Since its advent, the laser technology has developed rapidly, injecting new vitality into traditional optical technology, and greatly advancing natural sciences. Since the birth of the first laser in 1960, research on this technology has garnered widespread attention worldwide. A laser primarily consists of three components: a pump source, a resonator, and a gain medium. The pump source provides energy to the gain medium, which upon reaching a certain energy level, undergoes stimulated emission to achieve light amplification. The amplified light propagates in the resonator, where it undergoes multiple reflections and further amplification, ultimately forming a laser. Therefore, the gain medium is the core of the entire laser structure, and its characteristics play a crucial role in the performance of the laser.

With the high integration of optoelectronic devices, micro-lasers featuring miniaturization, easy integration, excellent beam quality, strong brightness, and fast response speed have attracted extensive attention and in-depth research. Micro-lasers typically use advanced low-dimensional semiconductor materials such as nanosheets, nanowires, nanofilms, and quantum dots as gain media. These novel low-dimensional materials possess excellent photoelectric properties such as wide optical response range, low optical gain loss, and relatively simple preparation methods. For the selection of gain media material, III-V/II-VI inorganic semiconductors and perovskites exhibit excellent optical gain characteristics, good stability, and the advantages of solution processing. These attributes open up new opportunities for the development of lasers.

In laser manufacturing, the preparation method of the gain medium is crucial, given that it directly affects the quality of the film and ultimately determines the performance of the device. At present, commonly used gain medium preparation technologies mainly include vacuum evaporation, molecular beam epitaxy, chemical vapor deposition, and wet methods. Vacuum evaporation and molecular beam epitaxy are characterized by high-cost equipment and slow growth rate, which can lead to inefficient utilization and waste of materials. Chemical vapor deposition usually requires higher temperatures to facilitate chemical reactions, resulting in by-products that may be toxic or corrosive, posing certain safety and environmental hazards. Wet methods refer to a series of technical methods for the reaction or treatment of materials in solution or slurry, requiring low-cost equipment and a simple preparation process. These methods can uniformly deposit a film on a large area, making it highly advantageous for large-scale production.

This review summarizes the latest developments and achievements of low-dimensional nanomaterials prepared by wet methods as laser media. First, the excellent optical properties of nanosheets, nanowires, and quantum dots are reviewed, and the research status of optically pumped lasers based on them is described in detail. These low-dimensional structures, used as gain media, encompass not only traditional III-V and II-VI inorganic semiconductors, but also emerging perovskite materials. Their unique electronic structures and ease of processing bring new vitality to the development of laser technology. On the basis of previous research results, the performance of typical low-dimensional optically pumped lasers is summarized in Table 1, which shows important parameters such as emission peak value, line width, and threshold value of lasers with different dimensions. The review then discusses the research progress of electrically pumped lasers. Despite the working current density of electric-pumped laser devices with a light-emitting diode (LED) as the carrier exceeds the theoretical threshold, no electrically pumped laser or ASE has been observed. This can be attributed to various losses within the LED, such as charge imbalance within the device, non-radiative Auger effect, and Joule heating. Finally, the prospects for the application of low-dimensional nanometer materials in semiconductor lasers based on wet methods is discussed.

Currently, low-dimensional semiconductor material lasers based on wet methods exhibit ultra-low threshold, high quality factor, and single mode output, demonstrating significant application potential in fields such as optical communication, optical information processing, and biomedicine. However, low-dimensional amorphous films treated by the solution method often exhibit surface defects that can hinder laser output. To reduce this loss, it is feasible to introduce passivating agents and doping heavy metal elements. Additionally, films prepared by wet methods may exhibit significant heterogeneity in thickness and composition, which needs to be addressed through continuous research and technological innovation.