Laser cooling technology
As one of the the Four Great Inventions of the twentieth century, laser technology, along with computer, semiconductor and atomic energy technology, has been widely used in many industries. However, when it comes to laser, most people can think of its application in mechanical processing.
In fact, in addition to industrial cutting, welding, and medical beauty applications Laser has many other uses, such as in cooling. The concept of laser cooling was first proposed by Soviet scholars in 1962. Before this concept caught the attention of the academic community, Soviet scholars remained silent for a period of time before proposing it. In 1985, the famous Chinese American scientist Steven Chu successfully achieved low-temperature environment by using laser to freeze atoms, and won the 1997 Physics Prize for this invention.
Doppler cooling technology
So why does the laser cool down? Generally speaking, the atoms of an object always move irregularly, which is called thermal motion in physics. The more intense the atomic motion, the higher the temperature of the object, and the lower the temperature Therefore, if there is a way to reduce the speed of atomic motion, the temperature of the object can be lowered. The principle of laser cooling can generally be understood as using a large number of photons to block the movement of atoms, thereby reducing the speed of atomic motion and achieving the goal of reducing the temperature of the object.
Laser is a highly concentrated energy beam because the light particles it emits have a uniform direction. When the laser beam enters the human body, due to the large number of particles entering the body, the particles in the object become so crowded that they cannot be used as before; Jump” This reduces the thermal motion of molecules.
In 1995, the Dankey team used Doppler cooling technology to cool cesium atoms to a low temperature of 2.8 nk. Physicists at the University of Bern in Germany have utilized this technology to achieve high-density photon concentration, which is a promising solar cell technology that will maintain the efficiency of the cell on cloudy days.
Anti Stokes fluorescence refrigeration technology
Doppler cooling is the most fundamental mechanism in laser cooling, and initially a technology called anti Stokes fluorescence cooling was developed. The concept of this technology was first proposed by P. Pringsheim in 1929.
In 1995, Epstein and his colleagues from the Space Refrigeration Technology Research Group at Los Alamos National Laboratory in the United States successfully obtained measurable cooling capacity on solid materials for the first time through laser-induced anti Stokes fluorescence.
In 1999, low-temperature physicist E. excited hole excitons in GaAs/GaAl semiconductor quantum well materials using a doped sapphire laser, achieving anti Stokes fluorescence emission of hole excitons. The relationship between refrigeration efficiency and refrigeration temperature at different temperatures is given.
In 2010, scientists used lasers to freeze molecules to near absolute zero, marking the first time that single-molecule laser cooling had achieved such low temperatures. This was a major advancement in the manufacture of quantum computers and the control of chemical and physical processes in matter.
With the continuous development of technology, laser cooling has begun to gain many applications, such as atomic etching, atomic optics, high-resolution, atomic clocks, optical tweezers and other basic research. This technology can also be used for metal welding and human surgery, and it is believed that in the future, this technology will be more widely applied.
In fact, in addition to industrial cutting, welding, and medical beauty applications Laser has many other uses, such as in cooling. The concept of laser cooling was first proposed by Soviet scholars in 1962. Before this concept caught the attention of the academic community, Soviet scholars remained silent for a period of time before proposing it. In 1985, the famous Chinese American scientist Steven Chu successfully achieved low-temperature environment by using laser to freeze atoms, and won the 1997 Physics Prize for this invention.
Doppler cooling technology
So why does the laser cool down? Generally speaking, the atoms of an object always move irregularly, which is called thermal motion in physics. The more intense the atomic motion, the higher the temperature of the object, and the lower the temperature Therefore, if there is a way to reduce the speed of atomic motion, the temperature of the object can be lowered. The principle of laser cooling can generally be understood as using a large number of photons to block the movement of atoms, thereby reducing the speed of atomic motion and achieving the goal of reducing the temperature of the object.
Laser is a highly concentrated energy beam because the light particles it emits have a uniform direction. When the laser beam enters the human body, due to the large number of particles entering the body, the particles in the object become so crowded that they cannot be used as before; Jump” This reduces the thermal motion of molecules.
In 1995, the Dankey team used Doppler cooling technology to cool cesium atoms to a low temperature of 2.8 nk. Physicists at the University of Bern in Germany have utilized this technology to achieve high-density photon concentration, which is a promising solar cell technology that will maintain the efficiency of the cell on cloudy days.
Anti Stokes fluorescence refrigeration technology
Doppler cooling is the most fundamental mechanism in laser cooling, and initially a technology called anti Stokes fluorescence cooling was developed. The concept of this technology was first proposed by P. Pringsheim in 1929.
In 1995, Epstein and his colleagues from the Space Refrigeration Technology Research Group at Los Alamos National Laboratory in the United States successfully obtained measurable cooling capacity on solid materials for the first time through laser-induced anti Stokes fluorescence.
In 1999, low-temperature physicist E. excited hole excitons in GaAs/GaAl semiconductor quantum well materials using a doped sapphire laser, achieving anti Stokes fluorescence emission of hole excitons. The relationship between refrigeration efficiency and refrigeration temperature at different temperatures is given.
In 2010, scientists used lasers to freeze molecules to near absolute zero, marking the first time that single-molecule laser cooling had achieved such low temperatures. This was a major advancement in the manufacture of quantum computers and the control of chemical and physical processes in matter.
With the continuous development of technology, laser cooling has begun to gain many applications, such as atomic etching, atomic optics, high-resolution, atomic clocks, optical tweezers and other basic research. This technology can also be used for metal welding and human surgery, and it is believed that in the future, this technology will be more widely applied.