High electro-optical conversion efficiency is one of the most distinctive features of semiconductor lasers as compared to other types of lasers. Its further increase remains a significant objective. Further enhancing the efficiency of edge-emitting lasers (EEL), which represent the highest efficiency among semiconductor lasers at present, is challenging. The efficiency of vertical cavity surface emitting lasers (VCSELs) has always been relatively low compared to EEL. This paper, combining modeling with experiments, demonstrates the potential of multi-junction cascaded VCSELs to achieve high efficiency beyond that of EELs, our simulations show, that a 20-junction VCSEL can achieve an efficiency of more than 88% at room temperature. We fabricated VCSEL devices with different numbers of junctions and compared their energy efficiency. 15-junction VCSELs achieved a maximum efficiency of 74% at room temperature under nanosecond driving current, the corresponding differential quantum efficiency exceeds 1100%, being the largest electro-optical conversion efficiency and differential quantum efficiency reported until now for VCSELs.

During the implementation of laser wireless power transmission (LWPT), various factors, such as clouds and atmospheric turbulence, can potentially result in nonuniform irradiation, leading to a power mismatch of the photovoltaic (PV) array. Dynamic reconfiguration technology which adopted in solar energy system is an effective method to improve the power output of PV arrays, but the current execution speed and accuracy cannot meet the fast response requirements of LWPT. In this article, a novel adaptive threshold iteration algorithm for irradiance equalization based on total-cross-tied (TCT) configuration is proposed. Based on this algorithm, a large number of data samples characterized and labeled by irradiance and optimal layout are obtained in the simulation platform. The irradiance values are then converted into current values of special nodes for the training of deep neural networks, which simplifies both model complexity and hardware complexity. A theoretical analysis of the simulation was performed on a 3×4 scale PV array, followed by the design of the hardware circuit and evaluation of the experimental results with metrics. The results show that the output power enhancement of the array can reach up to 63.29% compared to TCT-type configuration. The conversion efficiency is improved by 17.21%, and the reconfiguration execution time is about 61 ms.

Improving the output power and efficiency of broad-area diode lasers is a prerequisite for the further development of fiber lasers, solid-state laser industries, and direct semiconductor laser applications. At present, the large amount of Joule heat generated by large drive currents and limited wall-plug efficiency presents the largest challenge for improving these lasers. In this paper, a multi-junction cascade laser with low Joule heat generation is demonstrated, showing large power and conversion efficiency. We fabricated devices with different junction numbers and compared their output power. We present double-junction lasers emitting at ~915 nm with an emitter width of 500 μm, delivering 132.5 W continuous wave output power at 70 A, which is the highest power reported so far for any single-emitter laser. The power conversion efficiencies are 66.7% and 60%, at 100 W and 132 W, respectively.

The development of high-performance tunnel junctions is critical for achieving high efficiency in multi-junction solar cells (MJSC) that can operate at high concentrations. We investigate silicon and tellurium co-doping of InGaAs quantum well inserts in p⁺⁺-GaAs/n⁺⁺-GaAs tunnel junctions and report a peak current density as high as 5839 A cm⁻² with a series resistance of 5.86 × 10⁻⁵ Ω cm². In addition, we discuss how device performance is affected by the growth temperature, thickness, and V/III ratio in the InGaAs layer. A simulation model indicates that the contribution of trap-assisted tunneling enhances carrier tunneling.

Compared to 9xxnm laser diodes emitting at 808nm are more prone to catastrophic optical mirror damage (COMD) and thermal rollover due to the shorter wavelength, resulting in lower device power. In this paper, we optimize a structure based on InGaAsP/InGaP to improve the conversion efficiency and use facet passivation to improve the COMD level. Laser diodes with 100μm emitter width and 5mm cavity length are fabricated. The continuous wave (CW) output power reaches 19W at 20A without COMD, which is the maximum CW state of art power reported so far for 808nm laser diodes. The slope efficiency reaches 1.28W/A and the maximum electro-optic conversion efficiency is 59.1%. The internal loss and internal quantum efficiency of the devices are 0.61cm-1 and 98%, and the characteristic temperature T0 and T1 at high temperatures are 165K and 637K. The device can reliably work at 10A under 35±C heatsinks temperatures for over 2000h.