Design and analysis of novel multimode optical filters indielectric waveguide

A new multimode filter design for wavelength multiplexing/demultiplexing applications is investigated. An asymmetric bend generates a number of higher-order modes with appropriate amplitudes from a single-mode incident wave containing two wavelengths. These modes, after travelling along a straight section of multimode waveguide, are recombined in the output Y-branch in such a way that the optical signals at two wavelengths are split and redirected toward different output branches. The structure is analyzed by a combination of finite-difference/time-domain (FD/TD) procedure and a recently developed physical optics method. Numerical results on a sample structure are presented and issues related to the accuracy of results are addressed     

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     

An optical tap based on the twin waveguide laser-amplifier withasymmetric flared output waveguides

An optical tap based on the twin waveguide laser-amplifier with asymmetric flared output waveguides is presented. The new optical tap exhibits gain, allows the tap channel gain to be electrically controlled over a dynamic range of 30 dB, without greatly affecting the through channel gain and is optically broadband. The general features of the optical tap can be understood from coupled mode theory     

Dispersion compensation by optical phase conjugation in silicon waveguide

The use of a silicon-waveguide-based optical phase conjugator at the mid-span of a fibre link for dispersion compensation is experimentally demonstrated, enabling transmission of optical data at up to 40 Gbit/s over 320 km of standard fibre with clear open eye diagrams at the receiver. In addition, the feasibility of dispersion compensation for multiple DWDM channels simultaneously is demostrated. A signal conversion efficiency of -10 dB is obtained with a pump intensity of 37.5 MW/cm² in the waveguide.     

Design and analysis of coplanar waveguide optical modulator using finite element method

An analysis is given on the finite element method (FEM) for calculating the various parameters of optical modulators and a computer program is written to solve the finite element equation. Based on this method, a Mach-Zehnder type electro-optic modulator with coplanar waveguide (CPW) electrode is designed and fabricated. When compared with the Fourier series method, small differences on the 3-dB bandwidth, characteristic impedance and half-wave voltage, etc. are obtained.     

Design of finite-length metal-clad optical waveguide polarizer

The performance of optical metal-clad waveguide polarizers is analyzed in this paper with a view to optimizing the extinction ratio, a condition for which power of the TM mode is completely attenuated is identified here. In general, such a condition corresponding to an infinitely high extinction ratio can be met for a wide range of buffer layer thicknesses by selection of metal film thickness and polarizer length. When a very thick (e.g., semi-infinitely thick) metal film is used, the aforementioned condition can be met with a properly chosen buffer layer thickness and polarizer length. The numerical results show that all the polarizers designed here for realization of infinitely high extinction ratios have either quite low or reasonably acceptable attenuations for the TE mode     

线性损耗和双光子吸收下硅基波导调制不稳定性

为了分析线性损耗和双光子吸收对硅基波导调制不稳定性的影响,采用理论论证和数值模拟相结合的研究方法,推导了调制不稳定性增益谱、峰值增益、峰值增益频率和调制带宽的表达式。论证了波导的线性损耗、双光子吸收系数和脉冲光功率等参量对调制不稳定性的影响,并对给定结构参量的脊波导进行了仿真分析。结果表明,即使在微弱的光功率(几十毫瓦)下,在反常色散区仍然存在强烈的调制不稳定性现象,其增益是相同功率下光纤介质的102～102倍;峰值增益频率和增益带宽随波导的线性损耗指数衰减;峰值增益也随双光子吸收系数指数减少。这为硅基波导调制不稳定性实验研究和超连续谱产生提供了理论参考。     

Measurement of optical nonlinearity in silicon rich nitride waveguide ring resonators

The optical nonlinearities of amorphous silicon rich nitride corresponding to /spl chi//sup (3)/ in a static electric field have been measured by tracking wavelength shifts in the resonances of optical waveguide ring resonators as a function of an applied electrical field. The magnitude of the nonlinearity measured agrees well with expected values.     

Imaging of modes in a silicon nitride optical waveguide byphotoelectron microscopy

Modes in a tapered rectangular silicon nitride optical waveguide on silicon were viewed using high-magnification photoelectron microscopy. A thin cesium antimonide photocathode film was deposited on the guide, with laser illumination introduced through an optical fiber attached to the substrate edge. Although elaborate preparation of the sample and chamber for ultrahigh-vacuum is not necessary, high-resolution images were obtained; hence, this method is suitable for practical application     

Silica-based optical waveguide on terraced silicon substrate as hybrid integration platform

A silica-based optical waveguide on a silicon substrate with terrace regions is proposed. Because the substrate is equipped with a low-loss waveguide and an optical bench at the same time, it is applicable to a hybrid integration platform.<>     

面向SOI波导-单模光纤耦合的硅微透镜设计

硅光集成的优势在高速光电子领域不断凸显,被广泛应用于各种通信场景中。在硅基集成技术发展过程中,其面临的一个典型技术难点是硅波导与单模光纤的耦合。本文设计了波导边缘集成的硅微透镜结构,经BPM法(Beam Propagation Method)计算验证该结构可实现3μm厚SOI波导与纤芯直径86μm单模光纤90的近场耦合效率,具备高集成度、高耦合效率、多场景适用等优点。     

Design and fabrication of low-loss polymer waveguide components for on-chip optical interconnection

This paper reports the fabrication and characterization of straight and curved polyimide waveguides for on-chip optical signal distribution in GaAs-based optoelectronic integrated circuits. Polyimide ridge waveguides with propagation losses (at 830 nm) as low as 0.6 dB/cm have been fabricated. S-bends and splitters with low curvature losses and good splitting ratios have also been successfully fabricated and tested. The effects of the material properties and radius of curvature on the optical losses are presented, and the advantages of this polymer technology are discussed.     

