Li Jian didn't put all the credit on himself, Jiang Sicheng felt after hearing it, how could a freshman student know so much professional knowledge, this is materials science, chemistry and electronic engineering must be proficient.

"I'll go to the film, and I'll use the materials I tested today."

Without the interest of talking to Li Jian, Jiang Sicheng put all his attention on the quartz fiber again, Li Jian scratched his head, the outer layer of the optical fiber is mainly for protection, as for the use of light conduction to increase the refractive index, it is best to apply a layer of carbon, Jiang Sicheng definitely did not expect this at present.

"Mr. Jiang, carbon can be considered for the film."

"Huh?"

Jiang Sicheng didn't respond, but lowered his head with the quartz fiber and thought, Wei Gang, who had already finished the wire drawing work, hurriedly walked over and pulled Li Jian,

"What do you know, how to recommend to Teacher Jiang indiscriminately, this is Teacher Jiang has a good temper, if it were other teachers, they would have kicked you out a long time ago."

Wei Gang got the benefit of Li Jian, and he wanted to speak for Li Jian at this time, but seeing that Jiang Sicheng was not angry but fell into deep thought, he couldn't help but guess, could it be that Li Jian was right again this time, Mr. Jiang had encountered problems in the past, but he hadn't considered it like this.

"Carbon, carbon, what's your name? Talent, what a talent, I made so many materials, I didn't even think of carbon, okay, just use him. ”

Wei Gang hurriedly told Jiang Sicheng about Li Jian's name again, and said that he had told him Li Jian's name twice just now, but Mr. Jiang didn't remember it, and his brain didn't seem to pretend to be anything except things related to experiments.

I did an afternoon of experiments. It's already past the time to eat, and those classmates who are okay have already gone to eat. Waiting to come back in the evening for the light signal transduction test, Li Jian also wanted to leave. was kept by Jiang Sicheng and asked other classmates who ate to help him bring some food back.

Li Jian can only complain that he can't live because of his own sin, knowing that these technical nerves are not interested in eating or anything at all, and he is like that, but he still told him about carbon, if it is a good body, it will be okay to endure it like this, but his body is malnourished.

"Why didn't you integrate more medical books into the chip in the first place, no. Even if I integrate medical books, it only improves the theoretical foundation, and the real treatment and salvation depends on the doctor's own experience, even if I write a few medical books, I can't train a large number of qualified doctors. ”

When the classmates came back one after another after eating, Li Jian took the buns that Li Yuncong helped bring back, and watched Jiang Sicheng put his share aside, his movements were meticulous and slight, as if he had just fallen in love for the first time, and gently connected the light source to the light signal detector.

"Wei Gang, prepare for the record."

Jiang Sicheng found that his hands were shaking a little. When I verified the film I had been waiting for for half a year just now, I wasn't so nervous, how to test the quartz fiber made by my students, and I was nervous like this.

What are you afraid of? Fear of failure. Isn't it normal for students to fail in their first experiments?

Jiang Sicheng suddenly found that what he was afraid of was not failure. It's about how you should face this experiment if it succeeds. After working hard for half a lifetime to study optical information transmission technology, he was surpassed by his own students. And it was surpassed on the first day of participation, which is too shocking.

Is he his own student, doesn't count, this is the first day he came to the laboratory, he, he's here to be a master.

Jiang Sicheng's hand finally didn't press down, the light source didn't start, his gaze swept over Li Jian, and only he knew the complexity.

"Toot!"

After waiting for a long time and calming down his mood a little, Jiang Sicheng's hand finally didn't press down, but Li Jian walked to the side of the laser emitter, adjusted it and pressed the switch, the light information was transmitted, and the LCD screen that was tested also lit up.

The wait is long, especially for researchers who are anxious to know the results.

Only Li Jian was eating buns one bite at a time, he didn't know how complicated the mood of Taishan Beidou, who he once admired very much, was at the moment, and he didn't know how much psychological pressure he had caused to this future bull in the optical communication technology industry.

"Hmm!"

There was only a slight sound of machines running in the silent laboratory, and this surprised nasal sound made the entire laboratory look nervous, Jiang Sicheng looked at Wei Gang, who was recording data, and his eyes were full of questions.

"Mr. Jiang, this, this is unlikely, although the data has not been detected yet, but, but the light attenuation is actually zero! No, it's not zero, it's negative. ”

Wei Gang's face was full of surprise, he couldn't believe that his eyes and hands had already checked up and down the record book several times before he reminded him, yes, this is not logical.

Photoelectric electromagnetic waves, as long as they are propagated, will inevitably decay, how can it not only not be attenuated, but enhanced, which is contrary to common sense.

"Wait until the test is complete."

Jiang Sicheng's brain was spinning rapidly, and at this moment he didn't have time to think about whether Li Jian was a master or a student, why didn't it decay, why did it fill up the loss as if there was a relay in the middle after transmission, and even some surplus?

"When the positive trivalent erbium ion is excited by the light with a wavelength of 980 nm or 1480 nm to absorb the energy of the pumped light, it transitions from the ground state to the pump state of the higher energy level. Due to the short lifetime of the particles in the pump state, they quickly relax from the pump state to the metastable state in a non-radiative manner, and the particles have a long lifetime in this energy and gradually accumulate. When a 1550 nm signal light passes through, the metastable positive trivalent erbium ions transition to the ground state by stimulated radiation, which also emits light at a wavelength of 1550 nm. The light emitted during the jump from the high-energy state to the ground state complements the attenuation loss of the signal light, so that the signal light is amplified continuously with attenuation during the propagation of the fiber. ”

Li Jian gently explained to Jiang Sicheng, and the voice was like a flash of thunder, smashing into Jiang Sicheng's mind.

"The incorporation of erbium into an ordinary quartz fiber, coupled with a semiconductor laser with two wavelengths of 980 nm or 1480 nm, basically constitutes an amplifier that directly amplifies the 1550nm optical signal. Quartz optical fiber can transmit a variety of different wavelengths of light, but the optical attenuation rate is different, the light in the 1550nm band has the lowest attenuation rate (only 0.15 dB/km) when transmitted in quartz fiber, and the attenuation rate is almost the lower limit. Therefore, when optical fiber communication uses 1550nm wavelength light as signal light, the loss of light is minimal. Therefore, as long as the optical fiber is doped with erbium of tens to hundreds of ppm, it can play a role in compensating for the optical loss in the communication system. The erbium-doped fiber amplifier is like a "pumping station" of light, so that the optical signal can be transmitted without weakening from station to station. (To be continued......)