Quantum Optoelectronics

Abstract:

Photoluminescence measurements in mono- and bilayer-MoS2 on SiO2 were undertaken to determine the thermal effect of the MoS2/SiO2 interface on the optical bandgap. The energy and intensity of the photoluminescence from monolayer MoS2 were lower and weaker than those from bilayer MoS2 at low temperatures, whilst the opposite was true at high temperatures above 200 K. Density functional theory calculations suggest that the observed optical bandgap crossover is caused by a weaker substrate coupling to the bilayer than to the monolayer.

Abstract:

<jats:p>Semiconductor photonic nanowires are critical components for nanoscale light manipulation in integrated photonic and electronic devices. Optimizing their optical performance requires enhanced photon conversion efficiency, for which a promising solution is to combine semiconductors with noble metals, using the surface plasmon resonance of noble metals to enhance the photon absorption efficiency. Here, we report plasmon-enhanced light emission in a hybrid nanowire device composed of perovskite semiconductor nanowires and silver nanoparticles formed using superfluid helium droplets. A cesium lead halide perovskite-based four-layer structure (CsPbBr3/PMMA/Ag/Si) effectively reduces the metal’s plasmonic losses while ensuring efficient surface plasmon–photon coupling at moderate power. Microphotoluminescence and time-resolved spectroscopy techniques are used to investigate the optical properties and emission dynamics of carriers and excitons within the hybrid device. Our results demonstrate an intensity enhancement factor of 29 compared with pure semiconductor structures at 4 K, along with enhanced carrier recombination dynamics due to plasmonic interactions between silver nanoparticles and perovskite nanowires. This work advances existing approaches for exciting photonic nanowires at low photon densities, with potential applications in optimizing single-photon excitations and emissions for quantum information processing.</jats:p>

Abstract:

<jats:title>Abstract</jats:title> <jats:p>High-resolution spectroscopy unveils the fundamental physics of quantum states, molecular dynamics, and energy transfers. Ideally, a higher spectral resolution over a broader bandwidth is the prerequisite, but traditional spectroscopic techniques can only partially fulfill this requirement even with a bulky system. Here we report that a multi-frequency acousto-optic phase modulation at a chip-scale of soft polydimethylsiloxane can readily support a 200-times higher 0.5-MHz spectral resolution for the frequency-comb-based spectroscopy, while co-located plasmonic nanostructures mediate the strong light-matter interaction. These results suggest the potential of polydimethylsiloxane acousto-optic phase modulation for cost-effective, compact, multifunctional chip-scale tools in diverse applications such as quantum spectroscopy, high-finesse cavity analysis, and surface plasmonic spectroscopy. </jats:p>

Abstract:

Thyroid cancer remains prevalent worldwide, with its incidence steadily increasing in recent decades. Although ultrasonography is currently the primary screening method in clinical practice, its relatively low specificity has contributed to increased overdiagnosis. Furthermore, conventional ultrasonography is associated with challenges such as high inter- and intra-observer variability and limited functional imaging capabilities, which together reduce its diagnostic accuracy. To address these limitations, researchers have explored complementary image-based techniques to assess the vascularity surrounding cancerous nodules. This comprehensive review provides an overview of recent clinical trials investigating advanced ultrasound (US)-based imaging techniques for diagnosing thyroid cancer in humans. Specifically, we explore the use of photoacoustic imaging and ultrafast US Doppler techniques, highlighting their potential to enhance triaging accuracy by enabling the analysis of both structural and functional characteristics of thyroid nodules in vivo. Integrating these innovative approaches into existing ultrasonography protocols could significantly enhance the precision of thyroid cancer diagnosis.