Abstract

Radio-frequency (RF) oscillators are key components in many radio and also radio-over-fiber (RoF) systems. Here, we propose a novel technique to extent the tunable range of the radio frequency generated by optoelectronic oscillators. The proposed optoelectronic oscillator includes an intensity modulator, a photodetector, an optical circulator, a Febry-Perot laser diode, and a broad band RF amplifier. All those devices compose a single feedback loop. The key device in the system is the Febry-Perot laser. By utilizing injection locking of Febry-Perot laser diode rather than the commonly used radio-frequency band-pass filter, a high Q microwave filter is formed in optical domain. Theoretical analysis of the optoelectronic oscillator as well as the tunablity of microwave filter is provided. The central frequency of the microwave filter is a function of the optical wavelength and effective injection power, i.e. the injection power at the transverse-electric (TE) mode of the F-P laser. Thus, the central frequency of the high Q band-pass can be simply tuned by tuning the wavelength and the injection power of the injection light. Experiment is done to verify the theoretical analysis, and a tunable range from 11.074 GHz to 39.400GHz is demonstrated experimentally.

© 2010 Optical Society of America