The principle of the operation of a Gunn laser is based on the band to band recombination of impact
ionized non-equilibrium electron-hole pairs in propagating high field space-charge domains in a
Gunn diode, which is biased above the negative differential resistance threshold and placed in a
Fabry-Perot or a vertical micro cavity (VCSEL).
In conventional VCSEL structures, unless specific measures such as the addition of oxide apertures
and use of small windows are employed, the lack of uniformity in the density of current injected
into the active region can reduce the efficiency and delay the lasing threshold. In a vertical-cavity
structured Gunn device, however, the current is uniformly injected into the active region
independently of the distributed Bragg reflector (DBR) layers. Therefore, lasing occurs from the
entire surface of the device.
The light emission from Gunn domains is an electric field induced effect. Therefore, the operation
of Gunn-VCSEL or F-P laser is independent of the polarity of the applied voltage. Red-NIR
VCSELs emitting in the range of 630-850 nm are also possible when Ga1-xAlxAs (x < 0.45) is used
the active layer, making them candidates for light sources in plastic optical fibre (POF) based short-distance
data communications. Furthermore the device may find applications as an optical clock and
cross link between microwave and NIR communications.
The operation of a both Gunn-Fabry-Perot laser and Gunn-VCSEL has been demonstrated by us
recently. In the current work we present the potential results of experimental and theoretical studies
concerning the applications together with the gain and emission characteristics of Gunn-Lasers.