecting the measurement results. In known methods, precision and expensive auxiliary instruments are required to ensure that the rotation axis is located in the plane of line-structure light. In this paper, a simple, flexible and real-time calibration method is proposed. Firstly, a plane calibration board with tessellated pattern is placed incline on the rotating stage. Secondly, recoded several pictures of the calibration board while the stage rotating several angles. Thirdly, the parameters of camera (include the intrinsic parameters and the extrinsic parameters, such as rotating matrixes and transform vectors between the local coordinates of these planes and the global coordinate of sensor) can be estimated from these pictures. Then, the global coordinates of these control points were calculated according to these parameters. Finally, the axis parameters of the working stage can be optimized with these control points because the global coordinates of same control point in different position are in circle. This method is proved by experiment, and the root-mean-square error is 0.04mm.

We have simulated the OSNR sensitivity, filtering tolerance, chromatic dispersion tolerance, and nonlinear tolerance of optical DPSK and DQPSK formats with and without RZ carving in 40Gbit/s transmission systems. The results show that RZ-DPSK has the highest OSNR sensitivity, and is most robust against fiber nonlinearity in dispersion compensated systems with moderate channel spacing. The DQPSK systems have the highest filtering tolerance and dispersion tolerance, and is least affected by the reduction of the channel spacing. The simulations of long haul dispersion compensated systems show that RZ-DPSK has better performance in single channel system and WDM system with 100GHz channel spacing, while RZ-DQPSK has better performance in WDM system with 50GHz channel spacing.

The wavelet transform has a lot of uses in the field of optical information processing. It's an effective technology applied to joint transform correlator system. It realizes the detection, identification and positioning of target. Joint transform correlator has not only high speed for identification but also high accuracy for positioning. This paper has discussed the application of Gauss wavelet function on identifying target in clutter background. In fact, it is difficult for joint transform correlator to identify target because the target image information which is collected by the imaging sensor has a lot of background noises. So we propose and demonstrate that the availability of using Gauss wavelet function. We use the method of wavelet transform and morphology algorithm to extract object edge, and get more sharp correlation point. Our computer simulation and optical experimental results showed that the image feature extraction performance of the proposed algorithm is effective and competitive to other image processing algorithm reported in the literature.

The joint transform correlator was an effective system for the target detection and recognition, major character was that the reference template and the target were simultaneous processed; Fourier transform was operated by Fourier transform lens with the speed of light; the joint transform power spectrum was obtained through the first Fourier transform, then got the correlation peaks through the second Fourier transform. The power spectrum of the joint transform correlator was recorded by the Charge Coupled Device (CCD) matrix camera. The contrast of the power spectrum was relatively lower, so some important information, such as the Young's interference fringes, were displayed very fuzzy, even couldn't see in some images, the output correlation peaks were seriously affected. For enhancing the power spectrum's contrast, the power spectrum may be filtered with the high-boost filtering. By filtering, the contrast of the Young's interference fringes was greatly improved and displayed relatively clear, so the contrast of the correlation peaks were greatly enhanced, the recognition ratio of the target detection and recognition by the joint transform correlator was increased. As the experiment examples, the target recognition of a car and a warship in cluttered scenes were presented. The experiments showed that the contrast of the Young's interference fringes was improved after the joint transform power spectrum was processed by the high-boost filtering. At the same time, the output correlation peaks were obviously enhanced too. So the high-boost filtering was very effective method for filtering in the joint transform power spectrum.

Joint transform correlator is one of the most successful optical pattern recognizers which is composed of Ar⁺ laser, spatial filter, Fourier transform lenses, EALCD (electrically addressed liquid crystal displays) and CCD (Charge Coupled Device). It has many applications in industry and military. The bottle technologies are how to recognize the target in clutter scene and how to increase the brightness of the correlation peak which represents the detected target. In this paper, we researched joint transform correlator (JTC) for infrared target detection, and used wavelet transform technology to increase the contrast of input image which contains target and reference objects, reduced the high frequency noise and realized target detection in clutter scene. According to our requirement, we selected the two-order spline wavelet, and made input image have discrete binary wavelet transformed. Because edge always contains much information of image, we adopted the method of modular maximum to extract the edge of different scales after wavelet transform mentioned above. In addition, combined with threshold division which could eliminate some of the clutter, we could get the remarkable edge. As experiment result, we detected the infrared image, both with computer correlation matched method and optical JTC method. The experiments show that the wavelet transform technology is one of the best data processing methods for the target detection in clutter background.

A new technique for recording hologram is proposed. The recording system looks like in-line holography, while the recording results are the off-axis holograms. The reference beam comes from the object wave itself, therefore the hologram is named self reference hologram. The principle is discussed briefly and demonstrated experimentally.

