分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: To develop highly sensitive, stable and repeatable surface-enhanced Raman scattering (SERS) substrates is crucial for analytical detection, which is a challenge for traditional metallic structures. Herein, by taking advantage of the high surface activity of 1T' transition metal telluride, we have fabricated high-density gold nanoparticles (AuNPs) that are spontaneously in-situ prepared on the 1T' MoTe2 atomic layers via a facile method, forming a plasmonic-2D material hybrid SERS substrate. This AuNP formation is unique to the 1T' phase, which is repressed in 2H MoTe2 with less surface activity. The hybrid structure generates coupling effects of electromagnetic and chemical enhancements, as well as excellent molecule adsorption, leading to the ultrasensitive (4*10^-17 M) and reproducible detection. Additionally, the immense fluorescence and photobleaching phenomena are mostly avoided. Flexible SERS tapes have been demonstrated in practical applications. Our approach facilitates the ultrasensitive SERS detection by a facile method, as well as the better mechanistic understanding of SERS beyond plasmonic effects.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Generally, a superconducting nanowire single-photon detector (SNSPD) is composed of wires with a typical width of ~100 nm. Recent studies have found that superconducting strips with a micrometer-scale width can also detect single photons. Compared with the SNSPD, the superconducting microstrip single-photon detector (SMSPD) has smaller kinetic inductance, higher working current, and lower requirement in fabrication accuracy, providing potential applications in the development of ultra-large active area detectors. However, the study on SMSPD is still in its infancy, and the realization of its high-performance and practical use remains an opening question. This study demonstrates a NbN SMSPD with a saturated system detection efficiency (SDE) of ~92.2% at a dark count rate of ~200 cps, a polarization sensitivity of ~1.03, and a minimum timing jitter of ~48 ps, at the telecom wavelength of 1550 nm when coupled with a single mode fiber and operated at 0.84 K. Furthermore, the detector's SDE is over 70% when operated at a 2.1-K closed-cycle cryocooler.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: C-H bond activation enables the facile synthesis of new chemicals. While C-H activation in short-chain alkanes has been widely investigated, it remains largely unexplored for long-chain organic molecules. Here, we report light-driven C-H activation in complex organic materials mediated by 2D transition metal dichalcogenides (TMDCs) and the resultant solid-state synthesis of luminescent carbon dots in a spatially resolved fashion. Through the first-principle calculations, we unravel that the defects and oxidized states in 2D TMDCs lead to efficient C-H activation and chemical reaction. Furthermore, we exploit the light-controlled point-and-shoot chemical reaction for versatile carbon dot patterning and optical encoding of encrypted information. Our results will shed light on 2D materials for C-H activation in a variety of organic compounds for applications in organic chemistry, photonic materials, and environmental remediation.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Erbium-doped lithium niobate on insulator (LNOI) laser plays an important role in the complete photonic integrated circuits (PICs). Here, we demonstrate an integrated tunable whisper galley single mode laser (WGSML) by making use of a pair of coupled microdisk and microring on LNOI. A 974 nm single-mode pump light can have an excellent resonance in the designed microdisk, which is beneficial to the whisper gallery mode (WGM) laser generation. The WGSML at 1560.40 nm with a maximum 31.4 dB side mode suppression ratio (SMSR) has been achieved. By regulating the temperature, WGSMLs output power increased and the central wavelength can be changed from 1560.30 nm to 1560.40 nm. What's more, 1560.60 nm and 1565.00 nm WGSMLs have been achieved by changing the coupling gap width between microdisk and microring. We can also use the electro-optic effect of LNOI to obtain more accurate adjustable WGSMLs in further research.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Faint light spectroscopy has many important applications such as fluorescence spectroscopy, lidar and astronomical observations. However, long measurement time limit its application on real-time measurement. In this work, a photon counting reconstructive spectrometer combining metasurfaces and superconducting nanowire single photon detectors (SNSPDs) was proposed. A prototype device was fabricated on a silicon on isolator (SOI) substrate, and its performance was characterized. Experiment results show that this device support spectral reconstruction of mono-color lights with a resolution of 2 nm in the wavelength region of 1500 nm ~ 1600 nm. The detection efficiency of this device is 1.4% ~ 3.2% in this wavelength region. The measurement time required by this photon counting reconstructive spectrometer was also investigated experimentally, showing its potential to be applied in the scenarios requiring real-time measurement.