  Merging photonic structures and optoelectronic sensors into a single chip may
yield a sensor-on-chip spectroscopic device that can measure the spectrum of
matters. In this work, we propose and realize an on-chip concurrent
multi-wavelength infrared (IR) sensor. The fabricated quad-wavelength IR
sensors exhibit four different narrowband spectral responses at normal
incidence following the pre-designed resonances in the mid-wavelength infrared
region that corresponds to the atmospheric window. The device can be applied
for practical spectroscopic applications such as non-dispersive IR sensors, IR
chemical imaging devices, pyrometers, and spectroscopic thermography imaging.
