Based on optofluidics and the principle of total internal reflection, a 1×2 few-mode waveguide optical switch is proposed. The proposed few-mode optical switch has small volume, low insertion loss and simple structure. It can be directly connected with a few-mode fiber to reduce the coupling loss. The mode field distribution and transmission characteristics of the two-mode switch (LP01 and LP11) are discussed. After the optical switch structure parameters are optimized, the minimum insertion losses are respectively 0.54 dB and 0.42 dB at two output ports, and the crosstalks are respectively -20.4 dB and -48.0 dB. The transmission characteristics of the four-mode switch (LP01, LP11, LP02 and LP21) are also analyzed. The insertion losses of four-mode optical switch are less than 0.34 dB, and the crosstalks are less than -23.19 dB. Our work provides a new method for seeking high-performance, miniaturized and integrated fewmode optical switches.
Based on microfluidics and optical communication technology, an optofluidic switch is proposed, where the hot bubble driving technology is used. And switch-on or switch-off and the optical path switching are realized by a hot bubble in the microchannel. The growth and condensation of the gas bubble in the microchannel is controlled by temperature. The optical switch has the advantages of small volume, simple and compact structure, low driving voltage, low power consumption, no mechanical moving parts and easy operation. This paper introduces the structure, processing technology and working principle of this optical switch.
In this paper, a microfuidic Mach-Zehnder (M-Z) filter is proposed. It has the advantages of small size, simple structure, convenient manufacture and flexible adjustment. In the proposed filter, one arm of the M-Z Interferometer is the sensing arm and the other arm is the reference arm. The sensing arm has adjustable refractive index because the microchannel is filled with liquid which could be replaced. The reference arm is not contacted with the outside. The comb filter spectrum of the M-Z filter can be adjusted by changing the refractive index of liquid in the microchannel. This paper presents the structure, working principle and related theories of the microfluidic M-Z filter. The proposed M-Z filter can promote the application of microfluidics in the optical communication.
A temperature sensor with micro ring-assisted Mach-Zehnder filter is presented. It has a micron size. A micro-ring cavity is coupled in one of the arms of the Mach-Zehnder interferometer, in which some temperature-sensitive liquid is injected into the cavity by using the microfluidic technique. The temperature change can be detected by analyzing the output spectrum of the sensor. In order to achieve the good filtering performances, the arm-length difference of common MachZehnder filters is usually the order of millimeter. While the M-Z arm-length difference of the temperature sensor presented in this paper is only about 10um. The sensor has good filtering performances. Its extinction ratio is 10dB and the 3dB bandwidth is less than 1nm. In addition, the resolution of the temperature detection is 0.1°C. Moreover, the temperature detection range of the proposed sensor can be adjusted by changing the refractive index of liquid in the micro ring cavity.
As one of the core devices in all-optical networks, optical switches can convert optical signal physically and logically. Here a 2×2 microfluidic optical switch is proposed. It switches the optical path by ionic liquid and air in a microchannel, and uses the magnetohydrodynamics (MHD) microfluidic drive technology. The proposed optical switch possesses the merits of simple structure, easy operation and low actuation voltage. There are no movable mechanical parts in this optical switch, so its volume is small. The structure, working principle and related theory of the proposed optical switch are described in this paper. The conducted research can promote the application of microfluidics in the optical communication.
Here a refractometer with the liquid prism is proposed. It has a simple structure, low cost and a large measurable refractive index range. When the vertex angle of liquid prism is 30°, the measurable refractive index range is up to 1.00-3.86, while the common refractometers have only the measurable range of 1.30-1.70. The optical system of this refractometer is design, where the angle of field is 80° and the total length is 110mm. A linear array CCD is used as the image receiver. The design results show that MTF is 0.35 in the tangential surface and 0.55 in the sagittal surface at the Nyquist frequency of 70lp/mm and the full field. The MTF values of other fields are more than 0.6, and the maximum distortion is 0.37%.
The optical switch is the core component of all-optical communication networks. Optofluidics is the integration of optics and microfluidics (lab on the chip). Here, based on optofluidics and optical communication technology, a 2×2 optical switch structure is proposed. The proposed switch uses a micro droplet and a microfluidic drive technology based on the electrowetting on dielectric (EWOD) to realize the optical path conversion. The optical switch has a small volume, simple structure, low power loss. Meanwhile it has no movable micromechanical elements and is easy to be operated. Here the structure and working principle of the optical switch are introduced.
With the development of optical communication, the optical attenuator becomes an important passive device. It is widely used in power equalization of DWDM system and photo detectors. Here an optofluidic variable optical attenuator (VOA) based on magnetohydrodynamic drive is presented. This chip uses microfluid and compressible air to adjust optical attenuation, where the fluid-drive technology uses magnetohydrodynamic (MHD) drive. The driving pump consists of two electrodes and a permanent magnet (NdFeB) that under the microfluidic channel. Only several volts voltage is needed in operation. There are no movable mechanical parts in this variable optical attenuator, so its volume is small. This variable optical attenuator has a simple structure and a low voltage advantages, and it is easy to control and integrate. The proposed VOA gives a new method for looking for small, low voltage and adjustable VOAs.
A variable optical attenuator (VOA) based on S-shape polymer waveguide is demonstrated at the wavelength λ = 1.55 micron. The VOA consists of straight input and output waveguides, an S-shape waveguide and a pair of deposited electrodes. The cladding material of S waveguide is Poly (methyl methacrylate/disperse red 1) (PMMA/DR1) and the core material of S waveguide is SiON. The refractive index of the polymer cladding at S waveguide is modified by the applied electric voltage. Light scatters at the S waveguide and the VOA has large energy loss in the original state at voltage-off. In the voltage-on state, the refractive index of the polymer of the S waveguide reduces, and energy loss changes as the voltage increases. The attenuation of the VOA can be controled and adjusted by the applied voltage. The beam propagation method(BPM) and finite element analysis are employed to simulate and analyse the VOA. The results show that the VOA has large variable attenuation range of 45.2dB and low insertion loss of 0.8dB.
Liquid prism is a sort of prism composed of liquid. It can create adaptive systems by taking advantage of the
unique properties of liquids. The liquid prism can be applied in optical communication, biochemistry and medicine,
optical imaging system, etc.. Here the liquid prism is applied in refractometers to analyze the refractive index, density,
concentration and dispersion of liquid. Comparing with Abb refractometer, this refractometer uses a liquid prism instead
of several solid prisms, thus its weight and cost are reduced. In addition, the measuring range of the refractive index may
be 1.15~2 and excels Abb refractometer (n:1.33~1.70) to meet measurement of some new liquid materials such as ionic
liquids, liquid crystals, and so on. Moreover, it can avoid the measuring error resulting from liquid uniformly coating on
the prism and leaking light in Abbe refractometer. So it takes on broad market foreground.
Liquid prism is a sort of prism composed of liquid as the body. It can singly work or be integrated on the
optofluidic chip, which takes advantage of the unique properties of liquids to create adaptive systems. The optical
properties of the prism can be flexibly changed by filling liquid or not as well as by adjusting the concentration of liquid.
Taking advantage of this point, the liquid prism can be applied in optical communication, dye lasers, liquid analysis in
biochemistry and medicine fields, optical imaging system, optical measurements and optical experiments, etc.. The liquid
prism can serve as both the refraction prism and reflection prism in application. Here an optical switch based on the
liquid prism and two approaches to analyze liquid by the liquid prism are presented and the optical properties of
corresponding liquid prisms are discussed. Here the liquid prism is used to change light path in the optical switch or to
analyze the refractive index, density, concentration and dispersion of liquid.
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