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VCSEL laser diode advantages and classification.

2021-11-24
The full name of VCESL is a vertical cavity surface emitting laser, which is a semiconductor laser structure in which an optical resonant cavity is formed in the direction perpendicular to the semiconductor epitaxial wafer and the laser beam emitted is perpendicular to the surface of the substrate. Compared with LEDs and edge-emitting lasers EEL, VCSELs are superior in terms of accuracy, miniaturization, low power consumption, and reliability.

product advantages
Compared with the performance of other semiconductor lasers, the advantages of VCSEL are as follows:
1. The outgoing beam is circular, has a small divergence angle, is easy to couple with optical fibers and other optical components, and has high efficiency.
2. It can realize high-speed modulation and can be applied to long-distance, high-speed optical fiber communication systems.
3. The active area is small in size, and it is easy to achieve single longitudinal mode and low threshold operation.
4. The electro-optical conversion efficiency can be greater than 50%, and the expected working life is 100,000 hours or more.
5. Easy to realize two-dimensional array, apply to parallel optical logic processing system, realize high-speed, large-capacity data processing, and can be applied to high-power devices.
6. The chip can be tested before the device is packaged, and the product can be screened, which greatly reduces the cost of the product.
7. It can be applied to laminated optical integrated circuits, and can also use micro-machinery and other technologies.

Classification
1. Classified according to structure
VCSEL devices are divided into top-emitting structure and bottom-emitting structure according to their structure.
The top-emitting structure is grown on an n-type GaAs substrate using MOCVD technology, using DBR as a laser cavity mirror, and the quantum well active region is sandwiched between n-DBR and p-DBR.
The bottom emission structure is generally used to produce the 976-1064nm band. The substrate is usually thinned to less than 150μm to reduce the absorption loss of the substrate, and then a layer of anti-reflection coating is grown to improve the quality of the laser beam. Finally, the gain chip is mounted on the heat sink superior.
2. Classified by application
VCSEL can be divided into PS series, TOF series, SL series according to application.
PS series VCSEL is a low-power VCSEL chip that can be used in the field of proximity sensors to replace traditional LED light sources. Application fields include short-distance sensing, 3D sensing, biomedicine, etc.
The TOF series VCSEL can restore the 3D shape of the light source through time-of-flight sensing technology (D-TOF, i-TOF), and its application fields include face recognition, auxiliary camera, lidar, AR/VR, etc.
The SL series VCSEL is a structured light (SL) VCSEL laser, which calculates the distance, shape and other information of the object by analyzing the deformation of the reflected light spot of the illuminated object. The application fields include face recognition, AR/VR, etc.
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