Low Loss Two-Dimensional Adiabatic Tapered Coupler for Optical Waveguide Devices

The objective of this work is to develop a class of highly reliable, low loss input/output couplers for polymer and semiconductor waveguide devices. The adiabatic taper provides, theoretically, a lossless transition between different waveguide mode sizes. When an adiabatic taper is used in a waveguide input/output coupler, very low loss (<1dB) can be achieved in the coupling between standard single mode fiber and wavequide devices. TACAN Corporation is proposing a development of two types of couplers. The first type is a two-dimensional tapered polymer waveguide coupler defined either by the proposed photochemical process converting fiber coupler which converts an elliptical mode into circular mode without suffering major loss. Fusion splice along with thermal diffusion treatment will be used to fabricate the fiber mode converters. The tapered polymer wavequide coupler is a natural extension of the fabrication process. The mode converting fiber can be optimized to facilitate automatic production using a fusion splicing station, which will be potentially manufactured at very low cost. Preliminary coupler designs, demonstrative devices will be provided during the PHase I research.