有机聚合物光波导的研制

聚合物光电子器件是目前世界范围的一个研究热点,其本身所具有易于集成、响应快速、成本低廉一系列优点,在光通信方面有广泛的和极具吸引力的应用前景。介绍了制作有机聚合物光波导的工艺流程,并用两种方法制备出有机聚合物光波导。这对后续研究有很大的帮助。     

Optical Signal Processor Using Electro-Optic Polymer Waveguides

We have investigated an optical signal processor using electro-optic polymer waveguides operating at a wavelength of 1.55 $mu$m. Due to recent developments, many useful optical devices have become available such as optical filters, modulators, switches, and multiplexers. It will be useful to have a single optical device, which is reconfigurable to implement all of these functions. We call such a device an “optical signal processor,” which will play a similar role to digital signal processors in electrical circuits. We realize such an optical device in a planar lightwave circuit. Since the planar lightwave circuits are based on the multiple interference of coherent light and can be integrated with significant complexity, they have been implemented for various purposes of optical processing such as optical filters. However, their guiding waveguides are mostly passive, and the only viable mechanism to reconfigure their functions is thermal effects, which is slow and cannot be used for high-speed applications such as optical modulators or optical packet switches. On the other hand, electro-optic polymer has a very high electro-optic coefficient and a good velocity match between electrical and optical signals, thus, permitting the creation of high-speed optical devices with high efficiency. Therefore, we have implemented a planar lightwave circuit using the electro-optic polymer waveguides. As a result, the structure is complex enough to generate arbitrary functions and fast enough to obtain high data rates. Using the optical signal processor, we investigate interesting applications including arbitrary waveform generators.      

Stress-Induced Birefringence Characteristics of Polymer Optical Rib Waveguides

We report the detailed numerical investigation of stress-induced material birefringence in polymer rib waveguide for the design of nonbirefringent waveguide devices. To accurately simulate the stress-induced effects we propose a more realistic model in the finite element analysis which considers the stresses induced over the entire sequential fabrication process. It is observed that the birefringence is nonuniform, and it is different for different etch depth and core width. The maximum birefringence in the core layer is observed near the lower cladding which decreases to zero toward the top surface. The influence of this material anisotropy on the modal birefringence is analyzed also for different rib structures. We found the stress effects on the modal birefringence to be largely affected by etch depth, while core width has small effect. It is also found that the deeply etched core has better birefringence stability. Finally, an accurate design of the zero-birefringence waveguide is illustrated by taking the stress effects into account, and the results are compared with experimental data. Excellent agreement between calculated and experimental results confirms the potential application of this work to aid in the design of polarization-insensitive waveguide devices.     

Loss Measurements on Polymer Thin Film Optical Waveguides

Asimple setup for the measurement of transmission loss in polymer thin film optical waveguides is described.A new electro-optic polymer film has been prepared.The transmission loss of the film is measured before and after corona poling.And the loss is determined to be 1.84 dB/cm and 2.14dB/cm, respectively.     

Cost-Effective Multimode Polymer Waveguides for High-Speed On-Board Optical Interconnects

Cost-effective multimode polymer waveguides, suitable for use in high-speed on-board optical interconnections, are presented. The fundamental light transmission properties of the fabricated waveguides are studied under different launch conditions and in the presence of input misalignments. Low loss ($sim$0.04 dB/cm at 850 nm) and low crosstalk $(≪-{hbox {30 dB}})$ performance, relaxed alignment tolerances $(pm hbox{20} mu{hbox {m}})$ and high-speed operation at a 10-Gb/s data rate are achieved. No degradation in the high-speed link performance is observed when offset input launches are employed. Moreover, a range of useful waveguide components that add functionality and enable complex on-board topologies are presented. The optical transmission characteristics of the fabricated components are investigated and it is shown that excellent performance is achieved. Excess losses as low as 0.01 dB per waveguide crossing, the lowest reported value for such components, and bending losses below 1 dB for 90-degree and S-shaped bends are obtained even with multimode fiber launches. Moreover, high-uniformity power splitting and low-loss signal combining are achieved with Y-shaped splitter/combiners while a variable splitting ratio between 30%–75% is demonstrated with the use of multimode couplers. Overall, the devices presented are attractive potential candidates for use in on-board optical links.      

