强超短脉冲抽运下半导体光放大器中的非线性过程

建立了包含载流子浓度脉动(CDP)、自由载流子吸收(FCA)、受激辐射(SE)、双光子吸收(TPA)、光谱烧孔(SHB)和超快非线性折射(UNR)过程的半导体光放大器(SOA)理论模型,通过与已报道的实验结果的比较对模型进行了验证,实现了对已有 SOA模型的修正,并对UNR,FCA和TPA效应对强超短光脉冲传输特性的影响进行了分析.当脉宽为几个皮秒的强光脉冲注入工作于透明电流下的SOA时,其强度特性主要受FCA和TPA效应的影响.由于加入了FCA效应,使模型对200fs脉冲强度传输特性的仿真结果与实验结果 关键词： 非线性过程 强超短光脉冲 SOA理论模型 增益透明     

Placement of optimized semiconductor optical amplifier in fiber optical communication systems

This paper deals with the placement of semiconductor optical amplifier for 10 Gb/s non-return to zero format in single mode and dispersion-compensated fiber link. We investigated post-, pre- and symmetrical power compensation methods for different positions of the SOA in fiber link. The effect of increase in signal input power for the three power compensation methods is compared in terms of eye diagram, bit error rate, eye closure penalty and output received power. It is found that the post-power compensation method is superior to pre- and symmetrical power compensation methods. Further, the effect of variation in length of the standard single mode fiber and dispersion-compensated fiber for three power compensation configurations has also been observed. The impact of eye closure penalty is observed for large transmission distances for different signal input powers.     

Modeling of semiconductor optical amplifier RIN and phase noise for optical PSK systems

Phase modulation schemes are attracting much interest for use in ultra-fast optical communication systems because they are much less sensitive to fibre nonlinearities compared to conventional intensity modulation formats. Semiconductor optical amplifiers (SOAs) can be used to amplify and process phase modulated signals, but with a consequent addition of nonlinear phase noise (NLPN). Existing SOA NLPN models are simplistic. In this paper we show that a more accurate model can be used, which results in simple expressions for SOA nonlinear noise, in particular when used to amplify differential phase shift keyed modulated data. The model is used to calculate the optical signal to noise ratio introduced by a power booster SOA and the first inline amplifier of a 40 Gb/s NRZ-DQPSK single channel link.

     

增益半导体光放大器的特性

为满足半导体光放大器（SOA）在光纤到户FTTH系统接入网中的广泛应用,提出了基于光纤光栅外腔反馈型GC-SOA结构的全光增益机制,窄线宽激光光源经可变衰减器、隔离器和光纤光栅注入到SOA中,SOA的输出光经隔离器和光纤光栅送至光谱分析仪,通过光纤光栅反馈输入SOA形成钳制激光。对GC-SOA的阈值特性、增益特性及开关特性进行分析,结果表明:当注入电流小于GC-SOA的阈值电流时,增益随注入电流的增加而增加;当注入电流大于GC-SOA的阈值电流后,其增益不再随注入电流的变化而变化,实现了SOA的增益稳定,使SOA的饱和输出功率得到了提高。     

Ultra-short optical pulse shaping using semiconductor optical amplifier

Optical ultra-short pulse compression and amplification using semiconductor optical amplifier (SOA) is presented. Using pump-probe pulse configuration, we present an SOA model which includes the nonlinear effects such as, spectral hole burning (SHB), carrier heating (CH), two-photon absorption (TPA) and group velocity dispersion (GVD) taking into account gain spectrum effect. Then by adjusting time delay between the pump pulse and probe pulse we use the model for simultaneous compression and amplification of probe pulse. We also analyze the four wave mixing (FWM) signal during pulse compression process. It is shown that dispersive effect of GVD on output probe pulse becomes more important for larger cavity length and probe-pump pulses relative time delays.     

All optical latches using quantum-dot semiconductor optical amplifier

The design and performance of two optical latches, the Set-Reset (SR) latch and D-Flip-Flop has been studied. These latches are the building blocks of large optical processors. The latches are built using two optical logic operations NAND and NOT. Both NAND and NOT operations are realized by using Mach-Zhender interferometer (MZI) utilizing semiconductor optical amplifier with quantum dot active region (QD-SOA). Nonlinear dynamics including carrier heating and spectral hole-burning in the QD-SOA are taken into account together with the rate equations in order to realize the all-optical logic operations. Results show that this scheme can realize the functions of Set-Reset latch and D-Flip-Flop at high speeds (∼250 Gb/s). The dependence of the output quality (Q factor) on QD-SOA parameters is also discussed.     

Dynamic optical distortion in a KrF discharge amplifier

The dynamic optical distortion in a KrF amplifier was measured using a Sagnac interferometer. Maximum wavefront aberration at 249 nm was /3 using helium buffer gas, indicating the potential for transmitted beams very close to the diffraction limit.     

Nonlinear distortion of laser beams by optical glasses

The critical energy of thermal self-action in a number of optical glasses made in Russia is measured. It is emphasized that one should take into account the effect of thermoelastic stress when calculating this energy.     

