Self-Stabilized Optoelectronic Oscillator Using Frequency-Shifted Feedback and a Delay Line

Abstract

International audienceWe report a new scheme of photonic microwave oscillator at telecommunication wavelength. It consists of two monolithic distributed feedback (DFB) laser diodes, whose beat-note is stabilized by means of frequency-shifted optical feedback. The feedback beam is modulated by the delayed beat-note itself, and this permits to get a stable optically carried microwave without the need of any external reference. Dual and single sideband modulation schemes were tested by using an intensity modulator and a frequency shifter, respectively. The single sideband scheme results in a better stability and a 10 dB improvement of the phase noise. A phase noise level of -65 dBc/Hz, detection limited, at 100 Hz from a 12 GHz carrier is obtained

Synchronization of Two DFB Lasers Using Frequency-Shifted Feedback for Microwave Photonics

“…We also note that it is not always desirable to reduce the delay as much as possible. Indeed, a short delay may be attractive for integration purposes, however it is known that a km-long delay improves the stability and performances of opto-electronic oscillators [34].…”

Single-Sideband Hybrid Opto-Electronic Oscillator

“…The main interest of such a setup is that it allows the generation of single-sideband signals, which are thus insensitive to dispersion fading when propagating in optical fibers. The scheme presented in [2] offered good short-term performances. However, it could be affected by mode-hopping due to both the resonant modes of the optical feedback loop, and to those of the optoelectronic loop including the delay line.…”

“…Opto-electronic oscillators (OEO) are important building blocks in microwave photonics systems, allowing to obtain low-phase noise optically-carried radiofrequency signals. We have recently demonstrated an OEO scheme based on a monolithic dual-frequency source [1], whose beatnote is self-stabilized using frequency-shifted optical feedback, and a delay line [2]. The main interest of such a setup is that it allows the generation of single-sideband signals, which are thus insensitive to dispersion fading when propagating in optical fibers.…”

“…1(b) shows the RF spectrum on a larger span. The short (∼ 1 m) optical feedback loop results in broadly spaced external cavity modes, that are efficiently suppressed using a standard RF filter (on the contrary, longer loops require custom filters with high quality factors [2]). As a result, mode hops are completely absent.…”

Self-stabilized optoelectronic oscillator using optical feedback on integrated heterodyne source

“…1). These architectures permit to obtain a small beat note drift as the two lasers share correlated thermal and acoustic fluctuations, and enable one to finely tune the beating frequency up to 100 GHz thanks to the bias current [2,3]. The beat note is stabilized by means of a frequency-shifted optical feedback loop (delay τf) associated with an optical delay line τd ( Fig.…”