Optically Injected Semiconductor Laser for Photonic Microwave Frequency Mixing in Radio-Over-Fiber

Nonlinear dynamics of an optically injected semiconductor laser for microwave frequency mixing are experimentally investigated. Through optical injection, the laser is driven into the nonlinear period-one (P1) dynamical state and acts as a broadly tunable photonic microwave oscillator. With an external current modulation at an intermediate frequency, the P1 oscillation is modulated accordingly, thus achieving frequency up-conversion beyond the laser bandwidth. Using a 2.5-Gbps-grade laser, binary phase-shift keying (BPSK) data signal is up-converted from an intermediate frequency of 2 GHz to a subcarrier frequency as high as 20 GHz. While the direct modulation bandwidth limits the intermediate frequency, it does not limit the subcarrier frequency. The approach uses only low-cost lasers and requires no high-speed electronic mixers.