Simulation of Interferometer-Type Ultrafast All-Optical Gate Switches Based on Intersubband Transition in GaN/AlGaN Multiple Quantum Wells

Nobuo SUZUKI  

IEICE TRANSACTIONS on Electronics   Vol.E85-C   No.1   pp.174-180
Publication Date: 2002/01/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Ultrafast Optical Signal Processing and Its Application)
Category: Ultrafast All-Optical Switching, Optical Delay and Waveform Control
optical switch,  intersubband transition,  short pulse,  nonlinear optical waveguide,  FDTD,  

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Although all-optical gate switches based on the intersubband absorption in nitride quantum wells are predicted to operate at 1 Tb/s, realization of strong intersubband absorption at the optical communication wavelength is still difficult. An alternative approach is an interferometer-type gate switch utilizing refractive index change due to the intersubband absorption of a control pulse at a longer wavelength. Feasibility of Mach-Zehnder interferometer (MZI) gate switches, in which 1.55-µm pulses are controlled by 1.85-µm pulses, was theoretically investigated by finite-difference time-domain (FDTD) simulator. Although the effective phase shift does not reach π, 22.5% of the signal pulse energy was predicted to be gated by a 10-pJ control pulse in the MZI switch. Even 1.3-µm pulses can be controlled by 1.85-µm pulses at the expense of the switching energy. This approach provides a way to process signal pulses at the optical communication wavelength utilizing strong intersubband absorption at a longer wavelength.