Fabrication of 1×2 asymmetric plastic optical fiber coupler for portable optical access-card system

An optical code generating device using plastic optical fiber (POF) coupler for a portable optical access card system is presented. The code generating device has been constructed using asymmetric hollow POF coupler design. The device provides a unique series of output light intensities which are successively used as an optical code. Ray tracing models of various coupler designs showed a linear relationship between the tap-off ratio (TOFR) and the waveguide tap width. The asymmetric POF coupler has been fabricated on metal-based materials using machining technique. The results for the simulated and fabricated metal-based 1×2 asymmetric couplers show the same linear characteristics between the TOFR and the tap width. The simulated devices show a TOFR variation from 18.6 to 49.9% whereas the TOFR for the fabricated metal-based devices varies from 10.7 to 47.7%, for a tap width of 500 mm to 1 mm. The insertion loss for the 1×2 asymmetric coupler at the tap line varies from 12.7 to 21.2 dB whereas for the bus line, the average insertion loss is about 12 dB.