自差型光电反馈半导体激光器的量子AM和FM噪声谱

本文研究了自差型光电反馈(SHOE)半导体激光器(LD)的量子噪声,给出了AM与FM噪声谱的解析表达式,讨论了反馈环路参数的选择对量子噪声的影响。     

集成外腔半导体激光器的量子噪声

本文首次用半经典理论给出了集成外腔(IEC)半导体激光器(LD)的量子AM和FM噪声谱。指出IEC LD的噪声特性主要取决于有源区和外腔的长度及折射率的变化。     

强度反馈对半导体激光器量子噪声的改善

本文研究了强度负反馈对半导体激光器(LD)量子AM噪声的抑制。     

超高速调制下DSM—LD动态特性的研究

本文首先分析了高速调制下DSM—LD的动态特性,并着重分析了在小信号调制下的特性,然后讨论了Chirp效应的产生和抑制Chirp噪声的措施。     

大功率InGaAsP/GaAs量子阱半导体激光器的直流和1/f噪声性质

对大功率InGaAsP/GaAs量子阱(QW)半导体激光器(LD)的直流(DC)特性和小注入下的低频噪声(LFN)特性进行了实验研究.DC检测发现,V-J和I dV/dI-I可以对LD的电流泄漏作出判断.LFN检测发现,小注入下的1/f低频电压噪声幅值Bv(I)∝I<'βv>.理论分析和老化实验均表明,电流指数βv与载流子输运和电流泄漏机制之间有很好的相关性,存在电流泄漏和无辐射复合的器件其|βv|较小,可靠性较差.     

强度调制光发射机信噪比的研究

用于光发射机的半导体激光器(LD)的噪声性能直接决定着光通信系统的性能。许多方法被用来抑制LD的噪声。但在抑制LD噪声的同时,也将改变其调制特性。另外,当对LD直接调制时,其动态频率漂移(DFS)也直接影响到光通信系统的性能。因此,应综合考虑作为光发射机的噪声及DFS特性,才能完善和正确估价光IM发射机的性能。     

单量子阱激光器的Langivin噪声分析

本文通过在速率方程中加入Langivin噪声项和相位方程,以定量分析量子阱激光器（QW－LD）噪声特性,这样,能系统地表征量子噪声（尤其是影响线宽等参数的相位噪声）特性,我们对单量子阱激光器的噪声特性进行了模拟分析,并得到了有用的结果,如相位噪声谱和激射特性,我们发现在感兴趣的频域内有较大的噪声,并且噪声强度依赖于偏置电流的大小 。     

宽带DFB-LD组件的研究

讨论了LD Chirp噪声的产生机理及抑制措施。通过采用外电路补偿等方法,研制出了调制带宽达4.7GHz的DFB—LD组件。     

(双稳外腔)LD分析中扰动近似的有效性研究

在两种不同调制(增益和损耗调制)情况下,对半导体激光器(LD)速率方程组的扰动近似处理有效性进行了分析.结果表明,在电流(或增益)调制情况下,扰动近似法所忽略的二阶小量在量级上确实与保留的一阶小量的平方相当;在损耗调制的情况下,系统变化前后的阈值载流子密度不同,被忽略的二阶小量可能会达到与一阶小量可比拟的程度.以可调谐双稳外腔半导体激光器(ECLD)为例,指明了在损耗调制下,扰动近似分析可能会失效.     

光电反馈半导体激光器调相特性的研究

本文研究了光锁相环(OPLL)式光电反馈半导体激光器(LD)的相位调制特性,特别研究了引起相位调制特性曲线振荡的原因以及抑制振荡的方法.     

Effects of carrier transport on relative intensity noise and critique of K factor predictions of modulation response

The maximum possible intrinsic modulation bandwidth in semiconductor lasers is conventionally written in terms of the K factor. Although this is often sufficient in bulk lasers, it is usually not true in quantum well lasers where carrier transport can significantly affect the high speed properties. Analytical expressions are presented, which include the effects of carrier transport, for the modulation response and the relative intensity noise in quantum well lasers. It is shown that in the presence of significant transport effects, the K factor is not an accurate measure of the maximum possible intrinsic modulation bandwidth.<>     

负频反馈半导体激光器的量子噪声

相干光通信系统和相干光学测量对LD的噪声特性要求十分严格,因此LD的噪声及其抑制一直是近年来人们十分关注的问题.为了抑制LD的量子噪声,已采用了几种方法,但这又带来了机械稳定性的问题.最近报道了用NFFB抑制LD的线宽和FM噪声,对此也已有了理论解释但是在的分析中未引入反馈项,相当于开环的情况;的分析中则将反馈项引到了相位方程中,这是不符合客观情况的.本文给出的模型不仅解释了FM噪声的抑制,而且也解释了AM噪声的增大.得到的线宽与实验     

量子阱半导体激光器调制特性和噪声的电路模拟

给出一种量子阱半导体激光器（QWLD）小信号等效电路模型,可以作为含有QWLD系统计算机辅助设计的模型。模型包括QWLD的高速调制特性和噪声,对QWLD的调制特性和噪声进行了模拟,并对比了已发表的模拟和实验结果。     

