This PDF file contains the front matter associated with SPIE Proceedings Volume 7990, including the Title Page, Copyright information, Table of Contents, and the Symposium and Conference Committees listings.

The non-invasiveness of autofluorescence technology may reduce sampling error and time delay for histopathology diagnosis. We establish biophotonic methods and guidelines to visualize and interpret early epithelial tissue changes that signify disease. Flexible and rigid fiber endomicroscopy instrumentation design parameters feasible for translation towards clinical use are in development.

A multi-longitudinal-mode fiber laser sensor is proposed and experimentally demonstrated base on beat frequency demodulation method. A novel laser cavity is formed by a FBG, a section of erbium-doped fiber and a broadband reflector. The proposed laser sensor has ultra-stable frequency information due to self-phase matching of FBG, and high signal to noise ratio.

A surface-enhanced Raman scattering (SERS) optical fiber sensor using biconical taper multi-mode fiber (MMF) is proposed. It is fabricated by fused elongating a multi-mode fiber and then coated the silver colloid on its waist. The main advantage of this sensor is that it can increase the SERS active substrate region to make more molecules be excited to produce Raman signal. Silver colloid is selected as the active substrate of SERS. A modified immobilizing process is introduced to increase the thickness of the immobilized layer and reduce the preparation time. Various concentration of R6G is used to detect the performance of the sensor. Strong Raman signal is detected from the waist of the tapered fiber. The detection sensitivity is up to 10^-9M.

A hybrid coupler composed of a slot plasmonic waveguide and a dielectric waveguide is proposed and its coupling characteristics are analyzed. The simulation results show that the ultra-small mode of the slot plasmonic waveguide can be excited efficiently by the dielectric waveguide mode within the coupling length of just several microns, which provides an interface between the slot plasmonic devices and dielectric devices. Meanwhile, based on this hybrid the coupler, a highly integrated refractive index sensor could be realized.

We present some novel periodic structures with different internal nanopatterns based on multi-exposure two-beam interference lithography. Two-dimensional quasi-crystal structures are fabricated with precisely control of exposure directions and doses as well as the total number of exposures. Experimental fabrication of microstructures are demonstrated and comparied with numerical simulations of intensity distributions. The size of the fabricated samples is around 1 square centimeter. The diffraction spectra of the fabricated samples are measured and tested. The experiment results show such a fabrication technology is very promising for making diverse large-area microstructures with complex internal nanopatterns.

A fiber sensor configuration suitable for simultaneous measurement of temperature and strain is investigated. The sensor consists of a high-birefringence fiber loop mirror concatenating with an erbium-doped fiber. The high-birefringence fiber used in the configuration is capsule shaped polarization maintaining fiber, which serves as the sensor element. While the erbium-doped fiber acts as the temperature compensation module. By monitoring the peak power variation and peak wavelength shift, it is feasible to simultaneously measure temperature and strain. The experimental results show that the mean square errors for temperature and stain are 0.35°C and 13.34με, respectively. The proposed sensor configuration shows several merits, including simple in structure, easy fabrication, low cost and high sensitivity.

A hollow-core Bragg fiber with the fundamental photonic crystal bandgap around 3000 cm^-1 was fabricated and injected with methane/nitrogen mixed gas with 0.5% methane concentration. A very sharp absorption line of methane gas around 3000 cm^-1 within the transmission band of hollow-core Bragg fiber was observed using the Fourier transform infrared spectroscopy, which demonstrated that hollow-core Bragg fiber can be used as a mid-infrared waveguide and minimized gas cell simultaneously, showing great potential in trace gas sensing.

'Liquid lens' technologies promise significant advancements in machine vision and optical communications systems. Adaptations for machine vision, human vision correction, and optical communications are used to exemplify the versatile nature of this technology. Utilization of liquid lens elements allows the cost effective implementation of optical velocity measurement. The project consists of a custom image processor, camera, and interface. The images are passed into customized pattern recognition and optical character recognition algorithms. A single camera would be used for both speed detection and object recognition.

