VCSELlähteet

VCSEL sources, also known as Vertical-Cavity Surface-Emitting Lasers, are semiconductor laser diodes that emit light vertically from the surface of the chip. Unlike edge-emitting lasers which produce a beam from the side, VCSELs emit a circular, low-divergence beam from a precisely defined area. This characteristic allows for wafer-level testing and straightforward integration into two-dimensional arrays.

The basic structure of a VCSEL consists of an active region sandwiched between two highly reflective distributed Bragg reflectors (DBRs). These DBRs are composed of multiple alternating layers of different semiconductor materials, forming a resonant cavity. When current is injected into the active region, electrons and holes recombine, producing photons. These photons are reflected back and forth within the cavity, stimulating more photon emission. When the gain within the cavity exceeds the losses, lasing occurs, and a beam of light is emitted perpendicular to the wafer surface.

VCSELs are known for their low threshold current, high modulation speeds, and relative ease of manufacturing. Their surface-emitting nature simplifies packaging and enables the creation of parallel optical links and sensing arrays. Applications for VCSELs are diverse and include optical communication, data storage (like CD/DVD/Blu-ray players), 3D sensing (such as facial recognition and gesture control), proximity sensors, and optical mice. Their ability to be manufactured in large arrays also makes them suitable for high-volume, cost-sensitive applications.