Innovations in Semiconductor lasers

The semiconductor laser uses a single-crystal semiconductor material as the active medium, stimulating emission at the transition between quantum energy levels in regions with a high concentration of free charge carriers to produce optical amplification.

FREMONT, CA: There has been a proliferation of uses for laser technology since its inception in the 1960s. There are many traditional and novel applications for laser technologies today. Among the uses are material processing, optical communications, automotive front illumination, medical surgery, and 3D sensing. There are numerous lasers in the laser landscape, including diode lasers, fiber lasers, DPSSLs, CO2 lasers, and excimer lasers. Traditional applications include the industrial, scientific, and consumer sectors, but many applications, such as the military and the medical fields, replace conventional methods.

Semiconductor lasers are quantum generators based on an active medium of single-crystal semiconductor material, in which optical amplification is achieved by stimulated emission at the transition between quantum energy levels in regions with a large concentration of free charge carriers.

The edge-emitting laser is a well-established, decades-old concept for semiconductor lasers. In a waveguide structure parallel to the semiconductor surface, light is emitted from the cavity mirror-like edges of the semiconductor chip. A significant gain and high output powers can be produced with a somewhat lengthy active area of hundreds of micrometers to a few millimeters. Edge-emitting lasers (EELs) that are electrically pumped are compact, cost-effective laser emission sources applicable in various applications.

Vertical-cavity surface-emitting lasers (VCSELs) emit light perpendicular to the surface of the semiconductor instead of edge-emitting lasers. The vertical cavity consists of two dispersed Bragg mirrors with alternating layers of high- and low-refractive-index material with a quarter of the laser wavelength in thickness. Quantum wells or quantum dots electrically pumped in the active region between monolithically fabricated semiconductor mirrors result in single longitudinal mode functioning. VCSELs can emit lasers in single-transverse mode due to their oxide apertures, which constrain the current and the optical field.

Why are VCSELs so advantageous for 3D sensing?

Various infrared light sources, including LEDs, edge emitters, and VCSELs, could be utilized in Yole. LEDs are mature, inexpensive, and simple to manufacture. Typically, they are employed for 2D sensings, such as in driver monitoring systems. Edge emitters and VCSELs, on the other hand, are ideal light sources for 3D sensing, and the selection of one source over another will depend primarily on the output power required by the application. Time-of-Flight (ToF) applications require pulse speeds on the order of a millisecond, which VCSELs may provide. Yole Développement (Yole) predicts that the VCSEL market will increase from $794 million in 2021 to $1,742 million in 2026.