Patent ID: 8617471

Claim:
An on-chip optical absorption spectroscopy apparatus comprising: i) a substrate; ii) a bottom cladding disposed on the substrate; iii) a slab disposed on the bottom cladding, wherein the refractive index of the bottom cladding is lower than the refractive index of the slab; iv) a plurality of void columnar members etched through the slab, wherein the plurality of void columnar members form a periodic lattice with a lattice constant Î±; v) a core in the slab comprising an input side and an output side, wherein the core is free of void columnar members from the input side to the output side; vi) wherein the distance between immediately adjacent inter-row void columnar members between a first row of void columnar members of the lattice from the input side to the output side immediately adjacent both sides of the core, a second row of void columnar members of the lattice from the input side to the output side immediately adjacent the first row of void columnar members of the lattice, and a third row of void columnar members of the lattice from the input side to the output side immediately adjacent the second row of void columnar members of the lattice is not equal to the lattice constant Î±; vii) a photonic crystal slot waveguide comprising: a) a photonic crystal waveguide formed within the core; and b) one or more slot waveguides defined by one or more void slots within the photonic crystal waveguide, extending the entire length of the photonic crystal waveguide; c) an input impedance taper in the photonic crystal waveguide at the input side; d) an output impedance taper in the photonic crystal waveguide at the output side; viii) an input ridge waveguide beyond the photonic crystal waveguide coupled to the input impedance taper in the photonic crystal waveguide; ix) an output ridge waveguide beyond the photonic crystal waveguide coupled to the output impedance taper in the photonic crystal waveguide; x) wherein the one or more void slots within the photonic crystal slot waveguide extend into the input ridge waveguide and the output ridge waveguide; xi) wherein the photonic crystal slot waveguide supports one or more guided modes of a broadband source; and xii) wherein an output transmission spectrum intensity of the one or more guided modes of the broadband source varies as a function of absorbance of an analyte within the photonic crystal slot waveguide.