Optical fiber sensors using grating-assisted surface plasmon-coupled emission (GASPCE)
View Patent ↗The present invention relates to a new fluorescence detection platform based on the integration of grating-assisted surface plasmon coupled emission (GASPCE). This innovation builds upon the traditional SPCE technique by adding a grating to the metal surface which thereby provides additional emission confinement. The original conical emission pattern associated with the traditional SPCE technique is “squeezed” into a “two-beam” emission pattern that is more readily interrogated and collected by a waveguiding structure. With the GASPCE method and system of the present invention, a fluorescence emission can be coupled into optical waveguide with greater efficiency. As such, the integration of the GASPCE and existing optical fiber networking offers distributed real-time sensing capabilities. Also, the integration with an integrated optical chip may enable multi-channel array sensing or high-throughput florescence sensing.
1. A grating assisted surface plasmon coupled emission system comprising:
a surface plasmon-coupled emission (SPCE) structure including an emitting material, an electrically conductive, light penetrable layer and a substrate layer wherein the electrically conductive, light penetrable layer is positioned between the emitting material and the substrate layer and supports surface plasmon resonance and the substrate layer is a transparent dielectric medium supporting the electrically conductive, light penetrable layer; and
a periodic photonic structure defining a grating having a grating period directing an optical emission from the emitting material into a two-dimensional confinement in the azimuthal and polar directions propagating into the substrate layer.
2. The system of claim 1 wherein the optical emission is fluorescence, Raman scattering, or second harmonic generation.
3. The system of claim 1 wherein the electrically conductive, light penetrable layer is a metal layer.
4. The system of claim 3 wherein the metal layer is silver, gold, or aluminum.
5. The system of claim 1 wherein the substrate layer is a glass or polymer material.
6. The system of claim 1 wherein the periodic photonic structure is a grating structure.
7. The system of claim 6 wherein the grating structure has a uniform periodicity and a groove depth with arbitrary undulated profiles.
8. The system of claim 1 wherein the grating is formed by the electrically conductive, light penetrable layer of the SPCE structure having a corrugated surface.
9. The system of claim 1 wherein the grating is formed by a corrugated surface of the substrate layer.
10. The system of claim 1 wherein the grating is formed via a refractive index perturbation in the substrate layer of the SPCE structure.
11. The system of claim 1 further comprising:
a waveguide structure having a coupling portion positioned about parallel with the substrate layer and receiving the optical emission at a transmission angle to trap the optical emission.
12. The system of claim 1 wherein the substrate layer is an integrated optical chip having a multiple grating-assisted surface plasmon-coupled emission (GASPCE) surface thereon.
13. The system of claim 11 , wherein the waveguide structure is an optical fiber.
14. The system of claim 1 , wherein the grating period satisfies the condition Λ=2π/G where Λ is the grating period and G=k gaspce +k spw is the sum of the wavevectors of the optical emission coupled into the substrate and a surface plasmon wave induced in the electrically conductive, light penetrable layer.