Nonlinear Response of the Semiconductor Laser with Pump Current Modulation

The influence of tuning the lasing monochromatic radiation frequency _g within the amplification band on the nonlinear response of the semiconductor laser with harmonic modulation of pump current is investigated theoretically. It is established that the principal features of the behavior of the nonlinear amplitude-detuning characteristic (ADC) are determined by the relation between the current modulation frequency _m and the main resonance frequency of the laser _r. If _{m r}, then with increase in _g the response decreases monotonically mainly due to the decrease of its dynamic component. The exception is provided by the spectral regions where peaks on the ADC appear because of the explicitly nonlinear lasing regimes (period doubling, chaos, etc.) When _m < _r, the resonance conditions for induced oscillations are satisfied only for definite spectral intervals within the amplification band and a dip appears on the low-frequency side of the ADC. With decreasing _m, the dip boundary shifts to a more high-frequency region of the band corresponding to smaller local resonance frequencies. The peaks on the ADC corresponding to the radiation period doubling shift to the region of smaller values of _g on increase in _m.     

非线性简并光学参量放大系统的量子起伏

解析求解了P表象中考虑抽运吃空后的非线性含时简并光学参量放大系统获得压缩光所满足的福克尔-普朗克（Fokker-Planck）方程,并且计算了它在阈值附近及远离阈值的量子起伏。研究表明：若略去与η成正比的项,则通解很自然地过渡到线性近似解。计及与η成正比的项后,该解与Drummond等在阈值附近的微扰展开理论相比,基本相符。但在远离阈值处,微扰展开理论不适用,而该结果在阈值附近以及远离阈值的整个区域均是适用的。当μ→0压缩很小时,起伏趋近于真空起伏;而μ〉〉1,压缩增大时,趋近1／1＋μ线性理论。     

Influence of Nonlinear Refraction on the Spectral Characteristics of GaAlAs/GaAs Lasers

Numerical modeling of the spectral characteristics of single-frequency lasers is carried out by using a model which takes into account nonlinear refraction. It is shown that account for nonlinear refraction allows one to obtain satisfactory coincidence of the experimental and theoretical spectral characteristics of quantum-well lasers.     

相位、振幅调制两用声光调制器设计

针对实际应用中大多的光调制器只能实现单参数调制的情况,提出一种既可以调相又可以调幅的声光调制器的设计方案.运用矩阵级数解法求解正常声光相互作用Raman-Nath方程,通过计算机编程进行数值求解,得到衍射光的衍射光强和附加位相变化,从而指出以往解法的一些不合理性,并找到声波功率和衍射光的光强和位相的关系,为声光效应的位相调制和振幅调制设计提供了一种可行的方法.结合调制声波频率,可在同一个调制器上进行调幅、调相、调偏转方向.     

Characteristics of the Phase Noise Correlation of Injection Locked Lasers for RF Signal Generation and Transmission

Theoretical and experimental results on phase noise characteristics of an optical radio-frequency generation and transmission system using heterodyne photo-detection and side band injection locking is reported. Optical phase noise correlation of the lasers is achieved by noise transfer from a modulated master laser. Our investigation takes into account phase noise enhancement in optical comb generation, injection dynamic, path delay, and fiber dispersion. Theoretical expressions are derived from an adiabatic approximation and compared with experimental measures.     

10G/40G无载波幅度相位调制系统性能研究

无载波幅度相位调制(Carrierless Amplitude and Phase,CAP)是超高速短距离光通信系统中的一种备选的方案,由于其成本低、频谱效率高、功耗小等优点,近年来越来越受到研究人员的关注。基于MATLAB与VPI联合仿真,探究10G/40G速率CAP系统中关键参数对系统性能的影响,包括数字滤波器滚降系数、滤波器抽头数,通过仿真找出最优系统参数值,同时对时钟偏移带来的影响也做了研究,以期为以后设计短距离CAP光通信系统有所帮助。     

Modulation Characteristics of Tunable Quantum-Well Heterolasers at the Radiation Frequency Tuning

The influence of the tuning of the radiation frequency of quantum-well heterolasers within the limits of their amplification band on the output laser radiation parameters at different frequencies of pump-current modulation has been numerically simulated using two optical models of an active medium under the assumption that the excess of the invariable component of the pump current over its threshold value at any point of the amplification band is constant. It has been established that the amplitude-detuning characteristics of the lasers studied are linear at high current-modulation frequencies and nonlinear at medium ones. The behavior of the nonlinear spectral response of a laser diode is explained by its multiresonance structure and is mainly determined by the ratio between the pump-current modulation frequency and the maximum resonance frequency of the laser. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 4, pp. 473–478, July–August, 2005.     

