Waveguides for enhanced total internal reflection fluorescence microscopy
Evanescently-coupled planar waveguides for enhancing total internal reflection fluorescence microscopy are disclosed. The waveguides include multiple thin layers of one or more materials on a cover slip arranged resonantly enhance the optical field at the surface of the layer stack by evanescently coupling to a leaky guided mode.
1. A cover slip for resonant enhancement of an evanescent optical field, comprising a cover slip having:
(i) a coupling layer directly adjacent a glass substrate having a refractive index n c , and a thickness more than about one-half an optical excitation wavelength; and (ii) one or more guide layers on the coupling layer having a refractive index n gi that is more than a medium of a specimen; wherein n c is less than refractive indices of any layer subsequent to a coupling layer; and wherein a guide layer thickness and guide layer refractive index support a leaky guided mode.
2. The cover slip of claim 1 , wherein each of the one or more guide layers has a refractive index between 1.5 and 4.0.
3. The cover slip claim 1 , wherein the coupling layer has a refractive index between 1.0 and 1.5.
4. The cover slip of claim 3 , wherein the coupling layer includes one or more of MgF 2 , CaF 2 , PTFE/Teflon, or nanoporous silicates/aerogels.
5. The cover slip of claim 1 , wherein the collective thickness of the one or more guide layers ranges from 0.1 times the optical excitation wavelength to 10 times the optical excitation wavelength.
6. The cover slip of claim 1 , wherein the one or more guide layers include one or more of TiO 2 , ZnO, Al 2 O 3 , TeO 2 , SiN X , conjugated polymers, or chalcogenide glasses.
7. The cover slip of claim 1 , further comprising a specimen thereon wherein the specimen includes a fluorophore.
8. The cover slip of claim 1 , wherein the one or more guide layers include one or more of ZnO and/or Al; 2 O 3 and the coupling layer includes one or more layers of MgF 2 .
9. The cover slip of claim 1 , wherein the one or more guide layers include a layer of ZnO between two layers of Al 2 O 3 and the coupling layer includes MgF 2 .
10. The cover slip of claim 1 , wherein the optical excitation wavelength ranges between 300-700 nm.
11. The cover slip of claim 1 , wherein the one or more guide layers on the coupling layer have n gi that is more than about 1.33.
12. The cover slip of claim 1 , wherein the thickness of the coupling layer directly adjacent the glass substrate is 600 nm or more.