Fourier series expansion method for gain measurement from amplified spontaneous emission spectra of Fabry-Perot semiconductor lasers

A gain measurement technique, based on Fourier series expansion of periodically extended single fringe of the amplified spontaneous emission spectrum, is proposed for Fabry-Perot semiconductor lasers. The underestimation of gain due to the limited resolution of the measurement system is corrected by a factor related to the system response function. The standard deviations of the gain-reflectivity product under low noise conditions are analyzed for the Fourier series expansion method and compared with those of the Hakki-Paoli method and Cassidy's method. The results show that the Fourier series expansion method is the least sensitive to noise among the three methods. The experiment results obtained by the three methods are also presented and compared.     

三段式F-P半导体激光器的光谱特性分析

通过微加工法可以在FP半导体激光器中引入具有反射功能的缺欠点或面来改进激光器的光谱特性。利用射线法,推导了含有两个缺欠点的微加工获得的FP半导体激光器的输出谱表达式,并根据平均载流子密度近似(MCA)计算出名义阈值载流子密度Nth与实际载流子密度N之差ΔN,从而对模式抑制比(MSR)可作计算分析。     

微加工获得的F-P半导体激光器的光谱特性分析

利用微加工法可以在FP半导体激光器中引入具有反射功能的缺欠点或面来改进激光器的光谱特性。作者导出了含有多个缺欠点的微加工获得的FP半导体激光器(MMLD)的输出谱表达式,并对MMLD振荡模的边模被抑制的情况作了简要的说明。     

Accuracy of Fabry-Perot method of semiconductor laser gain measurement

The Fabry?Perot (FP) method of semiconductor laser gain measurement, first proposed by Hakki and Paoli (1975), is widely used. It is based on the measurement of the FP resonances excited by spontaneous emission. Its validity rests on the assumption that a single mode is significant. We show, using a simplified laser model, that this assumption is valid only when the power mirror reflectivity is very small, or near the laser oscillating frequency. For example, the error is in the order of 20% when the power facet reflectivities are equal to 37% and the modal gain is unity. These results apply to both index-guided and gain-guided lasers.     

Measurement of gain spectrum for semiconductor lasers utilizing integrations of product of emission spectrum and a phase function over one mode interval

A technique based on the integration of the product of amplified spontaneous emission spectrum and a phase function over one mode interval is proposed for measuring the gain spectrum for Fabry-Perot semiconductor lasers, and a gain correction factor related to the response function of the optical spectrum analyzer (OSA) is obtained for improving the accuracy of the measured spectrum. Gain spectra with a difference less than 1.3 cm/sup -1/ from 1500 to 1600 nm are obtained for a 250-/spl mu/m-long semiconductor laser at an OSA resolution of 0.06, 0.1, 0.2, and 0.5 nm. The corresponding gain correction factor is about 9 cm/sup -1/ at a resolution of 0.5 nm. The gain spectrum measured at a resolution of 0.5 nm has the same accuracy as that obtained by the Hakki-Paoli method at a resolution of 0.06 nm for a laser with a mode interval of 1.3 nm.     

射线法研究两段式半导体激光器模谱

由于两区载流子密度不同，两段式双稳半导体激光器（ＴＢＬＤ）两区界面反射不为零，这将使器件的输出模谱变得复杂，利用射线法，推导了ＴＢＬＤ的端面输出模谱表达式，在此基础上讨论了界面反射的影响以及由界面及端面构成的子腔对模谱的调制。     

板条激光器用光腔的模式计算:快速傅里叶变换法

本文使用快速傅里叶变换法对三维光腔衍射积分方程作了数值解,用以说明板条固体激光器用新型棱镜腔的模式特性.     

光纤光栅傅里叶变换光谱分析的研究

阐述了光纤光栅用作分光元件时 ,通过测量光纤光栅附近区干涉条纹 ,经快速傅里叶变换达到测量光谱的原理。讨论了波长测量范围和光谱分辨率。给出了在设计光纤光栅和确定探测器参数时应该考虑的几个问题。该光谱分析方法具有光谱分辨率高、结构简单、造价低等优点。     

Measurement of semiconductor laser gain and dispersion curvesutilizing Fourier transforms of the emission spectra

A new technique for the measurement of semiconductor laser gain and dispersion spectra is presented. The technique is based on an analysis of the subthreshold emission spectrum by Fourier transforms. Applications of this method to AlGaInP-based interband laser diodes and mid-infrared intersubband quantum cascade lasers are discussed. A good agreement between the measured dispersion of the refractive index and tabulated values in the literature was found     

Measurement of optical cavity properties in semiconductor lasers byFourier analysis of the emission spectrum

We present several observations on a novel method for the evaluation of the internal loss properties in semiconductor lasers. The method we use involves Fourier analysis of the Fabry-Perot mode spectrum when operating the device below lasing threshold. The observation of various structural features in the Fourier transform domain allows us to extract important information on the laser cavity. As one example, the amount of cavity propagation loss/gain, or net gain, can be derived from the decay rate of harmonics of the Fourier spectrum. A comparison between experimental and calculated gain versus wavelength data for lasers fabricated in the AlGaAs, AlGaInP, and AlGaInN material systems is given. As a second example, this method also allows the identification of the density and strength of intracavity scattering centers. This is an important capability for the fabrication of blue diode lasers in the gallium-nitride material system     

Effect of nonlinear gain on the bandwidth of semiconductor lasers

The effect of nonlinear gain on the frequency response of semiconductor lasers at high bias powers is analysed using the multimode rate equations. In spite of the strong damping of the relaxation oscillations due to nonlinear gain, bandwidths of over 40 GHz appear to be attainable in semiconductor lasers.     

