We report the first demonstration of channel optical waveguide directional couplers. The closely spaced channel waveguides were fabricated in GaAs by proton implantation. Optical coupling was observed at 1.15 μ with complete light transfer out of the initial channel into adjacent channels in lengths of typically 2 mm.

A GaAs distributed-feedback laser was fabricated and pumped optically. A narrow stimulated spectrum was obtained around 0.83 μ with threshold pumping power of ∼2 × 105 W/cm2.

No abstract

Laser action was observed in GaAs epitaxial films using corrugation feedback. The output wavelength was found to depend on the corrugation period. The loss, threshold gain, and feedback parameters were determined and compared with theoretical predictions.

Two-channel imbedded directional couplers were fabricated with proton implantation, yielding complete light transfer in 2 mm. Ridged channel guides were fabricated by ion-micromachining epitaxial layers, and a method of directional coupling was demonstrated.The development of useful integrated optics circuits requires channel waveguides of small dimensions fabricated with close tolerances. We have investigated ways of making channel guides in GaAs, both imbedded guides and ridged. In addition to single channel guides, we have investigated the coupling properties of dual channel imbedded guides and have made a bridged structure for coupling ridged guides. Finally, we look at the use of a directional coupler as a light switch.The imbeddd channels were fabricated in GaAs by 300-keV proton implantation' in a fashion similar to the fabrication of a multichannel directional cou-.pler. 2 Bombardment causes defect centers in the material, which trap the free carriers. This compensation of the free carriers eliminates their negative plasma contribution to the index of refraction and thus increases the index. For the samples used here (N-type GaAs -2 x 1018/cc) the index increase is An -0.005. The channel guides were formed by implanting the protons through a proton-resistant gold mask, 2 gm thick. The pattern was ion-machined into the gold through a photoresist mask. The implanted guides have cross-sectional dimensions of 3 gm x 3 m and are single mode in both confinement directions, an important requirement for many optical circuit elements. We measured a single channel loss of 6 cm-' for the first order mode; this loss is determined by the particular implanting and annealing conditions and is comparable with losses in planar implanted guides.' The mode profiles and losses were studied in a fashion similar to Ref. 1. We have found that ion implantation provides an excellent means of making smooth imbedded optical circuits.

No abstract

A 50-keV focused Ga+ beam formed in a two-lens microprobe column with prefinal lens deflection was used to expose dot arrays in a negative acting bilevel resist. Dot arrays 600 μm×600 μm with 600-Å-diam resist posts on 0.6 μm centers (incorporating 1024×1024 dots) were fabricated with ion exposure times of 18 s. By reducing the beam dwell time by a factor of 2, roughly 300-Å-diam posts were fabricated. Since the ions stop in the bottom resist layer and do not enter the substrate, the optical properties of underlying material should not be altered by damage from the exposure process.

A 50-keV focused Ga + beam formed in a two-lens microprobe column with prefinal lens deflection was used to expose dot arrays in a negative-acting bilevel resist. Dot arrays 600 X 600 f-lm with 6OO-A-diam resist posts on O.6-f-lm centers (incorporating 1024 X 1024 dots) were fabricated with ion exposure times of 18 s (beam dwell times of 16f-ls/post). By reducing the beam dwell time by a factor of 2, roughly 300-A.-diam posts were fabricated. Since the ions stop in the bottom resist layer and do not enter the substrate, the optical properties of underlying material should not be altered by damage from the exposure process.