Switches and frequency converters based on cross-gain modulation in semiconductor optical amplifiers

The large-signal theory of frequency converters based on cross-gain and cross-phase modulations in a semiconductor optical amplifier is developed, for the case in which pump and probe are injected from the same facet (co-propagating case). Simple expressions for the bandwidth of cross-gain modulation are derived for single and cascaded SOA's, and large-signal simulations are carried out for cascaded SOA's, pointing out some important system issues. In the cascaded case, the effect of the loss between the SOA's is highlighted.     

基于半导体光放大器交叉增益调制的波长转换的理论分析

本文利用小信号理论模型分析了基于半导体光放大器交叉增益调制的波长转换 ,获得了波长转换效率的解析表达式。结果表明 ,波长转换的频带响应宽度受到光放大器驱动电流、波导中的光功率以及转换波长的影响。     

基于SOA中XGM效应的全光译码器的研究

文章基于半导体光放大器(SOA)中的交叉增益调制(XGM)效应.提出一种全光译码器的实现方案.该方案具有XGM效应本身的优点,如效率高、工作波长范围宽、逻辑运算只与输入光功率有关、不需要进行精确的相位控制和对偏振不敏感等.分析了该方案的工作原理,并使用OptiSystem软件对这种全光译码器进行了仿真.最后分析了全光译码器的输出功率和输出消光比与输入泵浦光功率、探测光功率之间的关系.     

Passive optical equalization of wavelength converters based onfour-wave mixing in semiconductor optical amplifiers

We demonstrate equalization of the frequency-shift dependent conversion efficiency of four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs). The wavelength converter provides fixed input tunable output wavelength conversion for ten wavelength-division-multiplexing (WDM) channels with 100-GHz spacing. Equalization is achieved by using a fiber Bragg grating (FBG) at the output of the fixed input tunable output wavelength converter. This method provides constant conversion efficiency to within ±1.5 dB over all WDM channels and can be easily adapted to other types of wavelength conversion     

Broad-band wavelength conversion based on cross-gain modulation and four-wave mixing in InAs-InP quantum-dash semiconductor optical amplifiers operating at 1550 nm

Wavelength conversion based on four-wave mixing (FWM) and cross-gain modulation (XGM) is experimentally demonstrated for the first time in a 1550-nm InAs-InP quantum-dash semiconductor optical amplifier. Continuous-wave FWM with a symmetric conversion efficiency dependence on detuning direction and FWM mediated short-pulse wavelength conversion are demonstrated. Using XGM, we have successfully implemented short-pulse wavelength conversion over 10 THz and error-free data conversion of a 2.5-Gb/s data sequence over 7.5 THz. The pulsed XGM experiments suggest that adjacent regions within an inhomogeneously broadened gain spectrum are partially coupled which increases the operational bandwidth, but at the expense of speed.     

Efficiency and noise performance of wavelength converters based onFWM in semiconductor optical amplifiers

All optical frequency converters are key devices for new-conception optical networks. A theoretical model is presented to evaluate performances of frequencies converters based on highly nondegenerate four-wave mixing (FWM) in semiconductor amplifiers. Conversion efficiency and noise performances are evaluated in generic saturation conditions and compared with experimental results     

Performance of networks using wavelength converters based onfour-wave mixing in semiconductor optical amplifiers

In this paper, we examine the blocking performance of networks in which connections may be blocked due to either insufficient capacity or due to limitations in the transmission network. We use analytical expressions and network simulations to examine blocking in networks in which the quality of the received signal may be so poor that the connection is effectively blocked. In particular, we apply our analysis to networks which use wavelength converters based on four-wave mixing (FWM) in semiconductor optical amplifiers. We show that the performance improvements obtained using these wavelength converters can be significant, but this depends on whether the network uses fixed-frequency or tunable transmitters and receivers     

