2. Optoelectronics, the rapid development mainly based on quantum mechanics and materials science in the development, with particular attention is the development of optoelectronic semiconductors. LED, LD Shenqi these electronic devices is the result of this development, particularly the recent development of the organic photoelectric materials, and more is great to promote the progress of the photoelectric materials.
Why is the first semiconductor LED »
When the electronic conduction band jumped from the top to enter the zone at the time, a certain loss of energy, the energy becomes a photon emission out, is popular to say that the luminescence. Oh:) semiconductor laser is a direct bandgap semiconductor materials constitute the PN junction of material or PIN entered into a small laser. Semiconductor laser work of dozens of substances, has made laser Jia arsenide semiconductor material (GaAs), arsenic Gu (InAs), gallium nitride (GaN), antimony and Gu (InSb), curing the pot (cds), hoof-fu (CdTe), lead selenide (PbSe), tellurium and lead (PhTe ), Al Jia arsenic (A1xGa, -, As), Gu phosphorus arsenic (In-PxAS), and so on. Semiconductor laser incentive There are three main ways, that is, people-Note, optical pump-and-high-energy electron beam incentives. The vast majority of Semiconductor laser is the way of incentives, Notes, or to Pn guitar and forward voltage, so that the guitar in a regional plane stimulated emission, that is a positive bias of the diodes, also known as the semiconductor laser diode laser diode . On the semiconductor, electronics is due in the transition between the band, rather than in discrete energy levels between the transition, the transition energy is not a set value, which makes semiconductor laser output wavelength distribution in a very broad The scope. They issued by the wavelength of between 0.3-34um. Wavelength range of its decision on the materials used by the band gap, the most common is AlGaA: double-heterojunction laser, the output wavelength of 750 - 890nm. The world On the first semiconductor laser is available in 1962, after several decades of research, semiconductor laser achieved a surprising development, and its infrared wavelengths from the red light green to blue, gradually expanding the scope covered, the performance Parameters also have greatly increased their production by the proliferation of technology has to LPE Law Act (LPE), extension of gas (VPE), MBE Act (MBE), MOCVD method (metal organic compounds vapor deposition) , Chemical beam epitaxy (CBE) and their various combined, and other technology. Lasing closure of its current value from a few hundred mA down to a few dozen mA, until the sub-mA, its life expectancy by a few hundred to tens of thousands of hours, and 1 million hours from the initial low-temperature (77 K) under development to operate at room temperature for work, the power output by several milliwatts to kilowatts level (Array) it has a high efficiency, small size, light weight, simple structure, can Power for the direct conversion of laser energy, high power conversion efficiency (has reached more than 10 per cent, up to 50 per cent). Facilitate direct modulation, power-saving advantages, applications growing. At present, the fixed-wavelength laser diode to use the number of Habitat All of the first laser, the application of certain important areas over the past used the other lasers, has gradually been replaced by a semiconductor laser.
Semiconductor Laser is the biggest drawback: laser properties affected by temperature, the beam divergence angle greater (in general several times to 20 degrees), so in the direction and coherence of monochrome and other poor areas. But with the With the rapid development of science and technology, the semiconductor laser-depth study positive direction, the performance of semiconductor laser continuously improve. Semiconductor laser power can reach very high level, and beam quality has been greatly improved. Semiconductor laser as to The core semiconductor photonics technology in the 21st century information society will make more progress, play a bigger role.
半导体激光二极管的基本结构：垂直于PN结面的一对平行平面构成法布里——珀罗谐振腔，它们可以是半导体晶体的解理面，也可以是经过抛光的平面。其余两侧面则相对粗糙，用以消除主方向外其它方向的激光作用。
半导体中的光发射通常起因于载流子的复合。当半导体的PN结加有正向电压时，会削弱PN结势垒，迫使电子从N区经PN结注入P区，空穴从P区经过PN结注入N区，这些注入PN结附近的非平衡电子和空穴将会发生复合，从而发射出波长为λ的光子，其公式如下：
λ = hc/Eg ⑴
式中：h—普朗克常数； c—光速； Eg—半导体的禁带宽度。
上述由于电子与空穴的自发复合而发光的现象称为自发辐射。当自发辐射所产生的光子通过半导体时，一旦经过已发射的电子—空穴对附近，就能激励二者复合，产生新光子，这种光子诱使已激发的载流子复合而发出新光子现象称为受激辐射。如果注入电流足够大，则会形成和热平衡状态相反的载流子分布，即粒子数反转。当有源层内的载流子在大量反转情况下，少量自发辐射产生的光子由于谐振腔两端面往复反射而产生感应辐射，造成选频谐振正反馈，或者说对某一频率具有增益。当增益大于吸收损耗时，就可从PN结发出具有良好谱线的相干光——激光，这就是激光二极管的简单原理。 随着技术和工艺的发展，多层结构。
常用的激光二极管有两种：①PIN光电二极管。它在收到光功率产生光电流时，会带来量子噪声。②雪崩光电二极管。它能够提供内部放大，比PIN光电二极管的传输距离远，但量子噪声更大。为了获得良好的信噪比，光检测器件后面须连接低噪声预放大器和主放大器。
半导体激光二极管的工作原理，理论上与气体激光器相同。 ⑴波长：即激光管工作波长，可作光电开关用的激光管波长有635nm、650nm、670nm、690nm、780nm、810nm、860nm、980nm等。
⑵阈值电流Ith ：即激光管开始产生激光振荡的电流，对一般小功率激光管而言，其值约在数十毫安，具有应变多量子阱结构的激光管阈值电流可低至10mA以下。
⑶工作电流Iop ：即激光管达到额定输出功率时的驱动电流，此值对于设计调试激光驱动电路较重要。
⑷垂直发散角θ⊥：激光二极管的发光带在垂直PN结方向张开的角度，一般在15˚~40˚左右。
⑸水平发散角θ∥：激光二极管的发光带在与PN结平行方向所张开的角度，一般在6˚~ 10˚左右。
⑹监控电流Im ：即激光管在额定输出功率时，在PIN管上流过的电流。
激光二极管在计算机上的光盘驱动器，激光打印机中的打印头，条形码扫描仪，激光测距、激光医疗，光通讯，激光指示等小功率光电设备中得到了广泛的应用，在舞台灯光、激光手术、激光焊接和激光武器等大功率设备中也得到了应用。
半导体激光器又称激光二极管，是用半导体材料作为工作物质的激光器。由于物质结构上的差异，不同种类产生激光的具体过程比较特殊。常用工作物质有砷化镓（GaAs）、硫化镉（CdS）、磷化铟(InP)、硫化锌(ZnS)等。激励方式有电注入、电子束激励和光泵浦三种形式。 半导体激光器件，可分为同质结、单异质结、双异质结等几种。同质结激光器和单异质结激光器在室温时多为脉冲器件，而双异质结激光器室温时可实现连续工作。半导体二极管激光器是最实用最重要的一类激光器。它体积小、寿命长，并可采用简单的注入电流的方式来泵浦，其工作电压和电流与集成电路兼容，因而可与之单片集成。并且还可以用高达GHz的频率直接进行电流调制以获得高速调制的激光输出。由于这些优点，半导体二极管激光器在激光通信、光存储、光陀螺、激光打印、测距以及雷达等方面得到了广泛的应用。欢迎分享，转载请注明来源：内存溢出
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