最佳端焦耦合法测量交叉光波导损耗特性

本文利用最佳端焦耦合法对交叉光波导的损耗特性进行了测量和研究，绘制了波导损耗随交叉次数和交叉角的变化曲线。测量结果与预期特性相吻合。     

Design and characteristics of a branching component for bunched optical fiber using two graded-index rod lenses

An optical branching component is proposed for coupling bunched optical fiber to mono-core optical fibers and the component loss and crosstalk characteristics are investigated. The component is constructed with two graded-index (GRIN) rod lenses for matching different parameters between bunched and mono-core optical fibers. The method of analyzing mismatching and misalignment losses is based on geometrical optics. Measured losses are found to be in agreement with the calculated results and demonstrate that bunched optical fibers can be branched with low loss. Crosstalk measurements show that crosstalk attenuation greater than 30 dB can be easily maintained in the component.     

A finesse-enhanced Er-doped-fiber ring resonator

A two-coupler-type Er-doped-fiber ring resonator that compensates for the round-trip optical loss by optical amplification is proposed. Also proposed is a mode-filtered heterodyne method for resonant-linewidth measurements which does not demand narrow-linewidth light sources, but uses the beat noise between two uncorrelated lights filtered by the resonator passband. With this method, a finesse ⩾500 and a resonant linewidth ⩽17 kHz were confirmed from the Er-doped fiber ring resonator. The ring resonator was operated as a high-resolution optical spectrum analyzer     

Hydrogen permeation in optical fibres with hermetic carbon coatings

Hydrogen permeation has been measured for optical fibres with hermetic carbon coatings. Data obtained at elevated temperatures and high hydrogen pressures lead to predictions of extremely low permeation rates at typical operating conditions. In situ loss measurements have shown the existence of a lag time, during which no hydrogen reaches a fibre's interior     

Cladding alignment of butted optical fibers using a diffraction alignment device (DAD) and its application to mode-spot concentricity-error measurement

A novel technique which uses the interference of diffraction patterns to establish the mechanical alignment of butted optical fibers is described, and its application to mode-spot concentricity-error measurement is demonstrated. Complete spatial alignment to within 0.2 μm of relative offset and about 7-min of arc of relative tilt is achieved. In conjunction with a straightforward optical transmission loss apparatus, the method, when applied to mode-spot concentricity-error measurements, provides good agreement with alternative techniques. Accuracies are estimated and improvements suggested.     

Temperature and gain dynamics in flashlamp-pumped Er:YAG

A novel optical transmission method was used for measuring transient temperature dynamics inside an Er:YAG laser crystal during optical pumping with flashlamp pulses of different duration and spectral composition. Time-resolved measurements of the crystal gain at 2.94 μm were also performed for the same set of pumping conditions. The results are compared with predictions of a theoretical model for gain and temperature dynamics during optical pumping of Er:YAG. A good spatial resolution of the implemented temperature measurement method was utilized also to determine the lateral temperature profiles inside the laser rod under various pumping conditions     

Measurement of the complex permittivity of low loss polymer powders in the millimeter-wave range.

An improved measurement method of complex permittivity of low loss polymer powders is suggested. The measurements are done in the mm-wave range using a quasi optical resonator. The 2-D corrugated mode exciter is employed to improve suppression of undesirable higher modes. The model used for reconstructing complex permittivity takes into account ohm losses of metal mesh coupling that provide better accuracy of the reconstructing procedure. An example illustrating this method is reported.     

Automatic Polarization Control for Packet Transmission in a Hybrid Circuit and Packet-Switched Optical Network

We demonstrate automatic polarization control for packet transmission in an optical hybrid circuit and packet-switched network. The method combines a commercial automatic controller with a transmission scheme and a novel feedback circuit that ensures continuous feedback. Packet loss rate measurements show less than 0.1-dB power penalty when comparing packet transmission to continuous transmission. The controller causes an additional 0.3-dB power penalty.     

Measurement of mode field profiles and bending and transitionlosses in curved optical channel waveguides

Curved, single-mode, silicon oxynitride optical ridge channel waveguides have been characterized by measuring mode field profile alteration, bending loss, and transition loss. The results were compared to theoretical calculations. Near field imaging of the channel mode field profiles showed the effect of bend radius on mode shape. Good agreement was obtained between the measurements and profiles obtained from two-dimensional (2-D) beam propagation method calculations. The exponential dependence of bending loss on bend radius and the variation of transition loss on the lateral offset between channels having different bend radius were successfully modeled by two simple theories     

Thermal Aging Reliability of Package-Level Polymer Optical Waveguides

Polymer optical waveguides are viewed as a potential interconnect solution in board-level optoelectronic systems. In this paper, the optical loss changes in siloxane polymer waveguides during thermal aging conditions are studied for the wavelengths of 850 and 1310 nm. The optical loss in waveguides during intended operation and temperature exposure can increase due to factors such as oxidation of waveguides, increased absorption, and scattering. In addition to these inherent changes in the optical properties of the waveguides, physical failures such as delamination and cracking of waveguides will also increase the optical loss. This paper focuses on the first set of parameters that affects the optical loss and as a first step; the optical absorption of the polymer material is characterized through spectroscopy experiments. The thermal-aging dependent optical loss is determined for waveguide samples at several different accelerated temperature conditions. The temperature contours in a polymer waveguide with an embedded laser are determined from experiments as well as finite-element modeling. Using experimental data, analytical models have been developed that relate the optical loss with temperature and time, and provide a practical way of determining the reliability of the optical waveguides during field-use conditions.     

