Principle of semiconductor laser

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REVIEW: the semiconductor laser on the principle sounds like very large, in fact, a laser diode, as the working substance is a class of lasers to generate stimulated emission using a semiconductor material. If you want to know more about semiconductor lasers , you need to learn from the following aspects, Xiaobian and everyone. The opportunity has a special affinity for the prepared mind. O(∩_∩)O~

1. Semiconductor laser principle - introduction

A semiconductor laser refers to a laser that uses a semiconductor material as a working substance, which is also called a semiconductor laser diode (LD).

It is a laser developed in the 1960s. Semiconductor lasers are small in size, light in weight, reliable in operation, low in power consumption, high in efficiency, etc. They are widely used in optical fiber communication, optical discs, laser printers, laser scanners, laser pointers (laser pens), military fields, such as laser guidance tracking. , laser radar, laser fuze, optical ranging, laser communication power, laser analog weapons, etc.

2. Semiconductor laser principle - basic structure

A semiconductor laser is an optoelectronic device capable of emitting coherent radiation under the direction of current injection (the phases are the same, the wavelengths are substantially the same, and the intensity is large), and the structure thereof is as shown in the following figure. The shape and size are similar to those of a small power semiconductor transistor, with only one laser output window on the housing. The P region and the N region sandwiching the junction region are layered, and the junction region has a thickness of several tens of micrometers and an area of ​​less than about 1 mm 2 .

3. Semiconductor laser principle - generation principle

A semiconductor laser is a kind of coherent radiation source. It mainly relies on injecting carriers. To make it produce lasers, three basic conditions must be met:

1) doped by a high concentration PN junction is formed a forward injection carrier distribution hair turn the upper state population of particles a sufficient number of the lower state of stimulated emission dominates, i.e., greater than in;

2) has a cavity suitable feedback can play the proliferation of stimulated emission by the photon, thereby generating a laser oscillation;

3) forward current density reaches or exceeds the threshold, i.e., the gain loss at least equal to or greater than the gain photon photon loss.

Simply put, the three elements of work: by laser radiation, resonant cavity, gain greater than or equal to loss.

4. Semiconductor laser principle - working principle

The working principle of a semiconductor laser is to achieve a non-equilibrium load between a band of a semiconductor material (a conduction band and a valence band), or an energy band of a semiconductor substance and an impurity (acceptor or donor) level by a certain excitation method. The number of particles of the flow is reversed, and when a large number of electrons and holes in the state of the number of particles are recombined, a stimulated emission is generated to generate a laser. There are three main ways in which semiconductor lasers generate excitations: electro-injection, optical pump, and high-energy electron beam excitation:

1) Electrospray semiconductor lasers are generally semiconductor junction diodes made of materials such as GaAS (gallium arsenide), InAS (indium arsenide), and Insb (indium bismuth), which are excited by forward bias injection current. Generates stimulated emission in the junction plane region.

2) Optically pumped excitation semiconductor lasers generally use N-type or P-type semiconductor single crystals (GaAS, InAs, InSb, etc.) as working substances, and lasers emitted from other lasers as optical pump excitation.

3) High-energy electron beam-excited semiconductor lasers generally use N-type or P-type semiconductor single crystals (PbS, CdS, ZhO, etc.) as working substances, and are excited by externally injecting high-energy electron beams.

The above is some simple introductions about semiconductor lasers. I hope to help everyone. There are many related knowledge. Xiaobian carefully selected four articles on semiconductor lasers. I hope that everyone can learn more and strengthen the understanding of semiconductor lasers. . .

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