Signal Conversion for Radio-over-Fiber Uplink Using Double-Locked Semiconductor Lasers

Wireless communication using radio-over-fiber (RoF) has attracted much attention recently. With the advance of photonic devices, RoF signals can be transmitted over long distances with high immunity to electromagnetic interference (EMI). As the subcarrier frequencies of wireless signals continued to increase, uplink transmission is preferably all-optical with minimal use of expensive high-speed electronics. Effective conversion of microwave to optical signals has remained an interesting research area. In the proposed work, a recent double-locking technique on semiconductor lasers is considered for RoF uplink signal conversion. By remote optical control of a simple single-mode laser at the base station, uplink transmission without high-speed demodulation electronics is enabled. Conversion into both non-return- to-zero (NRZ) and return-to-zero (RZ) formats are proposed. As the laser can be controlled optically, subcarrier frequency can be easily tuned remotely. Furthermore, immunity to dispersion is to be investigated because of all-optical demodulation.