On-chip nanophotonic broadband wavelength detector with 2D-Electron gas

Miniaturized, low-cost wavelength detectors are gaining enormous interest as we step into the new age of photonics. Incompatibility with integrated circuits or complex fabrication requirement in most of the conventionally used filters necessitates the development of a simple, on-chip platform for easy-to-use wavelength detection system. Also, intensity fluctuations hinder precise, noise free detection of spectral information. Here we propose a novel approach of utilizing wavelength sensitive photocurrent across semiconductor heterojunctions to experimentally validate broadband wavelength detection on an on-chip platform with simple fabrication process. The proposed device utilizes linear frequency response of internal photoemission via 2-D electron gas in a ZnO based heterojunction along with a reference junction for coherent common mode rejection. We report sensitivity of 0.96 μA/nm for a broad wavelength-range of 280 nm from 660 to 940 nm. Simple fabrication process, efficient intensity noise cancelation along with heat resistance and radiation hardness of ZnO makes the proposed platform simple, low-cost and efficient alternative for several applications such as optical spectrometers, sensing, and Internet of Things (IOTs).

Rapid quantification of Psilocybin with reversed-phase HPLC and single-wavelength detection

The alkaloid psilocybin (4-phosphoryloxy-N,N-dimethyltryptamine) and the neurologically active psilocin (4-hydroxy-N,N-dimethyltryptamine) are the foremost compounds of pharmaceutical interest in Psilocybe mushrooms. As these compounds are infrequently analyzed in analytical labs, validated methods for rapid purity analysis are lacking. Newfound therapeutic use has invigorated academic and commercial interests in the molecules and new methods of production and available products are expanding. As a result, high-throughput methods of analysis for psilocybin must be improved to promptly determine chemical differences between mushroom genera or other sources of psilocybin and psilocin, as well as refined product purity. To address this, we developed an inexpensive HPLC technique for the efficient quantification of psilocybin and psilocin by using readily available equipment and dilute reagents. Aqueous ammonium formate (0.143 mM) was found to be preferable over techniques with much higher buffer concentrations or stronger acids for controlling psilocybin Zwitterion resolution. The chromatographic run time satisfied high-throughput analytical requirements with an efficient total runtime under 2 minutes. A standard octadecyl silica (C18) column provided excellent resolution between psilocybin and psilocin signals. The quality of the method was validated using certified analytical reference standards and was found to be accurate (3.5% bias, Psilocybin), reliable (0.32% RSD), and efficient (Psilocybin k’ = 1.78).

Preparation of hexagonal nanoporous Al2O3/TiO2/TiN as a novel photodetector with high efficiency

The unique optical properties of metal nitrides enhance many photoelectrical applications. In this work, a novel photodetector based on TiO2/TiN nanotubes was deposited on a porous aluminum oxide template (PAOT) for light power intensity and wavelength detection. The PAOT was fabricated by the Ni-imprinting technique through a two-step anodization method. The TiO2/TiN layers were deposited by using atomic layer deposition and magnetron sputtering, respectively. The PAOT and PAOT/TiO2/TiN were characterized by several techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray (EDX). The PAOT has high-ordered hexagonal nanopores with dimensions ~ 320 nm pore diameter and ~ 61 nm interpore distance. The bandgap of PAOT/TiO2 decreased from 3.1 to 2.2 eV with enhancing absorption of visible light after deposition of TiN on the PAOT/TiO2. The PAOT/TiO2/TiN as photodetector has a responsivity (R) and detectivity (D) of 450 mAW-1 and 8.0 × 1012 Jones, respectively. Moreover, the external quantum efficiency (EQE) was 9.64% at 62.5 mW.cm−2 and 400 nm. Hence, the fabricated photodetector (PD) has a very high photoelectrical response due to hot electrons from the TiN layer, which makes it very hopeful as a broadband photodetector.

Accurate and High-speed FBG Demodulator Using STM32 and DOG Algorithm

A multi-channel and high-speed FBG demodulator based STM32 is designed in this paper. The wavelength detection accuracy is improved using a difference of Gaussian (DoG) peak detection algorithm. The 16-channel FBG wavelengths are demodulated simultaneously and that the demodulation frequency can reach 1kHz. The experimental results show that the temperature sensitivity is 13.17 pm/ ºC. And meanwhile, the standard deviation and the average error of the FBG wavelength demodulated at the same temperature is 1.9 pm and 2.1 pm respectively.

Development and Validation of HPLC Method for Diphenhydramine Hydrochloride

Aim: The aim of present method development for Diphenhydramine HCl performed on HPLC is to obtain specific, more accurate and precise results as compare to spectrophotometric method. Methods: HPLC analysis was performed according to USP method with wavelength detection at 220nm and 1.0ml/min flow rate. Wufeng thermo HPLC system UV -100detector was used having column C18(4.6mm*250mm) 5. Methanol and water (4:1) mixture was used as mobile phase and pH was adjusted at 7.4 with the help of triethanolamine. Validation parameters like linearity, accuracy, precision, solution stability, robustness, LOD, LOQ and system suitability were successfully evaluated. Results: The regression co-efficient for calibration curve was 0.991 and % recovery was in range (80-110%), whereas no robustness was observed in this reported method. Conclusion: In summary, the expected linearity, accuracy and % recovery indicating that HPLC is more precise method than spectrophotometry and suggested that present method qualifies the validation criteria.

Anisotropic ultrasensitive PdTe2-based phototransistor for room-temperature long-wavelength detection

Emergent topological Dirac semimetals afford fresh pathways for optoelectronics, although device implementation has been elusive to date. Specifically, palladium ditelluride (PdTe2) combines the capabilities provided by its peculiar band structure, with topologically protected electronic states, with advantages related to the occurrence of high-mobility charge carriers and ambient stability. Here, we demonstrate large photogalvanic effects with high anisotropy at terahertz frequency in PdTe2-based devices. A responsivity of 10 A/W and a noise-equivalent power lower than 2 pW/Hz0.5 are achieved at room temperature, validating the suitability of PdTe2-based devices for applications in photosensing, polarization-sensitive detection, and large-area fast imaging. Our findings open opportunities for exploring uncooled and sensitive photoelectronic devices based on topological semimetals, especially in the highly pursuit terahertz band.

Cross-wavelength invisibility integrated with various invisibility tactics

As a superior self-protection strategy, invisibility has been a topic of long-standing interest in both academia and industry, because of its potential for intriguing applications that have only appeared thus far in science fiction. However, due to the strong dispersion of passive materials, achieving cross-wavelength invisibility remains an open challenge. Inspired by the natural ecological relationship between transparent midwater oceanic animals and the cross-wavelength detection strategy of their predators, we propose a cross-wavelength invisibility concept that integrates various invisibility tactics, where a Boolean metamaterial design procedure is presented to balance divergent material requirements over cross-scale wavelengths. As proof of concept, we experimentally demonstrate longwave cloaking and shortwave transparency simultaneously through a nanoimprinting technique. Our work extends the concept of stealth techniques from individual invisibility tactics targeting a single-wavelength spectrum to an integrated invisibility tactic targeting a cross-wavelength applications and may pave the way for development of cross-wavelength integrated metadevices.