半导体激光器非线性失真的理论和实验研究

对半导体激光器的非线性失真进行了理论分析，得出了计算二阶失真和三阶失真的理论公式，实验验证了理论结果，并发现国产ＤＨ－ＧａＡｌＡｓ半导体激光器的二阶失真严重，而三阶以上的失真却可以忽略。     

非线性掺铒光纤环镜中超短光孤子串的产生及放大

利用数值模拟方法证明了,双频弱连续波的拍频信号在分布增益的非线性掺铒光纤环镜内传输,能产生超短光孤子串.数值计算表明,当输入信号为重复率<20 GHz的拍频弱信号时,可在较短的环镜长度内产生占空比大且高质量的光孤子串.研究同时发现,输入信号的平均功率越大,所需环镜长度越短.与其他方法相比,该方法不仅能克服传统方法所产生的脉冲重复率受限的困难,而且在无需采用特种光纤的情况下,将弱信号转化为超短光孤子串.     

Influence of Radiation Polarization on the Nonlinear Response of a Semiconductor Laser with Pump Current Modulation

The influence of various lasing-radiation polarization states and types of optical dipole transitions on the nonlinear amplitude-detuning characteristics of quantum-well semiconductor lasers with pump current modulation has been theoretically investigated. It has been established that the narrowest spectral interval, where the response is nonzero, is realized in the case of TM-mode radiation and transitions to the heavy-hole states as well as in the case of TE-mode radiation and transitions to the light-hole states.     

Spatiotemporal Dynamics of Broad-Area Lasers with the Pump Modulation and Injection of External Optical Radiation

Radiophysics and Quantum Electronics - We study the possibility of stabilizing broad-area dynamic class B lasers, which include those with periodic pump modulation, by using injection of external...     

Transition to Amplitude Death in Coupled System with Small Number of Nonlinear Oscillators

In this work, we investigate the amplitude death in coupled system with small number of nonlinear oscillators. We show how the transitions to the partial and the complete amplitude deathes happen. We also show that the partial amplitude death can be found in globally coupled oscillators either.     

Combined Role of Synchronized Amplitude Modulation and Synchronized Phase Modulator for Soliton-Soliton Interaction

In this paper, the interaction between two solitons has been studied by the perturbation approach in the presence of synchronized amplitude modulation and synchronized phase modulation. The results show : the combined role of synchronized amplitude modulation and synchronized phase modulation can suppress effectively the interaction.     

光脉冲在孔硅波导中的非线性调制过程与波形特征分析

研究了具有不同中心载波波长的高功率双脉冲在微纳孔硅波导中的非线性光学过程和输出脉冲在时域与频域的波形特征。结果表明,由于双光子吸收、自由载流子吸收、自由载流子色散、自相位调制和交叉相位调制的非线性效应作用,在波导输出端,目标脉冲的不对称时域和频域脉冲波形被观察,而且脉冲波形的改变依赖于注入功率、初始宽度、波导长度和脉冲时延参数。     

高能量粒子测地声模与Dimits区漂移波相互作用

基于包含驱动和阻尼的三波非线性相互作用模型,构建了一个描述高能量粒子测地声模(EGAM)与Dimits区漂移波湍流相互作用的系统,并在系统的线性增长及非线性振荡阶段分别进行了解析和数值研究.更进一步的数值结果表明,在忽略EGAM的贡献时,该系统具有随着线性驱动/阻尼率等参数的变化,从极限环振荡经历倍周期分岔最终进入混沌的行为特征.在此基础上,形式上构建了本系统的非线性饱和Dimits区,并研究了EGAM对Dimits区漂移波的影响.结果表明,对于不同幅度和频率的EGAM,被调制后的漂移波将表现出受到激发或抑制的效果.对此,采用相空间分析的方法给出了相应的解释.     

