Gold nanoparticle coated silicon nitride chips for intracellular surface-enhanced raman spectroscopy

Using surface-enhanced Raman spectroscopy on gold-nanoparticle-decorated silicon nitride chips, we monitor the release of dextran-rhodamin molecules from capsules inside living cells. This demonstrates the feasibility of using photonic chips for intracellular sensing at visible wavelengths

Gold nanodome-patterned microchips for intracellular surface-enhanced Raman spectroscopy

While top-down substrates for surface-enhanced Raman spectroscopy (SERS) offer outstanding control and reproducibility of the gold nanopatterns and their related localized surface plasmon resonance, intracellular SERS experiments heavily rely on gold nanoparticles. These nanoparticles often result in varying and uncontrollable enhancement factors. Here we demonstrate the use of top-down gold-nanostructured microchips for intracellular sensing. We develop a tunable and reproducible fabrication scheme for these microchips. Furthermore we observe the intracellular uptake of these structures, and find no immediate influence on cell viability. Finally, we perform a proof-of-concept intracellular SERS experiment by the label-free detection of extraneous molecules. By bringing top-down SERS substrates to the intracellular world, we set an important step towards time-dependent and quantitative intracellular SERS

Enhancement of raman scattering efficiency by a metallic nano-antenna on top of a high index contrast waveguide

We theoretically study coupling of dipole radiation into integrated Si3N4 strip waveguides functionalized with a nanoplasmonic antenna. This structure enables efficient coupling of enhanced Raman signals into the fundamental TE-mode of the waveguide

Enhanced spontaneous raman signal collected evanescently by silicon nitride slot waveguides

We investigate the effect of waveguide geometry on the conversion efficiency of Raman signals collected by integrated photonic waveguides. Compared to strip-type photonic wires, we report a six-fold increase in conversion efficiency for silicon-nitride slot-waveguides

Near-infrared grating couplers for silicon nitride photonic wires

Silicon nitride is a promising high-index material for dense photonic circuits and applications in the visible-midinfrared wavelength regime. Design, fabrication, and optical characterization of silicon nitride waveguides at visible-near-infrared wavelength are presented. Finally, design and experimental results are presented for the first time for linear and focused grating couplers (GCs) at near-infrared wavelength (900 nm) for plasma-enhanced chemical vapor deposition silicon nitride wires (220 x 500 nm) and compared with theoretical simulations. An experimental efficiency of 5.7 and 6.5 dB and 1-dB bandwidth of 26 and 40 nm are reported for the linear and focused GCs, respectively

Silicon-nitride waveguides for on-chip Raman spectroscopy

The evanescent tail of the guided modes can efficiently excite Raman active molecules located in the cladding of a waveguide. Similarly, a significant fraction of the total emitted Stokes power is evanescently coupled to the same mode. Further, the enhancement effects inherent to the waveguide, alongside with the long interaction length, lead to an increased light-matter interaction, resulting in a higher sensitivity as required by spectroscopic applications, especially in the context of Raman spectroscopy. We calculate the spontaneous Raman scattering efficiency as a function of siliconnitride strip waveguide dimensions and show that under typical conditions, the overall efficiency is approximately two orders of magnitude higher than in confocal configuration in the free space. We also report the experimental demonstration of the use of silicon-nitride based photonic waveguides in a lab-on-a-chip context for Raman spectroscopy. To the best of our knowledge, this is the first demonstration of Raman spectroscopy using photonic waveguides

Compact silicon nitride arrayed waveguide gratings for very near-infrared wavelengths

In this letter, we report a novel high-index-contrast silicon nitride arrayed waveguide grating (AWG) for very near-infrared wavelengths. This device is fabricated through a process compatible with a complementary metal-oxide-semiconductor fabrication line and is therefore suitable for mass fabrication. The large phase errors that usually accompany high-index-platform AWGs are partly mitigated through design and fabrication adaptions, in particular the implementation of a two-level etch scheme. Multiple devices are reported, among which a 0.3-mm(2) device which, after the subtraction of waveguides loss, has a -1.2 dB on-chip insertion loss at the peak of the central channel and 20-dB crosstalk for operation similar to 900 nm with a channel spacing of 2 nm. These AWGs pave the way for numerous large-scale on-chip applications pertaining to spectroscopy and sensing

Efficiency of evanescent excitation and collection of spontaneous Raman scattering near high index contrast channel waveguides

info:eu-repo/semantics/publishe