Stability measurements of an optically injection-locked microwave oscillator

Abstract

Experimental results on the direct injection-locking of a microwave oscillator by an intensity modulated opiical si are presented. Starting with a free-running oscillator, RF specfrum measliements are done as we vary the modulation frequency of the optical signal impinging on t1 oscillator. The locking range (as much as 5 MHz) is measured for different modulating signal power levels on tl laser diode at the fimdamental frequency and at d 2nd, 3rd and 5th subbarmonics. Frequeiy stability measurements are conducted in both time domain (Allan variance) and frequency domain (power spectral density). It shows that tla phase noise and the long term stabiliy of the microwave oscilht are greatly improved under locked conditionS The Allan standard deviation of the microwave oscillator at i = 0.1 s improves from 10-6 t 1& reaching the precision limit of the nieasurement setup.