高精细DVD用蓝色半导体激光器

可录制和回放2h高质量电视图像的下一代DVD需要现行的DVD有3倍以上的信息量。用蓝色半导体激光器作光源,通过电流注入而使之产生室温脉冲振荡。这种激光器是采用有机金属气相生长技术把氮化镓(GaN)和氧化铟等半导体薄膜多层沉积在基板上,选择适当的方法控制超薄膜晶体界面,从而实现了沉积几个原子厚薄层的多重量子阱结构。由于实现了蓝色激光振荡,从而进一步扩大了实现高精细DVD的可能性。1.前言     

用外延法生长高功率叠层半导体激光器

法国汤逊一CSF公司的研究人员已用化学外延（＊＊E）法外延生长叠层二极管激光器。他们宣称,这种方法可开发费用效益高的高功率单片叠层半导体激光器。虽然诸如二极管泵浦＊d：YAG系统等高功率固体激光器正日益增多地分享以前只为普通闪光灯泵浦系统占领的市场,但如果＊d：YAG激光器的市场份额要继续增长的话,它们也仍面临几个障碍需要克服,这就是它们的输出功率、亮度和费用效益必须继续改善。尽管半导体材料具有高增益和良好热导率方面的优势,但一直存在输出功率低的问题,半导体激光器的总输出功率仍然不高,这主要是由于发射激…     

超高精度DVD用蓝光半导体激光器的发展

激光波长是限制DVD记录密度提高的关键因素,研制短波长激光器是超高密度VD用光源的重要发展方向。这里介绍这种短波长蓝光激光器（如GaN,ZnSe,SHG等）的特点及应用展望。     

光盘系统用半导体激光器

半导体激光器（ＬＤ）作为读取光盘信息的光源,是ＣＤ、ＤＶＤ播放机／ＲＯＭ等光盘系统的重要器件,它的性能往往决定系统的整体性能。文中叙述了光盘用ＬＤ的发展历程及特点,并着重介绍了近红外、红光、紫光、ＬＤ及双工ＬＤ的开发现状。     

下一代DVD将助蓝紫龟半导体激光器一统天下——蓝紫色激光器将成为下一代DVD的标准配置

每年市场出货量将达1亿台 2007年,基于蓝光光盘和HDDVD标准的下一代DVD市场终于启动了。预计到2010年左右,支持下一代DVD的PC、音／视频设备以及游戏机等,全球出货量有可能达到每年1亿台以上。继CD-ROM和DVD之后,下一代DVD将成为光盘主角。     

MBE生长高功率半导体激光器

对影响分子束外延（ ＭＢＥ） 材料生长的一些主要因素进行了细致的分析。利用ＭＢＥ生长出ＧａＡｌＡｓ／ＧａＡｓ 梯度折射率分别限制单量子阱激光器（ＧＲＩＮ－ ＳＣＨ－ ＳＱＷ） 材料。利用该材料制作出的列阵半导体激光器的准连续输出功率达到了６０ Ｗ（ｔ＝ ２００ μｓ,ｆ＝ ５０ Ｈｚ） ,峰值波长为８０８ ．４ ｎｍ 。     

台阶衬底半导体激光器

本文采用平板波导逼近法分析了台阶衬底激光器的波导机理.该激光器是在台阶衬底上通过一步液相外延而制成.提出了附加过冷度的概念和计算公式.获得了基横模稳定工作的台阶衬底激光器.     

980 nm高功率列阵半导体激光器

分析了影响列阵半导体激光器输出功率的因素．利用分子束外延生长方法生长出ＩｎＧａＡｓ／ＧａＡｓ应变量子阱激光器材料．利用该材料制作出的应变量子阱列阵半导体激光器准连续（１００ Ｈｚ,１００ μｓ）输出功率达到 ８０Ｗ（室温）,峰值波长为 ９７８～９８１ｎｍ．     

Reliability of semiconductor lasers used in current communication systems and sensing equipment

The degradation mechanisms that had occurred – but that have now been largely suppressed or eliminated – in established consumer equipment and optical communication systems have also become problems in current optical fiber communication systems. This is due to the requirements of recently developed communication systems for semiconductor lasers, which operate at higher performance levels under severe environmental conditions. In addition, semiconductor lasers have now become important optical sources in new application fields such as sensing equipment, and these new applications have in turn brought new reliability problems to semiconductor lasers. In this paper, the degradation modes and reliability of semiconductor lasers are reviewed and discussed in association with recently developed optical sensing equipment and communication systems.     

