Abstract
We present a new type of fiber-coupled photodetector with a thermal-based optical sensor head, which enables it to operate even in the presence of strong electro-magnetic interference and in electrically sensitive environments. The optical sensor head consists of three cascaded Fabry-Perot interferometers. The end-face surface is coated with copper-oxide micro-particles embedded in hydrogel, which is a new photo-thermal coating that can be readily coated on many different surfaces. Under irradiation, photons are absorbed by the photo-thermal coating, and are converted into heat, changing the optical path length of the probing light and induces a resonant wavelength shift. For white-light irradiation, the photodetector exhibits a power sensitivity of 760 pm/mW, a power detection limit of 16.4 μW (i.e. specific detectivity of 2.2 × 105 cm.√Hz/W), and an optical damage threshold of ~100 mW or ~800 mW/cm2. The response and recovery times are 3.0 s (~90% of change within 100 ms) and 16.0 s respectively.
Highlights
This work design[16], the optical sensor head is more sensitive than absorption-based designs[17]
The air gap created by the metal ring establishes the second reference Fabry-Perot interferometer (FPI), due to the glass-air and air-glass interfaces
The reflectance spectrum of the probe light is used as the output signal, and the reflective metal layer is necessary to prevent the probe light from entering the adjacent photo-thermal coating on the metal layer surface
Summary
We present a new type of fiber-coupled photodetector with a thermal-based optical sensor head, which enables it to operate even in the presence of strong electro-magnetic interference and in electrically sensitive environments. The probe light source and the photo-electric conversion module can be located remotely from the optical sensor head in the measurement environment. If the photo-thermal type is chosen for the photo-electric conversion module rather than the optical sensor head, the guided light is likely to be too weak for detection. To address the sequence of problems, we present for the first time a photodetector with an optical sensor head based on the photo-thermal effect, and a photo-electric conversion module based on the photo-electric effect to process the optical signal into an electrical signal outside the measurement environment.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
