Polymeric wavelength division multiplexing coupler with fiber guide and filter trench for bidirectional communication fabricated by one-step replication

We fabricated and characterized a polymeric bidirectional wavelength division multiplexing (WDM) coupler for a graded-index plastic optical fiber (GI-POF). We fabricated the device with fiber guides and a filter trench by a simple one-step soft lithography method. We evaluated the performance of the fabricated device with an optimal design structure at wavelengths of 850 and 790 nm. We determined the insertion loss, isolation, and directivity to be less than 3 dB, more than 20 dB, and more than 20 dB, respectively. We also demonstrated bidirectional communications with more than 2.5 Gbps/λ for an optical fiber length of 150m by aligning the GI-POF in the fiber guides and inserting a WDM filter in the filter trench with passive alignment.