Ever hear of a piezo-optomechanical circuit? We hadn’t either. Let’s break it down. Piezo implies some transducer that converts motion to and from energy. Opto implies light. Mechanical implies…well, mechanics. The device, from National Institute of Standards and Technology (NIST), converts signals among optical, acoustic and radio waves. They claim a system based on this design could move and store information in future computers.
At the heart of this circuit is an optomechanical cavity, in the form of a suspended nanoscale beam. Within the beam are a series of holes that act as mirrors for very specific photons. The photons bounce back and forth thousands of times before escaping the cavity. Simultaneously, the nanoscale beam confines phonons, that is, mechanical vibrations. The photons and phonons exchange energy. Vibrations of the beam influence the buildup of photons and the photons influence the mechanical vibrations. The strength of this mutual interaction, or coupling, is one of the largest reported for an optomechanical system.
In addition to the cavities, the device includes acoustic waveguides. By channeling phonons into the optomechanical device, the device can manipulate the motion of the nanoscale beam directly and, thus, change the properties of the light trapped in the device. An “interdigitated transducer” (IDT), which is a type of piezoelectric transducer like the ones used in surface wave devices, allows linking radio frequency electromagnetic waves, light, and acoustic waves.
The work appeared in Nature Photonics and was also the subject of a presentation at the March 2016 meeting of the American Physical Society. We’ve covered piezo transducers before, and while we’ve seen some unusual uses, we’ve never covered anything this exotic.