Laser, it should be said to be a household name, but if you really ask what is laser, I am afraid there will not be too many people to say it accurately. Laser, English is Laser, this Chinese name is very controversial, "Lease", "Thunder", "Light Edge", "Light Surplus Amplifier", how to call it, It seems that there is nothing to hear the word laser, I think that there is a relationship with the radium of the lady. Now I think is that it is one of the translations of Laser. Fortunately, there is the finals of Qian Xue Sen, this thing is also an official Chinese name. . The word Laser comes from the English first letters of five vocabulary.Light Amplification by Stimulated Emission of RadiationDirect translation is called the exciter radiation amplifier, although it is not like the cooling of the laser, but for the scientific research dogs of our related majors, this full name is very refined, the principle of laser production.
If you want to mention the principle of laser, you can’t really be anxious. You have to go around a big bend. If you come over, you will have a little stimulus for students who don’t know this.
The principle of laser must be said from the particle energy in the substance, and must be a specific particles in some particular substances, there are two or more energy states, sometimes in high energy, exciting, sometimes Low energy, like two or three o’clock in the morning.
When the particles are relaxed from high energy into low energy, the loss of loss is radiated in the form of photons.
The light source such as an incandescent lamp is emitted by spontaneous radiation. The number of high energy particles after power is increased, and spontaneous radiation occurs very frequently.
This process is calledSpontaneous radiationIt should be easy to see here, which is not a laser, although it is also light, it is not a laser, anyway is not a laser.
Spontaneous radiation is very tone, if the laser photon is like the military parade in Tiananmen Square, the spontaneous radiation photon is like a group of dissembled wild dogs, there is no organization of discipline, and its occurs, sometimes Come, sometimes chaos.
Since the excitement particles will lose energy to be slight, then, will it be exciting to get energy through some approach? The answer is affirmative, similar to the radiation process, the low energy particles will keep the passenger passing the photons, seeing the right will "hijack", sweep the energy of the photons, used to rise to high energy This process is calledAttractive absorption.
In 1917, Einstein proposed an idea, high-energy particles, may also like to stare at the photons passing by, when there is a favorite photon road, high-energy particles will not keep them, but to release energy with it. Walk, like love. The original particles lose energy, from high energy changes to low energy, and the variation of energy will generate a superior photon with the passing photons, this process is calledExcited radiation.
Radiation is the core portion of the laser, which can be seen as light before and after the radiation is amplified, and the resulting photon is consistent with the frequency of the original photon, which is the so-called coherence.
The passed photons are two changes from one change, that is, light is enlarged. At this time, the primary school language foundation is keenly discovered that the radiation radiation is amplified. The keywords of this name have all appeared, but it is still calm. At this time, the light still cannot be called laser, and there are two important issues need Solved, it is spontaneously radiation and attachment absorption introduced by the front pad.
The first thing to overcome is attractive. If the particles of the high and low level are staring at the photons passing, it is difficult to ensure that the last thing is more hijacked or the photons that are released. And in fact, the low-level particles under natural conditions are more than high-level particles. Here, you need to join the first person-oriented intervention, that is, in a way, let the low-level particles run to the high energy level, let everyone Are exciting. At this time, there is a very Cooool name, calledParticle number inversionOrExcited state. The method of producing particle number inversion varies depending on the substance used for radiation to generate laser light, which may be energized, or light, in summary is a means of input energy.
When the excited radiation is much greater than the charge absorption, it can begin to face another mountain, spontaneous radiation. Spontaneous radiation is naturally occurring in high energy particles. In other words, there is a high energy particle, it may happen, let alone, it has raised the low energy particles to high energy, and the spontaneous radiation process is naturally stopped. So the idea of ??solving the problem is that if you want to make the radiation much greater than spontaneous radiation.
The method is to add two mirrors on both ends of the working substance of the particle number inversion state, one end is a full mirror, and the other end is a portion of the mirror, which is referred to as a resonant cavity. When the exciusal radiation occurs, the appropriate photons are repeatedly jumped between the two mirrors, multiple times, repeatedly generates electrical radiation, and continuously enhances the beam.
A portion of the mirror can be transmitted at any time, and as the radiation is contrast, the transmitted beam is constantly enhanced. Since the two-sided mirrors are located in a particular direction, there is no stable oscillating for the direction in which the direction is not suitable, so that we can see that the laser has a clear direction, which is also the result of the resonant cavity screening.
It can be seen that as long as the light in line with the requirements can form a stable shock in the cavity, it is constantly being large, which is why the laser has a clear direction, as the propagation direction does not meet the requirements of the required light is screened.
This is also the basic principle of laser, and we will be asked to remember the three major elements of laser when learning laser principles.Working substance (gain medium),Pump source (energy input),Cavity, Understand and understand this, it is also possible to understand how the laser is generated, and under this condition, it is possible to determine that many lights seen in life are not laser.
For example, when the sun is laser? This is definitely not, according to the above, the laser is not natural, the sun is emitted by nuclear gatherings, and it is not the result of the radiation radiation. This should be everyone’s consensus, there is nothing to say . Is this laser pen playing in a child? Is this a laser? This is also likely to be laser, exclude individuals to take ordinary light-emitting diode confused, many laser pens use things such as laser diodes, of course, cost is also very low, as laser, intensity, coherence, etc. It is also quoruting, after all, the use is different. Is the laser sword inside the Science Fiction Movie Star War? Although the laser cutting is now doing, let the laser only spread a certain distance, do not spread this, it can’t be done, the things in the movie can be called the telescopic diode, and it will be a light without this idea. The sword came out, the cost is not high.
I didn’t just say a bunch, this is the first time I know about it, this year’s international light days, because of the organizers of the event, I was asked to write an article about science laser. I want to revise the article, I want to revise it. I would like to revise it. Although I am related to major, it is not studying the laser, the understanding is limited. In the future, there will be some other interesting optical knowledge. Of course, it is mainly to science. Try to avoid too deep.
I hope that the people in this article are mainly some non-professional people, or undergraduates must learn laser principles, or they have not learned, and even have just read research, but even have no entry levels of laser principles. People, can qualify first, what is the principle of the laser, and then fill the flesh and blood to understand the laser or enter the research work, of course, the professionalism is also welcome to criticize. If the response or if there is any reaction, I will write some articles about fiber communication, Fourier optical, nonlinear optical, and so on.
Author: Fu Ye Lei Lei know