Vertical-cavity surface-emitting laser

Thus, although the VCSEL production process is more labor and material intensive, the yield can be controlled to a more predictable and higher outcome.

In common VCSELs the upper and lower mirrors are doped as p-type and n-type materials, forming a diode junction.

In laboratory investigation of VCSELs using new material systems, the active region may be pumped by an external light source with a shorter wavelength, usually another laser.

The GaAs–AlGaAs system is favored for constructing VCSELs because the lattice constant of the material does not vary strongly as the composition is changed, permitting multiple "lattice-matched" epitaxial layers to be grown on a GaAs substrate.

However, the refractive index of AlGaAs does vary relatively strongly as the Al fraction is increased, minimizing the number of layers required to form an efficient Bragg mirror compared to other candidate material systems.

Any slight variation in aluminium would change the oxidation rate sometimes resulting in apertures that were either too big or too small to meet the specification standards.

The small active region, compared to edge-emitting lasers, reduces the threshold current of VCSELs, resulting in low power consumption.

High-power vertical-cavity surface-emitting lasers can also be fabricated, either by increasing the emitting aperture size of a single device or by combining several elements into large two-dimensional (2D) arrays.

[10] Improvements in the epitaxial growth, processing, device design, and packaging led to individual large-aperture VCSELs emitting several hundreds of milliwatts by 1998.

[11] More than 2 W continuous-wave (CW) operation at -10 degrees Celsius heat-sink temperature was also reported in 1998 from a VCSEL array consisting of 1,000 elements, corresponding to a power density of 30 W/cm2.

A record 3 W CW output power was reported in 2005 from large diameter single devices emitting around 980 nm.

Examples of such applications are: The surface emission from a bulk semiconductor at ultra-low temperature and magnetic carrier confinement was reported by Ivars Melngailis in 1965.

In 1979, a first demonstration on a short cavity VCSEL was done by Soda, Iga, Kitahara and Suematsu,[21] but devices for CW operation at room temperature were not reported until 1988.

[23] In 1989, Jack Jewell led a Bell Labs / Bellcore collaboration (including Axel Scherer, Sam McCall, Yong Hee Lee and James Harbison) that demonstrated over 1 million VCSELs on a small chip.