Fast Analysis for the Focusing of a Laser Beam with Amplitude Modulation and Phase Fluctuation Through an Aperture Lens

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｌａｓｅｒｂｅａｍｓｗｉｔｈａｍｐｌｉｔｕｄｅｍｏｄｕｌａｔｉｏｎｓ(ＡＭｓ)ａｎｄｐｈａｓｅｆｌｕｃｔｕａｔｉｏｎｓ (ＰＦｓ) ｐｒｏｐｏｓｅｄｂｙｔｈｅＬａｗｒｅｎｃｅ ＬｉｖｅｒｍｏｒｅＮａｔｉｏｎａｌＬａｂｏｒａｔｏｒｙ (ＬＬＮＬ)ｉｓａｔｙｐｉｃａｌｐｈｙｓｉｃａｌｍｏｄｅｌｆｏｒｈｉｇｈ ｐｏｗｅｒｌａｓｅｒｓ[1] .Ｉｎｈｉｇｈ ｐｏｗｅｒｌａｓｅｒｓｙｓｔｅｍｓ,ｓｕｃｈａｓｌａｒｇｅＮｄ∶ｇｌａｓｓｌａｓｅｒｆｕｓｉｏｎｄｒｉｖｅｒｓ,ｈｉｇｈ ｐｏｗｅｒｌａ…     

Fast Analysis for the Focusing of a Laser Beam with Amplitude Modulation and Phase Fluctuation Through an Aperture Lens

Based on the treatment that a rectangular function can be expanded into an approximate sum of complex Gaussian functions with finite numbers, the analytical expression for the focusing intensity distribution of a laser beam with amplitude modulation (AM) and phase fluctuation (PF) through an aperture lens is derived. The typical numerical examples are given and compared with those obtained from numerically integral calculation. The results show that our method can significantly improve the numerical calculation efficiency.     

室内可见光无载波幅度相位调制系统性能分析

针对室内可见光通信调制技术问题,提出翻转光无载波幅度相位调制和单极性光无载波幅度相位调制两种功率有效的调制方案,二者分别采用"正、负模块极性分组"以及"零值位置极性编码"方法实现信号单极性处理,以满足可见光通信"强度调制/直接检测"的要求.基于朗伯辐射模型,考虑到高斯背景光噪声的可见光直射传输信道,推导了包括直流偏置光无载波幅度相位调制在内的三种调制方案的误比特率闭式表达式,仿真验证了其准确性.在此基础上,分析比较了三者频带利用率,讨论了信道参量对光无载波幅度相位调制系统误码性能的影响,结果表明,在5m×5m×3m的室内场景下,与发射机辐射角为30°和45°相比,0°时的系统误码性能分别优于6.9dB和29.9dB;收发机距离为1m时,误码性能比2m时改善近12dB.     

高功率激光系统中非线性热像与模糊斑大小的关系

高功率激光系统中非线性热像的强度可能达到光学元件的损伤阈值,从而危及系统的安全运行。明确并避免引起最强热像大小的模糊斑,可以降低热像的破坏威胁。通过理论分析与数值模拟方法,研究了高功率激光系统中非线性热像光强与模糊斑大小的关系。根据角谱传输和Bespalov-Talanov小尺度自聚焦理论,推导出一定厚度非线性介质的热像光强表达式,得到了热像光强随模糊斑大小的变化规律,并用数值模拟结果进行了验证。结果表明,随着模糊斑尺寸的增大,热像光强先是单调增大,达到一最大值后单调下降;热像光强最大时对应的模糊斑大小基本上与由Bespalov-Talanov小尺度自聚焦理论决定的最快增长小尺度调制尺寸相同。     

Amplitude and Phase Characteristics of Signals at the Output of Spatially Separated Antennas for Paths with Scattering

Russian Physics Journal - Conditional statistical characteristics of the phase difference are considered depending on the ratio of instantaneous output signal amplitudes of spatially separated...