966, a Chinese scientist working for Standard Telecom Experimental Co., Ltd. in British Standard Telecom Experimental Co., Ltd., jointly published a paper entitled "Optical Frequency Dielectric Fiber Surface Waveguide" .
Paper title
In the paper, they clearly proposed that as long as the purity problem of glass fiber is solved (reduced impurities), the attenuation of the optical signal in glass fiber can be reduced.
When the attenuation rate drops to 20 db/km, this fiberglass can be used for practical communication.
Kao
, which is doing experiments, was later regarded as the foundational work of optical fiber communication theory. It opened the door to the fiber optic era and changed the direction of human communication technology.
Now we all know that this paper is of great significance. But in fact, the paper was not recognized by the industry at the beginning of its release.
At that time, no one believed Kao’s conclusion. Everyone believes that the "glass without impurities" envisioned by Kao does not exist.
In order to prove his theory, Kao visited glass factories around the world and tried to seek cooperation.
However, these factories rejected Kao. They do not intend to conduct in-depth research because such research is "meaningless and expensive".
At the end of 1966, things ushered in a turning point.
An engineer named William Shaver (William Shaver) visited the Post Office Research Laboratory in London, UK and saw the fiber optic communication project introduced by the laboratory and became very interested.
The company served by William Schaeffers is not an ordinary company, but the oldest glass manufacturing company in the United States - Corning Company (Corning Glass Works).
Corning Company was founded in 1851.
It is said that they made the glass bulbs that Edison invented in the electric lamp.
After returning to the United States, William Schafer reported his experience to the company's senior management and strongly recommended that the company conduct fiber research.
William Schafer's suggestion has received attention from senior management of Corning. Soon, they started the research and development of high-purity glass fiber in a low-key manner.
The person who led this work is Corning's R&D director - Bill Armistead (Bill Armistead).
Bill Amstead
He found company physicist Robert Maurer and assigned him two newly-employed young researchers (chemist Peter Schultz , experimental physicist Donald Keck ), thus forming a three-person research team.
From left: Donald Keck Robert Maurer Pete Schultz
As the leader of the group, Robert Maurer is a legendary figure.
Robert Maurier
He was born in 1924. He participated in World War II when he was young and won the Purple Heart Medal . After the war, he returned to university to study, obtained a doctorate in cryogenic physics from MIT , and joined Corning (1952).
It is worth mentioning that in December 1956, he published a theoretical paper about "glass is frozen liquid" in the Journal of Chemical Physics. It was once cited by Kao's classic paper, which was regarded as the earliest intersection between the two. After the
-person group officially launched the research, I found that I was facing a huge challenge.
At that time, the glass fiber with the highest purity had an attenuation rate of about 1000 dB/km. To reduce this value to 20 dB/km, it is not a 50-fold relationship, but an amazing 10-to-power coefficient relationship.
Zaojun Note: dB=10*lg(A/B), represents the ratio of two numbers (A and B). When A is twice as good as B, it is 3dB.When A is 10,000 times that of B, it is 40dB. When A is 1 million times B, it is 60dB.
For them, there are two possible starting solutions: first, use a large number of high-purity optical glass. Second, melt quartz (SiO2, silica ), because quartz can achieve high purity.
The first type is a relatively mature solution, and it was also the solution chosen by most colleagues at that time. However, Robert Maurel took a unique approach and chose the second option.
Afterwards he recalled: "If you do something different from what other people do, you have two advantages. One, you may succeed where they fail. Two, if you fail, you will collect information that they did not collect."
Silica is a very purity material. However, its melting temperature is extremely high and requires 1650°C. Ordinary ovens cannot reach such temperature at all.
After some investigation, Robert Maurel asked Dr. chemistry Frank Zimar (Frank Zimar) for help.
Frank Zima once built an oven for Corning's early semiconductor projects, which could achieve high temperatures of 2000°C.
