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Surface-emitting Semiconductor Lasers

Acronym: VCSEL, VECSEL (see below for the distinction of those)

Definition: semiconductor lasers where the generated light propagates in the direction perpendicular to the wafer surface

More general term: semiconductor lasers

More specific terms: vertical cavity surface-emitting lasers, vertical external cavity surface-emitting lasers

German: oberflächenemittierende Laser

Categories: optoelectronics, lasers

How to cite the article; suggest additional literature


Semiconductor lasers can be grouped into two classes:

  • Edge-emitting lasers, where the laser light propagates parallel to the wafer surface of the semiconductor chip and is reflected or coupled out at a cleaved edge.
  • Surface-emitting lasers, where the light propagates in the direction perpendicular to the semiconductor wafer surface.

Surface-emitting lasers are the newer type of semiconductor lasers. A major challenge is to reach the laser threshold, because the optical gain for the intracavity laser beam occurs only on a very small distance (in one or several quantum wells) and is therefore at most a few percent, often even below 1%. It is therefore necessary to realize a laser resonator with very low losses, i.e., Bragg mirrors with high reflectivity.

Surface-emitting semiconductor lasers are further subdivided into monolithic and external-cavity devices:

An advantage particularly of VCSELs is that many lasers can be fabricated on a single chip. After epitaxial growth, the chip only has to be sliced, and the single lasers can be packaged without further processing optical interfaces.

The VCSEL concept also allows the fabrication of two-dimensional laser arrays for much higher total output powers.

Vertical emission of light can also be achieved with a kind of laser diode which is based on a waveguide along the chip surface (as in an edge-emitting laser), but emits in the vertical direction because the light is reflected upward with a 45° mirror (horizontal cavity surface-emitting laser, HCSEL). This approach makes it possible to combine some of the advantages of edge-emitting and surface-emitting lasers.


The RP Photonics Buyer's Guide contains 11 suppliers for surface-emitting semiconductor lasers. Among them:

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[1]K. Iga et al., “Surface emitting semiconductor lasers”, IEEE J. Quantum Electron. 24 (9), 1845 (1988), doi:10.1109/3.7126
[2]M. Kuznetsov et al., “High-power (> 0.5-W CW) diode-pumped vertical-external-cavity surface-emitting semiconductor lasers with circular TEM00 beams”, IEEE Photon. Technol. Lett. 9 (8), 1063 (1997), doi:10.1109/68.605500
[3]K. Iga, “Surface-emitting laser – its birth and generation of new optoelectronics field”, J. Sel. Top. Quantum Electron. 6 (6), 1201 (2000), doi:10.1109/2944.902168
[4]S. Hoogland et al., “Passively mode-locked diode-pumped surface-emitting semiconductor laser”, IEEE J. Photon. Technol. Lett. 12 (9), 1135 (2000), doi:10.1109/68.874213
[5]A. C. Tropper et al., “Vertical-external-cavity semiconductor lasers”, J. Phys. D: Appl. Phys. 37, R75 (2004) (a good review), doi:10.1088/0022-3727/37/9/R01
[6]D. Lorenser et al., “Towards wafer-scale integration of high repetition rate passively mode-locked surface-emitting semiconductor lasers”, Appl. Phys. B 79, 927 (2004), doi:10.1007/s00340-004-1675-3

(Suggest additional literature!)

See also: semiconductor lasers, vertical cavity surface-emitting lasers, vertical external-cavity surface-emitting lasers, edge-emitting semiconductor lasers
and other articles in the categories optoelectronics, lasers


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