Ultrafast optical nonlinearity of low-temperature-grown GaInAs/AlInAs quantum wells at a wavelength of 1.55 /spl mu/m

Summary form only given. Materials with ultrafast response times and high optical nonlinearities are crucial for future Tbit/s fiber-based communication systems. One possibility to achieve ultrafast response times is using defect-rich bulk and low-dimensional III/V materials, which can be realized by molecular beam epitaxy (MBE) at low growth temperatures (LT). In contrast to well-established LT GaAs/AlAs, the absorption edge of LT GaInAs/AlInAs MQWs can be tuned to the crucial 1.55 /spl mu/m wavelength. Whereas in LT-GaAs:Be response times are as short as 100 fs, up to now the optical response of Be-doped LT GaInAs/AlInAs MQWs was much slower. In this work, we report for the first time an ultrafast absorption recovery time in LT GaInAs/AlInAs MQWs of only 230 fs at the communication wavelength of 1.55 /spl mu/m. The nonlinear transmission was studied at room temperature in pump-probe experiments with 140 fs pulses at a center wavelength of 1.55 /spl mu/m from a mode-locked Er:fiber laser.