Mode-switching in semiconductor lasers

In this paper, we experimentally analyze the modal dynamics of quantum-well semiconductor lasers. Modal switching is the dominant feature for semiconductor lasers that exhibit two or several active longitudinal modes in their time-averaged optical spectrum. In quantum-well lasers, these dynamics involve a periodic switching among several longitudinal modes, which follows a well-determined sequence from the bluest to the reddest mode in the optical spectrum. This feature is radically different from the well-known noise-driven mode-hopping occurring in bulk lasers which involves only two main modes. We analyze the differences in modal dynamics for these two kinds of laser by comparing the modal switching statistics and by studying the effects of noise and modulation in the pumping current.     

Q-switching of semiconductor lasers

A scheme forQ-switching semiconductor lasers is proposed and analyzed. The method is based upon electrooptic switching of the Bragg reflectivity of the grating reflectors forming the cavity of the semiconductor laser. The basic configuration, the operating principles, and the dynamic behavior of these lasers are described. Although the maximum initial inversion in this laser system is limited to a rather low value, the peak output power is found to be higher than the value usually obtained in a CW GaAs double-heterostructure (DH) laser by two orders of magnitude. A pulsewidth shorter than 100 ps is shown to be obtainable.     

Density-matrix theory of semiconductor lasers with relaxation broadening model-gain and gain-suppression in semiconductor lasers

The density-matrix theory of semiconductor lasers with relaxation broadening model is finally established by introducing theoretical dipole moment into previously developed treatments. The dipole moment is given theoretically by thek . pmethod and is calculated for various semiconductor materials. As a result, gain and gain-suppression for a variety of crystals covering wide wavelength region are calculated. It is found that the linear gain is larger for longer wavelength lasers and that the gain-suppression is much larger for longer wavelength lasers, which results in that single-mode operation is more stable in long-wavelength lasers than in shorter-wavelength lasers, in good agreement with the experiments.     

Saturation effects in semiconductor lasers

This paper describes a theory for a semiconductor active medium interacting with a laser field. In a semiconductor laser, the charge carrier transitions are inhomogenously broadened, and electron-electron and electron-phonon collisions tend to dephase the laser transitions and maintain thermal equilibrium among the carriers. These properties cause semiconductor lasers to frequency tune as though they are inhomogeneously broadened and to saturate as though they are homogeneously broadened. A theory that contains these two aspects of semiconductor laser behavior is presented. From it, we are able to calculate the loaded gain, efficiency, intensity, and carrier-induced refractive index of a semiconductor active medium.     

Natural linewidth of semiconductor lasers

A formula is given for the natural linewidth of high-gain lasers, which is applicable to arbitrary three-dimensional geometries. This formula agrees with Petermann's result for lasers with transversely inhomogeneous gains (K-factor) and with previous results for the effect of small mirror reflectivities. It does not agree with the Schawlow-Townes (ST) formula used by most authors in evaluating the ?=?nr/?ni factor of conventional semiconductor lasers. The difference between the two formulas is significant when the mirror power reflectivity is less than about 0.6. Furthermore, the modified formula gives directly the linewidth of lasers coupled to long external cavities. Saturation effects, however, are neglected in this letter.     

High-speed modulation of semiconductor lasers

An overview is given of the direct modulation performance of high-speed semiconductor lasers. The high-speed response characteristics are described using a cascaded two-port model of the laser. This model separates the electrical parasitics from the intrinsic laser and enables these subsections to be considered separately. The presentation concentrates on the small-signal intensity modulation and frequency modulation responses, and the large-signal switching transients and chirping. Device-dependent limitations on high-speed performance are explored and circuit modeling techniques are briefly reviewed.