Microresonator with gold nanorod array for laser wavelength measurement by photo-thermal conversion

In this study, we developed the resonator-based sensor device for measurement of laser wavelength changes in a wavelength division multiplexing (WDM) system for large capacity transmission. Laser light is absorbed into the gold nanorod array on the resonator beam, which has wavelength dependent absorption, resulting in temperature change of the beam. Therefore the wavelength change can be measured from resonant frequency shift. We observed the large resonant frequency shift when changing the laser wavelength. The shift was proportional to a cube of beam length and a laser power according to the developed equation. The maximum shift and resolution were 68.8 Hz/nm and 0.29 pm, respectively.