A novel concept of acousto-optic ring frequency shifters on silicon-on-insulator technology

• A novel concept of acousto-optic ring modulator on silicon-on-insulator technology is presented.
• A design is introduced to make SOI waveguide piezoelectric by putting ZnO on SOI layer.
• The resonance wavelength of the ring resonator with a radius of 50 μm shifts 22.7% of FSR by SAW modulation.

In this paper, a ring frequency shifter using surface acoustic waves (SAW) is developed on a silicon-on-insulator (SOI) technology, in which, a design is introduced to make SOI waveguide piezoelectric by putting ZnO on SOI layer. A simulation shows that the refractive index change of SOI waveguide with an overlayer of ZnO is about 10−3 by SAW of 100 mW. A finite-difference time domain (FDTD) is used to model the new concept of a ring frequency shifter using SAW of 100 mW. The results show that the resonance wavelength of a ring resonator with a radius of 50 μm shifts 22.7% of a free spectral range (FSR) due to the refractive index change of waveguide by SAW without change in transmission on resonances and finesse, a tiny change in bandwidth, Q-factor and FSR of a ring resonator.