Quantum noise of actively mode-locked lasers with dispersion and amplitude/phase modulation

A quantum theory for the noise of optical pulses in actively mode-locked lasers is presented. In the presence of phase modulation and/or group velocity dispersion, the linear operator that governs the time evolution of the pulse fluctuations inside the laser cavity is not Hermitian (or normal) and the eigenmodes of this operator are not orthogonal. As a result, the eigenmodes have excess noise and the noise in different eigenmodes is highly correlated. We construct quantum operators for the pulse photon number, phase, timing, and frequency fluctuations. The nonorthogonality of the eigenmodes results in excess noise in the pulse photon number, phase, timing, and frequency. The excess noise depends on the frequency chirp of the pulse and is present only at low frequencies in the spectral densities of the pulse noise operators.     

LDPC-Coded Optical Coherent State Quantum Communications

The problem of communication using optical coherent quantum states, in the presence of background radiation, is considered. Two modulation formats are studied, on-off keying (OOK) and M-ary pulse-position modulation (PPM). The bit-error-rate performance improvement due to low-density parity-check coding is reported. For OOK, it is assumed that the coherent state signal has a random phase. For an average number of noise photons N = 0.1, the required number of signal photons per information bit is six in the case of coded quantum OOK. For the same level of noise (N = 0.1) and assuming that signal phase is known, coded 16-ary PPM requires only 1.21 of signal photons per information bit.     

Analytical model of shot noise in double-barrier resonant-tunnelingdiodes

The shot noise in double-barrier diodes is analyzed using the stationary-state approach to resonant tunneling through the first quasi-bound level. Significant deviations from full shot noise are predicted. Significant shot noise suppression occurs in the entire positive differential resistance region below the current peak, and shot noise enhancement occurs in the negative differential resistance region above the peak. The physical basis for these effects is assumed to be the modulation of the double-barrier transmission probability by charge stored in the first quasi-bound level in the quantum well. The analysis confirms microwave noise measurements of high-speed double-barrier diodes     

A Michelson interferometer with balanced detection for thecharacterization of modulation and noise properties of semiconductorlasers

A Michelson interferometer with balanced detection, built to study semiconductor lasers, is analyzed. The quantum noise due to vacuum fluctuations, coupling losses, detector quantum efficiency, and spatial mode mismatches are included in the analysis. The limits for frequency noise detection and the sensitivity of the interferometer are examined. It is observed that under ordinary measurement conditions the frequency noise can only be measured up to slightly above the cavity bandwidth of the laser. Comprehensive measurement procedures are proposed, and experimental results showing the frequency modulation response, measured from 10 kHz to 8 GHz, of a three-section distributed feedback (DFB) laser and the frequency noise spectra, measured from 30 MHz to 8 GHz, of a two-section distributed Bragg reflector (DBR) laser are presented. These results reveal new cavity detuning effects in the noise characteristics of tunable DBR lasers     

单量子阱激光器小信号调制时的啁啾噪声

量子阱激光器具有良好的小信号调制频率响应 ,能作为高速光通信光源采用直接调制方式进行信号传输。与普通半导体激光器一样 ,直接调制将引起啁啾 ,从而影响光纤通信系统的性能。文中对小信号调制下单量子阱激光器的啁啾特性进行了研究和分析。得出了啁啾幅度和啁啾相位与调制频率的关系。对考虑与不考虑啁啾两种情况下 ,光脉冲在常规光纤中传输时的色散特性进行了模拟分析 ,发现了啁啾对系统的高阶色散有较大影响     

Modeling of intensity noise including squeezing in DFB andFabry-Perot semiconductor laser diodes

A new time-domain model using the quantum formalism of the positive-P distribution is used to investigate squeezing in laser diodes, taking into account longitudinal hole burning and distributed noise sources, under steady-state and large-signal modulation. Simulations indicate that the laser structure determines the lowest achievable intensity noise. With losses present or power escaping from the rear facet, this minimum noise may be much higher than expected from the device quantum efficiency. Squeezing appears more difficult in DFB lasers than in Fabry-Perot lasers in our simulations. Mode-partition noise is removed by low-loss passive DBR sections, and such laser diodes are promising sources with low-intensity noise. Intensity noise in the large-signal dynamic regime is also simulated, showing that intensity-squeezed light output is possible     

Intrinsic Dynamic Properties of High-Characteristic Temperature GaInNAs Laser Diodes Operating at 1.3 μm

The properties of a high-characteristic temperature (T₀=155K) 1.3-mum GaInNAs-GaAs laser are presented with an emphasis on laser dynamic characteristics evaluated by linewidth enhancement factor and relative intensity noise. It is found that the relatively high differential gain of GaInNAs-GaAs quantum wells leads to a small linewidth enhancement factor of 2.8, indicating a small magnitude of frequency modulation with modulation current. The relative intensity noise measurements indicate a relaxation frequency of 4.7 GHz at a moderate bias current, from which the maximum intrinsic modulation bandwidth was calculated to be 9.7 GHz. The experimental determination of the low linewidth enhancement factor and high relaxation frequency reinforce the potential of dilute nitride lasers for high-speed directly modulated fiber links