A near-infrared Raman spectroscopy system integrated with multimodal endoscopic imaging has been developed for in vivo diagnosis and detection of gastric malignancies during clinical gastroscopic examinations. In this study, 1238 high-quality in vivo Raman spectra in the range 800-1800 cm^-1 were acquired from gastric normal and malignant tissue within 0.5 second from 81 patients under the guidance of white-light (WL), narrow-band (NB) and autofluorescence (AF) imaging during clinical endoscopy. Significant differences in Raman spectral shapes and intensities between normal and malignant gastric mucosal tissue were observed, particularly in the spectral ranges 800-900, 1000-1100, 1250-1450 and 1600-1800 cm^-1, which primarily contain signals related to proteins, nucleic acids and lipids. Partial least squares discriminant analysis (PLS-DA) could identify in vivo Raman spectra of neoplasia with a sensitivity of 82.9% and specificity of 88.9% using leave-one-tissue site out cross validation. This study demonstrates that in vivo Raman spectroscopy in conjunction with multimodal endoscopic imaging modalities holds a great promise for improving the early diagnosis of gastric malignancies.

Miniature spectrometers with desirable properties such as being small in size, light weight and non-fragile provide solutions to a variety of promising application. In this work, through the developed algorithms, a low-cost chip-scale spectrometer is demonstrated in particular for LED spectrum sensing, as the market of LED lights has been booming and low-cost solution for testing and monitoring LEDs spectral characteristics become essential. The developed algorithms are in two forms, namely algebraic approach and training approach. For the algebraic approach, non-negative least square method is reported useful for spectrum reconstruction of narrowband LED spectra. For the training approach, FWHM measurement and peak wavelength measurement, the two major parameters for specifying monotonic LED spectra, are reported with accuracy within 1nm.

Experimental studies on humidity measurements by using a FBG-based humidity sensor with multi-layer polyimide coating are demonstrated. As an important sensing application, the FBG humidity sensors have many unique advantages, such as immunity to electromagnetic interference and compact size, over the conventional electrical humidity sensor. In the detection principle, The Bragg wavelength of the FBG sensor shifts with the volume of the moisture absorbed by the polyimide film coated on the FBG. Experimental results show a good linear relationship between the shifts of the Bragg wavelength of FBG sensor and the changes in the relative humidity level. The preliminary experiments for investigating the performances of this polyimide-coating FBG humidity sensor were carried out and several experimental results in measurements of the relative humidity in air and moisture in oil are presented.

Temperature stability based on high Ge-doped fibre Bragg grating (FBG) is presented. A high Ge-doped photosensitive fibre (PSF) used for writing FBG was manufactured. Temperature characteristic of the FBG from 20 to 300°C had been researched. The transmission efficiency is about 75% at 300°C.

We suggested a laser inspection method of interference and diffraction for checking if any defect in a RF device such as SAW filter and delay line. The real time optical metrology that we proposed can provide a visualized positional vibration, unlike the electric method that is capable of checking only product defect. It can substitute a conventional test method of electrical with finding out where the vibration is weak or disturbed by other service frequency module. The measuring limits with a single-mode laser source are also given and what measuring conditions should be satisfied for detecting a fine displacement or vibration like propagation of a surface acoustic wave in RF device. The interference and diffraction due to RF signal are analyzed by an optical interpretation. In this paper, a single mode laser and a 105MHz-center- frequency repeater filter were employed for experiments and theoretical analysis. The optical metrology providing visual energy distribution and real time inspection for surface acoustic wave is proposed for development of high quality multi-service and multi-frequency RF module.

The thory of RFA with backward Raman pumping and forward Raman pumping is studied by numerical solution combinating interpolation method and Runge-Kutta method. Meanwhile, the most complete characterization and comparison of RFAs with backward Raman pumping or forward Raman pumping for pump power, initial signal power and fiber length is obtained. Through the analysis and comparison, the results show that high-gain amplifier transistor is obtained in backward pumping comparing with forward pumping. Keywords-SRS; FRA; Backward Raman pumping; Forward Raman pumping

A fiber-optic relative humidity sensor is demonstrated by using photonic crystal fiber as the sensing element which is tapered and filled with the moisture sensitive polymer. The theoretical results show the loss varies from 0.063dB/cm to 75.847dB/cm when the relative humidity changes from 0 to 95%RH.

Signal processing is studied for Sagnac fiber distributed sensors. Wavelet de-noising and wavelet decomposition are comparatively used to analyze signals in frequency domain to give smoothed frequency spectra, based on which null frequencies of the spectra are found more accurately. The analysis is helpful to more accurately locate the disturbance.

