Wide wavelength tuning of sampled grating tunable twin-guide laser diodes

Tuning characteristics of widely tunable twin-guide (TTG) laser diodes with sampled gratings (SGs) are reported. Two SGs, providing slightly different reflection spectra, enable wide tunability by means of Vernier effect tuning. The device structure is vertically integrated and, hence, a DFB-like laser is obtained, which makes a phase tuning section unnecessary and facilitates easy and fast device characterisation. Although the tuning section can tune the SG reflection spectra by only /spl sim/2 nm, an overall tuning range of 28 nm has been achieved by employing Vernier effect tuning. Within the aforementioned tuning range, five supermodes are usable and can be tuned continuously without any mode-hops. The lasers operate at /spl sim/1.55 /spl mu/m wavelength and achieve a maximum output power of 12 mW.     

Continuously tunable photonic microwave true-time delay based on tunable chirped fibre Bragg grating

A simple scheme for the photonic microwave true-time delay with high tunability based on a tunable chirped fibre Bragg grating without centre wavelength shift is experimentally demonstrated. A large dynamic range of true-time delay from 20 to 200 ps was achieved for a microwave signal carried over an optical signal.     

Bragg grating fast tunable filter for wavelength divisionmultiplexing

A Bragg grating fast tunable filter prototype working over a linear tuning range of 45 nm with a maximum tuning speed of 21 nm/ms has been realized. The tunable filter system is based on two piezoelectric stack actuators moving a mechanical device thus compressing an apodized fiber Bragg grating. The filter allows both traction and compression and can work in transmission and in reflection. It is designed to work with a channel spacing of 100 GHz according to the ITU specifications for wavelength division multiplexing systems     

MEMS tunable SOI waveguide Bragg grating filter with 1.3 THz tuning range for C-band 100 GHz DWDM optical network

A MEMS tunable integrated waveguide Bragg grating-based filter for C-band optical dense wavelength-division multiplexing (DWDM) network is presented and analyzed in this work. Waveguide Bragg grating being a notch filter in the transmission spectrum is used to realize a tunable filter by varying the applied voltages to the fixed–fixed beam loaded with this grating. The strain across the grating is enhanced by choosing MEMS beam configuration such that the metal electrode is the bottom-most layer of the composite fixed–fixed beam. Device dimensions are chosen to achieve a narrow full width half maximum of 0.77 nm, allowing filtering of adjacent channels of 100 GHz DWDM network. A large Bragg wavelength shift of 10.4 nm (1552.52–1562.92 nm) was achieved at 45.8 V actuation providing tuning for 14 DWDM channels with inter-channel cross talk below ? 21 dB, with tuning range of 1.3 THz.

     

一种新型的可调谐非线性啁啾光纤光栅制造技术

利用Matlab模拟了一种新型的非线性啁啾光纤光栅,当对光栅施加纵向应力时,通过改变光栅的调制周期来实现光栅啁啾的非线性,应力的改变是通过磁场的磁致伸缩效应来实现的．     

Fabrication of chirped fiber grating with adjustable chirp andfixed central wavelength

We theoretically analyze and experimentally demonstrate a simple method for adjusting the chirp of chirped fiber gratings by temperature, while the central wavelength is temperature insensitive. Chirped fiber grating with tapered cross-section area is mounted under tension in a negative thermal-expansion coefficients material. The central wavelength is determined by the tension, and almost does not vary with temperature after packaging. The chirp can be adjusted by temperature. The grating in the package exhibits a linear variation in chirp of -0.00051 nm/cm/°C, and the temperature coefficient of central wavelength is -0.0018 nm/°C     

Apodized chirped fiber Bragg grating for postdispersion compensation in wavelength division multiplexing optical networks

In this paper, a postdispersion compensation unit is proposed leading to a better performance for the optical communication systems. This unit utilizes a chirped fiber Bragg grating (CFBG). For enhanced performance of the CFBG, a proper apodization function is chosen to improve the quality factor (Q‐factor) and the bit error rate (BER) of the system. A 110‐km wavelength division multiplexing (WDM) optical link is investigated. The system performance is evaluated through its Q‐factor, eye diagram, and BER showing best performance when using the Hamming apodization function.     

