Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE
All-optical bistable switching with gain in an InGaAs/GaAs quantum-well waveguide
Ta-Wei Kao, Patrick LiKamWa, Alan Miller, M. Ogawa, Robert M. Park, Paul W. Cooke
Abstract
The gain characteristics of strained layer InGaAs quantum well laser amplifiers grown on GaAs substrates have been characterized using a Ti-sapphire laser in both CW and self-mode- locked configuration. All-optical bistability was achieved in such a device through the nonlinear refractive index that arises as a result of the gain saturation of the diode amplifier at high optical intensities. The Ti-sapphire laser was modified to produce wavelength tunable pulses of the order of 150 fs with a 15 nm spectral bandwidth in order to measure the dynamics of the gain using a time resolved optical pump-probe technique. The gain saturation occurs on the time scale of the pulse width of the laser and the initial recovery is extremely fast. This initial speedy recovery on a time scale of 100 fs is followed by a slower recovery with a time constant of 3 ps followed by a much slower recovery of 500 ps.