Model for noise processes in semiconductor laser amplifiers:

A model for the noise processes in a Fabry-Perot semiconductor laser amplifier is presented. This model is based on the application of perturbation techniques to the travelling-wave rate equations for the amplifier. The model includes the effects of end-facet reflections and the backwards-travelling wave into the amplifier. The noise power spectral densities for the intensity, electron density and phase noise are derived. The model can be applied to an arbitrary gain profile and does not require homogenization of the photon field over the length of the device.     

Nonlinearities in semiconductor laser amplifiers

This review discusses the physical mechanisms of absorptive and dispersive nonlinearity in amplifiers resulting from interband and intraband electron transitions, with an assessment of the relative strengths and response times of these nonlinearities. Where appropriate, the potential applications of these nonlinearities in optical networks are also indicated.     

Lasing in tilted-waveguide semiconductor laser amplifiers

Abstact We have observed the transition from single-pass amplification of the fundamental mode to oscillation in the higher-order modes in tilted semiconductor-based amplifiers using numerical experiments based on a novel finite-difference time-domain treatment of the optical field that includes gain. These results correlate well with laboratory observations of gain-induced oscillation in such amplifiers.     

A laser amplifier model for system optimization

A laser amplifier system model has been developed, incorporating many of the features of real devices. The theoretical performance of systems with several amplifiers is investigated to illustrate the effects of optical filters and control techniques. Realistic and practical system limits are also identified.     

Four-wave mixing in semiconductor laser amplifiers: Applications for optical communication systems

Four-wave mixing in semiconductor laser amplifiers enables various applications in photonic switching including wavelength conversion, space and time switching, optical phase conjugation, and demultiplexing. Switching times faster than 1 ps are possible.     

The suppression of optical regenerator employing semiconductor laser amplifier loop mirror on the additive noise

In this paper, transmission properties of the regenerator employing a semiconductor laser amplifier loop mirror (SLALOM) are discussed. The ability of the regenerator to suppress the additive noise in the input data train is calculated. It’s shown that the regenerator can greatly suppress noise in communication system and improve their communication capacity by choosing suitable semiconductor laser amplifier(SLA) and the power of injected continuous wave.     

Slow light using semiconductor optical amplifiers: Model and noise characteristics

We developed an improved model in order to predict the RF behavior of the SOA valid for any experimental conditions. It takes into account the dynamic saturation of the SOA, which can be fully characterized by a simple measurement, and only relies on material fitting parameters, independent of the optical intensity and bias current. We used this new model to analyze and model the additive noise of the SOA in order to fully characterize the influence of the slow light effect on the microwave photonics link properties. To cite this article: P. Berger et al., C. R. Physique 10 (2009).     

On the amplified spontaneous emission noise modeling of semiconductor optical amplifiers

We perform a theoretical investigation of two modeling approaches for the amplified spontaneous emission (ASE) noise of a semiconductor optical amplifier (SOA), namely a stochastic time-domain and a deterministic frequency-domain approach. The theoretical results are compared to one another having as reference experimental measurements obtained from a commercial device. Special emphasis is placed on the modeling of the material gain as it is a key parameter in determining the ASE spectral characteristics. A comprehensive set of equations for both modeling approaches is developed and their numerical solution is analyzed in detail.     

A new model for a mode-locked semiconductor laser

We consider a new model for passive mode locking in a semiconductor laser comprising a set of delay differential equations. Bifurcations leading to the appearance and break-up of the mode-locking regime are studied numerically.     

Theory of noise in semiconductor laser emission

For the complex light field amplitude of a semiconductor laser an equation of a generalized van der Pol oscillator with a fluctuating driving term is derived from first principles. This equation is shown to be valid for optical band-to-band transitions with and withoutk-selection rule. Neglecting the nonlinearity in the saturation higher than of second order and also the intensity dependence of the dispersion this equation reduces to the standard van der Pol equation with a noisy driving term. From the general equation the linewidth and the noise of the intensity of the laser emission is calculated above and below threshold. The results are in agreement with the experimental data ofArmstrong andSmith.     

Propeller aircraft interior noise model,part I: Analytical model

Theoretical results are given for a basic propeller aircraft interior noise model. Results allow prediction of tonal levels in the cabin of a propeller-driven airplane at the blade passage frequency and its harmonics. Part I of this paper contains the analytical model, and in Part II scale-model and flight test comparisons are considered.     

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     

A 61-mJ, 1-kHz cryogenic Yb: YAG laser amplifier

We report a diode-pumped rod-type Yb:YAG laser amplifier operating at 1 kHz. Cryogenic cooling method was adopted to make the Yb:YAG crystal work with four-level behavior. A single-frequency fiber laser acts as the seed in an actively Q-switched Yb:YAG oscillator. The resonator delivers 5.75-mJ pulses at 1 kHz with a pulse duration of approximately 40 ns. The pulses were amplified to 61 mJ in a four-pass rod-type Yb:YAG amplifier with optical-to-optical efficiency of 24% in the main amplifier. The M² parameter of the output laser is <1.4.     

