Chapter 1024 is simple, right? (I am on a business trip today, so there may only be two chapters in the next few days))
But then again, if Chai Gong could find the answers to these questions himself, he wouldn't have to come to Gao Zhendong. Although his summary was not as detailed and organized as Gao Zhendong's, he could still see the basic problems.

But it's useless to see it, I can't handle it.

The top technical personnel must be able to do two things: be able to raise questions and be able to find solutions.

The problem is easier to solve, but he really has no solution.

"Chief Engineer Gao, how can I find the answers to these questions?"

Fortunately, the boss is in front of me. If he doesn’t know how to do it, can’t I just ask?
Gao Zhendong stood up and started writing on the weathered blackboard, explaining to him as he wrote.

To be honest, if anyone has the ability to install a camera on the blackboard in Gao Zhendong's reception room without being discovered, he can make a fortune.

"Don't think of light as too mysterious. Even for laser, there are not so many complicated and mysterious things in its application. Light is light. Many of its characteristics can be explained, understood and analyzed with intuition and common sense..." As soon as Gao Zhendong opened his mouth, Chai Gong felt like he had seen the world.

The truth is simple. Are you good at discovering the truth from your surroundings and life?
"In fact, the loss of light in the transmission medium is due to two major reasons: scattering and absorption. Do you understand this?"

Well, this is easy, Chai Gong nodded confidently.

"The reasons for scattering are nothing more than four aspects: disorder in material structure, structural defects in dielectric materials, particulate impurities in the material, and irregular density fluctuations. Except for the last one which may not be so intuitive, the other three are actually easy to think of, right?" Gao Zhendong asked Chai Gong with a smile.

Chai Gong’s first reaction was that these were mostly common things in life, and it would be fine if he didn’t mention them. But once he mentioned them, he felt that they didn’t require any advanced knowledge and could just rely on intuition.

Thinking back, what were you thinking about? If Chief Engineer Gao hadn't mentioned it, you wouldn't have thought of it, but now that he mentioned it, I can do it, right?
If it weren't for Gao Zhendong's four sentences, these things would have been swirling around in his mind, but he just couldn't summarize them in an orderly manner.

Another concern is that even if he has summarized these four problems, he will still worry about whether there are other problems and reasons in his mind, and this is a problem of self-confidence.

However, Gao Zhendong's confidence comes from another big shot, the Chinese-American scientist Charles Kao, who actually studied this problem a few years later.

Can what scholars do be called plagiarism?

Chai Gong began to think that this matter seemed simple: "Well, except for the last one which I couldn't quite think of, I can understand the others."

Gao Zhendong did not continue to explain, but asked a question: "What material do you think is easier to achieve the ideal state in these aspects?"

Chai Gong answered without hesitation: "Single crystal!"

The structure of polycrystalline is macroscopically disordered, and the scattering may be high. The same is true for mixed crystalline and amorphous materials, but only single crystals can be used.

High-purity single crystal materials are ordered. If they are well drawn and have mild defects, then as long as the size and wavelength are appropriately matched, the scattering loss will undoubtedly be relatively small.

I heard that there are high-purity silicon single crystals in China. They may be a bit expensive, but let’s solve the theoretical problems first.

Unexpectedly, Gao Zhendong laughed: "That's the theory, but think about it again?"

Um? ? ! ! !
It seems that there is something wrong with my thinking!

He thought about it for a long time and didn't think there was anything wrong with this judgment. In fact, there was nothing wrong with what he said before, but there was a problem he didn't think of.

He finally reacted when he saw Gao Zhendong spread out his hands and gestured to both ends.

Length! It is difficult to obtain such a long length with a single crystal, and it is completely impractical.

Who the hell has ever seen a kilometer-long single crystal?
"Ah, single crystals are not that long. It's my fault. I was too idealistic. I only cared about theory and didn't consider the practical application."

The woodcutter felt very embarrassed.

Gao Zhendong didn't laugh at him. This thing was indeed difficult to think about at the moment.

"You are right. From the perspective of material performance, cost and practicality, amorphous materials are the ones that can be considered now."

Gao Zhendong's guidance and analysis immediately clarified the range of materials. Chai felt that his mind suddenly became clear: "Chief Engineer Gao, I understand. To be honest, I used to just follow foreign papers and materials and try to make optical fibers, but I didn't know why I chose this material. Now I begin to understand."

Just these few words could help him avoid many detours on the road of fiber optics. The big boss is so terrifying.

Gao Zhendong nodded: "Right, so the easiest materials for us to choose now are nothing more than two types: highly transparent plastic and glass. Do you understand now?"

