Theory of refractive index variation in quantum well structure and related intersectional optical switch

Attention is focused on the deformation of electron wave functions due to an applied field in a quantum well (QW) neglecting the exciton effect. Compared to the electrooptic effect of bulk semiconductor, the theoretical refractive index variation in a QW structure due to this phenomenon is considerably larger at the wavelength corresponding to the energy gap between the first quantized energy levels in the conduction and valence bands. Since the absorption loss changes by the same mechanism, the appropriate wavelength region is estimated for larger index variation where the absorption loss is relatively smaller. The design of a related intersectional optical switch of a small size is discussed. A switch with a length of about 10 μm is achievable with an intersectional angle of more than 10° at a waveguide width of 1 μm. This optical switch is expected to be of high speed and is integrable monolithically with lasers