Edge Raman enhancement at layered PbI2 platelets induced by laser waveguide effect

Monolithic integration of optoelectronic integrated circuits (OEIC) requires high quantity etched laser facets which prevent the developing of more-highly-integrated OEIC's. The causes of facet roughness are not well understood, and improvement of facet quality is hampered by the difficulty in measuring the surface roughness. There are several approaches to examining facet roughness qualitatively, such as scanning force microscopy (SFM), scanning tunneling microscopy (STM) and scanning electron microscopy (SEM). The challenge here is to allow more straightforward monitoring of deep vertical etched facets, without the need to cleave out test samples. In this presentation, we show air based STM and SFM images of vertical dry-etched laser facets, and discuss the image acquisition and roughness measurement processes. Our technique does not require precision cleaving. We use a traditional tip instead of the T shape tip used elsewhere to preventing “shower curtain” profiling of the sidewall. We tilt the sample about 30 to 50 degrees to avoid the curtain effect.

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Controllable Electrochemical Synthesis of Ag Hierarchical Micro/Nanostructures with High SERS-Activity

NANO ◽

10.1142/s1793292020500435 ◽

2020 ◽

Vol 15 (04) ◽

pp. 2050043

Author(s):

Huayu Zhou ◽

Jingjing Wang ◽

Qiong Yang ◽

Menglei Chen ◽

Changsheng Song ◽

...

Keyword(s):

Indium Tin Oxide ◽

Current System ◽

Three Dimensional ◽

Constant Current ◽

Localized Surface Plasmon ◽

Excitation Wavelength ◽

Raman Signal ◽

Mixed Solution ◽

Raman Enhancement ◽

One Step

We report a one-step electrochemical deposition technique to prepare three-dimensional (3D) Ag hierarchical micro/nanostructured film consisting of well-crystallized Ag nanosheets grown on an indium tin oxide (ITO) conductive substrate. The Ag hierarchical micro/nanostructures were fabricated in the mixed solution of AgNO3 and sodium citrate in a constant current system at room temperature. Through reduction of Ag[Formula: see text] electrodeposited on the surface of ITO substrate, nanoparticles were grown to form nanosheets which further combined into 3D sphere-like microstructures. The 3D Ag micro/nanostructures have many sharp edges and nanoscale gaps which can give rise to good Raman-enhanced effect. Due to localized surface plasmon resonance (LSPR) effects, these special Ag micro/nanostructures exhibited good Raman-enhanced performance. Using Rhodamine 6G (R6G) molecules as probe molecule, we studied the influence of excitation wavelength on Raman enhancement. The results showed that the 532[Formula: see text]nm excitation wavelength is the best to obtain the strongest Raman signal and to reduce the influence of other impurity peaks. Using the as-synthesized Ag hierarchical micro/nanostructures, we can detect the 10[Formula: see text][Formula: see text]mol/L R6G aqueous solution, exhibiting great Raman-enhanced effect.

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SERS Biosensor Based on Engineered 2D-Aperiodic Nanostructure for In-Situ Detection of Viable Brucella Bacterium in Complex Matrix

Nanomaterials ◽

10.3390/nano11040886 ◽

2021 ◽

Vol 11 (4) ◽

pp. 886

Author(s):

Massimo Rippa ◽

Riccardo Castagna ◽

Domenico Sagnelli ◽

Ambra Vestri ◽

Giorgia Borriello ◽

...

Keyword(s):

High Performance ◽

Foodborne Pathogen ◽

Surface Enhanced Raman Spectroscopy ◽

High Performing ◽

Sensing Platform ◽

Food Detection ◽

Raman Enhancement ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

In Situ Detection

Brucella is a foodborne pathogen globally affecting both the economy and healthcare. Surface Enhanced Raman Spectroscopy (SERS) nano-biosensing can be a promising strategy for its detection. We combined high-performance quasi-crystal patterned nanocavities for Raman enhancement with the use of covalently immobilized Tbilisi bacteriophages as high-performing bio-receptors. We coupled our efficient SERS nano-biosensor to a Raman system to develop an on-field phage-based bio-sensing platform capable of monitoring the target bacteria. The developed biosensor allowed us to identify Brucella abortus in milk by our portable SERS device. Upon bacterial capture from samples (104 cells), a signal related to the pathogen recognition was observed, proving the concrete applicability of our system for on-site and in-food detection.