In this paper, we used hybrid optoelectronic joint transform correlator (HOJTC) for recognition of moving target. HOJTC is one of the most successful optical pattern recognizer which is composed of laser, spatial filter, Fourier transform lenses, EALCD (electrically addressed liquid crystal displays) and CCD (Charge Coupled Device). It has many applications in the fields of industry and military affairs. The speed of armored vehicle is generally less than 80 km/h. CCD used as receiver can capture 25 frames per second. The difference caused by shape, scale and rotation always exists between template and target. Therefore, the optical correlator can only detect captured moving target about 3 to 5 serial frames. For some targets in cluttered scene, it even can not recognize the target, which means the tracked target is missing. It shows the influence of clutter and distortion brings great difficulty to correlation recognition. In order to realize scale invariable and rotation invariable, the method of adaptive threshold is applied. After processing the images of moving targets, we can reduce the influence of cluttered background. The effect brought by the changes of shape, scale and rotation is also reduced. Consequently, the ability of automatic recognition, location and tracking of moving target by HOJTC can be enhanced greatly. The experiments are performed to recognize moving tanks with high speed about 70 km/h. The experiments show that more than 80 serial frames can be recognized after target images are processed. The joint transform correlator can recognize even more than 150 frames when the target is in relative clean scene. It has great meaning for target detection and tracking. The conclusion can be drawn that the proposed method of adaptive threshold for moving target is feasible, and it could effectively enhance the ability of automatic recognition and tracking of a moving target.

Transmittance property of the metal film with periodic T-shape structure in the near infrared region has been investigated by using the two-dimensional Finite-Difference Time-Domain (FDTD) method. The T-shape means that the slits' width of the upper section is larger than the lower part in a cell. All slits are narrower than the illuminating wavelengths. The electromagnetic transmission peak waggles with wavelength increasing while augmenting the deepness of the upper section and fixing the total height of the grating film. The wider upper sub-wavelength slit displays larger waggle extent in the transmission spectrum. The sub-wavelength slits works as waveguide and effective indexes of the waveguide varied with the width of slits. The upper and lower sub-wavelength slits show different effective indexes due to they have different widths. Changing the deepness will adjust the length of the resonance cavity. The transmission spectrum waggles while deepening the upper slits, which is visible in Fabry-Perot resonance. The field distribution of the light with peak transmission in and near a cell of the grating testifies the Fabry-Perot effect. An analytical equation is also provided to approximately locate the transmission peaks. The T-shape structure in a cell of metal grating supplies a new way to modulate the transmission spectrum.

The photonic crystal combining with two single negative dispersive materials (one is negative permittivity and positive permeability, the other is negative permeability and positive permittivity) is considered and it's dispersive and transmission properties are studied theoretically. We show that this structure can possess a new type of photonic bandgap at the frequencies where the materials electric permittivity or magnetic permeability is zero. With the different ways of traditional Bragg bandgap and zero equivalent refractive index bandgap, the new bandgap decided by the dispersive characteristics of the materials, and this band gap distinguished itself from above two bandgaps in that it is sensitive to polarization mode of incidence wave and is scale-length invariant and robust against disorder. The difference of these bandgaps and the use of SNG dispersive material in gradual periodic photonic crystal are discussed.

The hexagonal superlattice pattern is obtained in a dielectric barrier discharge at atmosphere pressure by using a discharge device with two water electrodes. It is found that the formation of the hexagon superlattice pattern depends on the mixture gas of air and argon. The bifurcation scenarios of the discharge pattern as the applied voltage increasing at different air-concentration are obtained. The results show that the hexagon superlattice pattern bifurcates from the dot-line pattern as the applied voltage increasing. A phase diagram of the pattern types as a function of gas component and applied voltage is presented. It reveals that the applied voltage for pattern formation increases with the air-concentration increasing.

Good resource allocation strategy is able to alleviate the resource contention. Deflection routing is one of contention resolution optical burst switching networks of good connectivity. But the offset time maybe not enough for reserve resource if deflection routing adopted. Too much deflection adopted will deteriorate the network performance. Another issue is how to determine if a contending burst will be deflected or discarded. In this paper, little Fiber Delay Lines (FDL) is used to assure the offset time will be compensated in time, and an optimum scheme is proposed from three aspects as if the network situation permits deflection, if contending burst is worthy to be hold continuously and the impaction of alternative route on deflection. Numerical results show that our optimized deflection scheme can achieve not only preferred deflection, but also to keep wavelength link from overloading. It balances the network load and stabilizes the network performance some degree.

An implementation of orthogonal frequency division multiplexing (OFDM) multimode fiber communication system test bed developed in simulink is proposed in this paper. The system design and implementation is discussed. Based on the simulation system, the effect of different fiber lengths, various numbers of the OFDM subcarriers and transmission data rates on this system has been considered. The simulation results show that with the increase of fiber lengths, the systems bit error rate (BER) increase as follow. In addition, even though using a large number of subcarriers can reduce the amplitude variation cause by the magnitude response of the multimode fiber since the bit rate per subcarrier signal is small, the BER from the system with large number of subcarriers is not always better than the BER from the system with small number of subcarriers. The simulation system test bed is useful to make the following studies more convenient, and also is helpful to establish a practical system.

In the optical fiber communication system, optic passive components such as the optical coupler and acousto-optic modulator have polarization depending on loss (PDL) and polarization depending on gain (PDG). The polarizer can change the light of polarization to unpolarized light, so the apparatus and system dependence of polarization could be reduce. Base on the principle of the Lyot depolarizer, we verified the physics process of Lyot depolarizer and depolarize with improvement by matrix optics and theory of polarizer. Mathematics calculation with computer is used, and this paper provides the curves between residual polarization and crystal wedge. Different polarized states of incident light are obtained. Meanwhile, the results of model are analyzed. The error in produce processing is considered and calculated first time, which is influence the depolarization performance of depolarize. Based on simulate calculate and results, the configure parameters and tolerance design method of an improved Lyot depolarize are also establish.