Laser irradiation reduces MEMS oscillator thermal noise

Nippon Telegraph and Telephone Corporation (NTT) and Northeastern University jointly implemented the "laser cooling method" for reducing the thermal noise of MEMS mechanical oscillators by irradiating the laser. MEMS oscillator is mainly used for sensors and signal transmitters, the technology is expected to improve its accuracy. Laser Cooling is a method of cooling an object by emitting energy by irradiating it with laser light. This time, researchers used the crystal growth technology to achieve a 200 nm-thick semiconductor two-layer structure of GaAs and AlGaAs that is excellent in optical and piezoelectric characteristics, and processed into a mechanical Oscillator. With its sensitive light absorption characteristics, it absorbs only light of a specific wavelength and uses the internal voltage generated at this time as a braking force against thermal shock, thereby reducing thermal noise. The mechanical oscillator produced this time is a leaf spring of 20 μm in length, 14 μm in width and 0.4 μm in thickness. Just by irradiating the laser's root with a laser, the thermal vibration can be halved. In the past, laser cooling required the use of precision optical resonators. This method does not require an optical resonator and can also be used as a semiconductor integrated device. NTT and Northeastern University in the future will further promote research to improve the cooling effect, to achieve integration with laser components and room temperature work. The results of this visit are published in the "Nature Communications" electronic version (October 19).