Method and apparatus for enhanced evanescent fluorescence and color filtering using a high refractive index thin film coating

A method for enhancing the excitation and collection efficiency of a fluorescence sensor, comprising the steps of:

• providing an optical waveguide having a core, a core surface and at least one material surrounding and disposed upon said core surface, said waveguide having further a distal end and a proximal end;
• removing said material from one or more regions along a length of said distal end of said waveguide;
• applying a coating onto said core surface of each of said regions, said coating comprising a high index of refraction thin film, said coating having an index of refraction greater than said core;
• providing a light beam, at least a portion of said light beam directed into said waveguide at or near said proximal end;
• propagating said light beam through said waveguide toward said distal end so as to produce an evanescent field at an external surface of said thin film coating;
• placing said distal end into a liquid medium such that at least one of said regions is at least partially immersed in said medium, said medium containing molecules having fluorescent properties, said evanescent field stimulating fluorescence emission in at least some of said molecules;
• and
• collecting at least some of said fluorescence emission into one or more of said regions and propagating said emission through said waveguide to said proximal end.

A method for filtering fluorescence emission light frequencies, comprising the steps of:

• providing an optical waveguide having a core, a core surface and at least one material surrounding and disposed upon said core surface, said waveguide having further a distal end and a proximal end;
• removing said material in one or more regions along a length of said waveguide distal end;
• applying a coating onto said core surface of each of said regions, said coating comprising a high index of refraction thin film, said coating having an index of refraction greater than said core;
• adjusting the thickness of said thin film based on an interference characteristic of said waveguide and a known frequency bandwidth of light so as to preferentially detect a specific frequency bandwidth of light;
• providing a light beam which includes said known frequency bandwidth incident upon a proximal end of said waveguide;
• propagating said light beam through said waveguide toward said distal end so as to produce an evanescent field at an external surface of said thin film coating;
• placing said distal end into a liquid medium such that at least one of said regions is at least partially immersed in said medium, said medium containing molecules having fluorescent properties, said evanescent field stimulating fluorescence emission in at least some of said molecules;
• and
• collecting at least some of said fluorescence emission into one or more of said regions and propagating said emission through said waveguide to said proximal end.

A method for filtering light emission frequencies, comprising the steps of:

• providing an optical waveguide having a core, a core surface and at least one material surrounding and disposed upon said core surface, said waveguide having further a distal end and a proximal end;
• removing said material in one or more regions along a length of said waveguide distal end;
• applying a coating onto said core surface of each of said regions, said coating comprising a high index of refraction thin film, said coating having an index of refraction greater than said core;
• adjusting the thickness of said thin film based on an interference characteristic of said waveguide and a known frequency bandwidth of light so as to preferentially detect a specific frequency bandwidth of light;
• and
• collecting at least some of said specific frequency bandwidths into one or more of said regions and propagating said emissions through said waveguide to said proximal end.