LOW-TEMPERATURE BIREFRINGENCE IN ORDERED GAINP ALLOY STUDIED BY POLARIZED TRANSMISSION SPECTROSCOPY

The low-temperature birefringence of spontaneously ordered GaInP is st udied by using polarized transmission spectroscopy at 5 K. Refractive indexes n(o), n(e) and the birefringence Delta n(oe) = n(o)-n(e) are o btained by applying two independent techniques: (1) measuring the pola rized transmission spectra with polarization parallel to each of the t wo cleaved edges individually; and (2) measuring one transmission spec trum with a crosspolarization configuration. The results of these two techniques are consistent, and both give Delta n(oe) similar to 0.02 n ear the band-gap of partially ordered GaInP. Exact and approximate for mulae have been derived for analyzing the cross-polarization spectrum. A possible device-polarization rotator-is proposed based on the in-pl ane birefringence. (C) 1997 Elsevier Science Ltd.