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Surface Enhanced Raman Spectroscopy With Electrodeposited Copper Ultramicro-Wires With/Without Silver Nanostars Decoration

Nanomaterials ◽

10.3390/nano11020518 ◽

2021 ◽

Vol 11 (2) ◽

pp. 518

Author(s):

Margherita Longoni ◽

Maria Sole Zalaffi ◽

Lavinia de Ferri ◽

Angela Maria Stortini ◽

Giulio Pojana ◽

...

Keyword(s):

Raman Spectroscopy ◽

Surface Enhanced Raman Spectroscopy ◽

Anodized Aluminum ◽

Anodized Aluminum Oxide ◽

Electrochemical Preparation ◽

Deposition Parameters ◽

Raman Enhancement ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

Materials Used

The electrochemical preparation of arrays of copper ultramicrowires (CuUWs) by using porous membranes as templates is critically revisited, with the goal of obtaining cheap but efficient substrates for surface enhanced Raman spectroscopy (SERS). The role of the materials used for the electrodeposition is examined, comparing membranes of anodized aluminum oxide (AAO) vs. track-etched polycarbonate (PC) as well as copper vs. glassy carbon (GC) as electrode material. A voltammetric study performed on bare electrodes and potentiostatic tests on membrane coated electrodes allowed the optimization of the deposition parameters. The final arrays of CuUWs were obtained by chemical etching of the template, with NaOH for AAO and CH2Cl2 for PC. After total etching of the template, SERS spectra were recorded on CuUWs using benzenethiol as SERS probe with known spectral features. The CuUW substrates displayed good SERS properties, providing enhancement factor in the 103–104 range. Finally, it was demonstrated that higher Raman enhancement can be achieved when CuUWs are decorated with silver nanostars, supporting the formation of SERS active hot-spots at the bimetallic interface.

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Doping and plasmonic Raman enhancement in hybrid single walled carbon nanotubes films with embedded gold nanoparticles

Carbon ◽

10.1016/j.carbon.2021.04.079 ◽

2021 ◽

Vol 179 ◽

pp. 531-540

Author(s):

Anna Wroblewska ◽

Georgy Gordeev ◽

Anna Duzynska ◽

Stephanie Reich ◽

Mariusz Zdrojek

Keyword(s):

Carbon Nanotubes ◽

Gold Nanoparticles ◽

Single Walled Carbon Nanotubes ◽

Single Walled Carbon ◽

Raman Enhancement ◽

Walled Carbon Nanotubes

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Raman scattering in high-refractive-index nanostructures

Nanophotonics ◽

10.1515/nanoph-2020-0539 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Søren Raza ◽

Anders Kristensen

Keyword(s):

Raman Spectroscopy ◽

Refractive Index ◽

Raman Scattering ◽

Bound States ◽

Stimulated Raman Scattering ◽

Dielectric Materials ◽

High Refractive Index ◽

Surface Enhanced Raman Spectroscopy ◽

Raman Enhancement ◽

The Impact

AbstractThe advent of resonant dielectric nanomaterials has provided a new path for concentrating and manipulating light on the nanoscale. Such high-refractive-index materials support a diverse set of low-loss optical resonances, including Mie resonances, anapole states, and bound states in the continuum. Through these resonances, high-refractive-index materials can be used to engineer the optical near field, both inside and outside the nanostructures, which opens up new opportunities for Raman spectroscopy. In this review, we discuss the impact of high-refractive-index nano-optics on Raman spectroscopy. In particular, we consider the intrinsic Raman enhancement produced by different dielectric resonances and their theoretical description. Using the optical reciprocity theorem, we derive an expression which links the Raman enhancement to the enhancement of the stored electric energy. We also address recent results on surface-enhanced Raman spectroscopy based on high-refractive-index dielectric materials along with applications in stimulated Raman scattering and nanothermometry. Finally, we discuss the potential of Raman spectroscopy as a tool for detecting the optical near-fields produced by dielectric resonances, complementing reflection and transmission measurements.

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