Throughout the development of air lasing, it is not difficult to find that air lasing is not only of great significance for basic research such as strong field physics, nonlinear optics, and quantum optics, but also have significant advantages in technical fields such as remote detection.

From the perspective of basic research, air lasing is the result of the interaction between a strong laser field and a variety of material forms in the air with novel and rich physical connotation. First of all, the air lasing originates from the coherent radiation of excited atoms, ions, and molecules, which emphasizes the contribution of excited state and resonance effect in the strong field physics, and provides optical probes for studying the behavior of excited states under strong field conditions and strong field resonance interactions. Secondly, the gain mechanism of N₂⁺ lasers is controversial. In order to understand the behavior of N₂⁺ laser, it is necessary to consider both the strong ionization and the interaction between the laser field and N₂⁺ electron state, vibration dynamic state and rotating state. Therefore, the exploration of the N₂⁺ laser generation mechanism and physical nature has promoted the development of the theory of strong field interaction and revealed the new mechanism of strong field interaction. Finally, the generation of N₂⁺ lasing constructs a fully coherent quantum system of electronic states, vibration states, and rotational states. The establishment of the quantum coherence greatly enhances the nonlinear effect of molecular ions and provides an understanding of the gain mechanism of N₂⁺ lasing, which provides a new perspective and makes the coherent control of air lasing possible.

From the perspective of application, air lasing has advantages of high collimation, high coherence and high intensity, etc., and has significant advantages in remote detection. First of all, air lasing has good directivity. Therefore, the square attenuation law of traditional optical remote detection is effectively overcome. At the same time, the intensity of the air lasing is several orders of magnitude stronger than the fluorescence signal, and it has good coherence, which can excite pollutants or explosives molecules to produce nonlinear fingerprint spectrum to achieve simultaneous measurement of a variety of pollutants. As a result, the combination of air lasing and nonlinear fingerprint spectroscopy technology can develop a universal and highly sensitive new remote detection technology for environmental science and military and national defense. In addition, air lasing generally uses a femtosecond laser as the pump source. By using the filament effect of femtosecond laser, the vehicle-mounted TW-level pump laser pulse can realize long-distance transmission without diffraction, which lays an important foundation for the development of new technologies for remote detection based on air lasing. In addition, by using the unique light intensity clamping effect of femtosecond laser filament, it can also effectively avoid the influence of laser jitter, particle scattering in the atmosphere, airflow instability, complex cloud and fog environment and other factors on signal acquisition, which improves the stability of remote detection.

At present, various air lasing has been discovered one after another, the new physical effects of N₂⁺ lasers have been gradually revealed, and the possibility of using back lasers for remote detection has also been confirmed. However, as a newly developing research direction, air lasing still has some science problems and technical challenges that need to be solved urgently.

At the level of basic research, the following questions are worth further discussion. First, although the macroscopic image of the N₂⁺ lasing is clear, the problem of population inversion is still controversial. Coherent excitation of lasers can not only produce population transfer, but also establish coherence between energy states. The contribution of population inversion and quantum coherence to optical gain is difficult to distinguish. Second, the generation of air lasing includes the interaction of electrons, atoms, molecules, ions and other material forms with strong laser fields. It is a great challenge for theoretical research to establish a complete theoretical model containing these physical processes. Third, resonant excitation of molecules under the strong laser field will produce many novel strong field physics, nonlinear optics, and quantum optical effects. The air lasing phenomenon is just one example. More effects that are interesting need to be further studied and explored. These studies will broaden the theoretical framework of strong field physics, fill up the gaps in the study of excited state nonlinear optics and molecular ion nonlinear optics, and advance the study of quantum optics to new conditions of ultrafast strong field, new systems of molecular ions, and new scenarios at long distances.

In the terms of application and technology, the study of air lasing has just started, and there are still some key issues that need to be overcome. First, generating high-brightness back air lasing in a real atmospheric environment is the key to remote detection, and it is still an important technical challenge at present. Existing back air lasing is only produced in atoms or neutral nitrogen molecules. However, atomic lasing is mainly pumped from ultraviolet light, and the strong absorption of the atmosphere in the ultraviolet band and the lower energy of ultraviolet lasers limits its application in remote sensing.

Because the electron collision excitation is difficult to maintain the long-term gain, and oxygen has a strong quenching effect, it is difficult to operate in the atmosphere for back nitrogen lasing. Therefore, increasing the gain life and suppressing the negative effects of oxygen are the problems that must be solved in order to achieve the back nitrogen lasing. Second, when the air lasing is used for remote molecular detection, the molecule to be measured must be placed in the atmospheric environment, so how to suppress the background signal of the atmosphere, and then achieve high sensitivity detection of trace gas molecules is also a key problem to be solved. Third, air lasing also has broad application prospects in the fields of nonlinear ultrafast spectroscopy, combustion diagnosis, etc., which are worthy of further study.

In summary, the research of remote air lasing under the condition of the ultrafast strong field is expected to achieve important breakthroughs in basic research fields such as strong field molecular physics, ultrafast nonlinear optics, and quantum optics. It will also promote the development of remote detection, nonlinear spectroscopy, combustion diagnosis and other application technologies.