Epitaxial growth of inverted GaP for quasi phase matching nonlinear optical devices

GaP is an attractive material for quadratic nonlinear optical devices because of its large nonlinearity, wide transparency range in infrared region, high thermal conductivity and potential for monolithic integration with electronic/photonic semiconductor devices. Very small two-photon absorption coefficient (0.01 cm/GW at 1.064 mum) compared to that of GaAs (25 cm/GW at 1.064 mum) will open up high-power applications in the near infrared region. To achieve quasi phase matching (QPM) indispensable for isotropic nonlinear optical materials, it is essential to fabricate periodic spatially-inverted crystals. To fabricate inverted crystals, the authors have developed an epitaxial growth technique, sublattice reversal epitaxy, for growing inverted III-V semiconductors by inserting a thin intermediate layer of group-IV atoms. The authors have shown that sublattice reversal (i.e. spatial inversion) at GaAs can be achieved and fabricated QPM AlGaAs waveguiding devices. In this paper, the first successful sublattice reversal achieved for GaP is reported.