CdTe:V and CdTe:Ge for Homodyne Optical Detection at 1.06um

A light induced phase grating in photorefractive crystals couple the optical fields of the pump and signals beam in a very similar way as a beam splitter combines the signal and local optical fields in a coherent optical communications receiver. The advantages of photorefractive crystals are: 1) the absence of 3db loss in the output intensity of the signal beam unlike in the case of 50/50 beam splitter and, 2) Ease of wave front alignment of the pump and signal beams. Using a InP as a photorefractive crystal these advantages have been demonstrated by Davidson et al [1]. Photorefractive gain in InP is very sensitive to temperature and is reduced due to the electron-hole competition [2] in the crystal. Photorefractive sensitivity of both CdTe:V and CdTe:Ge is better by about a factor of three the photorefractive beam coupling experiments in these crystals indicate absence of electron-hole competition mechanism. Optimizing the photorefractivity in CdTe:V, Ge will improve the homodyne detection at 1.06 micrometer. Moreover, the spin off of this development will be their applications to build optical components like phase conjugations for near IR wavelengths, optical limiters and optical switches.