Studies on Timing Jitter in WDM Dispersion-Managed System by Variational Method

The variational method is employed to describe the basic properties of soliton parameters and to evaluate the timing jitter by considering multi-perturbations in wavelength-division-multiplexing (WDM) dispersion-managed soliton (DMS) system. The bit error rates (BER) of different dispersion managed systems, which induced by the timing jitter are given and compared. From that, there exist optimizations for the design of high-speed and long-distance practical WDM soliton system.     

High-performance and fabrication friendly polarization demultiplexer

A compact and fabrication friendly polarization demultiplexer (P-DEMUX) is proposed and characterized to enable wavelength-division-multiplexing and polarization-division-multiplexing simultaneously. The proposed structure is composed of a polarization-selective microring resonator in ultrathin waveguide and two bus channels in the silicon nitride-silica-silicon horizontal slot waveguides. In the slot waveguide, the transverse electric (TE) mode propagates through the silicon layer, while the transverse magnetic (TM) mode is confined in the slot region. In the designed ultra-thin waveguide, the TM mode is cut-off. The effective indexes of the TE modes for ultrathin and slot waveguides have comparable values. Thanks for these distinguishing features, the input TE mode can be efficiently filtered through the ultra-thin microring at the resonant wavelength, while the TM mode can directly output from the through port. Simulation results show that the extinction ratio of the proposed P-DEMUX for TE and TM modes are 33.21 dB and 24.97 dB, and the insertion losses are 0.346 dB and 0.324 dB, respectively, at the wavelength of 1551.64 nm. Furthermore, the device shows a broad bandwidth ($>100$ nm) for an extinction ratio (ER) of $>20$ dB. In addition, the proposed P-DEMUX also has a good fabrication tolerance for the waveguide width variation of $-20$ nm$\le \Delta w_{\rm g}\le 20$ nm and the microring width variation of $-20$ nm$\le \Delta w_{\rm r}\le $20 nm for a low insertion loss of $<0.75$ dB and low ER of $<-18$ dB.     

光子晶体四信道波分复用器的研究

提出了一种由2-D光子晶体构成的四信道波分复用系统。该系统包括利用光子晶体的线缺陷实现的波导部分和利用光子晶体微腔实现的频率选择部分。采用时域有限差分(FDTD)方法,研究了光在含点缺陷(即微腔)和线缺陷(即波导)的光子晶体中的传输特性,并给出了仿真结果。计算结果表明,该结构可以实现波长为λ=1550nm附近的四信道波分复用。     

Fiber to the Classrooms: Internet over Fiber Optical CATV System

This study proposed and demonstrated a directly modulated NTSC AM-VSB 77-channel plus Internet access system using a Fabry-Perot (FP) laser diode, an optical isolator, fiber Bragg grating (FBG), wavelength-division-multiplexing (WDM), channel conversion and two-way communication techniques over an existing multimode fiber (MMF) on the author’s campus. Performances of carrier-to-noise ratio (CNR) of >43dB composite second order (CSO) of >53dB and composite triple beat (CTB) of >53dB were obtained over a 2-km MMF transmission. The proposed two-way communication system is simple and suitable for fiber to the classrooms application.     

Fully reconfigurable optical add-drop multiplexer based on parallel configuration using Mach-Zehnder module

Reconfigurable optical add-drop multiplexer (ROADM) with the ability of dynamic configuration will be one of the core equipment for the future optical transport networks. This paper proposes an effective scheme for fully ROADM with parallel modularized structure and ability of upgrading. Each module consists of a Mach-Zehnder interferometer based on fiber Bragg grating (FBG), a 1 × 2 optical switch and a Y-model combiner. Optical signal with single wavelength or multiwavelength could be dropped or added at one drop port or add port by configuring the optical switch in each module. The proposed ROADM with four-stage parallel connection is designed and experimentally investigated to prove its performance and advantage in dynamic selection of the wavelengths and upgrading. It is also showed that this ROADM can also reduce the ununiformity of power at output port and drop port to improve the optical signal to noise ration (OSNR) of the whole system.     

Wavelength Conversion in WDM All-Optical Networks and Analytical Models

This paper gives a brief introduction to the various wavelength conversion techniques. In order to explain the applications and benefits of the wavelength conversion techniques in WDM all-optical networks, several analytical models are studied.