Grating couplers for (Bloch) long-range surface plasmons on metal stripe waveguides

Khodami, Maryam; Berini, Pierre

doi:10.1364/josab.36.001921

Cited by 14 publications

(17 citation statements)

References 33 publications

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“…Both Au and Pt stripes are lithographically defined and evaporated. Fabrication details and the optical operation of the LRSPPs waveguides are reported elsewhere [4,5,7].…”

Section: Electrode Structuresmentioning

confidence: 99%

“…Small, closely spaced metallic features of dimensions and separation in the micrometer range are of interest in electrochemical device applications or for integration with optical biosensors, e.g., based on surface plasmon-polaritons (SPPs) [1][2][3]. Optical biosensors exploiting long-range surface plasmon-polariton (LRSPP) waveguides have solicited significant interest because they enable compactness in integrated architectures, and offer very high sensitivity in an arrayed format [4][5][6][7]. LRSPPs are supported by a thin metal slab or stripe bounded by dielectrics of similar refractive index [8].…”

Section: Introductionmentioning

confidence: 99%

“…LRSPPs are supported by a thin metal slab or stripe bounded by dielectrics of similar refractive index [8]. For biosensing, the metal stripe is typically formed of Au and is supported by a cladding of low refractive index, e.g., a fluoropolymer such as Cytop, which has an index close to water and is thus well-matched to the index of aqueous biosensing media [5,6]. Alternatively, Au-sensing waveguides can be fabricated on a multilayer dielectric cladding, behaving optically as a 1-D photonic crystal (1DPC), and supporting Bloch LRSPPs within the bandgap of the 1DPC [4,5,7].…”

Section: Introductionmentioning

confidence: 99%

“…For biosensing, the metal stripe is typically formed of Au and is supported by a cladding of low refractive index, e.g., a fluoropolymer such as Cytop, which has an index close to water and is thus well-matched to the index of aqueous biosensing media [5,6]. Alternatively, Au-sensing waveguides can be fabricated on a multilayer dielectric cladding, behaving optically as a 1-D photonic crystal (1DPC), and supporting Bloch LRSPPs within the bandgap of the 1DPC [4,5,7]. Advantageously, the multilayer cladding in such structures can be formed of robust inorganic dielectrics (e.g., SiO 2 , Si 3 N 4 , Ta 2 O 5 ), allowing multiple wafer-scale processing steps to be applied thereon, thereby enabling a high degree of integration and conferring strength and resilience to the chips [7].…”

Section: Introductionmentioning

confidence: 99%

“…Motivated by the high sensitivity of Au stripe LRSPP waveguide biosensors [4][5][6][7], along with their suitability for high levels of integration, we investigate microelectrode systems suitable for integration with such optical biosensors, to ultimately enable multi-modal sensing strategies, of strong interest in, e.g., disease detection problems. The use of highvolume wafer-scale manufacturing tools and techniques in the fabrication of the sensors ensures a low chip cost.…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical Performance of Lithographically-Defined Micro-Electrodes for Integration and Device Applications

et al. 2021

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Small; lithographically-defined and closely-spaced metallic features of dimensions and separation in the micrometer range are of strong interest as working and counter electrodes in compact electrochemical sensing devices. Such micro-electrode systems can be integrated with microfluidics and optical biosensors, such as surface plasmon waveguide biosensors, to enable multi-modal sensing strategies. We investigate lithographically-defined gold and platinum micro-electrodes experimentally, via cyclic voltammetry (CV) measurements obtained at various scan rates and concentrations of potassium ferricyanide as the redox species, in potassium nitrate as the supporting electrolyte. The magnitude of the double-layer capacitance is estimated using the voltammograms. Concentration curves for potassium ferricyanide are extracted from our CV measurements as a function of scan rate, and could be used as calibration curves from which an unknown concentration of potassium ferricyanide in the range of 0.5–5 mM can be determined. A blind test was done to confirm the validity of the calibration curve. The diffusion coefficient of potassium ferricyanide is also extracted from our CV measurements by fitting to the Randles–Sevcik equation (D = 4.18 × 10−10 m2/s). Our CV measurements were compared with measurements obtained using macroscopic commercial electrodes, yielding good agreement and verifying that the shape of our CV curves do not depend on micro-electrode geometry (only on area). We also compare our CV measurements with theoretical curves computed using the Butler–Volmer equation, achieving essentially perfect agreement while extracting the rate constant at zero potential for our redox species (ko = 10−6 m/s). Finally, we demonstrate the importance of burn-in to stabilize electrodes from the effects of electromigration and grain reorganization before use in CV measurements, by comparing with results obtained with as-deposited electrodes. Burn-in (or equivalently, annealing) of lithographic microelectrodes before use is of general importance to electrochemical sensing devices

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“…Both Au and Pt stripes are lithographically defined and evaporated. Fabrication details and the optical operation of the LRSPPs waveguides are reported elsewhere [4,5,7].…”

Section: Electrode Structuresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Electrochemical Performance of Lithographically-Defined Micro-Electrodes for Integration and Device Applications

et al. 2021

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Tri-layer contact photolithography process for high-resolution lift-off

Northfield

Krupin

Tait

et al. 2021

Microelectronic Engineering

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Real-Time Convolutional Voltammetry Enhanced by Energetic (Hot) Electrons and Holes on a Surface Plasmon Waveguide Electrode

2022

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Surface plasmon polaritons (SPPs) propagating along a waveguide working electrode are sensitive to changes in the local refractive index, which follow changes in the concentration of reduced and oxidized species near the working electrode. The real-time response of the output optical power from a waveguide working electrode is proportional to the time convolution of the electrochemical current density, precluding the need to compute the latter a posteriori via numerical integration. Convolutional voltammetry yields complementary results to conventional voltammetry and can be used to determine the diffusion constant, bulk concentration, and the number of transferred electrons of electroactive species. The theoretical optical response of a waveguide working electrode is derived and validated experimentally via chronoamperometry and cyclic voltammetry measurements under low power SPP excitation, for various concentrations of potassium ferricyanide in potassium nitrate electrolyte at various scan rates. Increasing the SPP power induces a regime where the SPPs no longer act solely as a probe of electrochemical activity, but also as a pump creating energetic electrons and holes via absorption in the working electrode. In this regime, the transfer of energetic carriers (electrons and holes) to the redox species dominates the electrochemical current density, which becomes significantly enhanced relative to equilibrium conditions (low SPP power). In this regime the output optical power remains proportional to the time convolution of the current density, even with the latter significantly enhanced by the transfer of energetic carriers.

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Grating couplers for (Bloch) long-range surface plasmons on metal stripe waveguides

Cited by 14 publications

References 33 publications

Electrochemical Performance of Lithographically-Defined Micro-Electrodes for Integration and Device Applications

Electrochemical Performance of Lithographically-Defined Micro-Electrodes for Integration and Device Applications

Tri-layer contact photolithography process for high-resolution lift-off

Real-Time Convolutional Voltammetry Enhanced by Energetic (Hot) Electrons and Holes on a Surface Plasmon Waveguide Electrode

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