Laser Cooling Technology from huangxiangfeng's blog

Since the 1970s, laser cooling technology has been used by physicists to cool a variety of individual atoms, but with its cooling molecules has been difficult. When cooling with a laser, the energy level of the system needs to match the energy level of the cooled 1000mw laser pointer. The more atoms are contained in the molecule, the more complex the vibration and rotation of the atom, the more difficult the matching and the greater the cooling difficulty. This ultra-cold molecules are expected to be the basis of molecular quantum computers, in fact, the laser can not only be used to cool molecules, but also used to accurately let it back to the original state. If the physicists can control which part of the molecule vibrates, you can use this technique to store information.

The latest research is impressive because it is very necessary to cool the molecules to such a low temperature, but there is still a long distance from the molecular quantum computer, because the progress in this area is too slow. In addition, molecules that are cooled to near absolute zero may react more slowly, allowing for more detailed observation of their reactions, so the technique may become the gospel of chemists.

Based on the coherent polarization synthesis technique of fiber optic devices, the phase coherent polarization synthesis of fiber is realized by phase control and polarization control respectively. The technology is based on the full polarization maintaining fiber best burning laser pointer device, without considering the impact of spatial error, the system is stable, reliable, easy to combine with other fiber optic devices, in the phased array based spatial coherent optical communication system has great potential value.

In order to alleviate the influence of atmospheric turbulence on coherent optical communication, two kinds of technical means are used, namely "large diameter telescope + single aperture adaptive optics" and "phased array technology". Compared with the first technology, phased array technology has the advantages of small telescope size, low cost and high reliability. In the space coherent optical communication system based on the phased array, the received light beam is divided into multiple beams by the receiving array. Therefore, it is important to synthesize a plurality of sub-beams carrying a communication signal efficiently into a brightest laser pointer beam. Aiming at this problem, the research group proposed a coherent polarization synthesis technology based on fiber optic devices.

Two linearly polarized light beams can be combined into a beam of light using a fiber polarization beam splitter, and the synthesized beam is an arbitrary polarization state due to the change in the phase difference of the input beam. In order to control the synthetic beam as linearly polarized blue laser pointer light for the next level of synthesis or for the demodulation of the communication signal, the task group proposed two methods of phase control and polarization control, and carried out theoretical analysis and experimental verification. The results show that both methods can achieve efficient coherent polarization synthesis, synthesize multiple linearly polarized light efficiently into a polarization maintaining fiber and output linearly polarized light.