High Frequency Optoelectronc Oscillator

Low phase noise oscillators are core components for communications and radars. System timing jitter is fundamentally important for digital systems and phase noise is the figure of merit for RF systems. For multi-GB/s clocks, optoelectronic oscillators using optical delay for the clock period, appear to have significant advantages. The phase noise may be minimized because the delay variability lies only in stability of the refractive index, providing low noise figure devices are available. The significant phase noise may then be relegated to the clock period adjustment mechanism and the RIN noise on the optical source. Optoelectronic oscillators have been reported that use a collection of lasers, modulators, delays and RF amplifiers. Although phase noise is improved, the system is bulky and power consumptive. OPEL’s integrated version is based upon a non-linear switching device that performs as both a laser source and detector. Monolithically integrated control HFETs and optical waveguides, enable an oscillator with minimal chip space and phase noise approaching the quantum limit, since the RIN noise is that of the VCSEL (-160dB/Hz). The control noise is only the shot noise on the injection current (<10fs jitter). The Phase II effort will fabricate and demonstrate the first multi-GB/s monolithic OEO.