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Vertical-cavity surface-emitting laser (VCSEL) usually adopt a 2-D array structure with small-sized light-emitting cells in parallel to increase the output optical power and to improve the laser beam quality. However, with the down scaling of the chip size and the increasing of the array integration, the self-heating effect caused by the power dissipation of the VCSEL cell and the thermal coupling effect among VCSEL cells will lead to a sharp increase in the junction temperature of the VCSEL array. Due to the effect of thermal-opto-electro feedback, the optical performance and thermal reliability of the VCSEL array will be limited seriously, which propose urgent requirements for the thermal design of the VCSEL array. Based on the heat generation mechanism of VSCEL array, latest development of VCSEL array thermal design was reviewed in detail from the aspects of thermal-opto-electro modeling and thermal design methodology. The development trend of thermal design in VCSEL array was also prospected. [ABSTRACT FROM AUTHOR]

The electron transport layer (ETL)‐free perovskite solar cells (PSCs) have gained significant interest by simplifying the manufacture process and reducing the time/energy required for the fabrication of ETLs. Unfortunately, the performance of these ETL‐free PSCs still lags behind those of the conventional counterparts due to the slow electron extraction and undesired interfacial charge recombination loss at the buried interface. In this work, a facile and multifunctional biocolina thin layer is incorporated on the bottom electrodes to regulate the interface energy level alignment by forming an interface dipole layer, resulting in a suppressed nonradiative recombination and an improved charge extraction. Furthermore, the biocolina thin layer possess the capability to passivate the surface defects within the perovskite films while simultaneously facilitate the formation of perovskite crystals. Consequently, a remarkable enhancement in photovoltaic performance is observed in the biocolina‐based ETL‐free PSCs with an increase from 15.96 % to an outstanding 20.01 %. Additionally, the biocolina extends the stability and relieves the hysteresis effect through the interface defect passivation and inhibition of interface charge accumulation. This research contributes to the development of cost‐effective, simplified designs for highly efficient ETL‐free PSCs by modifying the bottom electrodes. [ABSTRACT FROM AUTHOR]

Halide perovskite materials are considered a promising optical gain medium for stimulated emission and have aroused tremendous interest in the field of laser research. The development of low‐threshold optically pumped amplified spontaneous emission (ASE) is critical for the advancement of continuous wave (CW) and electrically pumped micro‐nano lasers. In this work, an efficient ZnS additive is incorporated into the FA0.85MA0.15PbI2.55Br0.45 perovskite films to diminish the ASE threshold and extend the photostability by the dual‐site synergistic passivation. The experimental measurements and first‐principles calculations based on the density functional theory (DFT) are employed to elucidate the doping mechanism. The designed ZnS‐based perovskite films yield a mitigated ASE threshold of 8.5 µJ cm−2 with an elevated optical gain coefficient of 109.06 cm−1, which outperform those of the control films (12.7 µJ cm−2 and 74.10 cm−1). The in‐depth experimental characterizations and theoretical calculations have corroborated that the improvement of ASE performance can be ascribed to the dual‐site synergistic passivation effects of Zn2+ and S2−, which reduces the surface defects of perovskite films, suppresses the nonradiative charge recombination and improves the optical stability. This work provides a resultful strategy to construct the solution‐processed perovskite lasers with low thresholds and superior stability. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) laser has become an important way to solve micro-application problems in many fields. However, single wavelength distributed Bragg reflector (DBR) has many limitations in practical applications, such as signal transmission. How to realize multiwavelength DBR lasing output simply is a challenge. To achieve a stable multi-wavelength quantum dots laser in the near-infrared region, the perovskite CsPbI3 QDs laser with DBR structure is developed in this paper. A tetragonal crystal structure with complete bonding information and no defect is explained by X-ray diffractions (XRD) and Raman spectrum. The cross-section morphology of the DBR laser and the surface morphology of QDs is measured by scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. An elliptical light propagation field and a double wavelength laser radiation are obtained from the finite-difference time-domain (FDTD) simulation. The output of the three wavelength lasers at 770 nm, 823 nm, and 873 nm is measured. The emission time of a DBR laser is about 2 h, and the average fluorescence quantum yield is 60%. The cavity length selection and energy level model are put in place to clearly see the working mechanism. All the results suggest that an effective and stable CsPbI3 quantum dots DBR laser is realized. [ABSTRACT FROM AUTHOR]

Photogating effect based on vertical structure of 2D materials allows for the realization of a highly sensitive photodetector. A highly sensitive and broad‐spectrum (365–965 nm) photodetector is reported based on the indium selenide (InSe)/rhenium disulfide (ReS2) vertical heterostructure, where the top layer InSe serves as the photogate to regulate the channel current, enabling a large photoconductive gain of 106. The detectivity of the photodetector can reach 6.51 × 1013 Jones, making this one of the highest values among reported transition metal dichalcogenide photodetectors. The photodetector represents a high responsivity of 1921 A W−1, an ultrahigh external quantum efficiency (EQE) of 6.53 × 105%, and a fast response time of 21.6 ms. The outstanding properties of the InSe/ReS2 heterojunction reveal the promising potential in high‐efficient, ultrasensitive, broadband photodetectors. [ABSTRACT FROM AUTHOR]

The lateral wet-etching kinetics of an Al0.8Ga0.2As sacrificial layer, a typical configuration for optoelectronic devices, has been investigated in detail. Expanding the one-dimensional Si and AlAs oxidation modes to the Al0.8Ga0.2As sacrificial layer etching process, compact analytical formulas were obtained for the time evolution of the etch front and for the etch rate. Through both experiment and theoretical calculations, the lateral etching process parameters, A, B, and B/A, have been obtained for the different temperatures and etchant volume ratios. The etch rate is found to remain almost constant for a large range of etch length. However, when the etch temperature increases, a rapid increase in this rate is predicted. Activation energies for the process parameters, EA∼0.1 eV and EB∼0.5 eV, have also been obtained for the etchant volume ratio of 3:1 and the sacrificial layer thickness is 800 nm. [ABSTRACT FROM AUTHOR]

The lateral wet-etching kinetics of a [Al.sub.0.8][Ga.sub.0.2]As sacrificial layer is investigated. The etch rate is independent of the etch length but is affected by the temperature and hence they are very important for achieving a good control of the AlGaAs sacrificial layer etching process for microstructures in integrated optoelectronic devices.