XGM全光波长变换性能分析与优化设计

对基于半导体光放大器（ＳＯＡ）交叉增益调制（ＸＧＭ）的全光波长变换（ＡＯＷＣ）进行了性能分析,并提出了ＡＯＷＣ的简化系统模型,利用此模型详细分析了码速为２．５,５和１０Ｇｂｉｔ／ｓ归雾码的变换光消光比（ＥＲ）和信噪比（ＳＮＲ）与探测光功率（Ｐｃｗ）、信号光功率（Ｐｓ）和泵浦电流的关系,分析了优化设计ＡＯＷＣ的途径。     

All-optical signal up-conversion for radio-on-fiber applications using cross-gain modulation in semiconductor optical amplifiers

The authors present a novel scheme of up-converting optical intermediate frequency (IF) signals with an optical local oscillator (LO) signal using cross-gain modulation in a semiconductor optical amplifier. This scheme provides high conversion efficiency and is independent of the incident light wavelength and polarization. It can be useful for radio-on-fiber transmission system applications in which one remote LO signal is provided for several wavelength-division-multiplexing IF signals.     

Optimization of pump and signal powers for wavelength converters based on FWM in semiconductor optical amplifiers

We investigate the effect of input pump and signal powers on the noise performance and intersymbol interference (ISI) in a frequency-converter based on four-wave mixing (FWM) in a semiconductor optical amplifier. We demonstrate that there is an input pump power at which the noise figure of the frequency converter is a minimum, and a corresponding input signal power for which the output signal-to-noise ratio (SNR) is a maximum. We report bit-error-rate measurements which show that there is a trade-off between maximizing the output SNR, and minimizing intersymbol interference in the SOA. Consequently, the power penalty incurred in the frequency conversion can be minimized by careful selection of the input signal power. We show that power penalties of less than 1 dB are achievable.     

Influence of probe depletion and cross-gain modulation on four-wavemixing of picosecond optical pulses in semiconductor optical amplifiers

The influence of probe depletion (PD) and cross-gain modulation (XGM) on four-wave mixing (FWM) of picosecond optical pulses in semiconductor optical amplifiers has been investigated numerically. The effects of PD and XGM become more significant for shorter input pulsewidth, higher pulse energy and smaller pump-probe frequency detuning. Results indicate that if the effects of PD and XGM are neglected the FWM efficiency can be seriously overestimated     

Optical transient waveform monitoring based on cross-gain modulation in semiconductor optical amplifier

An all-optical transient waveform equivalent time sampling system based on cross-gain modulation(XGM) in semiconductor optical amplifier(SOA) is presented.A noisy SOA dynamic model and PIN equivalent circuit function are employed for system evaluating.The results show this SOA-XGM sampler with subtracting postprocessing can achieve picosecond sampling window.The shape of sampling window can be adjusted by SOA bias current and amplitude of control pulse.Compared with amplified spontaneous emission(ASE) noise of SOA and thermal noise in PIN,the jitter of sampling control pulse causes most sampling error.Simulations show that this SOA-XGM sampler can be a capable candidate for transient waveform sampling.     

40-Gbit/s 3-input all-optical priority encoder based on cross-gain modulation in two parallel semiconductor optical amplifiers

A 3-input all-optical priority encoder is designed.Proof-of-concept experiment is performed at 40-Gbit/s based on a cross-gain modulation (XGM) in two parallel semiconductor optical amplifiers (SOAs).O...     

Tunable wavelength filters based on nonlinear optical interactionsin semiconductor amplifiers

A novel class of narrow-band tunable wavelength filters is proposed and evaluated. Wavelength selectivity of the proposed filters Is derived from the finite time response of an optical nonlinearity. The nonlinearity is gain saturation in semiconductor optical amplifier structures. The filters are shown to have very narrow passbands tunable over the entire semiconductor gain bandwidth. The key to filter implementation is a device configuration in which the wave-mixing products can be isolated from the amplified inputs. Three integrated optics compatible configurations are considered and shown to have high filter throughputs 34 to 180% and subangstrom bandwidths     

