Broad tunable photonic microwave signal generation using optically-injected 1310 nm spin-VCSELs

We theoretically propose and demonstrate photonic microwave signal generation with a very broad tunability range from below 2.5 GHz to around 100 GHz. The proposed scheme is based on sustained oscillation dynamics produced in spin-VCSELs under right circularly polarized optical injection. The generated microwave frequencies can be tuned by detuning the frequency of the optical injection signal. The system also takes the advantage of polarization switching phenomena to generate broader microwave frequencies where the generated frequencies are equal to the sum of the absolute detuning frequency and the birefringence split between the spin-VCSEL modes which is 47.7 GHz. Sustained oscillation dynamics provokes tunable periodical oscillations through the adjustment of the frequency detuning and injection strength which can be used as a microwave signal generator. Enhancement of the RF power of the oscillations can be achieved by increasing the injection strength towards the locking regions. The microwave linewidth is reduced from 58 MHz to a medium linewidth of about 14 MHz under optical injection technique. This simple configuration paves the way for potential uses of spin-VCSELs in Radio-over-Fiber (RoF) applications and future technologies.