NTT Basic Research Laboratories has developed the world's first device using MEMS technology to control phonon flow, potentially advancing phononics for information processing.
Device Structure and Phononic Crystal Waveguide
•Fabricated a drum-like structure with a 30-micrometer diameter using gallium arsenide-based materials, where the film vibrates up and down.•Arranged 100 of these structures in a one-dimensional array with a mutual offset to create a phononic crystal waveguide.•Observed that phonons propagate along the waveguide, reflect back, and have a frequency-dependent propagation speed with a phononic band gap.•Found a slow phonon effect where phonon speed approaches zero near the band gap, allowing flow adjustment via the periodic structure.Phonon Control Mechanisms and Applications
•Placed a control MEMS resonator at the waveguide center; phonons at frequency f0 normally propagate through it.•Making the resonator vibrate at its natural frequency f1 blocks phonon propagation, acting as a phonon gate.•Vibrating the resonator at frequency f2 (equal to f0 minus f1) transfers energy from the phonon to the resonator, enabling temporary phonon storage.•This technology opens up the field of phononics for information processing, where phonons have not been widely used before.Key Takeaways
•The device uses a phononic crystal waveguide with a periodic structure to create a band gap and slow phonon effect for controlling phonon flow.•A MEMS resonator can act as a phonon gate by blocking propagation at specific frequencies or store phonons through energy transfer.•This breakthrough enables the development of phononics, a new field for information processing using phonons.Conclusion
This innovation in phonon control paves the way for practical applications in phononics, expanding beyond traditional uses of heat and sound.