半导体光放大器引起的光控器件中的信号损伤分析

在双环耦合全光缓存器的基础上分析了全光分组交换网络中以半导体光放大器（SOA）为相移器件的反馈型全光缓存器输出的信号损伤,包括SOA的非线性及载流子恢复时间限制引起的脉冲畸变与连续码流中的图样失真和SOA的自发辐射噪声累积引起的信噪比恶化及缓存器结构引起的“漏光”问题.理论分析及实验结果表明,在采用反相控制并注入高功率控制光的情况下,脉冲畸变与图样失真被抑制,由信噪比恶化及漏光决定的光分组的缓存圈数被限制在20—30圈.得到的结果对基于SOA的光缓存器及逻辑器件同样具有借鉴作用. 关键词： 全光分组交换 全光缓存器 信号损伤 半导体光放大器的噪声分析     

Intermodulation distortion characteristics of a semiconductor laser amplifier in subcarrier multiplexing

The intermodulation distortion (IMD) characteristics of a subcarrier multiplexed signal in semiconductor laser amplifiers have been calculated. The minimum value of the carrier to the second-order IMD with detuning decreases 3 dB for the amplifier under consideration when the facet reflectivity changes from 10^-4 to 10^-3. In the case of third-order IMD the minimum value of the carrier to IMD ratio with detuning decreases 10 dB for the same change of reflectivity.     

Hybrid flat gain C-band optical amplifier with Zr-based erbium-doped fiber and semiconductor optical amplifier

An efficient gain-flattened C-band optical amplifier is demonstrated using a hybrid configuration with a Zirconia-based Erbium-doped fibre (Zr-EDF) and a semiconductor optical amplifier (SOA). The amplifier utilizes a two-stage structure with a midway isolator to improve flat gain characteristic and reduce noise figure. At input signal power of −30 dBm, a flat gain of 28 dB is obtained from wavelength region of 1530 to 1560 nm with gain variation of less than 4 dB. The noise figure is maintained below 11 dB at the flat-gain region. This amplifier has the potential to be used in the high channel count dense wavelength division multiplexing system due to its simplicity and compact design.     

Multiwavelength fiber ring lasing by use of a semiconductor optical amplifier

A multiwavelength fiber ring laser obtained by use of a semiconductor optical amplifier (SOA) with a simple laser cavity configuration is reported. A Fabry-Perot filter was used in the fiber laser ring cavity to achieve more than 50 simultaneous wavelength lasing oscillations with a frequency separation of 50 GHz. The resulting stable broadband multiwavelength lasing operation was attributed to broadband and flat gain of the SOA, which has a gain flatness of 0.8 dB for more than 20 nm. The laser has a total output power of -3 dBm and a signal-to-spontaneous-noise ratio of 30 dB.     

Optical pattern recognition by use of a segmented semiconductor optical amplifier

A technique for high-speed, all-optical pattern recognition based on cross correlation in a segmented semiconductor optical amplifier (SSOA) is presented. A counterpropagating pump-probe setup is used to perform cross correlation of the spatial gain-loss pattern in the SSOA with the optical data pattern (pump), and the result is read out with a counterpropagating probe. Cross correlation of 4-bit patterns at 85 Gbits/s is experimentally demonstrated. Simulations show reasonable agreement with experimental measurements and are used to address scalability to higher bit rates and longer data patterns.     

半导体光放大器中光波传输特性研究

根据半导体光放大器(SOA)载流子速率方程和光波在SOA内的传输方程,采用分段的方法计算出光波功率和相位与载流子浓度的关系公式。在泵浦光输入功率分别为5mW和15mW情况下通过仿真得到泵浦光输出波形和归一化转换光波形,其中归一化转换光的波形变化可间接体现不同泵浦光输入功率对SOA内载流子浓度的影响。分析了泵浦光波长和SOA注入电流对探测光的归一化输出、相位和频率啁啾产生的影响。结果表明,随着泵浦光波长的增加,探测光的三种光波特性曲线逐渐趋于平缓。注入电流将会直接影响到SOA的载流子浓度,以此对探测光的输出产生影响,注入电流越大,探测光的频率漂移越远。     

Optical power equalization using Fabry-Perot semiconductor optical amplifier

A novel scheme of optical power equalization based on Fabry-Perot semiconductor optical amplifier (FPSOA) is proposed. Because of the gain characteristic of FP-SOA, real-time controlling mechanism according to input optical power is aborted in the scheme. The simulations show that 10-dB pulse peak power variation can be clamped in less than i dB. The influences of injecting current, pulse periods, and pulse width are discussed.     

Multiwavelength fiber laser using S-band erbium-doped fiber amplifier and semiconductor optical amplifier

A multiwavelength fiber ring laser that is based on an S-band erbium-doped fiber amplifier (EDFA) and a semiconductor optical amplifier (SOA) is developed. An optical switch is used to switch the multiwavelength fiber laser between S-band and L-band. This fiber laser can stably lase seven wavelengths in the S-band or 28 wavelengths in the L-band. Additionally, the lasing wavelengths with a signal-to-noise ratio of over 33 dB and a wavelength spacing of 100 GHz are demonstrated experimentally. The average powers of the lasing wavelength in the S-band and the L-band are −7.53 and −12.15 dBm, respectively.     

Intraband effects on ultrafast pulse propagation in semiconductor optical amplifier

High bit-rate (>10 Gb/s) signals are composed of very short pulses and propagation of such pulses through a semiconductor optical amplifier (SOA) requires consideration of intraband phenomena. Due to the intraband effects, the propagating pulse sees a fast recovering nonlinear gain which introduces less distortion in the pulse shape and spectrum of the output pulse but introduces a positive chirping at the trailing edge of the pulse.     

Smallest lithographic marks generated by optical focusing systems

We show that the combination of Bessel beams and photosensitive materials exhibiting polarization filtering properties allows one to reach the smallest mark that can be lithographically generated by focusing systems. This property is of interest in current optical data storage techniques.