The first question that needs to be answered when it comes to the laser diodes is what it is. Laser diodes have a very important role to play when it comes to modern photonics. This laser diode is mainly used for the purpose of construction and they appear to be pretty similar to the light emitting laser diodes.
Coherent laser light is the product of the laser diode. The first of the laser diodes was invented in the year 1962 by the research team from the General Electric (GE), from when their services are rendered by the different consumer and the industrial products. The recently developed and the pretty famous laser diode is the heterojunction laser diode which won the Nobel Prize for its inventors.
Laser diode characteristics:
There are several types of laser diodes but the following are the laser diode characteristics that differentiate the laser diode from the rest:
- The laser diodes are compact in nature due the fact that it only takes on chip to build a power visible laser diode. This chip has all the features engrossed in it that qualifies it to be a laser. This also makes the process of inserting direct bandgap semiconductor laser into the other instruments less complicated.
- The rate of efficiency when it comes to the laser diode is pretty high. With 50% efficiency level they consume visibly low amount of electricity.
- The laser diodes can also be used as a direct excitation even with small amount of current as a result of which even the conventional circuits could as well supply the laser.
- There is a very good possibility with the laser diode to be modulated directly with the help of the applied current.
- Another important feature of this laser diode is that they come real cheap because of the mass production and they are as well highly reliable as they are high quality laser diode.
- The waist of the really high power laser beam is pretty small this makes it easy for the beam to pass through the small spaces without affecting the surrounding elements.
The laser diode construction:
The manufacturing process of a laser diode is similar to that of any other semiconductor laser, for example the solar cell, the computer chips etc. However there is one major difference when it comes to working with laser diodes which is the presence of the long narrow channels in the laser diodes that exists between the different semi conductor layers which performs the function as a waveguide for the light beam. In the case of the rest of the LEDs, energy is released in the form of the light when electric currents passes through the laser diode, as a result of which the charge carriers combine together from the meeting point of the semiconductor layers. In the case of the laser diode the light beam that is produced is confined to the inside of the waveguide, where they are reflected and amplified till they are forced out through one end.
The different types of the laser diodes:
There are multiple varieties of the laser diodes that one could fine these days. The major difference between the different laser diodes is only the way in which these semiconductor layers are arranged. The basic criteria for differentiating laser diodes are as follows:
- The basic model of this laser diode has two semiconductor layers and they are considered to be inefficient.
- The quality of the laser diode is determined with the help of the increasing number of the semiconductor layers. More the number of semiconductor layers more would be the increase in the power of the laser diode.
- The most commonly found types of the laser diodes are the heterostructure, the quantum well and the distributed feedback.
The different types of the laser diodes are as follows:
1. Small edge emitting laser diodes: these diodes can to the maximum generate up to half a watt of power beam and the beam quality is very high. The emission of this beam might be diverted towards an open area otherwise it might also be coupled right into the single mode fiber. They might be further divided into two types namely the index guiding and the gain guiding.
2. Small laser diodes: they could be made as the distributor Bragg reflector lasers or the distributed feedback lasers. They are capable of achieving single frequency operations. You can also see them combined with the feature of tuning the wavelength many times.
3. External cavity diode lasers: they encompass the laser diode which is considered to be the gain medium here of the laser resonator which is comparatively longer than the other types. This is finished with additional optical element which could also be laser mirror. The linewidth of the emission in this case is often small and the wavelength is also tunable.
4. Slap coupled optical waveguide lasers: the highlighting feature about this type of laser diode is that they contain a gain region which is a multi quantum well. The capability of this type is that it could generate a watt power output and the diffraction of the beam is limited too because circular profile.
5. Broad area laser diodes: it has the capability to generate output up to few watts. However the quality of the beam in this case is not powerful like that of the lower power laser diodes. They are however better than few other types like the diode bars. When the broad area laser diodes are tapered they can produce a laser beam with highly improved quality and brightness.
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