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"Scientific progress and technological progress are often not achievements that can be accomplished by one person alone. Laser communication is just like this. Teacher Zhao Zhongyao is the actual host of the laser communication project. Zhou Guangzhao realized laser data communication for the first time. Professor Wang Dayan's technological breakthrough, We'll talk about that in a moment."
"After realizing the data communication of the laser carrier, there is another problem lying in front of us: what medium the laser propagates in."
"Laser propagating in the air will be severely attenuated due to distance, and there is often no direct line of sight between two communication terminals. We need a medium in which the laser can propagate with extremely low loss, and can also travel with the medium The bending changes the direction of propagation."
"Glass, as a laser transmission medium, has inherent advantages: tiny glass fibers can be bent without breaking; glass fibers are easy to manufacture, and the use of glass fibers with different refractive indices to make the surface and core layers of communication lines can allow laser light to flow freely in it." Reflection continues to advance. However, common glass cannot be used directly for laser communication, and its loss rate is still too large."
"How to reduce the loss rate of glass fiber to laser, to solve this engineering problem, it is necessary to study the scientific nature of light loss from its source."
"After telling some stories and divergent topics, I'm finally going to read the paper," Tang Hua said with a smile. "My paper mainly studies optical frequency dielectric fiber surface waveguides. It was actually published in March 1952. But in order to verify whether its technology is feasible, Wang Dayan and the Changchun Institute of Optoelectronics have conducted more than two years of exploration and experiments. Today, it can finally be said with certainty that this theory has withstood the test.”
……
It is now 1956. Not only has optical fiber been manufactured, the loss rate has been reduced from 20dB/km to 10dB/km and further reduced to 3.3dB/km, and optical fiber communication lines have been laid out.A thin optical fiber, pulled from Changchun to Beijing, can satisfy 500 telephone lines and 3 telegraph communications, and the call quality is significantly higher than that of copper cables.If there is no optical fiber, it is necessary to pull a coaxial cable with a core and a skinned egg thickness.
At the beginning of Tang Hua's thesis, he talked about the three most practical issues: dielectric loss, bending loss and radiation loss of the medium.In order to find out the sources of these three types of loss, we have to dig deeper into the surface phenomenon, until we reach the absorption band theory of solid molecules, which is almost the same.Then a conjecture or prediction is made: as long as the purity of the quartz glass is increased, the scattering loss of the quartz glass fiber can be improved from 200dB/km to 1dB/km.
After the paper was read, Tang Hua came down, followed by Zhao Zhongyao's paper, and his paper was about how to realize laser communication/optical fiber communication.The assistants of the laser communication team are Zhou Guangzhao and Wang Dayan, but Wang Dayan still has scientific research tasks in Changchun. Zhou Guangzhao is in the Soviet Union, but was sent to the Institute of Nuclear Physics here for advanced studies. Now I don’t know which nuclear base to follow.
"As expected, your so-called thesis turned into an introduction to product principles in the end."
Tang Hua stepped down and sat next to Lang Dao, and Lang Dao said to Tang Hua.
On the stage, Zhao Zhongyao was talking about the structure of the optical fiber communication system, optical fiber lines, signal enhancement, modulation and demodulation, and finally how to connect with the city telephone network and program-controlled switches...
Tang Hua chuckled.
It's not as interesting to engage in physical theory as invent... I'm an integration of basic research-applied technology-engineering realization-industrial rollout.
Speaking of medals, Khrushchev changed the awarding rules in the Soviet medal system that "heroes of labor are only awarded to Soviet citizens". Tang Hua now has gold stars for labor in addition to gold stars for heroes, which is quite good.
But the key point is that it is not difficult to apply the technology. It is a headache to read those theories and page after page of formula derivation in quantum mechanics and condensed matter physics.
"It's good to be able to elevate the introduction of product principles to a theoretical level, isn't it?" Tang Hua said to Landau.
……
Not only Tang Hua and Zhao Zhongyao read the papers, but also the high-energy laser that the Soviet Union has been obsessed with has now made progress.
After Zhao Zhongyao, Soviet scientists took to the stage to announce the development progress of high-energy lasers in recent years. Now they have produced a 50-kilowatt laser with stable output.Moreover, to Tang Hua's admiration, they came up with the idea of multi-laser focused irradiation, which was only applied in the American ABL system in the 20s.
The Soviet high-energy laser group conceived a seven-laser combined shooting system. The combined power of seven "headlights" is 350 kilowatts, which already has the lethality on the battlefield.
Their next step was also drawn with blueprints: a tracked laser launch vehicle and a power supply vehicle are paired, and the laser launch vehicle can destroy bunkers and tank targets within a few kilometers.
But this is just an idea - there are still many key systems that need to be made into a hard-kill weapon system for high-energy lasers.
……
"Comrades, I have a few different thoughts about the future of high-energy laser weapons."
For the discussion after the thesis, Tang Hua said first.
