Optical time division multiplexed networks for multi-terabit communication links require ultra-fast all optical switches to be feasible. This program will demonstrate an enabling technology, intersubband transitions in AlyGa1-yN/GaN multiple quantum wells (MQWs), that will permit the construction of terabit/sec switches at telecommunication wavelengths. The ultra-fast nature of the intersubband transition (~80 fs) is approximately three orders of magnitude faster than the carrier lifetime, and the wide band gap of the nitride materials offer advantages that make similar intersubband devices constructed out of other material systems impractical. All of these transitions and devices discussed are viable at room temperature. The thrust of this Phase I proposal is to validate the materials science that will enable the above technological applications. The proposed growth method for these structures, Atomic Layer Epitaxy (ALE), has distinct advantages over other more standard growth methods, including precision control of layer thickness and uniformity. Upon verification of the optical properties, optical switches will then be fabricated and characterized. The principal investigators will use their combined and extensive experience in the ALE growth technique, and nitride material characterization to demonstrate AlyGa1-yN/GaN (0.7 < y < 1.0) multiple quantum wells (MQWs) that exhibit intersubband transitions at telecommunications infrared wavelengths. Anticipated Benefits and
Potential Commercial Applications: A successful SBIR program will validate the potential of AlGaN/GaN MQW optical switches for ultra-fast terabit/sec, all optical switches. In addition to long haul telecommunication applications, the proposed AlGaN/GaN intersubband modulator has potential applications in avionics or other systems where ultrahigh bandwidth data networks are required. A large spin off benefit of this technology is that other multiple quantum well devices that have been previously realized in other materials systems, such as quantum cascade lasers, and intersubband photodetectors can then fabricated in the nitride material system.
