High-quality microwave sources are required in multiple applications (radar, wireless networks, satellites, etc.). Typically, low-noise microwave oscillators are made by applying frequency multiplication to an electronic source. This requires a cascade of frequency-doubling stages, which strongly reduces the power of the final signal. Recently, different techniques to produce microwave tones via optical means have been proposed. The resulting device is an optoelectronic oscillator (OEO). The advantages with respect to its electronic counterparts are immunity to electromagnetic interference, low weight, compactness, long-distance transport, amongst others.
In the FET-Open PHENOMEN project, aiming at the realization of RF processing using silicon-chip cavity optomechanics, UPV partner designed and demonstrated a novel OM cavity on a silicon chip displaying, for the first time, a localized mechanical mode at frequencies fm ≈4 GHz within a full phononic bandgap and with a large OM coupling rate. This property allows having a high-quality mechanical mode that can be efficiently excited and manipulated by an external input laser. When the laser is blue-detuned with respect to the resonance, the mechanical mode is amplified (as in SBS) and strongly modulates the laser, so after photodetection we have a pure microwave tone at fm. The phase noise of the generated microwave tone is as low as -101 dBc/Hz at 100 kHz, which is a remarkably good value for an OEO oscillating at GHz frequencies without any feedback mechanism. Therefore, the device behaves as an OEO of optomechanical nature: we have an optomechanical microwave oscillator (OMO).
The device demonstrated in PHENOMEN has three key advantages: i) it is fabricated in standard silicon technology, meaning that it can be manufactured in large volumes at low cost as well as that it can be easily interconnected with electronics; ii) it is extremely compact and low-weight, which makes it very suitable for space and satellite applications; iii) it can be easily connected to optical fibres. It is the aim of SIOMO to completely unveil its potential and address its transfer to the industrial sector via partner DAS, which will assess its potential for implementing an all-optical payload for SATCOM applications.
The main objectives of SIOMO are:
OEO performance assessment and application requirements (OBJ1).
Validation of the OEO in the DAS SATCOM testbed (OBJ2).
Benchmarking against competitors and elaboration of a technology transfer and exploitation plan (OBJ3).
