The main activity in silicon photonics carried out at IMM Bologna aims at exploring the recently discovered stress-induced Pockels effect in strained Silicon for realizing fast and CMOS-compatible optical switching devices, suitable for interconnection networks. Switching elements, such as microring resonators, can be realized on a standard Silicon On Insulator (SOI) substrate by depositing a film of silicon nitride (Si3N4, or SiNx), which induces a tensile stress in silicon lattice. Thus, through the strain-induced electro-optic (Pockels) effect, an electric field (with no flowing current) can be applied to rapidly change the tuning frequency of the microring resonator. This can lead to a significant reduction of the switching time, and the achievement of a breakthrough performance improvement in terms of speed, tunability, and power consumption with respect to currently power-hungry available photonic switching technologies, such as thermo-optic effect (only allowing for slow switching capabilities), or carrier-injection techniques (suffering from very high free-carrier-induced losses and allowing only a limited wavelength tunability).
The activities involving fiber optic systems are focused on devices and system, with application to sensing and metrology; in particular, optical amplification scheme are being studied based on Raman effect for the transport of optical frequencies over long distance through the fiber optic telecommunications networks, with important metrological applications. Moreover, study and experimental development of distributed optical fiber sensor systems based on Brillouin scattering is carried out, employing both Brillouin optical time domain analysis (B-OTDA) and optical frequency domain analysis (B-OFDA) techniques.
Some effort is also dedicated to amorphous silicon-based optical modulators fabricated by plasma deposition. The activity benefits of the versatile design and compatibility with electronic processing.
Contact Person: Gabriele Bolognini