Illumination of optical analytical devices
Optical analytical devices and their methods of use are provided. The devices are useful in the analysis of highly multiplexed optical reactions in large numbers at high densities, including biochemical reactions, such as nucleic acid sequencing reactions. The devices include optical waveguides for illumination of the optical reactions. The devices further provide for the efficient coupling of optical excitation energy from the waveguides to the optical reactions. Optical signals emitted from the reactions can thus be measured with high sensitivity and discrimination using features such as spectra, amplitude, and time resolution, or combinations thereof. The devices of the invention are well suited for miniaturization and high throughput.
1. An analytical device comprising:
an optical waveguide comprising an optical core and a cladding;
a metallic layer disposed on the surface of the cladding; and
a plurality of nanometer-scale apertures disposed in the metallic layer, such that optical energy passing through the optical core of the optical waveguide illuminates the plurality of apertures by an evanescent field that emanates from the waveguide;
wherein the optical core has a thickness, a width, and a cross-sectional area, and wherein the cross-sectional area is decreased at locations where the evanescent field illuminates the apertures; and
wherein the plurality of apertures do not extend into the optical core of the optical waveguide.
2. The analytical device of claim 1 , wherein the cross-sectional area is decreased by adiabatic tapers.
3. The analytical device of claim 1 , wherein the thickness of the optical core is maintained, and the cross-sectional area is decreased by decreasing the width of the optical core.
4. The analytical device of claim 3 , wherein the optical energy is transverse electric polarized light.
5. The analytical device of claim 1 , wherein the width of the optical core is maintained, and the cross-sectional area is decreased by decreasing the thickness of the optical core.
6. The analytical device of claim 5 , wherein the optical energy is transverse magnetic polarized light.
7. The analytical device of claim 1 , further comprising a plurality of local field enhancement elements associated with the plurality of apertures.
8. The analytical device of claim 7 , wherein the local field enhancement elements comprise a high dielectric material or metal in the vicinity of the apertures.
9. The analytical device of claim 8 , wherein the high dielectric material or metal is arranged in a geometric pattern around the aperture.
10. The analytical device of claim 9 , wherein the geometric pattern is selected from the group consisting of a circle, a series of concentric circles, a C aperture, a triangle pair, and a diamond.
11. The analytical device of claim 8 , wherein the high dielectric material or metal is Al 2 O 3 , copper, silver, gold, or aluminum.
12. The analytical device of claim 11 , wherein the high dielectric material or metal is Al 2 O 3 .
13. The analytical device of claim 11 , wherein the high dielectric material or metal is copper.
14. The analytical device of claim 7 , wherein the apertures are recessed into the cladding.
15. The analytical device of claim 7 , wherein the thickness of the cladding between the optical core and the metallic layer decreases in the vicinity of the apertures.
16. The analytical device of claim 15 , wherein the thickness of the cladding is from 150 to 300 nm.
17. The analytical device of claim 16 , wherein the thickness of the cladding is about 200 nm.
18. The analytical device of claim 7 , wherein the local field enhancement elements comprise the shape of the nanometer-scale apertures.
19. The analytical device of claim 18 , wherein the shape of the nanometer-scale apertures is selected from the group consisting of a C aperture, a triangle pair, and a diamond.
20. The analytical device of claim 1 , wherein the analytical device further comprises a plurality of analytes disposed in analyte regions within the plurality of nanometer-scale apertures.
21. The analytical device of claim 20 , wherein the plurality of analytes comprise a plurality of biological samples.
22. The analytical device of claim 21 , wherein the plurality of biological samples comprise a plurality of nucleic acids.
23. The analytical device of claim 1 , wherein the analytical device comprises at least 1,000, at least 10,000, at least 100,000, at least 1,000,000, or at least 10,000,000 nanometer-scale apertures.
24. The analytical device of claim 1 , wherein the width of the optical core is decreased by 5% to 90% at locations where the evanescent field illuminates the apertures.
25. The analytical device of claim 1 , wherein the width of the optical core is decreased by 10% to 20% at locations where the evanescent field illuminates the apertures.