Over the last decade, III-nitride materials have occupied the central stage in the semiconductor research with a predominant focus on applications as photonic devices operating in the visible and UV regions. The PI systematically investigated the properties of IIInitrides operating in the near infrared wavelength region, including refractive indices, optical losses, birefringence and temperature sensitivities. He has developed various photonic devices based on AlGaN/GaN planar lightwave circuits, such as waveguide couplers and array waveguide gratings (AWG) operating in 1550nm wavelength.
Since III-nitrides are semiconductor materials, carrier injection can be used to modulate the refractive index and to change the phase delay of the waveguide. Adding an electrode on each interference arm of an AWG made by AlGaN/GaN p-i-n heterojunction, for example, could make a wavelength demultiplexer switchable at high speed. Obviously, carrier-induced index change is a key step toward a real functional device for high-speed all-optical packet switch. He proposes to design, develop and optimize AlGaN/GaN-based p-i-n heterojunction structure in planar lightwave circuits to realize carrier injection and index tuning. The theoretical work will be focused on the p-i-n heterojunction structural design and the efficiency of carrier-induced index change, including bandfilling, bandgap-shrinkage and free-carrier absorption. The experimental work will concentrate on the fabrication, characterization and optimization of the AlGaN/GaN-based p-i-n heterojunction waveguide devices.
The intellectual merit of this proposal lies in the introduction of a new material group for applications in optical communications. Fast tuning of refractive index by carrier injection is the key to realize high-speed optical switch.
The broader impact of this proposal is two-fold. From the application point of view, the result of this research will enable a wide array of applications, which will have enormous impact in optical communications. From the material science point of view, a much greater and fundamental understanding will be gained for III-nitride semiconductors in terms of their optical and physical properties.
The unique properties of III-nitrides make them attractive for guiding and switch of light in the infrared wavelength region for optical communications, which may allow the creation of photonic devices with unprecedented properties and functionalities.
