Metal-based 1 × 2 and 1 × 4 asymmetric plastic optical fiber couplers for optical code generating devices

• Main Authors: Abd Rahman, M.K (Author), Ehsan, A.A (Author), Shaari, S. (Author)
• Format: Article
• Language: English
• Published: Electromagnetics Academy 2010
• Subjects: Asymmetric couplers; Codes (symbols); Fabrication; Fiber optic sensors; Insertion losses; Linear characteristics; Machining techniques; Optical access; Optical fiber coupler; Optical fiber fabrication; Optical fibers; Plastic optical fiber (POF); Plastic optical fibers; Waveguide core; Waveguide structure; Waveguides
• Online Access: View Fulltext in Publisher; View in Scopus

 An optical code generating device has been developed based on 1×2 and 1×4 asymmetric plastic optical fiber (POF) couplers. The code generating device provides a unique series of output power which are successively used as an optical code in a portable optical access-card system. The system is designed where the asymmetric POF coupler is embedded in an all passive portable unit. This device utilizes a tap-off ratio (TOFR) technique based on a simple variation of the tap width of an asymmetric Y-branch splitter design. A hollow-type waveguide structure is used where it eliminates the use of polymeric material for the waveguide core and allows simple fabrication and assembling of the device. The asymmetric POF coupler has been fabricated on metal-based materials using machining technique. The results for the simulated and fabricated 1×2 asymmetric couplers show the same linear characteristics between the TOFR and the tap width. The simulated devices shows a TOFR variation from 18.6% to 49.9% whereas the TOFR for the fabricated metal-based devices varies from 10.7% up to 47.7%, for a tap width of 500μm to 1mm. The 1 × 4 coupler designed using simple cascading of a Y-branch splitter with two 1 × 2 asymmetric couplers has been fabricated and shows similar characteristics as that of the designed 1×4 devices. The insertion loss for the 1 × 2 asymmetric coupler at the tap line varies from 9dB to 16dB whereas for the bus line, the insertion loss is about 9 ± 0.8dB. The insertion loss for the 1×4 asymmetric coupler at the output ports varies from 14dB to 22dB.