GaN-based intersubband transitions for ultrafast optical switching

摘要

Intersubband transitions (ISBTs) in nitride semiconductor quantum wells are a promising technology for realizing all-optical switching devices due to their ultrafast optical response. The ISBTs were achieved at optical communication wavelengths in GaN/AlN quantum wells, and it was shown that the ISBT wavelength is affected by a large built-in filed in the wells. The verification of the ultrafast absorption recovery (150 fs at a wavelength of 4.5 um) and the measurement of the saturation energy (0.5 pJ/μm{sup}2 at 1.48 μm) were carried out. Moreover, the ISBT was observed in a ridge waveguide structure and the insertion loss was measured for a GaN waveguide. Finally, simulation results indicated that the switching is achievable with extinction ratios of more than 10 dB at input pulse energies of 10-25 pJ.