一种反射率、带宽、波长可调的微环反射腔镜

基于SOI的光学微环谐振腔具备低功耗、高集成 、高灵敏等特点而被广泛应用于光互连、光通信和光信息传输 等很多方面,本文利用耦合模理论,微环谐振理论和热光调制理论,提出了一种可以同时达 到反射率可调、带宽可调和 波长可调的微环反射腔镜,波长选择在1550 nm 附近 ,微环半径设置为10 μm,硅波导尺寸选择220 nm的条波导,波导 宽度为450 nm。利用转移矩阵方法和matlab仿真软件计算并仿真讨论 了输出光谱与耦合系数k等参数的变化关系。仿真 结果证明,该器件反射率变化为15%(在 无损耗的情况下),带宽调谐范围为0.25 nm～0.95 nm,通过在微环上加热 电极可以实现一个FSR(自由光谱范围)范围波长的调谐。该器件在高速光网络传输、光增 益谱均衡和信道选择方面有着重要应用。     

Self-compensated dispersion tuning of a mode-locked fiber laserusing a linearly chirped fiber grating

A new approach of self-compensated dispersion tuning is developed to generate wavelength-tunable pulses from a fiber laser. A linearly chirped fiber grating is used in conjunction with a pair of optical circulators and modulators in the cavity. The wavelength has been electrically tuned while maintaining a constant operating frequency of 1 GHz. The laser exhibits a linear tuning relation with respect to the delay time between the electrical control signals. Three chirped gratings providing dispersions of 1446, 50, and 10 ps/nm are used respectively in the experiment and the results are compared. The highest tuning range is about 1 nm and is limited by the chirped bandwidth of the gratings     

Electronic wavelength tuning using acoustooptic tunable filter with broad continuous tuning range and narrow channel spacing

The use of acoustooptic tunable filters as tunable-wavelength filters in a multiwavelength network is reported. Fast ( approximately=3 mu s access time), broad, continuous tuning (1.3-1.56 mu m) and narrow channel spacing (4.5 nm) in a nine-channel distribution system were demonstrated. The combination of broad tuning range and narrow channel spacing allows channel selection in a distribution system with hundreds of wide-band wavelength-division-multiplexed channels. The wavelength switching time, measured as approximately=3 mu s, is important in many high-speed switching applications.<>     

Energy-efficient dynamic wavelength and bandwidth allocation algorithm with delay constraint for time and wavelength division multiplexed passive optical networks

Based on offline scheduling and node modular design,an energy-efficient dynamic wavelength and bandwidth allocation algorithm with the delay constraint (EE-DWBA-DC) was proposed.Optical line terminal (OLT) and optical network units (ONU) were considered to save energy.Under the constraint of packet delay,the number of active wavelengths could be reduced as much as possible and the length of polling cycle was increased.At the same time,the uplink and downlink transmission time of OLT and ONU were concentrated to reduce the state conversion times and extend its low-power duration.In addition,the high energy consumption voids of channels were attempted to be minimized.The simulation results verify that the proposed algorithm can reduce the energy consumption of OLT and ONU and the total energy consumption of the whole network under the premise of guaranteeing packet delay constraints.     

Time delay measurement of chirped fibre grating using bidirectional modulation of Mach-Zehnder modulator

A simple method for time delay measurement of a chirped fibre grating by using bidirectional modulation of a Mach-Zehnder modulator is proposed. The bidirectionally modulated light with time difference produces an interference fringe in the RF domain. The time delay of a chirped fibre grating can be obtained by measuring the period of the RF interference fringe from different wavelengths.     

Characteristics of super structure grating (SSG) DBR lasers underbroad range wavelength tuning

Spectral characteristics of the super structure grating (SSG) distributed Bragg reflector (DBR) lasers under broad range wavelength tuning are discussed. SSG DBR lasers show good spectral characteristics with broad range wavelength tunability. Under the directly intensity modulated condition, stable single longitudinal mode oscillations are also obtained over the broad wavelength tuning range     

Self-healing fibre grating sensor system using tunable multiport fibre laser scheme for intensity and wavelength division multiplexing

A fibre grating sensor system using a tunable multiport fibre laser scheme for intensity and wavelength division multiplexing is proposed. The power ratio (1:2:3) between each output port is used to address the sensing information. The network survivability is also considered. This fibre grating sensor system can enhance the sensing capacity and reliability.     

