Novel light emitter and wavelength converter device

We present a structure which is capable of being fabricated into two distinct devices, both with considerable potential in the field of optical communications in particular with reference to wavelength domain multiplexing. The structure is based on two back to back p-i-n GaxAl 1-xAs structures with a single quantum well of GaAs in each intrinsic region. The light emitter device operates by forward biasing either of the p-i-n elements. In forward bias holes flood into the quantum well in the intrinsic region. Electrons are prevented from doing so by a potential barrier. A longitudinal electric field applied along the central n-doped region heats the electrons in this region and gives them sufficient energy to overcome the barrier and flood into the quantum well and hence recombine with holes which are already present. The wavelength converter device operates with one p-i-n structure forward biased and one reverse biased. The forward biased element has a quantum well positioned near the p-doped region. Light of the appropriate wavelength is absorbed in this quantum well. The holes scatter out of the quantum well and drift into the p- doped region. The electrons are scattered out of the quantum well and drift towards the n-doped region, creating additional carriers through impact ionization, thereby creating gain. The electrons flooding over the n-doped region, must overcome a potential barrier to enter the forward biased element, therefore cold electrons are prevented from entering this region. Electrons which are able to overcome the barrier fall into a quantum well positioned near the barrier, where holes are already waiting, as in the light emitting device. ©2003 Copyright SPIE - The International Society for Optical Engineering.