面向光背板应用的低损耗单模聚合物光波导技术研究

系统地开展了基于光刻及湿法显影工艺制备的聚合物光波导散射损耗的理论及实验研究。研究了包括粗糙度、波导尺寸和工作波长等主要参数对散射损耗的影响,采用激光共聚焦显微镜测量了光波导侧壁及上下表面的粗糙度。实验结果表明,波导侧壁的平均粗糙度约为60nm,是上下表面粗糙度的3倍。因此,散射损耗主要由侧壁粗糙引起,其大小是上下表面粗糙引入散射损耗的9倍。基于上述理论及实验结果,通过优化波导设计,制备了工作于1310nm波长、平均损耗为0.35dB/cm的低损耗单模聚合物光波导,其作为高速高密度光背板的关键传输介质具有良好的应用前景。     

Thermal Modeling of Terahertz Quantum-Cascade Lasers: Comparison of Optical Waveguides

We compare a set of experimental lattice temperature profiles measured in a surface-emitting terahertz (THz) quantum-cascade laser (QCL) with the results of a 2-D anisotropic heat diffusion model. We evaluate the temperature dependence of the cross-plane thermal conductivity (kappa_perp) of the active region which is known to be strongly anisotropic due to its superlattice-like nature. Knowledge of kappa_perp and its temperature dependence is crucial in order to improve the temperature performance of THz QCLs and this has been used to investigate the longitudinal lattice temperature distribution of the active region and to compare the thermal properties of metal-metal and semi-insulating surface-plasmon THz optical waveguides using a 3-D anisotropic heat diffusion model.     

硅基SiO2光波导

在硅基上通过氢氧焰淀积的SiO2,厚度达到了20μm;通过掺Ge增加芯层的折射率,折射率比小于1%,并可调;用反应离子刻蚀工艺对波导的芯层进行刻蚀,刻蚀深度为6μm,刻蚀深宽比大于10;波导传输损耗小于0.6dB/cm(λ=1.55μm),并对波导的损耗机理和测试进行了分析与研究.另外,为实现光纤与波导的耦合,结合微电子机械系统技术,在波导基片上制作了光纤对准V形槽.     

Optical Pressure Sensors Based on Vertical Directional Coupling With Flexible Polymer Waveguides

An optical pressure sensor based on the radiation coupling in vertical direction between a channel waveguide and a flexible polymer waveguide is proposed. The flexible waveguide is bent by an applied pressure to reduce the separation distance between the two waveguides so that the light propagating in the channel waveguide is radiated into the flexible planar waveguide. By applying a pressure ranging from 100 to 500 kPa, the output intensity modulation of 20 dB is obtained by virtue of the efficient phase matched coupling between the waveguides made of the same polymer material. The large extinction ratio is useful to measure the pressure precisely for a wide range.      

硅基SiO_2光波导

在硅基上通过氢氧焰淀积的 Si O2 ,厚度达到了 2 0 μm;通过掺 Ge增加芯层的折射率 ,折射率比小于 1% ,并可调 ;用反应离子刻蚀工艺对波导的芯层进行刻蚀 ,刻蚀深度为 6 μm,刻蚀深宽比大于 10 ;波导传输损耗小于0 .6 d B/ cm(λ=1.5 5 μm) ,并对波导的损耗机理和测试进行了分析与研究 .另外 ,为实现光纤与波导的耦合 ,结合微电子机械系统技术 ,在波导基片上制作了光纤对准 V形槽     

Design and Fabrication of Monolithic Distributed Traveling-Wave Photodetectors Integrated With Polymer Optical Waveguides

We have designed and fabricated monolithic distributed balanced traveling-wave metal-semiconductor-metal photodetectors (MSM PDs) distributed along single-mode polymer optical waveguides. We demonstrate that monolithically integrated polymer optical waveguides on a semiconductor can provide efficient optical interconnects in an optoelectronic circuit. A responsivity of 0.44 A/W and a 3-dB bandwidth of 10 GHz were obtained in a PD array with five MSM PDs. A high photocurrent of 7.3 mA was measured in an array having eight MSM PDs. Impulse response measurements were performed and the results were compared with frequency domain results.     

Acoustic Surface Waveguides and Comparisons with Optical Waveguides

An overview is presented first of the various types of waveguides for acoustic surface waves which have been studied theoretically and experimentally. Many of these waveguides resemble certain waveguiding structures proposed recently for use in integrated and fiber optics. The similarities and differences between corresponding waveguiding structures in the two different fields are then discussed from the standpoints of their properties and their mechanisms of operation.     

Microwave Modeling of Optical Periodic Waveguides

A design procedure and experimental method is presented for modeling optical periodic waveguides by means of more convenient parallel plate microwave configurations. These models are suitable for verifying the beam-coupling properties of dielectric gratings that operate in the fundamental TE/sub 0/ surface-wave mode. In particular, blazed gratings with high coupling efficiencies have been constructed and their characteristics have been measured. The results have shown that previously developed design criteria, which are based on a simple Bragg-scattering approach, can yield highly efficient broad-band beam couplers that are not subject to critical fabrication tolerances.     

