Feasibility study on ultrafast Mach-Zehnder interferometer optical gate switches utilizing intersubband transition in GaN

摘要

The intersubband transition (ISBT) in GaN is expected to be applicable to Tb/s all-optical switches. However, realization of sufficiently strong nonlinear absorption at the communication wavelength is still difficult. Hence, feasibility of Mach-Zehnder interferometer optical gate switches utilizing the refractive index change due to strong intersubband absorption at a longer wavelength has been theoretically investigated. The results suggest that transmission of 1.55-μm signal pulses can be controlled by saturable absorption of 10-pJ control pulses at 1.85 μm. Gate operation even at 1.3 μm is predicted to be possible, although a higher switching energy is required.