Basic introduction to optical fiber
The tiny optical fiber is encapsulated in a plastic sheath so that it can be bent without breaking. Generally, the transmitting device at one end of the optical fiber uses a light emitting diode (LED) or a laser beam to transmit light pulses to the optical fiber, and the receiving device at the other end of the optical fiber uses a photosensitive element to detect the pulses.
In daily life, since the transmission loss of light in optical fibers is much lower than that of electricity in wires, optical fibers are used for long-distance information transmission.
Usually the two terms optical fiber and optical cable are confused. Most optical fibers must be covered by several layers of protective structures before use, and the covered cables are called optical cables. The protective layer and insulating layer on the outer layer of the optical fiber can prevent damage to the optical fiber from the surrounding environment, such as water, fire, and electric shock.
Optical cables are divided into: cable sheath, aramid yarn, buffer layer and optical fiber. Optical fiber is similar to coaxial cable, except that there is no mesh shield. In the center is the glass core through which light propagates.
In a multimode fiber, the core diameter is 50 μm and 62.5 μm, which are roughly equivalent to the thickness of a human hair. The diameter of the single-mode fiber core is 8μm~10μm, and 9/125μm is commonly used. The core is surrounded by a glass envelope with a lower refractive index than the core, commonly known as a cladding, which keeps light in the core. On the outside is a thin plastic jacket, or coating, to protect the cladding. Optical fibers are usually bundled and protected by a casing. The fiber core is usually a double-layer concentric cylinder with a small cross-sectional area made of quartz glass. It is brittle and easy to break, so an additional protective layer is required.
Note: 9/125μm means that the core of the fiber is 9μm and the cladding is 125μm. 9/125μm is an important feature of single-mode fiber. 50/125μm means that the core of the fiber is 50μm, and the cladding is 125μm, 50/125μm. It is an important feature of multimode fiber.
Among them, the BRICS optical cable plan is a submarine optical cable project that directly connects the five BRICS countries. Construction will start in early 2014 and be commissioned in mid-2015. The total length of the project is 34,000 kilometers, of which the submarine optical cable that directly connects the five BRIC countries is about 24,000 kilometers long.
In 2013, global 100G fiber revenue is expected to exceed US$1 billion for the first time. The company analyzed the financial results of the global optical network market in the first quarter of 2013 and found some trends, including a disappointing trend, that the overall growth of the market is still difficult, and only Japan's Fuji company profits year by year.
Although it is not uncommon for the optical fiber market to experience a recession in the first quarter, this decline is worrying because this is the fifth consecutive quarter that the market has declined, and quarterly revenue has reached the lowest value in six years.
The situation of 100G optical fiber is more optimistic, and it has shown strong growth regardless of the month-on-month and year-on-year. In the first quarter of 2013, 100G fiber shipments increased by 41% compared to the fourth quarter of 2012, and revenue increased by 24% compared to the fourth quarter of 2012. Based on this calculation, annual revenue is expected to exceed $1 billion for the first time. In the first quarter of 2013, 20 suppliers sold 100G optical fiber, and more manufacturers will join the market competition. Suppliers are cautiously optimistic, short-term orders are bullish, and long-term orders are not optimistic.