Integrated optical detector array, waveguide, and modulator based on silicon technology

An integrated optical (IO) hybrid circuit consisting of a photodetector array, waveguide, and acousto-optic modulator on a common silicon substrate has been fabricated. This IO hybrid circuit is a major step in the development of a combination optical-electronic processing system. In this device an array of p-n junction photodiodes was fabricated on a 2-in silicon wafer and a 7059 glass waveguide film sputtered over an SiO/SUB 2/ insulating layer on the wafer. Another SiO/SUB 2/ layer was deposited under the transducer electrode. The transducer was a 40-MHz lithium niobate rotated Y-cut crystal. A prism was used to couple in the light beam from a 5 mW He-Ne laser. The guided light beam was directed at one of the diodes in the array and pulsed RF signals were applied to the transducer. Oscillator frequencies of 40 MHz and 120 MHz were separately applied. Modulation depths of greater than 25 percent were produced. The fabrication of the optical guide photodiode and electrical interconnections on a single silicon wafer utilized standard IC fabrication techniques.     

新型反谐振反射光波导传感器的研究

为了寻找到性能更好、灵敏度更高的光波导传感器,在传统反谐振反射光波导结构的基础之上,提出了一种新型反谐振反射光波导传感器,对其反射率和传输损耗进行了模拟,并计算了它的灵敏度.结果表明,与传统表面均匀传感型反谐振反射光波导传感器相比,新型传感器直接将待测的样品作为波导层并且采用了周期结构的反共振层,使大部分光束集中在样品中传播,从而降低了传输损耗,提高了传感器的灵敏度,为波导传感器的制作提供了一定的数值参考.     

Design, tolerance analysis, and fabrication of silicon oxynitridebased planar optical waveguides for communication devices

Planar optical waveguiding structures for application in communication networks are highly demanding with respect to low insertion loss, efficient fiber-to-chip coupling, polarization independent operation, high integration density, reliable fabrication, and last but not least cost efficiency. When applying silicon oxynitride, which is a very versatile material, planar waveguiding structures can be designed having the potential of meeting all those requirements. In this paper, we will describe the design of such a waveguiding structure, demonstrate the practical feasibility of realizing this structure and discuss the preliminary measurement results     

Design and analysis of miniaturized all-optical binary to gray code converter using Y-shaped plasmonic waveguide for optical processors

In this paper, an all-optical miniaturized binary to gray code converter is designed and analyzed. The all-optical domain is now an alternative for electronic devices, where performance and speed are the key issues. Code converters are significantly used in digital data transmission in the areas of error detection and correction. Gray code is one of the cyclic codes, where the cyclic shift of each codeword is also a code word. An all-optical XOR gate, realized using a Y-shaped power combiner is used in this design to generate the desired gray code from the given binary code. The insertion loss and extinction ratio parameters are found to be 0.347 dB and 22.26 dB, respectively. The entire simulation is carried out using finite-difference time-domain method. The obtained practical results are verified mathematically using MATLAB.

     

Hybrid integration of a laser diode and high-silica multimode optical channel waveguide on silicon

An InGaAsP laser diode with 1.34 ?m wavelength and a high-silica multimode optical waveguide were integrated on a common Si substrate using an alignment guide, which is formed simultaneously with the waveguide, for laser diode mounting. The laser-waveguide coupling efficiency was 30%.     

A field-based numerical method for three-dimensional analysis of optical waveguide discontinuities

A field-based numerical method for simulation of field scattering at discontinuities along three-dimensional optical waveguides of arbitrary index profiles is presented. Different from the previous work based on directly diagonalizing the characteristic matrices, we developed a robust and efficient iterative scheme by using an improved Neumann series. Superb performance of the scheme in terms of accuracy and efficiency is demonstrated and verified.     

Design of aplanatic waveguide Fresnel lenses and aberration-freeplanar optical systems

A modification of the waveguide Fresnel lens design that has phase-shifting zones placed on the curved contour is suggested. It is shown that the selection of a suitable shape for this contour allows coma aberration to be eliminated. Computer simulation results are presented to demonstrate the significant improvement of the optical characteristics for curved contour lenses. The aplanatic homogeneous refracting waveguide lenses are also considered. It is found that thick aplanatic refracting lenses and the proposed Fresnel lenses have field curvature aberration of opposite sign. This fact allows planar optical systems free from low-order aberration to be designed by combining refracting and Fresnel lenses. An algorithm for producing such a system is presented     

硅基二氧化硅单模单偏振光波导的设计

在不增加工艺难度的前提下,利用硅基二氧化硅光波导的双折射效应并结合有效折射率方法, 设计了一种新型单模单偏振波导, 使得两个正交偏振模式中的TM 模式被截止, TE 模式可以通过. 利用三维有限差分光束传输法(3D -BPM ) 进行数值模拟,结果显示,对于TM 模式消光比可高达到50dB 以上.此种结构的光波导可以直接制作偏振器, 同时还易与其他波导器件集成.