We employ a statistical approach to estimate the number of photoluminescence quenching species as a function of doping concentration.

Infrared (IR) plasmonic nanoantennas (PNAs) are powerful tools to identify molecules by the IR fingerprint absorption from plasmon-molecules interaction. However, the sensitivity and bandwidth of PNAs are limited by the small overlap between molecules and sensing hotspots and the sharp plasmonic resonance peaks. In addition to intuitive methods like enhancement of electric field of PNAs and enrichment of molecules on PNAs surfaces, we propose a loss engineering method to optimize damping rate by reducing radiative loss using hook nanoantennas (HNAs). Furthermore, with the spectral multiplexing of the HNAs from gradient dimension, the wavelength-multiplexed HNAs (WMHNAs) serve as ultrasensitive vibrational probes in a continuous ultra-broadband region (wavelengths from 6 μm to 9 μm). Leveraging the multi-dimensional features captured by WMHNA, we develop a machine learning method to extract complementary physical and chemical information from molecules. The proof-of-concept demonstration of molecular recognition from mixed alcohols (methanol, ethanol, and isopropanol) shows 100% identification accuracy from the microfluidic integrated WMHNAs. Our work brings another degree of freedom to optimize PNAs towards small-volume, real-time, label-free molecular recognition from various species in low concentrations for chemical and biological diagnostics.

The photogating effect in hybrid structures has manifested itself as a reliable and promising approach for photodetectors with ultrahigh responsivity. A crucial factor of the photogating effect is the built-in potential at the interface, which controls the separation and harvesting of photogenerated carriers. So far, the primary efforts of designing the built-in potential rely on discovering different materials and developing multilayer structures, which may raise problems in the compatibility with the standard semiconductor production line. Here, we report an enhanced photogating effect in a monolayer graphene photodetector based on a structured substrate, where the built-in potential is established by the mechanism of potential fluctuation engineering. We find that the enhancement factor of device responsivity is related to a newly defined parameter, namely, fluctuation period rate (P f). Compared to the device without a nanostructured substrate, the responsivity of the device with an optimized P f is enhanced by 100 times, reaching a responsivity of 240 A/W and a specific detectivity, D*, of 3.4 × 1012 Jones at 1550 nm wavelength and room temperature. Our experimental results are supported by both theoretical analysis and numerical simulation. Since our demonstration of the graphene photodetectors leverages the engineering of structures with monolayer graphene rather than materials with a multilayer complex structure. it should be universal and applicable to other hybrid photodetectors.

Security is a prevailing concern in communication as conventional encryption methods are challenged by progressively powerful supercomputers. Here, we show that biometrics-protected optical communication can be constructed by synergizing triboelectric and nanophotonic technology. The synergy enables the loading of biometric information into the optical domain and the multiplexing of digital and biometric information at zero power consumption. The multiplexing process seals digital signals with a biometric envelope to avoid disrupting the original high-speed digital information and enhance the complexity of transmitted information. The system can perform demultiplexing, recover high-speed digital information, and implement deep learning to identify 15 users with around 95% accuracy, irrespective of biometric information data types (electrical, optical, or demultiplexed optical). Secure communication between users and the cloud is established after user identification for document exchange and smart home control. Through integrating triboelectric and photonics technology, our system provides a low-cost, easy-to-access, and ubiquitous solution for secure communication.

No abstract

The miniaturization of infrared spectroscopy enables portable and low-cost devices, which could revolutionize many scientific and technological fields including environment monitoring, pharmacy, and biosensing. As a promising approach, metamaterial technologies have been widely developed in miniaturizing all the individual components of infrared spectroscopy such as light sources, sensors, spectral filters, and photodetectors. However, a systematic consideration on the whole device level is still lacking. In this Perspective, we focus on the possible opportunities offered by metamaterials for ultracompact infrared spectroscopy. To start with, we review the recent metamaterial-related component-level demonstrations. Then, we draw attention to the potential role of metamaterials as a common platform for all the individual components. Finally, we discuss about the near field effect in metamaterial-mediated devices.

No abstract

We reveal the potential of step-index fibers consisting of a metaphosphate glass core and a silica cladding as an ultrafast octave-spanning supercontinuum source. The hybrid waveguide was fabricated by pressure-assisted melt filling and possesses a sophisticated dispersion behavior with two zero-dispersion points in the proximity of the Erbium laser bands. The fiber generates an octave-spanning supercontinuum from 0.7 to 2.4 μm if pumped at 1.56 μm with 30 fs pulses and energies as low as 300 pJ. Numerical simulations reveal soliton fission and double dispersive wave generation as the dominant broadening effect. This study highlights phosphate glasses as a promising new candidate for the next generation of broadband photonic devices, as they allow for high rare earth-doping levels and dispersion posttuning via plasmonic nanoparticle growth.