On-Chip Bimetallic Plasmo-Thermomechanical Detectors for Mid-Infrared Radiation

We present an on-chip radiation detector based on the bimetallic plasmo-thermomechanical fishbone nanowire arrays that are suspended on a silicon nitride waveguide to provide modulation on the propagating mode in the waveguide due to thermomechanical deflection. The design concept is scalable from visible to infrared (IR) spectrum. To demonstrate the concept, we design the suspended fishbone nanowires that are 18.6 μm long. The nanowire is composed of six strip antenna unit cells, and each unit cell has an absorption coefficient of 42.4% at 4.3-μm target wavelength. The nanowire array includes nine wires with a period of 3.1 μm. The device has a figure of merit of 2.64 × 10
^-2
μm
²
/μW. We investigate the modulation strength with respect to the IR radiation density at 4.3 μm, and the optimum readout power in the waveguide to avoid self-heating is also discussed.