A novel structure of Micro-Optic-Electro-Mechanical-System (MOEMS) gyroscope was designed. Optical waveguide diffractive component, electro-optical modulator and Surface Acoustic Wave (SAW) sensor etc. were integrated on a XY LiNbO3 substrate. The obtained sensitivity was 12 uVdeg^-1s^-1 in the angular rate range of 0-400deg/s.

A measurement system of plane displacement in rigid body was designed. Plane displacement was calculated by the cross-correlation of speckle image. Measurement results showed that the absolute-error and the opposite-error of the plane displacement less than ±14μm and ±6.25% respectively, under the displacement range of 300μm.

A refractive index sensor based on adjusting gap fiber Bragg grating was designed. Spectral characteristics of gap FBG are analyzed based on the coupled-mode theory with the transfer matrix method. As the refractive index of the media in the gap increased, the peak wavelength has a red-shift. Through measuring the reflectivity of the side band, the refractive index of media in the gap can be obtained.

Polarization properties of gratings can be used to develop new types of fiber Bragg grating (FBG)-based sensors. In this paper, the evolutions of states of polarization (SOPs) of transmitted light in linear birefringence gratings are studied by implementing the Jones formalism and the coupled mode theory. The relationship between the first normalized stokes parameter and polarization dependent loss is discussed. The results show that the corresponding wavelengthes of PDL maximum amplitude are the same as that of the first normalized stokes parameter all the while. And both of these two parameters increase monotonously with birefringence thus can be used for sensor. The effects of transmitted length, linear birefringence value and incident SOPs on PDL, the first normalized stokes parameter and the polarization states are discussed. The results show that the SOPs of different wavelengths will spread gradually with the increasing grating lengths or birefringence values.

An innovative temperature-insensitive metal package for Fiber Bragg grating (FBG) was designed to compensate the effect of temperature. The wavelength shift of FBG was tested with the new package and without the package, respectively. In the range of -20°C~100°C, the temperature sensitivity of the FBG was 1.7 pm/°C with the new package and 10.7 pm/°C without the new package, respectively. It shows that the new package for FBG can eliminate the wavelength shift with the temperature change. So it is suitable to use the FBG with the new package as an optical filter.

Distributed optical fiber temperature sensor (DTS) for underground coal gasification (UCG) system using is studied in this paper. By measuring temperature of reacting mine gasification process can be controlled. Calibration of DTS and experiment result are introduced. The results show that, DTS can play an important role in UCG systems.

A novel SOA-based, dual-wavelength, FBG laser sensor system for simultaneously measuring vibration, temperature and humidity is demonstrated. The sensor interrogations are completed with a wavelength matching method by adjusting temperatures of two TECs to control wavelengths of two reference FBGs matching with those of two sensor FBGs. Two corresponding TEC control signals are used as detection outputs for temperature and humidity measurements. Some experimental results on simultaneous measurements of vibration, temperature of the sensor system with a FBG vibration/temperature senor and a 10-layer polyimide coating FBG humidity sensor are presented. The fundamental system performances in respects of the frequency response of system in vibration measurements and the tracing of the Bragg wavelength of sensor FBG through a TEC temperature control method were also demonstrated. The experimental results verified that the proposed FBG laser sensor system has a desired detection performance. This sensor system can be used in many industrial measurement fields, particularly in the electrical power industry for condition monitoring of power generators as well as high-voltage power transformers.

A fiber-optic intrinsic Fabry-Perot (F-P) interferometric sensor was inscribed in a standard single mode fiber by inducing refractive index change in the core. It was written directly by using a femtosecond laser. The reflection spectrum of the fiber-optic F-P interferometric sensor was measured and was investigated as a temperature sensor. The sensitivity of the sensor is 9.2 pm/°C in the temperature range of -20~80°C.

We report an experimental study of a SMS fiber sensor for simultaneously measuring both displacement and temperature. By measuring both central wavelength spectral shifts and peak power variations, displacement and temperature can be independently determined with a demonstrated sensitivity to displacement of 0.62 μm and a temperature sensitivity of 1 °C by using a typical OSA which has a wavelength resolution of 10 pm and power measurement resolution of 0.01 dB.

A fiber-optic temperature sensor was fabricated and studied by using a tapered optical fiber which is coated with a quantum dots (QDs) doped sol-gel thin films. The CdSe/ZnS core-shell nanocrystals were trapped into sol-gel and coated on a tapered optical fiber. The dependence of photoluminescence (PL) spectrum on temperature change was studied. The sensor response is linear and repeatable to the temperature change.

