Planar and other waveguide refractive index sensors using metal cladding

A method of detecting the refractive index and identifying chemical species of a medium, comprising:

• providing a waveguide sensor comprising light guiding means having a refractive index N1, and a clad having a thin film metal clad segment o metal or metal oxide or other metal compound or alloy formed on a portion of the light guiding means, the metal clad segment having a refractive index N3 and an effective thickness and light transmissivity which in combination with a surrounding medium produces a localized refractive index and a controlled leakage of light which modulates the transmission of light through the light guiding means as a function of the refractive index of the surrounding medium, the remainder of the clad having a refractive index N2 less than N1 wherein the light guiding means is formed of a planar waveguide body;
• contacting the thin film metal clad segment with the medium;
• inputting a light signal into the light guiding means;
• detecting the changes in intensity of a light signal transmitted from the light guiding means.

A method of detecting the refractive index and identifying chemical species of a medium, comprising:

• providing a waveguide sensor comprising light guiding means having a refractive index N1, and a clad having a thin film metal clad segment of metal or metal oxide or other metal compound or alloy formed on a portion of the light guiding means, the metal clad segment having a refractive index N3 and an effective thickness and light transmissivity which in combination with a surrounding medium produces a localized refractive index and a controlled leakage of light which modulates the transmission of light through the light guiding means as a function of the refractive index of the surrounding medium, the remainder of the clad having a refractive index N2 less than N1;
• forming an overlayer or underlayer of a second material on the metal clad segment, the metal clad segment having a strong affinity for a chemical species of interest, the second material having a suitable refractive index to produce controlled light leakage in the presence of the chemical species;
• contacting the thin film metal clad segment with the medium;
• inputting a light signal into the light guiding means;
• detecting the changes in intensity of a light signal transmitted from the light guiding means.

A method of detecting the refractive index and identifying chemical species of a medium, comprising:

• providing a waveguide sensor comprising light guiding means having a refractive index N1, and a clad having a thin film metal clad segment of metal or metal oxide or other metal compound or alloy formed on a portion of the light guiding means, the metal clad segment having a refractive index N3 and an effective thickness and light transmissivity which in combination with a surrounding medium produces a localized refractive index and a controlled leakage of light which modulates the transmission of light through the light guiding means as a function of the refractive index of the surrounding medium, the remainder of the clad having a refractive index N2 less than N1;
• adding a catalyst to the metal clad segment for reacting the species of interest to form a reaction product and forming the metal clad segment specific to the reaction product;
• contacting the thin film metal clad segment with the medium;
• inputting a light signal into the light guiding means;
• detecting the changes in intensity of a light signal transmitted from the light guiding means.

Apparatus for detecting the presence of a particular chemical species, comprising:

• at least one planar waveguide body, each planar waveguide body having at least one thin film metal clad segment on a waveguide body, each metal clad segment having a different sensitivity to various chemical species;
• a light source operatively associated with each waveguide body to input a light signal into each waveguide body;
• detection means operatively associated with each waveguide body to detect signals produced by modulation by each metal clad segment;
• processing means for calculating information about one or more species from the detected signals produced by modulation by each metal clad segment.

Apparatus for detecting the presence of a particular chemical species comprising:

• a waveguide body having a pair of spaced parallel thin film metal clad segments on the waveguide body each metal clad segment having a different sensitivity to various chemical species;
• a light source producing a pair of parallel light beams which propagate down the waveguide body, one beam in alignment with each of the metal clad segments, wherein each beam is affected by only one of the metal clad segments;
• detection means operatively associated with the waveguide body to detect signals produced by modulation by each metal clad segment;
• processing means for calculating information about one or more species from the detected signals produced by modulation by each metal clad segment.

Apparatus for detecting the presence of a particular chemical species, comprising:

• a waveguide body having a pair o spaced parallel thin film metal clad segments, each metal clad segment having a different sensitivity to various chemical species;
• a light source operatively associated with the waveguide body to input a light signal into the waveguide body;
• detection means operatively associated with each waveguide body to detect signals produced by modulation by each metal clad segment;
• alternate viewing means positioned between the waveguide body and detection means for alternately passing a light beam affected by one of the clad segments while blocking a light beam affected by the other clad segment;
• processing means for calculating information about one or more species from the detected signals produced by modulation by each metal clad segment.

Apparatus for detecting the presence of a particular chemical species, comprising:

• a waveguide body having a pair of metal clad segments, each metal clad segment having a different sensitivity to various chemical species and each of which affects light of a different wavelength,
• a light source operatively associated with the waveguide body to input a light signal into the waveguide body;
• detection means operatively associated with each waveguide body to detect signals produced by modulation by each metal clad segment;
• processing means for calculating information about one or more species from the detected signals produced by modulation by each metal clad segment;
• wherein the light source and detection means produce and detect light at the two wavelengths.

Apparatus for detecting the presence of a particular chemical species, comprising:

• at least one wave guide body, each waveguide body having at least one thin film metal clad segment on a waveguide body, each metal clad segment having a different sensitivity to various chemical species;
• a light source operatively associated with each waveguide body to input a light signal into each waveguide body;
• detection means operatively associated with each waveguide body to detect signals produced by modulation by each metal clad segment;
• processing means for calculating information about one or more species from the detected signals produced by modulation by each metal clad segment;
• light blocking means positioned on at least one of the waveguide body and detection means for substantially blocking background light passing straight down the center of the waveguide body from reaching the detection means.

Apparatus for detecting the presence of a particular chemical species, comprising:

• at least one waveguide body, each waveguide body having at least one thin film metal clad segment on a waveguide body, each metal clad segment having a different sensitivity to various chemical species;
• a light source operatively associated with the waveguide body to input a light signal into the waveguide body;
• detection means operatively associated with each waveguide body to detect signals produced by modulation by each metal clad segment;
• processing means for calculating information about one or more species from the detected signals produced by modulation by each metal clad segment;
• wherein the detection means includes means for detecting light passing through the metal clad segments.