28 March 2000 Intersubband transition in AlGaN-GaN quantum wells for ultrafast all-optical switching at communication wavelength
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Proceedings Volume 3940, Ultrafast Phenomena in Semiconductors IV; (2000) https://doi.org/10.1117/12.381452
Event: Symposium on Integrated Optoelectronics, 2000, San Jose, CA, United States
Abstract
The intersubband transition (ISBT) in nitride quantum wells (QWs) is considered to be an excellent device mechanism for ultrafast optical switches capable of 1 Tb/s operation at room temperature. The 1.55-micrometers ISBT is feasible because of a large (approximately 2 eV) conduction band discontinuity in AlGaN/GaN QWs. The intersubband relaxation time in AlGaN/GaN QWs was calculated to be about 100 fs, which is 25 times shorter than that in AlAs/(In)GaAs QWs. The fast relaxation in nitride semiconductors is due to the strong interaction between electrons and LO-phonons. Intersubband absorption in the wavelength range of 3 - 7 micrometers was observed in MOCVD-grown AlGaN/GaN QWs, and the ultrafast response of the ISBT in nitrides was experimentally verified. The ISBT wavelength in the nitride QWs, however, was found to be affected by a strong built-in field (approximately MV/cm) caused by the spontaneous polarization and piezoelectric effect. A design to realize the ISBT at the communication wavelength in AlGaN/GaN QWs with a strong built-in field is discussed. Next, we report on an ultrashort pulse propagation model for nonlinear optical waveguides utilizing the intersubband absorption in AlGaN/GaN QWs. The finite-difference time-domain approach in conjunction with the rate equations describing the ISBT was adopted. Ultrafast optical gate operation in the waveguide was simulated.
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Nobuo Suzuki, Nobuo Suzuki, Norio Iizuka, Norio Iizuka, Kei Kaneko, Kei Kaneko, } "Intersubband transition in AlGaN-GaN quantum wells for ultrafast all-optical switching at communication wavelength", Proc. SPIE 3940, Ultrafast Phenomena in Semiconductors IV, (28 March 2000); doi: 10.1117/12.381452; https://doi.org/10.1117/12.381452
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