Abstract

Laser-beam (LB) writing is a useful technology for patterning of channel waveguides in photoresist coated on a substrate, as already reported by some researchers [1-3]. In particular, the authors developed the practical LB writing system which consisted of a closed-loop-controlled X-Y translation stage, a focusing optics of the 442-nm He-Cd laser and a LB intensity control circuit [3]. In this system, 3-to-8μm wide channel waveguides can be formed automatically over an area of 10×10 cm² with an accuracy of nearly 0.1 μm. Very precise waveguide patterning is thus possible because of extremely smooth movement of the X-Y stage whose translation speed fluctuation δν/ν is less than 10⁻⁴, as will be discussed below; therefore, when the focused LB is switched on/off regularly under a constant-speed movement of the stage, dots should be aligned with a uniform period in photoresist. In this paper, we demonstrate such a new LB periodic-dot writing used to form interdigital electrodes required for TE-TM mode conversion in Ti:LiNbO₃ waveguide wavelength filters.

© 1993 Optical Society of America