Single-mode optical Y-branching circuit using deposited silica guides (DS guides)

A new optical Y-branching circuit using embedded single-mode glass waveguides is presented. The glass waveguides were made by depositing core glass on a silica substrate after forming grooves to contain the core (DS guides). Waveguide transmission loss is 0.6 dB/cm. The loss caused at a branching point is 0.13 dB when the branching angle is 0.3°.     

Y branching silica waveguide 1*8 splitter module

Silica waveguide Y branching 1*8 splitters were fabricated and found to be highly reliable after housing. The silica waveguide has a splitting excess loss of 0.57 dB. The packaged device has a housing excess loss of 0.89 dB. The measured return loss was over 50 dB above room temperature. The loss deviation under heat cycle testing was 0.46 dB in the temperature range -20-+70 degrees C.<>     

Multimode Bragg diffractions in an ion-exchanged optical waveguide with a sputter-etched periodic surface corrugation

An optical diffraction phenomenon in an ion-exchanged planar optical waveguide with a sputter-etched periodic surface corrugation was experimentally investigated in detail. A single-mode incident beam simultaneously gave rise to several diffracted beams of different mode indices in different directions. This phenomenon was interpreted on the basis of the phase-matching diagram for the multimode Bragg diffraction by using measured wave vectors of the propagation modes and of the surface corrugation.     

A polymer optical waveguide with out-of-plane branching mirrors forsurface-normal optical interconnections

We have developed a simultaneous fabrication method using temperature control reactive ion etching (RIE) for channel optical waveguides incorporating plural out-of-plane branching mirrors made from polymer film. By using this method, the etching rate can be adjusted locally by controlling the temperature. This technology also enables the formation of trenches of various depths on the same polymer optical waveguide. We noted from scanning electron microscope (SEM) observations that simultaneous control of the mirror tilt angle and a smooth core surface could be achieved. To be specific, a heat treatment temperature of 130-135°C appears to be the optimum to maintain a rectangular cross section and to achieve a sufficiently smooth core surface for a polymethyl methacrylate (PMMA) waveguide. The measured propagation loss is small, in spite of the presence of a high-Δ waveguide (Δ=5.4%). For example, losses of 0.1, 0.3, and 0.7 dB/cm are measured at wavelengths of 650 nm, 850 nm, and 1.3 μm, respectively. From far-field pattern (FFP) measurements, we found that the mirror plane was almost rectilinear, and that the reflected light can be captured efficiently by a photodiode. In operational temperature tests, we showed that intensity fluctuations of the coupling light can be reduced to less than 1.5 dB for the temperature range between -25°C and +85°C by adopting a sandwich structure with glass plates     

Neodymium-doped silica optical waveguide laser on silicon substrate

A waveguide laser with a Nd-doped silica core fabricated on a Si substrate using flame hydrolysis deposition and reactive ion etching techniques is described The Nd ion concentration was about 2000 p.p.m. and the optical loss at 1.05 μm was 0.85 dB/cm. CW lasing at a wavelength of 1.0515 μm with a threshold of about 150 mW was achieved successfully with pumping at 0.80 μm     

Micro-optical waveguide on micro-actuating platform and its application in variable optical attenuator

We present a novel variable optical attenuator (VOA) using a new micro-optical waveguide (MOW) on micro-actuating platform (MAP) structure. The device consists of a fused biconical taper (FBT) coupler mounted on an electromechanical system where the axial stress over the waist of FBT coupler is precisely controlled. Its operation is based on change of coupling constant by compressive stress induced photoelastic effects on the waist zone. Three different types of devices operating near 1450 nm were fabricated with different cross-sectional morphologies at the FBT waists. The device with a circular cross section showed the highest stress sensitivity, where π phase shifts in the coupling constant were observed at an axial displacement of 9.5 μm. The proposed device showed a monotonic and continuous attenuation control up to 34.45 dB, with a very low PDL of 0.06 dB and a relatively low operating voltage of 15.3 V.     

Polysiloxane optical waveguide layer integrated in printed circuit board

A hybrid electrical-optical circuit board is demonstrated using polysiloxane as low-loss and high-temperature stable waveguide material system. After board lamination at 180/spl deg/C for two hours and a subsequent annealing at 230/spl deg/C for 5 minutes the waveguide insertion loss is 0.05 dB/cm at 850 nm wavelength.     

Fabrication of a high silica glass waveguide optical accessor

A four-port waveguide-type optical accessor, which is spliced with optical fibres by CO2, laser fusion, has been realised using high silica channel waveguides. The accessor shows excess loss of about 3 dB for both optical branching and mixing, together with low crosstalk of less than ?65dB.     

基于二氧化硅平面光波导的强度均衡的光脉冲对的产生

提出了一种基于平面光波导工艺的带有可调定向耦合器的非对称MZI结构.模拟结果显示,当定向耦合器的两个耦合臂的折射率独立改变时,定向耦合器的调制效果较好;当调制电极与耦合区的波导间距为0时,两个耦合臂的温度差达到最大.测试得到,AMZI的插入损耗为2.05 dB,延迟时间为151.4 ps,脉冲对的功率比近似为1.该器件有助于提高集成QKD器件的性能.     