Broad-range tunable wavelength conversion of high-bit-rate signalsusing super structure grating distributed Bragg reflector lasers

Tunable wavelength conversion of a 10 Gb/s signal over a broad wavelength range of about 90 nm is achieved by using a super structure grating distributed Bragg reflector laser. The extinction ratio dependence of converted signal light on input signal light power and bias current to the laser active region is discussed. The extinction ratio becomes large when the input signal light power increases and the bias current decreases. Bit error rate measurements show that error-free, penalty-free wavelength conversion is achieved when the extinction ratio is large (12.5 dB) and that the bit rate which error-free wavelength conversion is possible increases as the input signal light power increases. Twenty Gb/s signal wavelength conversion is also demonstrated     

114-nm wavelength tuning range of a vertical grating assistedcodirectional coupler laser with a super structure grating distributedBragg reflector

A vertical grating assisted codirectional coupler laser with a super structure grating distributed Bragg reflector is demonstrated. A record stepwise tuning range of 114 nm was measured with good side-mode suppression. The tuning behavior of the device is investigated showing a potential of a tuning range exceeding 100 nm with complete wavelength coverage     

DCG窄带反射滤光片再现波长和带宽的控制方法

本文从DCG的成像特性出发 ,讨论了用DCG制作全息窄带反射滤光片时 ,干板制备、曝光记录、显影处理以及暗反应和后光化反应对全息滤光片的再现波长和反射带宽的影响 ,并给出了控制再现波长和带宽的方法。     

基于可调谐激光器的光纤光栅波长解调系统误差分析与补偿

基于可调谐激光器的光纤(Bragg)光栅(FBG)波长解 调系统性能受激光器控制电路、调制参数以及光电探测器(PD)性 能、弱信号采集与放大电路等诸多因素的影响,着重研究了可调谐激光器调制参数中扫描频 率对光栅波长 解调系统的影响,发现波长解调误差随扫描频率的不同而呈现一定的规律,对波长解调误 差与激光器的 扫描频率进行了拟合。将拟合结果植入解调程序中,对激光器当前扫描频率下的解调波长进 行实时误差补 偿,并实验验证了误差补偿后的效果。结果表明,进行误差补偿后系统最大波长解调误差比 之前减小6.0 倍,其中由激光器扫描频率不同导致的波长解调误差和均方差(SD)分别比补偿之前减小2.2倍。最 终 使得基于可调谐激光器的FBG波长解调系统整体波长解调误差控制在1.38pm以内,有效地满足了高 速FBG系统对解调波长准确性和稳定性的要求,适用于高频动态信号的解调。     

Expansion of bandwidth of tunable dispersion compensator based on ring resonators utilizing negative group delay

In this paper, a novel method to expand the compensation bandwidth of a tunable dispersion compensator (TDC) based on ring resonators utilizing a negative group-delay peak is presented. The operation conditions of the ring resonator, where the negative group-delay peak appeared, are theoretically analyzed and then experimentally verified. The ratio of the usable bandwidth to the channel spacing (25 GHz) was increased from 75% to 86%, employing the proposed scheme of the expansion method. The improved dispersion-compensation characteristic was confirmed in a 10-Gb/s experiment.     

基于重叠写入啁啾光栅的Fabry-Perot腔的研究

以两段重叠写入的啁啾光栅作为反射面,构成光纤光栅Fabry-Perot(FP)腔.分别采用施加应力法和移动相位掩模板法,在同一段光纤中重叠写入啁啾光栅形成FP腔.使用啁啾量为1 nm的相位掩模板进行实验,两种方法曝光后的重叠啁啾光栅都可以形成明显梳状透射光谱.使用移动相位掩模板法,透射光谱的自由光谱范围(FSR)可达0...