TY  - JOUR
AB  - Optical endoscopy is the most commonly applied procedure for inspecting the gastrointestinal (GI) tract, and it is based on different approaches and designs, from using a flexible optical scope to swallowing a small camera capsule that obtains photographs as it advances through the digestive tract. Despite its wide use in GI diagnostics and theranostics, optical visualization only allows a superficial inspection of the wall lining (mucosa), therefore limiting the ability to obtain information from deeper GI layers. In the quest for developing methods to visualize under the mucosal layers, we review herein progress with optoacoustic endoscopy, a technique that captures optical contrast in high resolution deep inside tissues, enabling imaging beneath the surface of the mucosa. Optoacoustic endoscopy combines imaging of optical contrast with the resolution and depth penetration afforded by ultrasonography, thus merging highly advantageous characteristics for clinical applications. We review progress and the current status of the technology, its key endoscopic competitors, and challenges for clinical application. We further offer a perspective regarding future directions and the overall application potential of the technique to complement the current state-of-the-art.
AU  - He, H.
AU  - Englert, L.
AU  - Ntziachristos, V.
C1  - 67588
C2  - 53596
CY  - 1155 16th St, Nw, Washington, Dc 20036 Usa
SP  - 559–570
TI  - Optoacoustic endoscopy of the gastrointestinal tract.
JO  - ACS Photonics
VL  - 10
IS  - 3
PB  - Amer Chemical Soc
PY  - 2023
SN  - 2330-4022
ER  - 

TY  - JOUR
AB  - Plasmonic lasers generate strongly confined electromagnetic fields over a narrow range of wavelengths. This is potentially useful for enhancing nonlinear effects, sensing chemical species, and providing on-chip sources of plasmons. By placing a semiconductor gain layer near a metallic interface with a gap layer in between, plasmonic lasers have been demonstrated. However, the role of gain in this common design has been understudied, leading to suboptimal choices. Here, we examine planar metallic lasers and explore the effect of gain on the lasing behavior. We print semiconductor nanoplatelets as a gain layer of controllable thickness onto alumina-coated silver films with integrated planar Fabry-Pérot cavities. Lasing behavior is then monitored with spectrally and polarization-resolved far-field imaging. The results are compared with a theoretical waveguide model and a rate-equation model, which consider both plasmonic and photonic modes and explicitly include losses and gain. We find that the nature of the lasing mode is dictated by the gain-layer thickness and, contrary to conventional wisdom, a gap layer with a high refractive index can be advantageous for plasmonic lasing in planar Fabry-Pérot cavities. Our rate-equation model also reveals a regime where plasmonic and photonic modes compete in an unintuitive way, potentially useful for facile, active mode switching. These results can guide future design of metallic lasers and could lead to on-chip lasers with controlled photonic and plasmonic output.
AU  - Aellen, M.*
AU  - Rossinelli, A.A.*
AU  - Keitel, R.C.*
AU  - Brechbühler, R.*
AU  - Antolinez, F.V.*
AU  - Rodrigo, S.G.*
AU  - Cui, J.
AU  - Norris, D.J.*
C1  - 64165
C2  - 52097
CY  - 1155 16th St, Nw, Washington, Dc 20036 Usa
SP  - 630-640
TI  - Role of gain in Fabry-Pérot surface plasmon polariton lasers.
JO  - ACS Photonics
VL  - 9
IS  - 2
PB  - Amer Chemical Soc
PY  - 2022
SN  - 2330-4022
ER  - 

TY  - JOUR
AB  - Modern imaging technologies, including optoacoustic endoscopy, are based on the optoacoustic effect. Much promise is offered by the all-optical fiber-based approach, because fiber has a miniature cross section, is highly sensitive, and can be used in a variety of imaging and therapeutic techniques. We developed a probe based on a hollow-core microstructured optical waveguide (HC-MOW) with a hybrid nanostructured membrane. The membrane consisted of a free-standing single-walled carbon nanotube film and a Bragg reflector, which can be used as a source and a detector of ultrasound. Membrane vibrations were excited with an IR laser pulse and were read out by recording the intensity of the reflected visible CW laser light. We explained the nature of the intensity modulation of the reflected light and supported our explanation with numerical simulations of the membrane's vibration eigenfrequencies and thermal distribution. The membrane vibrations were also observed with raster-scanning optoacoustic mesoscopy. The transmittance of the HC-MOW between 400 nm and 6.5 μm and that of the hybrid nanostructured membrane in the NIR range enable potential optoacoustic sensing in the IR fingerprint region of biomolecules. This permits the optoacoustic probe to be used for medical endoscopic purposes.
AU  - Kaydanov, N.*
AU  - Perevoschikov, S.*
AU  - German, S.V.*
AU  - Romanov, S.A.*
AU  - Ermatov, T.*
AU  - Kozyrev, A.A.*
AU  - Cvjetinovic, J.*
AU  - MacHnev, A.*
AU  - Noskov, R.E.*
AU  - Kosolobov, S.S.*
AU  - Skibina, J.S.*
AU  - Nasibulin, A.G.*
AU  - Zakian Dominguez, C.M.
AU  - Lagoudakis, P.G.*
AU  - Gorin, D.A.*
C1  - 63555
C2  - 51586
CY  - 1155 16th St, Nw, Washington, Dc 20036 Usa
SP  - 3346–3356
TI  - Optoacoustic effect in a hybrid multilayered membrane deposited on a hollow-core microstructured optical waveguide.
JO  - ACS Photonics
VL  - 8
IS  - 11
PB  - Amer Chemical Soc
PY  - 2021
SN  - 2330-4022
ER  -