Birefringence in ordered (Al)GaInP

Abstract

We report on a way to examine the birefringence introduced by chemical ordering in ͑Al͒GaInP using waveguide structures. We find that ordered ͑Al͒GaInP is positively birefringent far below the band gap, while approaching the band gap it becomes negatively birefringent. The dispersion of the measured birefringence is compared with calculations that take into account the strongly anisotropic absorption at the band gap due to the splitting of the valence bands. We will show how the polarization state of light traveling along the ͓011͔ direction in chemically ordered ͑Al͒GaInP waveguides is affected by the reduced crystal symmetry introduced by CuPt B -type ordering. Birefringence leads to a conversion of transverse electric ͑TE͒ and transverse magnetic ͑TM͒ polarized light within 60 m. This can be understood due to new modes in the waveguide, the ''supermodes,'' with an orientation tilted with respect to the TE/TM orientation. In the ͓011͔ direction, the common TE/TM modes stay unchanged. With a simple theory of mode coupling, it is possible to understand the observed polarization behavior. A transfer-matrix method for anisotropic planar waveguides is used to achieve a more detailed analysis. Consequences and possibilities for applications are considered.

Embrittlement of nuclear reactor pressure vessels

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Infrared dielectric function and phonon modes of highly disordered(AlxGa1−xHofmann1, Leibiger2, Gottschalch3 et al. 2001Phys. Rev. B322230View full textAdd to dashboardCite

“…10,16,64 Therefore, the samples chosen here are highly disordered and were studied at visible wavelengths 12 prior to their investigation here. Accurate line-shape analysis of the FIR-SE data is presented.…”

Atomic ordering of AlInP grown by MOVPE using TBP with different V/III ratios in pure ambient N2

“…The lattice symmetry of an ordered alloy reduces from T d (totally disordered) to C 3v (perfectly ordered CuPt-B) [8]. Atomic ordering in the CuPt-B lattice causes many changes in the electronic and optical properties of the III-V semiconductor alloys such as valence band splitting [9], bandgap reduction [10], optical anisotropy [11], second-harmonic generation [12], birefringence [13], and conductivity anisotropy [14]. The degree of ordering in an epitaxial semiconductor film is found to be dependent on the growth conditions.…”