Abstract: A waveguide for use in polarization mode converters and polarization modulators using extrinsic strain to prerotate the principal axes and control birefringence is disclosed herein. The invention relates to the orienting of principal propagation axes in an optical waveguide by pre-stressing the waveguide, using an extrinsic stress, to re-orient the principal propagation axes from an unstressed orientation to a substantially ideal orientation. The waveguide is preferably stressed by an extrinsic strain inducer which applies a shear force to the waveguide to induce anisometry in the waveguide structure.

Abstract: Disclosed is a print quality test structure for devices manufactured by lithography. The test structure allows for visual inspection of the print quality of the device. The test structure decouples the effects of overexposure, underexposure and focus so that corrections can be made for future device manufacturing. By visually inspecting each device during lithography, devices of poor quality can be reworked, and costly testing on all devices can be avoided through device screening.

Abstract: Groove patterns on substrates coated with photoresist are made using the technique of photolithography by exposing photoresist via a reticle. In the instant invention, the pattern is provided on the reticle with a period larger than the final period to be printed on the photoresist. The complete pattern is obtained by subjecting the photoresist to two or more exposures and aligning the substrate relative to the reticle between exposures. In a further embodiment the slits on the reticle defining the line width of the grooves are larger than required and photoresist is subjected to multiple partial exposure. Both embodiments significantly reduce diffraction caused by the reticle and improve the resolution of the technique.