Theory of intensity noise in semiconductor laser emission

The intensity fluctuations expected in the output of cw semiconductor lasers are studied analytically using linearized multimode rate equations. Spontaneous emission causes intrinsic fluctuations of the laser wave. A power-independent contribution to the intensity fluctuations may occur due to inversion-induced modulation noise. The correlation of the low-frequency noise of different laser modes is investigated. The results are in agreement with experimental data reported in the literature.     

Population and current noise in semiconductor laser junctions

The population noise in a semiconductor laser is calculated by means of the quantum mechanical Langevin method. The resulting population noise is given by 〈δ N _c ² 〉=(T _c/2) (rate in+rate out)+K(¯n), whereN _c is the total number of electrons in the conduction band in the active region,T _c is a relaxation time. The first expression is the usual shot noise term. The transition rates are the sum of the rates due to the light field, the pumping and the spontaneous emission. The last termK(¯ n) is caused by the light field fluctuations;¯n is the mean number of photons in the laser mode.K(¯ n) consists of two parts: a) The main part is proportional to the intensity noise of the light field, which increases below but near threshold and gets constant above threshold. b) There is a second term due to the fact that parts of the fluctuations of the population and of the light field are correlated. — The noise spectrumS _I(ω) of the junction currentI is calculated for low frequencies. Beyond the usual shot noise termS _I(0)=2eI, additional noise is found in and above the threshold region, a) mainly because of the fluctuations of the light field in the laser mode and b) to a small amount, because the absorption processes due to the laser photons weaken the forward current, which is carried by emission processes, while the absorption noise adds to the emission noise.     

Quantum design of semiconductor active materials: laser and amplifier applications

We present an overview of a novel first‐principles quantum approach to designing and optimizing semiconductor quantum‐well material systems for target wavelengths. Using these microscopic inputs as basic building blocks we predict the light‐current (LI) characteristic for a low power InGaPAs ridge laser without having to use adjustable fit parameters. Finally we employ these microscopic inputs to develop sophisticated simulation capabilities for designing and optimizing end packaged hi gh power laser structures. As an explicit example of the latter, we consider the design of a vertical external cavity semiconductor laser (VECSEL).     

一种估计半导体激光器1/f噪声参数的新方法

对含白噪声的1/f分形信号小波变换系数的方差随尺度变化的关系进行适当的变换,提出了一种基于最小二乘法的估计半导体激光器1/f噪声参数的新方法.实验表明,该方法可以有效地提取出淹没在白噪声中的激光器1/f噪声,而且估计出的噪声信号的功率谱与对比仪器的测量结果有较好的一致性.     

频率啁啾光脉冲在行波半导体激光放大器中的传播特性

本文就行波半导体激光放大器(TW-SLA)中载流子引起的群速度色散对激光脉冲传播特性的影响作了理论研究.由于载流子引起的群速度色散效应,使远离饱和区工作的TW-SLA会对有频率啁啾的光脉冲产生展宽或压缩.本文就TW-SLA参数、频率啁啾参数跟脉冲增宽因子的关系作了理论研究.结果表明,线性的TW-SLA具有对低能量光脉冲压缩的可能性.因此,在光学通信系统中,它可用作对光纤损耗及色散的补偿元件.     

A novel actively and passively mode-locked semiconductor optical amplifier fiber ring laser

A novel actively and passively mode-locked semiconductor optical amplifier fiber ring laser was presented, where semiconductor optical amplifier provided cavity gain and introduced nonlinear polarization rotation, whereas, intensity modulator not only acted as modulator but also polarizer. The pulses with duration below 3 ps (FWHM) and peak power about 16 mW at a repetition rate of 10 GHz can be obtained in our system and the system stability may be enhanced. To investigate system parameters effects on mode-locked pulses, a theoretical model was developed.     

Simulation on semiconductor optical amplifier intensity noise reduction for future spectrum-sliced optical networks

Spectrum-slicing techniques employing incoherent light are an economic, practical and therefore attractive solution for future all-optical networks, especially for wavelength-division multiplexing (WDM) transmission systems in local area networks (LAN). However, spectrum-sliced methods exhibit a large excess intensity noise factor that limits the performance of the system. In this paper, we investigate noise suppression of spectrum-sliced incoherent light using a saturated semiconductor optical amplifier (SOA). The system incorporating the noise reducing SOA is modeled and simulated using OptSim software, and the results are compared to practical schemes from the literature. Performance comparisons are made with two different broadband sources test-beds. The characteristics of the SOA gain saturation are also presented. In both cases, it is found that a high degree of intensity noise is suppressed by the use of the non-linear gain saturation characteristics of the SOA so as to achieve better system performance. The position of a modulator in the system is also investigated in order to greatly reduce the excess intensity noise.