The first one can tell you that the most important thing is the laser with at least 10 kW, and the carbon dioxide laser is the most studied at present! However, it seems that 10 kW is not enough. Now we are studying the experimental 100 kW laser. In addition, there are a series of beam expanding, shaping and focusing systems and ablation targets. I don't know what the target material is, but it seems that as long as it can stick to the bottom of the spacecraft and be ionized during ablation, the problem is not great.

The specific details are that the bottom of the spacecraft is ablative material and supported by a bracket. Below it is a laser, which is shaped, focused and irradiated on the ablative material.

The principle is that when the laser beam irradiates the substance, the ionized substance forms plasma and is ejected backward, thus giving the spacecraft an upward power.

I don't do research in this field. It's too detailed to explain clearly. You can go to China HowNet or SPIE to check. Recently, there is no latest research progress in the world. It should be the successful development of 100 kW CO2 laser.