Wide-band polarization-free wavelength conversion based on four-wave-mixing in semiconductor optical amplifiers

Wide-band polarization free wavelength conversion based on four-wave mixing in semiconductor optical amplifiers (SOAs) subject to two pump beams has been studied in detail. With equalized forward and backward pump power, polarization independence of the converted signal was experimentally achieved when the wavelength detuning was larger than 1.24 nm. This is independent of the SOA bias current. When the wavelength detuning between the signal and one pump beam was fixed at 1.6 nm, the amplitude of the converted signal was nearly constant over a 58-nm wavelength range. A new theoretical analysis allows for signals of arbitrary polarization state to be considered. The experimental results are in good agreement with the theory developed here.     

Long wavelength vertical-cavity semiconductor optical amplifiers

This paper overviews the properties and possible applications of long wavelength vertical-cavity semiconductor optical amplifiers (VCSOAs). A VCSOA operating in the 1.3-μm wavelength region is presented. The device was fabricated using wafer bonding; it was optically pumped and operated in reflection mode. The reflectivity of the VCSOA top mirror was varied in the characterization of the device. Results are presented for 13 and 12 top mirror periods. By reducing the top mirror reflectivity, the amplifier gain, optical bandwidth, and saturation output power were simultaneously improved. For the case of 12 top mirror periods, rye demonstrate 13-dB fiber-to-fiber gain, 0.6 nm (100 GHz) optical bandwidth, a saturation output power of -3.5 dBm and a noise figure of 8.3 dB. The switching properties of the VCSOA are also briefly investigated. By modulating the pump laser, we have obtained a 46-dB extinction ratio in the output power, with the maximum output power corresponding to 7-dB fiber-to-fiber gain. All results are for continuous wave operation at room temperature     

Cross-polarization modulation in semiconductor optical amplifiers

The polarization sensitivity of semiconductor optical amplifiers can be assessed in terms of gain or in terms of induced phase shift. Although the former aspect has received a lot of attention, the latter is rarely mentioned in the literature. Nevertheless, this birefringence leading to a rotation of the lightwave polarization at the output of the device may give rise to some interesting or unwanted effects. An optical control of the birefringence can be applied to wavelength conversion, signal regeneration, all-optical switching or gating. In this letter, the variation of the birefringence with input polarization and input power is measured     

Noise transfer characteristics in wavelength conversion based on cross-gain saturation in a semiconductor optical amplifier

Wavelength conversion based on cross-gain saturation in a semiconductor optical amplifier is studied from the viewpoint of how fluctuation in the input signal is transferred to the converted signal. Experiments in which a signal light with amplifier ASE noise is converted show that fluctuation in the "on"-level is suppressed while fluctuation in the "off"-level is enhanced due to the in/out relation of the converter.     

Regenerative properties of wavelength converters based on FWM in a semiconductor optical amplifier

A detailed experimental investigation of the regenerative properties of the four-wave mixing (FWM) for the conventional nonreturn-to-zero data format is reported. A key feature in the proposed scheme, and contrary to the conventional approach, is application of the ON-OFF keying modulation on the pump wave. Measurement of the static transfer functions of the FWM process in a semiconductor optical amplifier shows that certain operating regimes exist, mainly related to the power levels "one" and "zero" of the modulated pump, where a significant improvement of the extinction ratio (ER) can be achieved. This conclusion has been confirmed by dynamic measurements at 2.4 Gb/s, where up to 3-dB improvement in the ER has been observed.     

Realization of all-optical wavelength converter based ondirectionally coupled semiconductor optical amplifiers

We propose a novel all-optical wavelength converter based on directionally coupled (DC) semiconductor optical amplifiers (SOA) and simulate its characteristics using a simple model to find out such advantages as extinction enhancement and digital response. We then fabricate devices in the 1.55 μm band, and successfully demonstrate the wavelength conversion operation with the above-mentioned advantages. Very compact size and no need of active/passive integration are other significant merits of DC SOA's