Dielectric microcavity fluorosensors excited with a broadband light source

Abstract

A microresonator sensor apparatus has a microcavity resonator that defines equatorial whispering gallery modes (EWGMs), whose frequencies are separated by the free spectral range (FSR). The EWGMs lie in a plane perpendicular to a microcavity resonator axis. A light source is optically coupled to inject light into the microcavity resonator. The light source produces output light having an output spectrum whose bandwidth is approximately equal to or broader than the FSR of the EGWMs. One or more fluorescent materials are excited using the excitation light coupled into the microcavity resonator. A fluorescent signal arising from fluorescence of the one or more fluorescent materials is then detected.

1 . A method of taking fluorescent measurements, comprising: 
 coupling excitation light into multiple resonant modes of a microcavity resonator;    exciting one or more fluorescent materials using the multiple resonant modes; and    detecting a fluorescent signal arising from fluorescence of the one or more fluorescent materials.    
   
   
       2 . A method as recited in  claim 1 , wherein the multiple resonant modes comprise at least two whispering gallery modes (WGMs).  
   
   
       3 . A method as recited in  claim 2 , wherein the at least two WGMs comprise at least two adjacent WGMs.  
   
   
       4 . A method as recited in  claim 2 , wherein the at least two WGMs comprise at least two equatorial whispering gallery modes (EWGMs).  
   
   
       5 . A method as recited in  claim 1 , wherein coupling the excitation light comprises generating the excitation light using a light source and passing the excitation light from the light source to the microcavity resonator via an optical waveguide.  
   
   
       6 . A method as recited in  claim 5 , wherein generating the excitation light comprises generating the excitation light in a laser.  
   
   
       7 . A method as recited in  claim 5 , wherein generating the excitation light comprises generating the excitation light in a light emitting diode.  
   
   
       8 . A method as recited in  claim 5 , wherein the optical waveguide comprises a tapered fiber.  
   
   
       9 . A method as recited in  claim 5 , wherein the optical waveguide comprises a planar or channel waveguide.  
   
   
       10 . A method as recited in  claim 1 , wherein detecting the fluorescent signal comprises detecting light propagating in free space from the microcavity resonator.  
   
   
       11 . A method as recited in  claim 1  further comprising optically filtering the fluorescent signal before detecting the fluorescent signal.  
   
   
       12 . A method as recited in  claim 1  further comprising attaching an analyte to the microcavity resonator, the one or more fluorescent materials being associated with the analyte.  
   
   
       13 . A method as recited in  claim 12  further comprising attaching the one or more fluorescent materials to the analyte before attaching the analyte to the microcavity resonator.  
   
   
       14 . A method as recited in  claim 12  further comprising attaching the one or more fluorescent materials to the analyte after attaching the analyte to the microcavity resonator.  
   
   
       15 . A method as recited in  claim 1 , wherein the excitation light has a bandwidth sufficiently broad so as to be capable of coupling into at least five resonant modes of the microcavity resonator.  
   
   
       16 . A method as recited in  claim 1 , wherein the excitation light has a bandwidth sufficiently broad so as to be capable of coupling into at least ten resonant modes of the microcavity resonator.