将负折射率材料引入到空芯Bragg光纤包层中,形成具有正负折射率介质层交替的空芯Bragg光纤, 运用传输矩阵理论对该Bragg光纤的束缚损耗特性进行分析和计算, 并与传统的全正折射率介质层Bragg光纤的束缚损耗进行对比。结果发现: 在最低损耗方面含负折射率材料的空芯Bragg光纤没有表现出任何优势, 但在最低损耗点附近的损耗小于全正折射率介质层Bragg光纤, 损耗曲线比较平滑, 并且传输波长范围较宽; 当空气作为一个介质层的材料时, 两种Bragg光纤的束缚损耗特性几乎一致; 当减小包层折射率对比时出现了与全正折射率介质层Bragg光纤不同的现象, 损耗曲线变的更为平滑, 说明传输波长范围变宽了。

分析了具有反共振反射的蜘蛛网包层塑料空芯光纤在1.3 μm波段的损耗特性及其与结构参数的关系。将光纤包层等效为周期性多层膜，用渐近转移矩阵法进行数值模拟。为优化光纤结构参数，分析了包层层数N，高折射率层厚度d2和高、低折射率比值n2∶n1对损耗的影响。计算结果表明，随着N的增加，损耗首先快速下降最后达到一个固定值；模式损耗随d2的增加呈线形增大趋势，n2∶n1越大，反共振波长处的损耗越低。在此基础上，用模拟退火优化算法对空气层厚d1和纤芯半径rco进行了最优化求解。最后，用以上求得结构参数的优化组合即N=3，d2=2.648 μm，n2∶n1=1.49∶1.0，d1=3 μm和rco=100 μm，计算得到最低损耗是0.449 dB/km。

提出了一种基于非对称双芯光子晶体光纤的新型宽带模式转换器。对光纤参数与模式有效折射率之间的分析,通过调整纤芯内层空气孔的直径及掺杂介质棒的折射率,使两个纤芯中需要转换的模式之间实现了宽带的相位匹配。数值模拟结果表明,一种长仅为5.9 mm的双芯光纤,在保证传输损耗小于0.5 dB的前提下,其工作带宽达160 nm且偏振相关损耗小于0.28 dB。

开发资源丰富、可再生、清洁的新能源是全球一项紧迫的战略任务。在概述现有能源技术的基础上, 从光学和光学技术角度重点对太阳能的直接利用、太阳能电池以及太阳能分解水制氢进行了分析。指出了利用简单有效的太阳能跟踪聚焦系统, 以及耐热、低损耗、低成本和宽光谱传输的空芯塑料光纤, 可以加大对太阳能的直接利用和普及推广; 在太阳能电池方面, 应重点研究和发展各种薄膜太阳能电池, 采用对可见、紫外和红外光谱吸收的、具有不同带隙的复合材料和采用多结器件, 以进一步提高电池的转换效率和降低成本; 在太阳能分解水制氢方面, 应该把直射到地球表面的、从紫外-可见-红外的宽太阳光谱, 利用空腔辐射器作一个变换, 转换成绝大部分位于水分子有强烈吸收带的红外区。同时利用催化剂(敏化剂), 对水进行红外光催化分解反应, 或者利用红外多光子离解这有可能取得工业化规模制氢的突破。

We investigate the coupling characteristics of photonic crystal fiber composed of two cores with different index profiles. The index curves of the fundamental modes of the two cores can cross at a desired wavelength by choosing appropriate index profiles of the cores. As a result, wavelength-selective coupling is achieved. The designed coupler can be applied as an optical fiber bandstop filter with 26-nm bandwidth.

This paper explores the possibility of realizing a hollow-core optical fiber, whose cladding is composed of cylindrical alternating layers of air and high-index material with supporting structure. The optical properties and the design criteria of the proposed fiber are evaluated by the compact two-dimensional (2D) finite-difference time-domain (FDTD) method. In particular, the influence of the number and width of supporting strips on the leakage loss of the fiber is investigated. Furthermore, the mechanical performances of the fiber are estimated by finite-element method, confirming that hollow-core fibers with a reasonable size and number of supporting strips are reliable.

The loss properties of air-core plastic photonic bandgap fibers are analyzed by multipole method. Despite the relatively large absorption loss of plastics (PMMA), the contribution of material absorption loss can be reduced significantly through appropriate selection of operating wavelength, number of cladding air-hole rings, radius of air-core, and position of photonic band gap. The transmission loss in this type of fiber can be decreased by an order of magnitude in comparison with that of conventional plastic optical fiber.

In this paper, a novel multipriority reservation protocol for plastic optical fiber access network based on optical code division multiplexing access (OCDMA) technology is proposed. Conventional OCDMA system only allows finite units to transmit and access simultaneously according to the number of channels. The protocol is proposed to resolve this problem. By using the reservation scheme and a distributed arbitration algorithm, channel collision and destination conflict can be avoided. The protocol can efficiently support the transmission of multimedia messages that require the different time-delays. At the same time, each optical network unit is equipped with a fixed optical encoder/decoder that is always tuned to channel forcontrol and the tunable optical encoder/decoder that is tuned to any of channel for data. The network throughput and average delay have been investigated by numerical analysis and simulation experiments. It is shown that the multipriority reservation protocol in this POF access network based on OCDMA technology is valid and efficient.

本文首次将波矢量的匹配条件应用于标量近似有限元法求解条形波导,从而将二维问题简化成两个一维问题.其结果除了具有标量近似有限元法的一切优点外,还为节省计算机的存储和时间提供了一条新的途径.

本文回顾了我国在过去十年中导波光学、波导制备和测试、波导器件、单片集成以及微加工技术等方面所取得的进展,指出了集成光学的发展趋势和需求。