Novel all-optical 10 μm waveguide modulator based on intersubband absorption in GaAs/AlGaAs quantum wells

Abstract

Efficient all-optical modulation of mid-infrared radiations based on photoinduced intersubband absorption of a GaAs/AlGaAs multiquantum well structure is demonstrated at room temperature. The sample designed for mid-infrared waveguiding was grown by molecular beam epitaxy. A double-resonance spectroscopy of both interband and intersubband transitions of the quantum wells is presented. The intersubband resonance is found at 9.56 μm. An AlGaAs laser diode is used to optically pump the quantum wells. On/off modulation ratios as high as 150:1 are obtained with only 45 mW pump power and for mid-infrared input powers up to 0.5 W. The frequency bandwidth of the device is presently comparable to that of acousto-optic modulators available at mid-infrared wavelengths.