As one of the major inventions of humans in the 20th century, lasers have now been integrated into all aspects of the economy and society. The 2018 Nobel Prize in Physics was awarded to three scientists who made breakthrough contributions in the field of laser physics, highlighting the important role of lasers.
Literally, laser refers to the amplification of light by stimulated radiation. When a beam of light passes through an object, stimulated radiation can occur under certain special conditions, and the emitted light is exactly the same as the incident light. This process is like amplifying the incident light through a light cloning machine.
Due to its unique optical properties, the laser is also known as the "brightest light", the "most accurate ruler" and the "fastest knife". The laser also has excellent directionality. For example, the earth is about 380,000 kilometers away from the moon. If laser irradiation is used, the spot formed on the surface of the moon is less than 2000 meters. In the same situation, the light spots generated by other light sources have already covered the entire moon.
Since the invention of the first laser in 1960, lasers have been widely used in fiber optic communications, beauty, printing, ophthalmic surgery, weapons and ranging. Ashkin, one of the winners of the Nobel Prize in Physics in 2018, invented the optical technique in the 1980s, using a focused laser to clip tiny objects like a scorpion. Today, ray has become an indispensable tool for many physicists, chemists, and biologists to help them accurately manipulate atoms, molecules, bacteria, viruses, and cells, opening the door to microscopic phenomena.
According to the working mode, the laser can be divided into continuous laser and pulsed laser. Pulsed lasers appear as light pulses one after the other in time, and their peak power is much greater than that of continuous lasers. To put it bluntly, the continuous laser is like a calm water surface 10 meters deep, and the pulse laser forms a wave with a height of 1000 meters like a water surface of 1 meter deep. The width of the laser pulse can be shorter than 1 picosecond (1 picosecond is equal to one trillionth of a second), even to the femtosecond (1 femtosecond is equal to one billionth of a second). Concentrating energy in such a short period of time, the peak power can be imagined.
In 2018, two other Nobel Prize winners, Mulu and Strickland, invented the chirped pulse amplification technology in 1985, and obtained ultra-short pulses with extremely high peak power. This ultra-short laser with high peak power enables precise cutting and drilling on different materials. It has been widely used in laser vision correction surgery and precision machining, such as mobile phone display and internal small parts. In the study of the internal dynamic process of matter, the use of femtosecond laser pulses can take pictures of atoms and molecules, allowing scientists to gain insight into the secrets of the microcosm.
In addition, with the help of helium pulse amplification technology, many countries are building super-strong laser devices. China has a very solid foundation in this field and has achieved breakthrough results in recent years. With this powerful laser device, extreme physical conditions can be created in the laboratory, and it is expected to reveal new physical laws.
There is no doubt that a rich and diverse range of laser technologies provides us with a powerful tool for understanding the world and changing the world. I believe that with the joint efforts of scientists, more magical laser technology will continue to emerge.