包括增益压缩因子的半导体激光器行波速率方程

对包含增益压缩因子的半导体激光器（ＬＤ）的稳态速率方程组进行了求解，得到了隐函数形式的解析解，并以此讨论了增益压缩因子对某些ＬＤ稳态特性的影响。     

Measurement of integrated tuning elements for SIS mixes with a Fourier transform spectrometer

Planar lithographed quasioptical mixers can profit from the use of integrated tuning elements to improve the coupling between the antenna and the SIS mixer junctions. We have used a Fourier transform spectrometer with an Hg-arc lamp source as an RF sweeper to measure the frequency response of such integrated tuning elements. The SIS junction connected to the tuning element served as the direct detector for the spectrometer. This relatively quick, easy experiment can give enough information over a broad range of millimeter and submillimeter wavelengths to test both design concepts and success in fabrication. One type of tuning element, an inductive wire connected in parallel with a series array of 5 SIS junctions across the terminals of a bow-tie antenna, shows a resonant response peak at 100 GHz with a 30% bandwidth. This result is in excellent agreement with theoretical calculations based on a simple L-C circuit. It also agrees very well with the RF frequency dependence of the mixer gain measured using the same structure. The other type of tuning element, an open-circuited stub connected in parallel with a single SIS junction across the terminals of a bow-tie antenna, exhibits multiple resonances at 110, 220, and 336 GHz, with bandwidths of 9–15 GHz. This result is in good agreement with theoretical calculations based on an open-circuited stub with small loss and small dispersion. The position and the bandwidth of the resonance at 110 GHz also agrees with the RF frequency dependence of the mixer gain measured using similar structures.     

傅里叶变换光谱仪准直性误差检测技术

克服准直性误差对傅里叶变换光谱仪光谱性能的影响是研制傅里叶变换光谱仪的难点,定镜动态校准技术是解决该问题的好方法,而准直性误差检测是实现动态校准技术的关键.介绍了一种基于相位检测的傅里叶变换光谱仪准直性误差检测装置,该装置采用相位检测法实时检测动镜倾斜角,并用FPGA实现了相位检测算法,具有实时性好、测量精度高的优点,为实现动态校准系统打下了基础.给出了实测的动镜动态倾角曲线.     

Measurement of spontaneous emission factor for vertical-cavitysurface-emitting semiconductor lasers

Using a method based on measurement of modulation frequency harmonics, we have determined experimentally the spontaneous emission factors of GaAs-AlGaAs QW vertical cavity surface-emitting semiconductor lasers with square windows of widths 10, 15, and 30 μm. The values obtained are of the order 10^-4 and scale as the reciprocal of the window width. We have also assessed the reliability and accuracy of the modulation frequency harmonic measurement technique by comparison with the prior technique based on curve fitting to the light-current characteristic     

Generation of arbitrary optical waveforms by Fourier synthesisusing three continuous-wave semiconductor lasers

Arbitrary optical waveforms have been successfully generated by Fourier synthesis using three independent continuous-wave semiconductor lasers. The lasers were phase-locked to each other using a nonlinear phase-locking scheme. By controlling their amplitude and phase, triangular and trapezoidal waveforms as well as ordinary pulses have been generated     

Effect of gain nonlinearities on the dynamic response ofsingle-mode semiconductor lasers

The effect of gain nonlinearities on the dynamic response is studied using a nonperturbative form of the nonlinear gain in the signal-mode rate equation. The nonperturbative form is different from that used previously and leads to qualitative and quantitative differences in the intensity dependence of the important dynamic parameters such as the frequency and the damping rate for relaxation oscillations. The results are important for the design of high-speed semiconductor lasers and suggest that the new form of the nonlinear gain should be used for modeling the modulation response in both the small-signal and large-signal regimes     

Gain compression and asymmetric gain due to the Bragg gratinginduced by the standing waves in Fabry-Perot lasers

The Bragg grating induced by the pattern of standing waves in a Fabry-Perot laser diode is shown to give a significant contribution to nonlinear gain. An analytic expression is derived for the contribution leading to a simple universal relation between the damping rate of relaxation oscillations, the square of the relaxation resonance frequency, and the carrier diffusion time. The effect of the standing wave grating cannot explain present data from various experiments, which indicated that there must be additional important contributions to nonlinear gain     

半导体激光器线宽展宽因数的测量

光反馈自混合干涉技术是一种新出现的有别于传统双光束干涉的测试技术.文章基于此技术对半导体激光器进行线宽展宽因数的测量,以激光器HL7851G为对象进行了大量的实验,实验结果与线宽测量法基本一致,相对误差只有3.22%.相比线宽测量法,光反馈自混合法具有成本低、精度高的优点,是一种更加简洁有效的测量方法.