Hybrid integrated plasmonic-photonic waveguides for on-chip localized surface plasmon resonance (LSPR) sensing and spectroscopy

Abstract

We experimentally demonstrate efficient extinction spectroscopy of single plasmonic gold nanorods with exquisite fidelity (SNR > 20dB) and high efficiency light coupling (e. g., 9.7%) to individual plasmonic nanoparticles in an integrated platform. We demonstrate chip-scale integration of lithographically defined plasmonic nanoparticles on silicon nitride (Si3N4) ridge waveguides for on-chip localized surface plasmon resonance (LSPR) sensing. The integration of this hybrid plasmonic-photonic platform with microfluidic sample delivery system is also discussed for on-chip LSPR sensing of D-glucose with a large sensitivity of ∼ 250 nm/RIU. The proposed architecture provides an efficient means of interrogating individual plasmonic nanoparticles with large SNR in an integrated alignment-insensitive platform, suitable for high-density on-chip sensing and spectroscopy applications.

On-chip surface-enhanced Raman spectroscopy using nanosphere-lithography patterned antennas on silicon nitride waveguides

“…Surface-enhanced Raman scattering (SERS) allows to dramatically increase the Raman signal from molecules in the close vicinity of plasmonic nano-antennas, even up to the limit of single-molecule detection [14]. Recent efforts succeeded in combining plasmonic antennas with Si [15] and SiN [16][17][18] waveguides, providing proof-of-concept experiments for integrated localized surface plasmon resonance (LSPR) sensing [18] and even waveguide-excited and -collected SERS [17]. However, all these approaches rely on multiple electron-beam lithography steps with critical alignment for writing both the waveguides and the nano-antennas.…”

Design and implementation of nanoantennas on integrated guides and their application on polarization analysis and synthesis.

“…These results can be relevant for studying spin-orbit coupling effects (such as the SCUE of guided modes) in a photonic integrated platform, including not only silicon but also active III-V materials, with applications in multiple disciplines ranging from quantum processing to optical processing. In addition, this envisage that the existence of relevant transverse spin must be properly considered when coupling plasmonic metallic scatterers or nanoantennas to silicon waveguides [56,101,102].…”

“…The left-part of this silicon photonic integrated circuit includes plasmonic elements for enhanced Raman [55] and refractomeric biosensing [55] of a certain fluid. The right-part of the PIC includes electrooptical (with a plasmonic slot Mach-Zehnder interferometer [56]) and all-optical (with a rod-based hyperbolic metamaterial [58]) modulation/switching. Nanoantennas are used as transducers between the outer world and the waveguides: the input port includes a highly directive Yagi-Uda [46] for highly directional coupling and polarization-dependent output nanoantennas for polarization multiplexing of the output radiated light.…”

“…Recent experiments have demonstrated the excitation of subwavelength-size plasmonic nanostructures placed on top of silicon and silicon nitride waveguides at visible and infrared wavelengths [46,55,56,100,101,102,103]. The coupling between the guided field and the nanostructure takes place in the evanescent region of the waveguide, which is excited by the fundamental TE-like mode having the fundamental electric field component parallel to the chip plane (see Figure 3.1(a)).…”

“…The coupling between the guided field and the nanostructure takes place in the evanescent region of the waveguide, which is excited by the fundamental TE-like mode having the fundamental electric field component parallel to the chip plane (see Figure 3.1(a)). This results in relatively small interaction efficiencies (typically < 10% although ~19% is reported in [102]) so in many occasions a number of nanostructures need to be placed on the waveguide (see Figure 3.1(b)) in order to produce observable effects (a dip in transmission) at the waveguide output [56,101,102]. Such weak coupling produces low power contrast (< 2) between maxima and minima in the measured spectra at the waveguide output, preventing its use in applications such as biosensing or all-optical switching which require high contrast to differentiate states.…”