Methods and apparatus for mid-infrared sensing

摘要

A chip-scale, air-clad semiconductor pedestal waveguide can be used as a mid-infrared (mid-IR) sensor capable of in situ monitoring of organic solvents and other analytes. The sensor uses evanescent coupling from a silicon or germanium waveguide, which is highly transparent in the mid-IR portion of the electromagnetic spectrum, to probe the absorption spectrum of fluid surrounding the waveguide. Launching a mid-IR beam into the waveguide exposed to a particular analyte causes attenuation of the evanescent wave's spectral components due to absorption by carbon, oxygen, hydrogen, and/or nitrogen bonds in the surrounding fluid. Detecting these changes at the waveguide's output provides an indication of the type and concentration of one or more compounds in the surrounding fluid. If desired, the sensor may be integrated onto a silicon substrate with a mid-IR light source and a mid-IR detector to form a chip-based spectrometer.

主权项

1. A method of sensing at least one molecule, the method comprising:
guiding a mid-infrared beam having at least one spectral component in a range of about 1.5 μm to about 12.0 μm from a first end of a semiconductor waveguide, disposed on a pedestal made of crystalline silicon extending from a silicon substrate, to a second end of the semiconductor waveguide; exposing an outer surface of the semiconductor waveguide to the at least one molecule so as to reduce an intensity of the at least one spectral component via absorption by the at least one molecule; and detecting the intensity of the at least one spectral component at the second end of the semiconductor waveguide.