Fast saturable absorption and 10 GHz wavelength conversion in Al-quaternary multiple quantum wells

We measured the absorption recovery times in reverse biased AlInGaAs multiple quantum well material designed to emit at around 1.5 μm wavelength. Absorption recovery times as low as 2.5 ps were found at -4V bias, with values below 5 ps consistently found for biases above 3 V. The short absorption recovery times obtained under reverse bias were confirmed by using cross-absorption modulation in the material to demonstrate wavelength conversion of a 10 GHz pulse train, showing both up and down conversion of the incident pulses.