Cross-propagating Bloch Surface Waves: Guiding Light to Develop a Photonic Nano-CT Scan Analogue
DescriptionSignificant advances in sensing complex molecules have been achieved using nano-architecture structures (NAS) that obtain information on the shape and function of nearby complex biomolecules by measuring their far-field response with and without analyte. Clearly, as NAS have their own optical response, analyte detection is a second-order effect. For example, when utilizing chiroptical methods, the spectral shifts of a chiral material (the chiral probe) to left and right-hand circularly polarized light (LH and RH, respectively) are denoted as ΔλLHand ΔλRH, and the corresponding dissymmetry, which is defined as ΔΔλ = ΔλRH− ΔλLH, characterizes the chiroptical response of such materials. Thereafter, the quantities of interest are the differences in the dissymmetry measured upon interaction of the chiral probe with the molecules (analytes) of interest. Not surprisingly, it is generally accepted that current state-of-the-art approaches to NAS-related discoveries are restricted to analyte detection rather than actually sensing the analyte’s structure. We propose to develop a new approach to examining NAS by using the coherent superposition of cross-propagating Bloch surface waves (cp-BSW) to systematically probe the N-th dimensional parameter space defined by the number (N) of resonances in a given NAS that can be excited by the cp-BSW.To this end we will integrate five strategies that have been utilized in this field. The first one is to use giant, 103–104, evanescent BSW, using a recently reported analytical strategy to design multiple BSW resonances with arbitrary wavelengths, angles of incidence, and polarizations. Second, to form the coherent superposition of cp-BSW resulting in rich near-filed polarization and structure that depend on the parameters of the excitation beams (intensity, polarization, and phase of each beam exciting the BSW device). Third, the design of NAS engineered to support multiple N-th resonances that can be selectively tuned as function of the parameters of the beams exciting each BSW. Fourth, the use of advanced sensing of the resulting total internal reflection (TIR) by utilizing an interferometric, phase sensitive, detection scheme. Lastly, advanced optical characterization setups, including Muller matrix ellipsometry (MME), spectroscopic imaging ellipsometry, and single nanoparticle optical spectroscopies, such as scattering, PL, and/or surface-enhanced Raman spectroscopy (SERS). The rationale for this proposal is that non-trivial polarization states and local near-field structures resulting from the cp-BSW can be controlled by the parameters of the beams exciting each BSW. Coupling of these complex near fields with suitable engineered NAS can then be used to selectively tune predefined resonant modes; thus defining a N-th dimensional parameter space to probe the complex molecules on the vicinity of the NAS (as function of the parameters of the beams exciting the BSW). Clearly the implementation of this approach will enable a general and rich platform for structural sensing of complex molecules and will have tremendous potential for future applications in biomedicine, pharmacology, chemical sensors, low-threshold lasers, and optical modulation or switching among others uses.
|Effective start/end date||1/01/23 → …|