Polarization rotation is an important effect in integrated lightwave systems. Some elements of the lightwave system expect to receive their inputs in certain desirable polarizations. Other elements have a requirement for performing a polarization rotation on their received inputs signals. For example, balanced polarization diversity heterodyne receivers require 45.degree. rotation whereas polarization controllers require a dynamic rotation capability as large as 90.degree..
Polarization rotation has been demonstrated in both lithium niobate (LiNbO.sub.3) waveguide devices and in semiconductor group III-V waveguide devices. In the lithium niobate devices, periodically etched silicon dioxide films have been applied over the waveguide to induce a periodic stress for changing the refractive index of the waveguide via the photo-elastic effect. See, for example, K. Yamanouchi et al., IEEE J. Quantum Electronics, Vol. QE-16, No. 6, pp. 628-34 (1980). Generally, lithium niobate devices utilize the electrooptic effect to achieve polarization rotation. See, for example, U.S. Pat. No. 4,966,431 issued to F. Heismann on Oct. 30, 1990. For the semiconductor devices, polarization rotation has been demonstrated by using periodic electrodes in conjunction with the electrooptic effect. See, for example, F. Reinhart et al., IEEE J. Quantum Electronics, Vol. QE-18, No. 4, pp. 763-6 (1982) and M. Schlak et al., Electronics Lett., Vol. 22, pp. 883-5 (1986). Operation of the semiconductor devices generally requires application of large voltages with, in some devices, a maximum rotation capability much less than 90.degree..