20 dB contrast GaAs/AlGaAs multiple quantum-well nonresonant modulators

The authors report a successful fabrication of nonresonant GaAs/AlGaAs multiple quantum well (MQW) modulators with a contrast ratio of more than 20 dB and a wide bandwidth of 3 nm. The optical path, as long as 8 mu m, is attained by fabricating a high-purity thick MQW layer with a residual carrier concentration of less than 10/sup 14/ cm/sup -3/ and introducing a high-reflectivity AlAs/AlGaAs quarter-wavelength mirror. The driving wavelengths are located at the absorption edge, resulting in the low-absorption loss.<
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