Patent ID: 7973924

Claim:
A sensor for determining a characteristic of a target substance, said sensor comprising: an electromagnetic wave source of supplying an electromagnetic wave; a photonic sensor element having a photonic crystalline structure and configured to include: a sensor waveguide for introducing said electromagnetic wave, and a sensing resonator electromagnetically coupled to said sensor waveguide for resonating the electromagnetic wave of a specific wavelength, said sensing resonator being exposed to an atmosphere including the target substance so as to vary a characteristic of said electromagnetic wave emitted from said sensing resonator; and a detector configured to receive the electromagnetic wave emitted from said sensing resonator to recognize an intensity variation of the electromagnetic wave and issue a signal indicative of a characteristic of said target substance; wherein said detector is configured to determine a density of said target substance based upon a characteristic variation of said electromagnetic wave and issue said signal indicative of the density of the target substance, wherein said photonic sensor element includes within said photonic crystalline structure a reference waveguide; and a reference resonator, said reference waveguide introducing said electromagnetic wave from said source, said reference resonator being electromagnetically coupled to said reference waveguide to resonate the introduced electromagnetic waver at said specific wavelength, said reference resonator being concealed from said target substance, said detector comprising: an output intensity meter providing a detection signal indicating an intensity of the electromagnetic wave of said specific wavelength emitted from said sensing resonator; a reference intensity meter providing a reference signal indicating an intensity of the electromagnetic wave of said specific wavelength emitted from said reference resonator; and a density meter comparing said detection signal with said reference signal so as to obtain an attenuation of the electromagnetic wave of said specific wavelength, thereby calculating the density of said target substance based upon said attenuation.