Controlling Phonons and Photons at the Wavelength-Scale: Silicon Photonics Meets Silicon Phononics
1 Controlling phonons and photons at the wavelength-scale: silicon photonics meets silicon phononics AMIR H. SAFAVI-NAEINI1,D RIES VAN THOURHOUT2,R OEL BAETS2, AND RAPHAËL VAN LAER1,2 1Department of Applied Physics and Ginzton Laboratory, Stanford University, USA 2Photonics Research Group (INTEC), Department of Information Technology, Ghent University–imec, Belgium .Center for Nano- and Biophotonics, Ghent University, Belgium Compiled October 9, 2018 Radio-frequency communication systems have long used bulk- and surface-acoustic-wave de- vices supporting ultrasonic mechanical waves to manipulate and sense signals. These devices have greatly improved our ability to process microwaves by interfacing them to orders-of- magnitude slower and lower loss mechanical fields. In parallel, long-distance communications have been dominated by low-loss infrared optical photons. As electrical signal processing and transmission approaches physical limits imposed by energy dissipation, optical links are now being actively considered for mobile and cloud technologies. Thus there is a strong driver for wavelength-scale mechanical wave or “phononic” circuitry fabricated by scalable semiconduc- tor processes. With the advent of these circuits, new micro- and nanostructures that combine electrical, optical and mechanical elements have emerged. In these devices, such as optomechan- ical waveguides and resonators, optical photons and gigahertz phonons are ideally matched to one another as both have wavelengths on the order of micrometers. The development of phononic circuits has thus emerged as a vibrant field of research pursued for optical signal pro- cessing and sensing applications as well as emerging quantum technologies. In this review, we discuss the key physics and figures of merit underpinning this field.
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