"It would be great if the laser hard-kill system could be installed on land or on a mobile platform of a ship. However, from the thesis of Comrade Alexander Molo just now, we found that it still has a long way to go before it can be put into practical use. "
"Actually, the application of laser weapons is not only on the ground, and should not even be limited to the air. I think the deployment position of laser weapons can be higher."
Tang Hua drew the earth and then drew the orbit of an artificial satellite outside the earth, "Space. There is no air in space. The beams emitted by laser weapons will not attenuate in the air, nor will the speed of light diverge due to the air. It is more meaningful. Fortunately, since the laser is erected at an altitude of several hundred kilometers, its interception range is very wide."
"A laser weapon system, a space nuclear reactor, we send it into space, let it reach the first cosmic speed, this system can continue to operate in the sky for several years or even 10 years, during this time, it It will be an interceptor platform in space capable of shooting down missiles heading towards the Soviet Union. Academician Korolev, can we send these things into space now?"
Sergei Korolev, director of the Jet Science Institute of the Soviet Union and academician of the Academy of Sciences, nodded desperately.
After nodding for a while, Korolev shook his head again: "But not now."
Alexander Molo: "Why not now? You've been working on big rockets. Then tell me when it will work"
Korolev: "This is a secret project of the National Defense Committee, and I can't tell you yet."
Alexander Molo: "Our high-energy laser is also a secret project of the National Defense Council."
……
The Soviet intercontinental missile and artificial satellite projects were established almost at the same time. When the R-7 intercontinental missile was developed, it was ready to use the first and second stages of this missile to launch artificial satellites.According to Korolev's theoretical calculations, R-7, as a carrier rocket, can send a load of 1000 to 1400 kilograms into low-Earth orbit.
About a week ago, on January 1956, 1, the National Defense Industries Board formally signed an executive order to send the first artificial satellite into space in 31 or 1957.
总之科罗廖夫现在身上担着洲际导弹和运载火箭两个担子。作为洲际导弹，R-7要能把3.4吨重的弹头投到8800公里外（苏联当时典型的150万吨当量辐射内爆氢弹重3.4吨）。作为运载火箭，R-7要在1957年做测试飞行，1958年把一枚不小于1吨的卫星送上太空。
Of course, both projects are secret projects.
Tang Hua: "Comrade Moluo, can you estimate, if the laser is launched into space, then the weight of the laser itself is at least how many tons?"
Alexander Molo checked his materials and papers, and answered after a while: "10 tons."
Korolev: "10 tons, then there is nothing I can do now."
Tang Hua: "Indeed, to allow a 10-ton object to reach the first cosmic velocity of 7.9 km/s, it requires a large rocket."
Korolev: "For artificial satellites, we must first conduct the most basic principle test. After passing, we will try to launch a small object into space to see if it works. If it works, we will gradually give it Add some functionality to this small thing. At the same time, design a larger satellite that operates in space. The development of anything is like this. I can say for sure that the small thing we launched for the first time will definitely not reach 10 tons."
……
Tang Hua suddenly felt that Qian Xuesen should be called to the meeting next time.The positions and roles of Korolev and Qian Xuesen in China and the Soviet Union are highly overlapping, and the exchanges between the two may spark some sparks.
But this time, I did not expect that Korolev would also come to the annual meeting of laser physics.Could it be that Korolev found out that the Chinese laser gyroscope is already practical?
"Greetings, Comrade Cherenkov."
Pavel Alekseevich Cherenkov, whose main achievement is the Cherenkov radiation.For this discovery, he was awarded the Nobel Prize in Physics in 1958.
But it was too late for Tang Hua to get involved. Cherenkov radiation was discovered in 1934.
At that time Cherenkov was studying what happens when radiation passes through a fluid and observed a bluish glow.Physicists in Europe had observed a similar phenomenon a few years earlier, but thought it was the fluorescence of water.Cherenkov carefully excluded impurities in the water that caused the fluorescence in his experiments, but the blue glow remained.This shows that this is a new radiation.
Cherenkov radiation is the short-wave radiation emitted when the moving charge in the medium exceeds the speed of light in the medium. This research was not very useful in the 30s, but in the 50s, the particle physics community discovered that Cherenkov radiation was used to study emitted particles. It was very easy to use, so Cherenkov was selected by the Nobel Committee.
Tang Hua: "Comrade Cherenkov, I seem to have heard some rumors that the Nobel Prize Committee is very optimistic about Cherenkov radiation, maybe you will win a Nobel Prize in Physics within two or three years. "
Cherenkov: "Maybe there are some possibilities, but it is definitely not now. Academician Tang Hua, the 1956 Nobel Prize in Physics, the transistor may be the final winner."
Tang Hua: "Oh?"
……
Cherenkov's guess is correct. The 1956 Nobel Prize in Physics went to William Shockley, John Bardeen, and Walter Bratton, the three who discovered the transistor effect and made the transistor in the laboratory. .
It's just that these three people... are all in a bit of trouble now.Among them William Shockley was in the most trouble.