Wavelength multiplexing in single-mode fiber couplers

Theoretical and experimental studies of wavelength-division multiplexing in a single-mode fiber optic coupler fabricated by mechanical polishing are reported. The variable spacing geometry of the device allows fine tuning of the center wavelength of operation. Wavelength selectivities ranging from 200 to 35 nm have been experimentally demonstrated, with cross talk ranging from 50 to 10 dB. Selectivity control is simply achieved by proper choice of the interaction length of the coupler. The dependence of the multiplexer behavior on all relevant parameters is investigated and found to satisfy predicted results.