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We introduce two types of dielectric metasurfaces, consisting of 3 × 3 regions, which manipulate wavefront by different feature heights. Both polarization-dependent and polarization-independent metasurfaces are realized for phase depth of 0 ∼ 2π at 1550 nm, with considerable average transmittance of 80.1 and 85.1 %, respectively. The phase modulation capability can be extended over a broadband range of 1460.1–1618.0 nm for optical communications, by carefully designing nanofeature sizes. Moreover, the entire metasurfaces with nanofeatures of varying heights can be fabricated in a single process by using direct laser writing with high-precision, which is beneficial for mass production and promising in developing efficient and ultracompact devices.

We report on an index-coupled distributed feedback (DFB) quantum cascade lasers (QCLs) of high single-mode stability by using of a grating reflector (GR) to reflect effectively light of a specific wavelength. Fabrications of the QCLs were performed with λ∕4 equivalent phase shift (EPS) or sampled Moiré grating (SMG) structure, which regulates the light intensity distribution in the cavity and coupling strength. Both EPS-GR and SMG-GR QCLs demonstrate a high emission wavelength precision and a side-mode-suppression-ratio (SMSR) of 24.5 dB at the injection current of 5 A and the pulse width of 5 μs, offering considerable output power even at the edge of the gain spectrum. Furthermore, we investigated the arrays of EPS-GR and SMG-GR QCLs with lower threshold current and higher output power by introducing semi-insulated InP (Fe) ranging from 8.25 to 8.67 μm and 8.16–8.63 μm, respectively. The present QCLs via a GR are prospective for applications requiring single-mode stability and wide tunability.

Vertically aligned nanowire arrays, with high surface-to-volume ratio and efficient light-trapping absorption, have attracted much attention for photoelectric devices. In this paper, vertical β-Ga2O3 nanowire arrays with an average diameter/height of 110/450 nm have been fabricated by the inductively coupled plasma etching technique. Then a metal-semiconductor-metal structured solar-blind photodetector (PD) has been fabricated by depositing interdigital Ti/Au electrodes on the nanowire arrays. The fabricated β-Ga2O3 nanowire PD exhibits ∼10 times higher photocurrent and responsivity than the corresponding film PD. Moreover, it also possesses a high photocurrent to dark current ratio (Ilight/Idark) of ∼104 and a ultraviolet/visible rejection ratio (R260 nm/R400 nm) of 3.5 × 103 along with millisecond-level photoresponse times.

Abstract Mesoporous silica nanofibers were synthesized within the pores of the anodic aluminum oxide template using a simple sol–gel method. Transmission electron microscopy investigation indicated that the concentration of the structure-directing agent (EO20PO70EO20) had a significant impact on the mesostructure of mesoporous silica nanofibers. Samples with alignment of nanochannels along the axis of mesoporous silica nanofibers could be formed under the P123 concentration of 0.15 mg/mL. When the P123 concentration increased to 0.3 mg/mL, samples with a circular lamellar mesostructure could be obtained. The mechanism for the effect of the P123 concentration on the mesostructure of mesoporous silica nanofibres was proposed and discussed.

High-performance p-B-n infrared photodetectors based on In 0.53 Ga 0.47 As / Ga 0.51 As 0.49 Sb type-II superlattices with an Al 0.85 Ga 0.15 AsSb barrier on an InP substrate have been demonstrated. These photodetectors exhibit 50% and 100% cutoff wavelengths of ∼ 2.1 μm and ∼ 2.6 μm, respectively. At a bias voltage of −100 mV bias voltage, the device exhibits a peak responsivity of 0.618 A/W at 2.1 μm, corresponding to a quantum efficiency of 36.5%. The device exhibits a saturated dark current shot noise limited specific detectivity (D*) of 4.12 × 10 10 cm · Hz 1 / 2 / W (at a peak responsivity of 2.1 μm) under −100 mV applied bias at 300 K. [ABSTRACT FROM AUTHOR]

This paper details the fabrication of GaN-based microdisks with a single porous n-GaN layer positioned beneath the multiple quantum wells region on a modified green light-emitting diode epiwafer. Simulations of the longitudinal light field distribution reveal effective confinement of the light field within the multiple quantum wells region due to the presence of the single porous layer. The porous layer also demonstrates sufficient conductivity as determined through calculations and serves as an effective method for thermal dispersion. Under optical pumping, all microdisks exhibit clear whispering gallery mode (WGM) lasing at room temperature, with the lowest threshold of 13.50 μJ/cm2 achieved in a 2-μm-diameter microdisk. These findings suggest that integrating the single porous layer into GaN microdisks is a highly promising approach for achieving high-efficiency WGM micro-laser diodes with effective electrical injection and heat dispersion. [ABSTRACT FROM AUTHOR]

Power Schottky barrier diodes (SBDs) face an inherent trade-off between forward conduction loss and reverse blocking capability. This limitation becomes more severe for ultra-wide bandgap (UWBG) SBDs due to the large junction field. A high Schottky barrier is usually required to suppress the reverse leakage current at the price of an increased forward voltage drop (VF). This work demonstrates a Ga2O3 junction barrier Schottky (JBS) diode that employs the embedded p-type NiO grids to move the peak electric field away from the Schottky junction, thereby allowing for the use of an ultra-low barrier TiN Schottky contact. This JBS diode concurrently realizes a low VF of 0.91 V (at forward current of 100 A/cm2) and a high breakdown voltage over 1 kV, with the VF being the lowest in all the reported vertical UWBG power diodes. Based on the device characteristics measured up to 200 °C, we further analyze the power loss of this JBS diode across a wide range of operational duty cycles and temperatures, which is found to outperform the TiN/Ga2O3 SBDs or NiO/Ga2O3 PN diodes. These findings underscore the potential of low-barrier UWBG JBS diodes for high-frequency, high-temperature power electronics applications. [ABSTRACT FROM AUTHOR]