VCSELlähteitä

VCSEL sources, or Vertical-Cavity Surface-Emitting Lasers, are a type of semiconductor laser diode. Unlike edge-emitting lasers that produce a beam from the side of the chip, VCSELs emit a laser beam perpendicular to the surface of the semiconductor wafer. This surface emission allows for wafer-level testing and the fabrication of two-dimensional arrays of lasers, which are key advantages for mass production.

The basic structure of a VCSEL consists of an active region sandwiched between two highly reflective mirrors. These mirrors are typically distributed Bragg reflectors (DBRs), made of alternating layers of semiconductor materials with different refractive indices. The cavity formed between these mirrors is very short, often only a few wavelengths of light. This short cavity leads to a high optical gain and a low threshold current, meaning VCSELs require less power to operate.

One of the prominent features of VCSELs is their circular, low-divergence output beam. This beam can be easily coupled into optical fibers, making them ideal for short-reach optical communication applications, such as in data centers and local area networks. They are also used in sensing applications, like 3D sensing and proximity detection, due to their compact size, low power consumption, and ability to be integrated into arrays. The wavelength of emission can be tuned by modifying the semiconductor materials used in the active region and DBRs, allowing for operation across various parts of the optical spectrum.