Finite Element Analysis Waveguides of Optical

A finite element program for the analysis of anisotropic optical waveguides is described. The appearance of spurious numerical modes, due to the fact that the functional is nonpositive definite is discussed and a possible solution to the problem is presented. For isotropic waveguides it is shown that both EH- and HE-type modes can be very accurately approximated by two different scalar finite element programs. Finally, a method for calculating the attenuation of leaky modes in a single material integrated optic waveguide using this scalar finite element method is proposed.     

Radiation Fields of Optical Stripline Waveguides

Dispersion characteristics and radiation fields of an optical stripline waveguide radiating into free space are calculated. The waveguides are fabricated as multiple layers of differing dielectric materials. A top layer is etched to form a "cap" with an effective waveguide in a layer below the cap. Confinement of the fields to the waveguide is obtained in the vertical direction by dielectric discontinuities, while lateral confinement occurs because of spatial interference of a continuum of plane waves. The radiation field of the fundamental mode in a plane perpendicular to the waveguide layers is characterized by the layer widths and index discontinuities. Beamwidths of the fundamental mode in the plane parallel to the dielectric layers are developed in terms of the waveguide parameters. Values of these parameters which yield the best optical confinement under the stripe can be obtained.     

Insights Into Correlation Between Board-Level Drop Reliability and Package-Level Ball Impact Test Characteristics

The ball impact test (BIT) is developed based on the demand of a package-level measure for the board-level drop reliability of solder joints in the sense that it leads to fracturing of solder joints around the intermetallics, similar to that from a board-level drop test. In this paper, both board-level drop test and package-level ball impact test are examined numerically for solder joints of different Sn-Ag-Cu compositions. We propose a stress-based drop reliability index that involves the strength of intermetallics and the maximum interfacial normal stress the solder joints have experienced during the drop impact process. Correlations between the drop reliability index and BIT characteristics are found to be dependent on solder compositions. However, the correlations appear to be universal, i.e., independent of solder compositions, when certain constant multipliers are introduced     

MOS型波导光学特性分析

本文分析了MOS型波导中金属包层对波导光学特性的影响,给出了TE模传播常数和吸收损耗系数的近似计算公式.为了消除由金属包层引起的吸收损耗,结合计算实例讨论了氧化物缓冲层所需厚度的选择.     

Fabrication of DAST Channel Optical Waveguides

In order to use the large, electro‐optic coefficient of a nonlinear optical ionic crystal, 4‐(p‐dimethylaminostyryl)‐1‐methylpyridinium tosylate (DAST), a channel optical waveguide structure is needed. We successfully fabricated a waveguide using two methods: by a dry‐etching technique and by photo‐bleaching. Because DAST has a large optical loss, parts of the waveguide should be composed of a transparent polymer. We used photolithography and a reactive ion etching method to fabricate a serially grafted (conjunct) waveguide of DAST with a transparent polymer waveguide. The waveguide was also fabricated by photobleaching, whereby the refractive indices of the crystal’s a‐ and b‐axes were decreased by degrading the crystal. The cladding part of the DAST waveguide was photobleached by irradiating with UV light. The under‐ and over‐cladding layers of these channel waveguides were composed of a UV‐cured resin that did not dissolve the DAST crystal. The loss of the crystal waveguide for the crystal b‐direction was around 10 dB/cm, due to the scattering loss of the DAST single crystal.     

H:LiNbO3光波导

铌酸锂晶体具有良好的光声和电光性质，因而基于铌酸锂的集成光学器件已引起人们的广泛关注。质子交换法是一种制备铌酸锂光波导的重要方法。质子交换铌酸锂光波导具有制作工艺简单，折射率增量大，抗光折变能力强及可实现单偏振激励等特点。本文对质子交换铌酸锂光波导的制作工艺、波导特性及其应用进行了讨论，并指出目前应加强质子交换光波导、质子交换生长动力学和交换工艺的研究。     

Single-Mode Pulse Dispersion in Optical Waveguides

The limitations of a widely used method for analyzing pulse distortion in a single-mode waveguiding structure are derived. The results are applied to propagation in optical waveguides, and for cases where material dispersion is dominated by a broad resonance line, pulse attenuation is found to be much more serious than the broadening of the pulse. In extremely low-loss regions, however, other effects may cause the reverse to be true.