Spectrometer employing a Mach Zehnder interferometer created by etching a waveguide on a substrate

An interfering spectrometer comprising:

• a substrate having an input end for receiving white light and an output end;
• a waveguide for conducting the white light said waveguide being etched upon said substrate, said waveguide having a plurality of optical paths of nearly equal physical length for passing the white light from the input end of said substrate to the output end of said substrate, at least one of the optical paths being a reference path, and at least one other of the optical paths being a sensing path having a sample area adapted to be exposed to a sample under test, each of the optical paths having an input end and an output end, the input ends of the optical paths being joined together upon the input end of said substrate to form an input path for the white light, the output ends of the optical paths being joined together upon the output end of said substrate to form an output path for recombining the white light from the optical paths;
• input coupling means connected to said input path for receiving the white light;
• means for linearly varying over time the optical length of at least one of said reference paths, the intensity of the white light at the output path being modulated depending on a phase difference between the light in the reference paths and the light in the sensing paths;
• photo detecting means for converting electromagnetic intensity to an electrical signal, said photo detecting means having an input and an output;
• an output coupling means for passing recombined white light from said output path to the input of said photo detecting means;
• current to voltage conversion means having an input coupled to the output of said photo detecting means, said current to voltage conversion means further having an output;
• analog to digital conversion means having an input coupled to the output of said current to voltage conversion means whereby the output of said analog to digital conversion means represents the intensity of the light in said output path;
• digital signal processing means having an input coupled to the output of said analog to digital conversion means, said digital signal processing means comprising:
• means for calculating the optical intensity of the light in said output path as a function of wavelength;
• means for comparing the optical intensity of the light in the output path when a sample is present in the at least one sensing path to the optical intensity of the light in the output path when no sample is present in the at least one sensing path;
• means for displaying the results of said comparison.