Low-Cost Encoding Device for Optical Code Division Multiple Access System

Problem statement: Instead of using Fiber Bragg Grating (FBG) to develop the coded spectrums, which consist of expensive elements, the grating also are highly sensitive to environmental changes and this will contribute to the increment of capital and operational expenditures (CAPEX and OPEX). Approach: This study presented the development of low-cost 16-ports encoding device for Optical Code Division Multiple Access (OCDMA) systems based on Arrayed Waveguide Grating (AWG) devices and optical switches. The encoding device is one of the new technologies that used to transmit the coded data in the optical communication system by using AWG and optical switches. It provided a high security for data transmission due to all data will be transmitted in binary code form. The output signals from AWG were coded with a binary code that given to an optical switch before it signal modulate with the carrier and transmitted to the receiver. The 16-ports encoding device used 16 Double Pole Double Throw (DPDT) toggle switches to control the polarization of voltage source from +5 V to -5 V for 16 optical switches. When +5 V was given, the optical switch will give code '1' and vice versa. Results: We found that the insertion loss, crosstalk, uniformity and Optical Signal-Noise-Ratio (OSNR) for the developed prototype are <12 dB, 9.77 dB, <1.63dB and ≥20 dB. Conclusion: We had successful developed the AWG-based OCDMA encoding device prototype and characterized using linearity testing and continuous signal testing. The developed prototype was expected to be applied in the optical communication system on Passive Optical Networks (PONs).