Sub-picometer multi-wavelength detector based on highly sensitive nanomechanical resonator

Abstract

The wavelength division multiplexing (WDM) method for near infrared (NIR) optical fiber (1530–1565 nm) is the system that is wildly used for intercontinental communication. WDM achieves high-speed and large-capacity communication, but costs a lot because the high-resolution (∼10 pm) wavelength locker for wavelength stabilization only corresponds to a single wavelength. In this report, we propose a highly sensitive sub-picometer multi-wavelength detector that substitutes a typical single-wavelength detector for WDM. Our wavelength detector consists of a narrow band (FWHM < 10 nm) photonic absorber with an aligned gold nano-fin array on a high-Q (Q-factor > 20 000) nanomechanical resonator. The photonic absorber confines and transforms the illuminated NIR light wave into thermal stress, and then, the thermal stress in the nanomechanical resonator will appear as the eigenfrequency shift of the nanomechanical resonator. Through experimental works with an NIR laser and optical Doppler vibration meter, the sensitivity of our wavelength detector was determined to be 0.196 pm in the 10-nm-range of the NIR region. Our sub-picometer multi-wavelength detector will achieve a fast, wide-band, and cost-effective optical communication system.