Vertical-cavity surface-emitting laser

Simple vcsel

Real vcsel

Vertical-cavity surface-emitting laser (VCSEL) is a type of semiconductor laser diode with laser beam emission perpendicular to the top surface, contrary to conventional edge-emitting lasers which emit from surfaces formed by cleaving the individual chip out of a wafer. VCSELs are used in various applications including fiber optic communication, laser printers, optical mice, and biomedical devices.

Structure and Operation

VCSELs consist of a p-n junction sandwiched between two distributed Bragg reflector (DBR) mirrors. The DBR mirrors are made of alternating layers of materials with different refractive indices, creating a high reflectivity mirror. The active region, where the light is generated, is located between these mirrors. When a current is applied, electrons and holes recombine in the active region, emitting light. The light is then amplified as it bounces between the DBR mirrors and eventually exits perpendicular to the surface.

Advantages

VCSELs offer several advantages over traditional edge-emitting lasers:

• Low manufacturing cost: VCSELs can be tested on the wafer before being cut into individual devices, reducing the cost of production.
• High efficiency: They have lower threshold currents and higher power conversion efficiency.
• Ease of packaging: The vertical emission allows for simpler and more compact packaging.
• Wavelength stability: VCSELs exhibit less wavelength shift with temperature changes compared to edge-emitting lasers.

Applications

VCSELs are widely used in various fields:

• Fiber optic communication: They are used in data transmission over optical fibers due to their high speed and efficiency.
• Laser printers: VCSELs are used in the printing process to create high-resolution images.
• Optical mice: They provide precise tracking by emitting light that reflects off surfaces.
• Biomedical devices: VCSELs are used in medical imaging and diagnostic equipment.

Related Technologies

• Edge-emitting laser
• Distributed feedback laser
• Quantum cascade laser
• Light-emitting diode

See Also

• Semiconductor laser
• Optoelectronics
• Photonics
• Laser diode