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Single-pixel imaging (SPI) uses a single-pixel detector instead of a detector array with a lot of pixels in traditional imaging techniques to realize two-dimensional or even multi-dimensional imaging. For SPI using compressed sensing, the target to be imaged is illuminated by a series of patterns with spatial resolution, and then the reflected or transmitted intensity is compressively sampled by the single-pixel detector to reconstruct the target image while breaking the limitation of the Nyquist sampling theorem. Recently, in the area of signal processing using compressed sensing, many measurement matrices as well as reconstruction algorithms have been proposed. It is necessary to explore the application of these methods in SPI. Therefore, this paper reviews the concept of compressive sensing SPI and summarizes the main measurement matrices and reconstruction algorithms in compressive sensing. Further, the performance of their applications in SPI through simulations and experiments is explored in detail, and then their advantages and disadvantages are summarized. Finally, the prospect of compressive sensing with SPI is discussed. [ABSTRACT FROM AUTHOR]

Organic photodetectors (OPDs) have aroused intensive attention for signal detection in industrial and scientific applications due to their advantages including low cost, mechanical flexibility, and large-area fabrication. As one of the most common organic light-emitting materials, 8-hydroxyquinolinato aluminum (Alq3) has an absorption wavelength edge of 460 nm. Here, through the introduction of Ag nanoparticles (Ag NPs), the spectral response range of the Alq3-based OPD was successfully extended to the near-infrared range. It was found that introducing Ag NPs can induce rich plasmonic resonances, generating plenty of hot electrons, which could be injected into Alq3 and then be collected. Moreover, as a by-product of introducing Ag NPs, the dark current was suppressed by around two orders of magnitude by forming a Schottky junction on the cathode side. These two effects in combination produced photoelectric signals with significant contrasts at wavelengths beyond the Alq3 absorption band. It was found that the OPD with Ag NPs can stably generate electric signals under illumination by pulsed 850 nm LED, while the output of the reference device included no signal. Our work contributes to the development of low-cost, broadband OPDs for applications in flexible electronics, bio-imaging sensors, etc. [ABSTRACT FROM AUTHOR]

Hot-electron photodetectors (HEPDs) are triggering a strong surge of interest in applications of image sensors and optics communication, since they can realize photoelectric responses when the incident photon energy is lower than the bandwidth of the semiconductor. In traditional HEPD systems, the metal layers are dressed with regular gratings, which can only excite plasmonic resonance over a narrow bandwidth, limiting the hot-electron photoelectric effect. To break this limitation, hybrid plasmonic nanostructures should be applied in HEPDs. Here, we propose a TiO2 based HEPD device incorporated with a hybrid plasmonic nanostructure, which consists of Au nanoparticles (Au NPs) and a conformal transparent Au film. With the assistance of the plasmonic resonances excited in this hybrid nanostructure, the spectrum of the photocurrent response is significantly broadened from the UV band to the visible and near-infrared (NIR) ranges. It is demonstrated that at the wavelengths of 660 nm and 850 nm, the photocurrent in the hybrid HEPD device is enhanced by 610% and 960%, respectively, compared with the counterparts without the addition of Au NPs. This work promotes the development of high performances HEPDs, offering an alternative strategy for realizing photodetection and image sensing in the NIR range. [ABSTRACT FROM AUTHOR]