Optical return loss measurements and simulation of an arbitrary array of concatenated reflective elements on field-installed optical links

A new simple model, based on the zigzag diagram of transmission-line theory, is used to predict the optical return loss (ORL) for an arbitrary array of concatenated reflective elements on a typical optical network. A very good agreement to ORL measurements performed on different types of optical fiber plant is found.     

星形网光链路损耗与分光比求解方法探析

分析和研究了星形光纤网中光链路损耗和光分路器分光比的求解方法,通过实例着重介绍了比较复杂的广义星形网中各光分路器分光比与整个网络的全程光链路损耗的求解思路、方法和步骤。     

Optical fibre diameter variations and their effect on backscatter loss measurements

Diameter variations in optical fibres are shown to affect back-scatter loss measurements by a mechanism which primarily involves attenuation of the backward travelling light. A simple model which predicts anticorrelated loss features when measured from opposite ends of the fibre is verified experimentally.     

Antimony oxide-doped silica fibers fabricated by the VAD method

This paper presents a study of antimony oxide as an alternative dopant material for silica optical fibers using the VAD method. It takes a detailed look at fabrication processes and their conditions for graded-index multimode fibers having a 1.0-percent relative refractive index difference. Results reveal a minimum loss value and a residual OH ion content of 7.0 dB/km at 1.65μm and 50 ppb. Furthermore, measurements are made for fundamental properties, such as loss reliability, refractive index dispersion, and transmission loss below the 1.0-μm wavelength due to Sb⁴⁺centers. Finally, the paper discusses the advantages and suitable applications for antimony oxide-doped silica fibers.     

Vertically tapered epilayers for low-loss waveguide-fiber coupling achieved in a single epitaxial growth run

Next-generation optical-communications systems require on-wafer integration of active and passive opto-electronic components to increase operating speed and reduce packaging costs. Increased coupling efficiencies between semiconductor waveguides and optical fibers are of particular interest. A simple and cost-effective method of fabricating a mode-size converter monolithically integrated with a semiconductor waveguide is presented. An on-wafer mode-size converter reduces the number of interfaces in an opto-electronic circuit and improves the coupling efficiency between semiconductor waveguide and optical fiber. Vertically tapered epilayers are deposited in a single epitaxial growth run using shadow-masked growth by chemical-beam epitaxy, avoiding complex and expensive processing and regrowth stages. Waveguides that taper vertically and horizontally over /spl sim/1 mm for gradual expansion of the mode size are demonstrated. Waveguide loss measurements showed that there was negligible loss across the tapered regions. A loss of <2 dB/interface was achieved compared with /spl sim/8 dB/interface for a butt-coupled discrete device.     

Loss measurements in stress-induced optical waveguides fabricated by an embossing process

Stress-induced light guides have been fabricated by an embossing process. The results of detailed loss measurements show that these waveguides can exhibit low optical attenuation.     

弯曲光波导端面修饰的设计方法

光波导的弯曲损耗一直是集成光学中一个值得人们重视的问题,为有效地减小光波导弯曲损耗,弯曲光波导的设计成为集成光学波导设计中的一个重要内容.本文在弯曲光波导保形变换方法的基础上,应用几何光学分析方法给出了波导弯曲损耗产生的简洁的物理图像,从而深入地分析了弯曲损耗产生的根本原因,并由此提出了弯曲光波导端面修饰的设计方法.理论分析表明,与传统的弯曲的光波导设计相比,该种设计方法可以有效地减小导波的模式泄漏,从而减小波导弯曲损耗.尤其是在弯曲光波导曲率半径、材料折射率等参数被设定的情况下,该种设计方法成为一种有效的设计方法.     

Nonlinear optics in fibers for fiber measurements and special device functions

Nonlinear optical effects in fibers are significant in three respects. They present undesirable transmission limitations for long-distance optical fiber communication systems due to the intensity-dependent loss and pulse waveform distortions. On the useful side, they provide efficient frequency conversion means for generating frequency-shifted optical sources for a variety of spectroscopic applications including optical fiber measurements and optical device characterization. In addition, nonlinear optical effects also can provide useful special optical device functions such as optical amplification, optical gating, optical pulseshaping, and waveform equalization. This paper gives a brief review of the latter two aspects of nonlinear optics in fibers.     

Loss distribution measurement of silica-based waveguides by using ajaggedness-free optical low coherence reflectometer

The loss distributions in silica-based waveguides are successfully measured using a jaggedness-free optical reflectometer (OLCR). The OLCR reduces jagged fluctuations which appear in Rayleigh backscattering measurements undertaken with conventional OLCRs to within ±1 dB by averaging the wavelength-dependent Rayleigh backscatter signals. Constant loss distributions and a step-like loss increase in the waveguides were clearly observed     

基于光二分路器的多路分光比的设计

提出一种设计多路分光器分光比的新方法--分解组合法.将多路分光器视为光二分路器的各种组合,分解后,引入等效光纤长度的新概念,将分光损耗对等折算为一定长度的光纤损耗,再利用光二分路器分光比的简便设计方法,巧妙地设计出多路分光器的各路分光比.