Birefringence of GaN/AlGaN optical waveguides

This is the published version. Copyright © 2003 American Institute of PhysicsWe have experimentally studied the birefringence of wurtzite GaNgrown on a sapphire substrate. The measurements were done with single-mode GaN/AlGaN planar optical waveguides on c-plane grownheterostructure films. The refractive indices were found to be different for signal optical field perpendicular or parallel to the crystal c axis (n⊥≠n∥). More importantly, we found an approximately 10% change in index difference Δn=n∥−n⊥ with variation of the waveguide orientation in the a–b plane, and a 60° periodicity was clearly observed. This is attributed to the hexagonal structure of nitride materials

GaN-based waveguide devices for long-wavelength optical communications

This is the published version. Copyright © 2003 American Institute of PhysicsRefractive indices of AlxGa1−xN with different Al concentrations have been measured in infrared wavelength regions. Single-mode ridged optical waveguidedevices using GaN/AlGaN heterostructures have been designed, fabricated, and characterized for operation in 1550 nm wavelength window. The feasibility of developing photonic integrated circuits based on III-nitride wide-band-gap semiconductors for fiber-optical communications has been discussed

III-nitride-based planar lightwave circuits for long wavelength optical communications

Abstract—Planar lightwave circuits based on III-nitride widebandgap semiconductors are proposed and the feasibility of developing III-nitride-based novel photonic integrated circuits for applications in fiber-optical communications is discussed. III-nitrides have low attenuation in the near-infrared wavelength region because of their wide bandgaps, while as semiconductors their refractive indexes can be modulated by carrier injection. III-nitrides are also well known for their ability to operate at high temperatures, high power levels and in harsh environments. These characteristics make III-nitrides ideal candidates for tunable optical phased-array (PHASAR) devices for optical communications.We have characterized the optical properties of Al Ga1 N epilayers in the 1550-nm wavelength region, including the refractive indexes and the impact of Al concentrations. Single-mode ridged optical waveguide devices using GaN–AlGaN heterostructures have been designed, fabricated and characterized for operation in the 1550-nm wavelength window. The birefringence of wurtzite GaN grown on sapphire substrate has been observed. Refractive indexes were found to be different for signal optical field perpendicular and parallel to the crystal axis ( =). More importantly, we found an approximately 10 % change in the index difference 1 = with varying the waveguide orientation within the plane, and a 60 periodicity was clearly observed. This is attributed to the hexagonal structure of the nitride materials.Various functional waveguide devices have been realized, including 2 2 directional couplers and eight-wavelength array-waveguide gratings. Theoretical predictions of temperature sensitivity and the efficiency of carrier-induced refractive change are provided. Index Terms—Integrated optics, optical communication, planar waveguides, semiconductor devices, semiconductor materials, semiconductor waveguides, wavelength division multiplexing. I