Light propagation in strip and slot waveguide arrays for sensing

Abstract

Light propagation in strip and slot waveguide arrays for sensing are proposed and analyzed with a new theory of quantum walk. The waveguide arrays are designed on silicon-on-insulator and can be fabricated with mature and costefficient complementary metal-oxide semiconductor technology. A new slot waveguide array modified by conventional strip waveguide array with electric field mainly confined in the cladding region is investigated. Quantum walks have an exact mapping to classical phenomena as verified by experiments using bright laser light, so that they are introduced in our work as theoretical foundation. We take the width of waveguide of 450 nm and the coupling distance of 200 nm for strip waveguide array, and 420 nm and 180 nm for slot waveguide array, but with a 100nm slot in the center of waveguide. At last the waveguide array covered by a thin layer of graphene is investigated, which brings higher sensing property as well as a much better biocompatibility. With the monochrome light injection the intensity distribution at the end of the arrays changes with the refractive index of the sensing area (cladding region) and it can be explained by quantum walks theory. The designed waveguide arrays can possess compact footprint and high refractive index resolution, reaching 1E-11 RIU theoretically.

Ultra-Stable Molecular Sensors by Sub-Micron Referencing and Why They Should Be Interrogated by Optical Diffraction—Part I. The Concept of a Spatial Affinity Lock-in Amplifier

“…In addition, any surface plasmon resonance imaging sensor using distributed referencing is essentially a digitally locked-in sensor [ 15 ]. Other options for a digital spatial lock-in could include arrays of LSPR (localized surface plasmon resonance) sensors [ 55 ] or arrays of slot waveguides [ 56 ]. These would need to be functionalized in an alternating manner and being separated at sufficient mutual distance to avoid coupling (crosstalk) between the sensing elements.…”