Laser direct writing of optical waveguide structures.

A maskless technique for laser direct writing of optical waveguide structures is presented. It utilizes a commercially available UV-curable, optical-quality polymer (Norland 61) spun onto a substrate in a manner analogous to photoresist and subsequently exposed using the 350-256-nm lines of an Ar-ion laser. After exposure, the substrate is developed in a solvent such as cyclopentanone, which removes the unexposed regions of the polymer. An electron micrograph of a laser-written optical waveguide is shown and discussed. The curing of the optical polymer is by photon-induced polymerization, making the process relatively insensitive to substrate parameters and permitting deposition on a variety of materials. Preliminary measurements show the loss in these guides to be acceptable for many uses in integrated optics.