Narrowband HgCdTe infrared photodetector with integrated plasmonic structure.

The application of plasmonic structure has been demonstrated to improve the performance of infrared photodetectors. However, the successful experimental realization of the incorporation of such optical engineering structure into HgCdTe-based photodetectors has rarely been reported. In this paper, we present a HgCdTe infrared photodetector with integrated plasmonic structure. The experimental results show that the device with plasmonic structure has a distinct narrowband effect with a peak response rate close to 2 A/W, which is nearly 34% higher compared with the reference device. The simulation results are in good agreement with the experiment, and an analysis of the effect of the plasmonic structure is given, demonstrating the crucial role of the plasmonic structure in the enhancement of the device performance.

A spectrally selective visible microbolometer based on planar subwavelength thin films.

In this work, we experimentally demonstrate a new type of compact, low-cost, visible microbolometer based on metal-insulator-metal (MIM) planar subwavelength thin films, which exploits resonant absorption for spectral selectivity without additional filters and has the advantages of compact design, simple structure, cost-efficiency, and large format fabrication. The experimental results show that a proof-of-principle microbolometer exhibits spectrally selective properties in the visible frequency range. At a resonant absorption wavelength of 638 nm, a responsivity of about 10 mV W-1 is achieved at room temperature at a bias current of 0.2 mA, which is about one order of magnitude higher than that of the control device (a bare Au bolometer). Our proposed approach provides a viable solution for the development of compact and inexpensive detectors.

Long-wavelength infrared selective emitter for thermal infrared camouflage under a hot environment.

Thermal infrared camouflage as a kind of counter-surveillance technique has attracted much attention owing to the rapid development of infrared surveillance technology. Various artificial optical structures have been developed for infrared camouflage applications under cold ambient environment (low thermal radiation), but the realization of infrared camouflage under a hot environment (high thermal radiation) is also highly desirable and has been rarely reported. Here, a lithography-free, ultra-thin, high performance long-wavelength infrared (LWIR) selective emitter for thermal infrared camouflage in a high radiation environment is proposed and experimentally demonstrated. Experimental results show that our designed selective emitter exhibits average emissivity higher than 90% over the LWIR range from 8 to 14 µm and low emissivity less than 35% outside this window. Numerical simulations were performed to optimize the geometrical structures and reveal that such a selective emission effect is attributed to the combination of multiple hybrid plasmonic resonances. LWIR thermal images show that the selective emitter can perfectly blend into the high radiation backgrounds. Furthermore, it is found that the sample displays angle-independent emission properties, indicating that our emitter offers great potential for application in evading large-angle detection.

Decline of three farmland pest species in rapidly urbanizing landscapes.

Urbanization is a pressing challenge for earth's humans because it is changing not only natural environments but also agricultural lands. Yet, the consequences of cropland loss on pest insect populations that largely depend on these habitats remain largely unclear. We used a 17-year data set to investigate the dynamics of three moth pest species (i.e., striped stem borer, yellow stem borer, and pink stem borer) and their driving forces across the largest mega-urban region of China. Total abundance of three pest species is declined by about 80%, which was strongly associated with cropland loss during rapid urbanization. Our findings indicate that not only the increasing conversion of natural areas to human-dominated landscapes but also that of agricultural lands to urban landscapes can be critical to insect populations. It is therefore essential to monitor and understand the insect dynamics in rapidly urbanizing regions, which are currently found in many developing countries worldwide.

Flexible Transparent Heat Mirror for Thermal Applications.

Transparent heat mirrors have been attracting a great deal of interest in the last few decades due to their broad applications, which range from solar thermal convection to energy-saving. Here, we present a flexible Polyethylene terephthalate/Ag-doped Indium tin oxide/Polydimethylsiloxane (PAIP) thin film that exhibits high transmittance in visible range and low emissivity in the thermal infrared region. Experimental results show that the temperature of the sample can be as high as 108 °C, which is ~23 °C higher than that of a blackbody control sample under the same solar radiation. Without solar radiation, the temperature of the PAIP thin film is ~6 °C higher than that of ordinary fabric. The versatility of the large-area, low-radiation-loss, highly-transparent and flexible hydrophobic PAIP thin film suggest great potential for practical applications in thermal energy harvesting and manipulation.

Co-Doped Zn1-xCdxS nanocrystals from metal-organic framework precursors: porous microstructure and efficient photocatalytic hydrogen evolution.

Nanoporous Co-doped Zn1-xCdxS were facilely fabricated via adopting ZIFs as templates, and Cd(NO3)2 and thiourea as precursors. The highly porous microstructure and uniform Co-doping of the photocatalyst afford a high H2-production rate (45.2 and 422.2 times larger than those of Zn0.5Cd0.5S and CdS), providing an effective way for the development of high performance nanoporous photocatalysts.