An optical fiber curvature sensor is fabricated by using a short section of polarization maintaining fiber (PMF) as the sensing component spliced in an optical fiber Sagnac loop. The length of the sensing element for the curvature sensing is about 142 mm. The sensitivity of the curvature measurement of 0.0344 m^-1/pm is achieved experimentally. The propose sensor is more convenient and simply than that of photonic crystal fiber (PCF).

A microstructured fiber based surface plasmon sensor with a high sensitivity of 2.4×10^-6 was proposed using an central analyte-filled channel in the core region. Through the analyte modulation, the variation trend of the resonance loss with the analyte refractive index was demonstrated to be contrary to that of the sensitivity. In this way significantly enhancement in the detection accurary can be achieved. The resolution of the sensor was also improved by properly choosing the size of the central hole. With analyte infiltration into the core, the calibration curve of the sensor can be effectively linearized, partially alleviating the difficulty in data processing.

By employing the enhanced phase transfer of single microring resonator, the enhanced intensity sensing is obtained based on the dual microring resonator with coupled mode theory. The two times higher sensitivity than the conventional microring sensor is demonstrated based on the FDTD simulation.

A Mach-Zehnder interferometer-coupled microring is experimentally demonstrated for optical sensing with a high sensitivity (~111 nm /RIU), a high extinction ratio (>26dB), and a very large quasi free-spectral-range (>100 nm), which helps to obtain a large measurement range. The MZI-coupled microring sensor still has good performance when the reflective index of the ambient materials largely changes (1<n<1.538).

Imagistic investigation of the metal-ceramic crowns and fixed partial prostheses represent a very important issue in nowadays dentistry. At this time, in dental office, it is difficult or even impossible to evaluate a metal ceramic crown or bridge before setting it in the oral cavity. The possibilities of ceramic fractures are due to small fracture lines or material defects inside the esthetic layers. Material and methods: In this study 25 metal ceramic crowns and fixed partial prostheses were investigated by radiographic method (Rx), micro computer tomography (MicroCT) and optical coherence tomography (OCT) working in Time Domain, at 1300 nm. The OCT system contains two interferometers and one scanner. For each incident analysis a stuck made of 100 slices was obtain. These slices were used in order to obtain a 3D model of the ceramic interface. Results: RX and MicroCT are very powerful instruments that provide a good characterization of the dental construct. It is important to observe the reflections due to the metal infrastructure that could affect the evaluation of the metal ceramic crowns and bridges. The OCT investigations could complete the imagistic evaluation of the dental construct by offering important information when it is need it.

In this paper, we will introduce the research on sensor design for IOT (Internet of Things) and laser manufacturing, and supporting the establishment of local area IOT. The main contents include studying on the structure designing of silicon micro tilt sensor, data acquisition and processing, addressing implanted and building Local Area IOT with wireless sensor network technology. At last, it is discussed the status and trends of the Internet of Things from the promoters, watchers, pessimists and doers.

The objectives of this study are focused on non-invasive investigations of interfaces obtained after repairing metal-ceramic crowns with ceramic repair systems. The noninvasive systems involved in this study are OCT, SEM, AFM and RX. These investigation systems are non-invasive and the samples are not destructed during the investigation.

PURPOSE: The goal of our study was to investigate the changes in enamel surface roughess induced by the application of different chemical substances by atomic force microscopy and scanning electron microscopy. METHOD: Five sound human first upper premolar teeth were chosen for the study. The buccal surface of each tooth was treated with a different chemical agent as follows: Sample 1 - 38% phosphoric acid etching (30s) , sample 2 - no surface treatment (control sample), 3 - bleaching with 37.5 % hydrogen peroxide (according to the manufacturer's instructions), 4 - conditioning with a self-etching primer (15 s), 5 - 9.6 % hydrofluoric acid etching (30s). All samples were investigated by atomic force microscopy in a non-contact mode and by scanning electron microscopy. Several images were obtained for each sample, showing evident differences regarding enamel surface morphology. The mean surface roughness and the mean square roughness were calculated and compared. RESULTS: All chemical substances led to an increased surface roughness. Phosphoric acid led to the highest roughness while the control sample showed the lowest. Hydrofluoric acid also led to an increase in surface roughness but its effects have yet to be investigated due to its potential toxicity. CONCLUSIONS: By treating the human enamel with the above mentioned chemical compounds a negative microretentive surface is obtained, with a morphology depending on the applied substance.