Broadband mode converter and multiplexer based on dielectric-loaded plasmonic waveguides

We theoretically demonstrate a broadband mode converter and multiplexer based on plasmonic waveguides loaded with structured dielectrics. The proposed device can realize conversions between a fundamental TM₀ mode and a first order TM₁ mode, as well as (de)multiplex them with another TM₀ mode. Our design exhibits as wide as 400 nm bandwidth and as short as 6~7 μm coupling length. This work has potential application in high density photonic integrated devices for both computing and communication applications.     

利用NOLM实现连续光到归零码脉冲和波长的同时变换

利用非线性光学环路镜成功地实现了连续光到超短光脉冲和波长的同时变换.最大波长变换间距大于35nm.实验系统中采用增益开关分布反馈半导体激光器(GSDFB-LD)产生的超短光脉冲作为控制光,采用波长可调半导体激光器作为信号光.在变换过程中在1.55μm附近首次观测到了波长的反相变换.当信号光和控制光脉冲走离大于40.7ps时,变换信号脉冲发生畸变,变换脉冲展宽.     

用超磁致伸缩调谐光纤光栅的光分/插复用器

提出并研究了一种新型多信道切换的全光分/插复用器,它主要由光纤Bragg光栅(FBG)和一对光环行器组成.采用了一种高效的超磁致伸缩材料(GMM)使FBG产生有效的Bragg波长偏移.用控制电流来调控FBG的应变和Bragg波长偏移.用4只相同的FBG与波长叠加技术相结合,可建立能提供15种不同下路信道方式的OADM.     

A Communication Multiplexer Problem: Two Alternating Queues with Dependent Randomly-Timed Gated Regime

Two random traffic streams are competing for the service time of a single server (multiplexer). The streams form two queues, primary (queue 1) and secondary (queue 0). The primary queue is served exhaustively, after which the server switches over to queue 0. The duration of time the server resides in the secondary queue is determined by the dynamic evolution in queue 1. If there is an arrival to queue 1 while the server is still working in queue 0, the latter is immediately gated, and the server completes service there only to the gated jobs, upon which it switches back to the primary queue. We formulate this system as a two-queue polling model with a single alternating server and with randomly-timed gated (RTG) service discipline in queue 0, where the timer there depends on the arrival stream to the primary queue. We derive Laplace–Stieltjes transforms and generating functions for various key variables and calculate numerous performance measures such as mean queue sizes at polling instants and at an arbitrary moment, mean busy period duration and mean cycle time length, expected number of messages transmitted during a busy period and mean waiting times. Finally, we present graphs of numerical results comparing the mean waiting times in the two queues as functions of the relative loads, showing the effect of the RTG regime.     

Characteristics of a Grating-Folded Optical Directional Coupler

We developed a new optical add/drop multiplexer composed only of a grating-folded directional coupler. We found that in this multiplexer, the power drop becomes maximal when the grating-coupling strength is equal to that of directional coupling. At this maximum power, both power transfer between the waveguides and power reflection take place simultaneously at the grating. The power drop approaches 1 when the grating length increases.     

Analysis of Ti:LiNbO3 zero-gap directional coupler for wavelength division multiplexer/demultiplexer

For the purpose of multichannel integrated-optical wavelength division MUX/DEMUX design, the wavelength tuning method of Ti:LiNbO₃ zero-gap directional coupler is analysed by effective-index based matrix method (EIMM). In this method, first, the 2D refractive index profile of the Ti:LiNbO₃ zero-gap directional coupler is transformed into lateral 1D effective-index profile by WKB method. Finally, matrix method is applied to this effective-index profile and the propagation constants are computed from the resonance peaks of the excitation efficiency versus propagation constant characteristics. It has been shown that the channel wavelength tuning can be achieved by varying the Y-branching angle at the input and output of the device or by a slight variation of two-mode-section length. The method of electro-optic fine tuning of the channel wavelength and channel separation of the device has also been investigated. A cascaded structure with proper parameters for four-channel application is also simulated and the results are presented.     

Monolithically integrated photonic-crystal devices with photodiodes

In this paper, we demonstrate the monolithic integration of a conventional waveguide, a photonic crystal demultiplexer, a photonic crystal taper coupler, photonic crystal waveguides, and photodiodes in InGaAsP-based material to form a planar nano-optics system. Photonic crystal demultiplexers consist of hexagonally arranged air holes. Finite-difference time-domain method is implemented to investigate the performance of the demultiplexer. The system is fabricated using e-beam lithography and conventional photolithography. The input light at wavelengths of 1530 and 1550 nm can be separated using the demultiplexing system. These can then be detected by photodiodes that exhibit a wide-bandwidth performance of 22 GHz.     

光网络中光纤光栅构成的波长分插复用器理论及进展

本文从光网络角度详细叙述、分析了各种光纤光栅构成的波长分插复用器技术的发展及理论 ,并指出了不同种类分插复用器各自适用的范围 ,表明了光纤光栅构成的波长分插复用器在光网络中的重要性。     

一种通带平坦的粗波分复用/解复用器件的研制

随着粗波分复用(CWDM)系统在城域网和接入网中日益广泛的应用,人们对粗波分复用／解复用器的研究也逐渐展开。报道了一种8通道波长间隔为20nm的粗复用／解复用器。该器件基于阵列波导光栅(AWG)原理设计,利用平面光波导技术(PLC)制作,采用多模干涉输入结构和“S”形阵列波导结构,实现了较宽的通带宽度和较低的串扰。实验测得1dB带宽大于10nm,相邻串扰大于24dB,非相邻串扰大于32dB。介绍了其设计原理和制作过程,给出了光束传播法(BPM)数值模拟结果,并和实验结果进行了对比。     

16×0.8nm硅基二氧化硅阵列波导光栅设计

给出了更为合理的阵列波导光栅(AWG)的设计原则。在设计时兼顾了输出谱的非均匀性Lu和输出通道数N的要求,克服了设计中可能引起通道数N丢失和不考虑输出谱非均匀性Lu的缺点。用该方法设计了折射率差为0 75%和16×0 8nm的硅基二氧化硅AWG。采用广角有限差分束传播方法(FD BPM)对所设计的AWG进行了输出谱的模拟,得到了插损为 1.5dB、串扰为 48dB、通道非均匀性约为1dB的AWG,设计指标达到了商用要求。