Infrared phase modulators with multiple quantum wells

The intraband transition of a graded Ga/sub 1-x/Al/sub x/As/AlAs quantum well is analyzed for its suitability as a phase modulator at infrared wavelengths. Using the effective mass model and numerically solving Schrodinger's equation for a graded energy well with an external electric field, it is found that significant phase changes are possible for comparatively small voltages even for operation far from the absorption resonance. In an example, the calculated value for V/sub pi / at 10.6 mu m is 150 V, an improvement by over two orders of magnitude over conventional bulk electrooptic material for that wavelength regime.<
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