Improving thermal stability of opto-electronic oscillators

Some of the methods for improving thermal stability of opto-electronic oscillators (OEO) is discussed. The OEO is a special class of oscillator that is based on converting continuous light energy from a pump laser into Radio frequency (RF) signals. It uses optical techniques that are potentially suitable for generating microwave signals with extremely low phase noise by taking advantage of long low-loss optical delay lines. Its operation involving both optical energy and microwave signals is suitable as a stable clock for all optical analog-to-digital converters (OADCs) as its output may be obtained both directly as a microwave signal and as intensity modulation. The temperature sensitivity of OEOs is of concern due to the changes in the index of refraction of optical fibers. Experimental analysis have demonstrated a reduced temperature sensitivity of the OEO using SC-PCF, where the factor of three improvement in the thermal sensitivity has been measured for SC-PCF-based OEO.