Light control by SAW in a ring resonator (a) geometry of an AO frequency shifter, and (b) cross-section of an AO frequency shifter

Compact and integrated optical frequency shifters have received increasing attention as important system components in many different applications such as sensors and detection systems, which increase the cost and the complexity of the system, different from bulk acousto-optic frequency shifters for this purpose. Especially, the frequency shifters are fabricated in the SOI material system because SOI technology makes it possible to dramatically reduce the footprint.

Because light-confining resonating structures can enhance the effect of refractive index change on the transmission response, scientists of TIPC, CAS present a novel process to control light in a ring resonator using acoustic beam. Though the operation speed is lower than those of all-optical devices, acoustic optical devices are expected to be much faster than thermo-optical ones.

A ring frequency shifter by SAW on SOI waveguide is developed. The ZnO thin film is designed on top of the SOI to make the excitation of SAW possible due to silicon being a non-piezoelectric substrate. The refractive index change of SOI waveguide by SAW is discussed. A FDTD method is performed to model the ring resonator with SAW and no SAW.

Optics & Laser Technology, 2014