K-Band High Stablity and Resolution Frequency Synthesizers Using Forced Opto-Electronic Oscillators

Abstract

Forced opto-electronics oscillator (OEO) is a very promising way to build low phase noise oscillators. Forced techniques of self-injection locking phase locking (SILDPLL) are integrated with narrowband tunable RF filters to build OEO system to further reduce the phase noise and suppress side mode generated among standard OEOs because of long fiber delays. The narrowband tunable RF filter is based on an optical wavelength tuned transversal filter using a fiber Bragg grating as delay element cascaded with current tuned YIG filter to accomplish a 2kHz frequency resolution over K-band. Second harmonic generated frequency synthesized signals with close-in to carrier phase noise of −127 dBc/Hz at 10 kHz offset are reported by Vπ operation of a Mach-Zehnder (MZM) over 18 GHz to 22 GHz. 19” rack mount system is also constructed and long-term stability of 4.5 kHz over 60 min is measured at K-band, while a 3.5 kHz drift is measured for a tabletop realization.