Appl. Phys Lett. 111, 013102 (2017)

Credit: AIP PUBLISHING LLC

By adding a gold nanofin photonic absorber to a high Q-factor nanomechanical resonator scientists in Japan have made a highly sensitive wavelength detector with subpicometre resolution. The miniature device built by Etsuo Maeda and Reo Kometani from the University of Tokyo has a wavelength sensitivity of ∼0.2 pm in a 10-nm range in the near-infrared (1,545–1,555 nm). Incident light in this spectral window is absorbed by the gold nanofin array and induces thermal stress, resulting in a frequency shift of the eigenfrequency of a silicon nanomechanical resonator underneath, on the scale of up to 40 kHz. The exact wavelength of the incident light is determined precisely by measuring the size in the shift in mechanical resonant frequency using a laser Doppler vibration meter. Importantly, the device operates at the transmission wavelength of optical communications systems.