With the help of Frank Zima, in 1967, Robert Maurel's group pulled out the first experimental single-mode fiber based on titanium-doped silica. After testing, the attenuation of this fiber is still high, but it has been greatly improved compared to before. This strengthens the research team's confidence.
Later, after repeated attempts, the research team gradually mastered the drawing skills of optical fiber prefabricated rods and key technologies such as soot deposit treatment. The optical fibers they manufactured have continuously improved their attenuation rate indicators and gradually approached the theoretical value. The research progress of the
-person group has been strictly kept confidential by Corning. Until May 11, 1970, Corning applied for two patents based on the achievements it has achieved.
The first patent is Robert Maurel and Pete Schultz's "Fused Quartz Optical Waveguide" for optical fibers with pure quartz cladding and doped quartz cores.
The second patent is Donald Keck and Pete Schultz's "Method for the Production of Optical Waveguide Fibers", covering the well-known internal vapor deposition (IVD) process.
On July 22, 1970, the research team pulled out 6 optical fibers from 6 titanium-doped preform rods of different components.
htmlOn 7th, they tested these fibers. When testing a 29-meter-long fiber, they got an amazing attenuation result - 17 dB/km. This is the first time ever to reach the paper goal of 20 dB/km.
Donald Keck excitedly recorded this number in his notebook and wrote the words "Whoopee (haha means, expressing excitement)!".
9 meters of fiber is shorter, which may affect the accuracy of the test results. In order to be more rigorous, on August 21, they pulled out another 210-meter optical fiber and tested it.
When Donald Keck's helium-neon laser entered the fiber core, he was surprised to see a very bright red flash. He realized that this was a Fresnel reflection from the far end of the fiber. At this time, he recorded the test results of the fiber attenuation rate - 16.9 dB/km.
Finally, they can breathe a sigh of relief. The world's first low-loss experimental optical fiber that conforms to the theory was officially born.
Research team and their finished fiber products (lower left corner)
At the end of September 11970, Robert Maurel flew to London and announced the research results of his team at the "Waveguide Trunk Communication" conference hosted by the British Society of Electrical Engineers, which caused a sensation in the entire industry.
Later, the UK Post Office Laboratory and Standard Telecom Laboratory tested their fibers specifically to verify their results.
Corning's optical fiber was successfully developed and was not launched commercially. Because their optical fiber uses titanium-doped , there are still some technical defects.
Two years later, in June 1972, Corning replaced the titanium-doped core with germanium-doped fiber core , and used external vapor deposition (OVD) to create an multi-mode fiber with a loss as low as 4 dB/km.
This optical fiber not only has lower attenuation, but also has stronger practicality and a simpler manufacturing process.
Pete Schultz (1972) who was using the OVD method to make germanium-doped fiber prefabricated rods
Later, due to the economic recession, Corning's development encountered some problems, which affected their commercial promotion of fiber optic technology.
In order to raise funds, with the support of Corning Chairman and CEO Amory Houghton, Corning's optical fiber business head Chuck Lucy (Chuck Lucy), signed a joint development agreement to share development costs.
These protocols accelerate the commercial implementation of fiber optic technology. In 1976, the United States AT&T company installed the world's first experimental fiber optic communication system in Atlanta , with a length of about 1.25 miles (about 2,000 meters).
years later, in 1979, Japan Telecommunications Company (NTTh) developed an extremely low loss quartz fiber of 0.2 dB/km. This attenuation value is basically close to the theoretical limit of scattering.
980, Lake Placid Winter Olympics used fiber optic cables to transmit TV signals for the first time, and it was a huge success.
The story later should be familiar to everyone.
htmlIn the 180s and 1990s, fiber optic technology rose rapidly and became an important transmission medium in wired communication. Entering the 21st century, optical fiber has completely replaced metal cables and become the backbone base of the entire communication network. The amount of data that a single optical fiber can transmit has long exceeded the TB/s level.
Today, the global annual demand for optical cables exceeds 500 million core kilometers. These optical fibers transmit massive data, support the development of the entire society, and make great contributions to the progress of mankind's civilization.