Laser-diode pumping of waveguide laser based on Nd-doped silica planar lightwave circuit

The authors describes an improvement in the lasing threshold in Nd-doped silica planar-lightwave-circuit (PLC)-type lasers fabricated on Si substrates in which the scattering loss was reduced by an improved fabrication technique. Lasers with core widths from 6 to 30 mu m were fabricated by flame hydrolysis deposition and reactive ion etching techniques. Based on an investigation of the lasing threshold dependence on core width, a minimum lasing threshold was obtained in a waveguide laser with an 8 mu m wide core. A threshold of 25 mW and a slope efficiency of 1.2% for laser-diode pumping at 805 nm were obtained in the waveguide laser.<>     

Equivalent circuit model for a waveguide probe with application to DRA excitation

A simple equivalent circuit is used to model an arbitrarily loaded waveguide probe with emphasis on probe-excited dielectric resonator antennas. The values of the lumped inductance and capacitance are obtained via the method of moments analysis for the problem of a short-circuited probe acting as a waveguide scatterer. For problems involving the excitation of an external load, the aperture through which the probe extends to the load is modeled by a shunt capacitance, and an additional transformer is introduced to model the coupling to the load. Expressions for these circuit parameters are obtained using curve-fitting techniques and are employed to determine the lengths and positions of an array of waveguide probes used to feed external loads with feeding currents of desired relative values. The procedure is applied to synthesize waveguide-fed antenna arrays to achieve a specified radiation pattern. The scanning capabilities and the effect of the mutual coupling are studied by comparing radiation patterns obtained from the analysis of the whole array and from the pattern multiplication principle.     

溶胶—凝胶法制备PZT薄膜的结构和波导特性

采用溶胶－凝胶方法制备了ＰＺＴ（５０／５０）薄膜，用椭偏仪和透射光谱分别测量并计算了年鉴备在Ｓｉ（１１１）、石英玻璃基片上薄膜的折射率、研究了薄膜的相结构与折射率之间的关系以及折射率和消光系数的色散关系。用棱镜耦合的方法测量了薄膜的波导损耗，并给出了波导损耗与工艺过程的关系。     

保偏SiO_2光波导环形谐振腔温度特性研究

利用低压化学气相淀积(LPCVD)技术研制了Si基SiO2保偏光波导环形谐振腔,通过测试不同温度下的谐振曲线,得到了谐振腔双折射率差温度系数,进而利用琼斯矩阵法建立了谐振腔温度特性分析模型,分析了温度波动对谐振腔两个偏振态输出谐振曲线的影响。分析表明,研制的Si基SiO2保偏光波导环形谐振腔芯片具有较好的温度特性,能在较大温度范围内避免温度波动带来的两个偏振态谐振谷的重叠现象。     

Single-mode 1×3 integrated optical branching circuit designusing phase-front accelerators

Proposes a novel design for symmetric single-mode 1×3 integrated optical branching circuits as optical power dividers using relatively low-index phase-front accelerator regions in the Y-branch structures. By varying the location and the area of such regions, an equally distributed power can be obtained at the three output ports     

Computer-aided design of an axially symmetrical magnetic circuit and its application to electron-beam-focusing devices

This paper presents a method of computer simulation useful for analysis of an axially symmetrical magnetic circuit with exciting coils, magnetic poles, and permanent magnets. The vector magnetic potential is obtained by the use of the well-known successive over-relaxation method, so that devices having magnetic hysteresis characteristics can be analyzed easily and accurately. In this program, the magnetization intensity distribution within the magnet is taken into account. The new computer programming system is applied to a magnetic shielding hollow sphere, a bar magnet, a ring magnet, and a periodic permanent-magnet structure for traveling-wave tubes, and the flux distribution for these magnetic circuits is shown. The results are seen to be in good agreement with theoretical and experimental values.     

低损耗太赫兹波导及其成像应用

高性能的太赫兹功能器件在太赫兹波的产生、传输及探测上都有着重要意义.报道了一种Kagome型低损耗太赫兹波导及其成像应用.首先根据反谐振波导理论设计了0. 1 THz处低损耗的太赫兹波导,其理论损耗低至0. 012 cm~(-1).然后使用3D打印技术制备波导实物,实验测得其损耗为0. 015 3 cm-1,波导末端光束发散角为6±0. 5°.最后基于该波导搭建了可重构太赫兹成像装置,分别实现了对隐藏刀片、矿石的反射和透射成像,在地下远距离勘探领域具有潜在的应用前景.     

4.65 Gbit/s optical four-bit pattern matching using silica-based waveguide circuit

An ultra-fast coherent optical pattern matching circuit fabricated with silica-based waveguides on a silicon substrate is presented. This circuit can detect any specified pattern in an ultra-fast optical signal sequence. Experimental four bit pattern matching is successfully demonstrated at a bit-rate of 4.65 Gbit/s.<>     

Genetic algorithm-based characterization of the optical properties of flame-hydrolysis deposited silica waveguides

Genetic algorithms have been demonstrated to be a robust method for the calculation of the refractive-index profile of annealed germanium-doped flame-hydrolysis deposited (FHD) silica layers using measurements of the effective refractive indexes of the different modes of propagation. A nonuniform refractive-index profile in depth was obtained, which agrees well with the germanium concentration and density profiles measured for the films.     

The branching nonhomogeneous Poisson process and its application to a replacement model

In studying and analysing the failure patterns of complex system, plausible stochastic models are needed to represent the sequence of events. A simple and frequently used model is derived by the assumption that the times-between-failures of a system are exponentially distributed and independent. Experience has shown, however, that successive times-between-failures are not exponentially distributed and not independent.These deviations are due to imperfect search of failed components. We constitute a plausible stochastic process which describes the sequence of events, and obtain the interval reliability and the expected number of failures.As an application of these results, we deal with the replacement model where a system undergoes minimal repair before time T and is replaced at time T. We discuss an optimum policy minimizing the total expected cost per unit time.