Well, isn’t this returning to the main business of our Northeast Institute of Optics? But this time, Engineer Chai is very clear about why we have to return to this business.

"So which one do you think is better at present, plastic or glass?" Gao Zhendong asked the question again.

Chai Gong was not completely ignorant. He thought for a while and said confidently, "Glass!"

Gao Zhendong didn't say whether it was right or wrong: "Why?"

"The main reasons for the scattering of the two are the latter two, particles and irregular density fluctuations. Plastics inevitably introduce impurities and particles during the manufacturing process. Although they can be removed through dust-free and other means, it will increase costs. Glass has an advantage. The high enough temperature during the production process can decompose most of the impurity particles." Chai Gong was very confident. Speaking of glass, I am not sleepy anymore. Gao Zhendong smiled and clapped his hands: "Well, it makes sense. What about the density fluctuation problem?"

"This..." Well, this thing has indeed not been studied before.

Gao Zhendong quickly gave him the answer: "Someone has already done research on this. You can use this formula to calculate it. As for the origin of this formula, you can look for a paper published in 1956."

He wrote a simple formula on the blackboard and also wrote down the source of the formula.

Chai Gong was full of admiration for Gao Zhendong's extensive knowledge and strong memory.

"According to the formula, for inorganic glass, at a virtual temperature of 1000 degrees Celsius, the loss caused by density fluctuation is about 1dB/km."

Virtual temperature is a rather complicated concept, but fortunately professional glassmakers can still understand it.

"So low?" Although he is not an expert in communications, he knows from his little research that this loss can meet the communication requirements, but the loss of optical fiber is caused by more than one factor.

"So as long as the process is proper, there is no need to worry about inorganic glass in this regard," said Gao Zhendong.

For Chai Gong, the knowledge Gao Zhendong taught him clearly explained in theory why glass should be used. This is called knowing the fact and the reason, which can completely eliminate the interference factors that cause transmission loss, which will be of great help to his future work.

"Of course, you also have to consider one issue, which is the crystallization of glass."

For glass, crystallization during the production process is a structural defect. Fortunately, this worker Chai understands it.

"Okay, Chief Engineer Gao, we are familiar with this. We can use rapid cooling to suppress the number and size of grains...ah...this..."

At this point, the woodcutter seemed to find this thing very familiar and was stunned.

Gao Zhendong laughed: "Hahaha, did you remember something?"

"Fused quartz glass! Fused quartz glass! Isn't this the fused quartz glass you taught us!!" Chai Gong shouted.

Rapid cooling to obtain the most perfect amorphous state possible, isn't this what Chief Engineer Gao taught me about fused quartz glass?

Chai Gong once again experienced the terrifying level of the top bosses. A material that they just got casually could actually be used here!

Gao Zhendong smiled and nodded, and issued the first specific scientific research task: "Yes, that's it. But you need to solve a practical engineering problem here, which is to study how much scattering loss is caused by the grains of fused silica glass. Here, you can start with the Rayleigh scattering law."

Gao Zhendong knows the answer, but it would be better to let the comrades do some specific research. Firstly, this will provide a source of data, and secondly, it will greatly enhance the confidence of the comrades.

"Okay, okay!" Chai Gong happily wrote it down in his notebook. Although this was only his first specific task, he felt that he had learned much more than this task!
"Well, then, the scattering problem is solved, right? It's very simple, right?"

Listening to Gao Zhendong's words, Chai Gong felt that there seemed to be some truth in them, but he always felt that something was wrong.

It's so simple!

If it weren't for your detailed analysis and guidance, I would still be confused now.

Well, you may think it's simple, but I refuse to admit it.

But he could only say this in his heart, so he had to hold back his anger and continue studying.

"Mr. Gao, this is the case with scattering, but what about absorption?"

"It is well known that absorption bands in solids are caused by the natural vibration frequencies of molecules and electrons, while in glass they are mainly caused by impurity ions."

I do not know……

The wood worker wanted to complain, but he held it back.

It doesn’t matter if you don’t know. Now that you know, you can go back and find some relevant materials to study carefully, otherwise you will not be able to keep up with Chief Engineer Gao’s thinking at all.

But Gao Zhendong's next sentence returned to his professional scope.

"You should be familiar with which impurity ions in high-quality inorganic glass cause the most severe absorption, right?"

I don’t understand the theory, but I know the phenomenon. It’s so interesting to ask Chief Engineer Gao questions. Although the theory may be difficult to understand at the moment, when it comes back to the phenomenon, he can always find a point of entry from his own work.

"Iron! Iron ions! Including divalent iron and trivalent iron!"

(End of this chapter)