Common optical fiber faults and their solutions
The thin optical fiber is encapsulated in a plastic sheath so that it can bend without breaking. Generally, the transmitting device at one end of the optical fiber transmits the optical pulse to the optical fiber using a light emitting diode (LED) or a laser beam, and the receiving device at the other end of the optical fiber detects the pulse using a photosensitive element.
In daily life, because the transmission loss of light in optical fiber is much lower than that of electricity in wire, optical fiber is used for long-distance information transmission.
Usually, the terms optical fiber and optical cable are confused. Most optical fibers must be covered by several layers of protective structures before use. The coated cable is called optical cable. The protective layer and insulating layer of the outer layer of the optical fiber can prevent the damage of the surrounding environment to the optical fiber, such as water, fire, electric shock, etc. Optical cables are divided into: cable skin, aramid fiber, buffer layer and optical fiber. Optical fiber is similar to coaxial cable, but there is no mesh shield. The center is the glass core of light propagation.

In multimode fiber, the diameter of the core is 50 μ M and 62.5 μ M two kinds, roughly equal to the thickness of human hair. The diameter of single-mode fiber core is 8 μ m~10 μ m. The common is 9 / 125 μ m。 The outside of the core is surrounded by a glass envelope with a lower refractive index than the core, commonly known as the cladding, which keeps the 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 an outer shell. The fiber core is usually a double-layer concentric cylinder made of quartz glass with a small cross-sectional area. It is brittle and easy to break, so it needs to add a protective layer.
Description: 9 / 125 μ M means that the core of the optical fiber is 9 μ m. Cladding 125 μ m，9/125 μ M is an important feature of single-mode fiber, 50 / 125 μ M means that the core of the optical fiber is 50 μ m. Cladding 125 μ m，50/125 μ M is an important characteristic of multimode fiber.
The BRICs optical cable plan is a submarine optical cable project directly connecting five BRICs countries, which will be started in early 2014 and put into use in mid-2015. The total length of the project is 34000 km, of which the submarine optical cable directly connecting the five BRICs countries is about 24000 km.
In 2013, the global revenue of 100g optical fiber 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 is, the overall growth of the market is still difficult, and only the profit of Fuji company in Japan increases year by year.
Although it is not uncommon for the optical fiber market to decline in the first quarter, this decline is worrying because it is the fifth consecutive quarter of decline in the market and quarterly revenue has reached the lowest level in six years.
The situation of 100g optical fiber is relatively optimistic, showing strong growth both month on month and year-on-year. In the first quarter of 2013, the shipment volume of 100g optical fiber increased by 41% compared with the fourth quarter of 2012, and the revenue increased by 24% compared with the fourth quarter of 2012. Based on this calculation, the 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.
Optical fiber is the abbreviation of optical fiber. It is a kind of fiber made of glass or plastic, which can be used as a light transmission tool. Optical fiber network is very useful in life. Once there is a fault, it will cause great trouble. How to eliminate the common faults and troubleshooting methods of optical fiber network become more and more important.
First, whether the indicator light of optical fiber transceiver or optical fiber module and twisted pair port indicator light are on
If the optical port (FX) indicator of the transceiver is not on, please determine whether the optical fiber link is cross linked; One end of the optical fiber jumper is connected in parallel; The other end is cross connection. If the optical port (FX) indicator of a transceiver is on and the optical port (FX) indicator of B transceiver is not on, the fault is at the end of a transceiver: one possibility is that the optical transmitting port of a transceiver (TX) is broken because the optical port (Rx) of B transceiver cannot receive optical signals; Another possibility is that there is a problem with the optical fiber link of the optical transmission port of a transceiver (TX) (the optical cable or optical jumper may be broken).
The twisted pair (TP) indicator light is not on. Please make sure whether the twisted pair connection is wrong or connected incorrectly. Please test with on-off tester; Some transceivers have two RJ45 ports: (to hub) indicates that the connection line connecting the switch is a through line; (to node) indicates that the connection line connecting the switch is a cross line; There is an MPR switch on the side of some generators: it indicates that the connecting line connecting the switch is a through line mode; DTE switch: the connection line connecting the switch is in the cross line mode.
Second, use optical power meter to detect
Luminous power of optical transceiver or optical module under normal conditions: multimode: - 10dB -- 18db; Single mode 20km: - 8dB -- 15dB; Single mode 60km: - 5dB -- 12dB; If the luminous power of the optical fiber transceiver is between: - 30dB -- 45dB, it can be judged that there is a problem with the transceiver.
Third, whether the half / full duplex mode is wrong
Some transceivers have FDX switches on the side: indicating full duplex; HDX switch: indicates half duplex.
Fourth, whether the optical cable and optical fiber jumper have been disconnected
a. Optical cable on-off detection: use laser flashlight, sunlight and illuminant to illuminate one end of the optical cable connector or coupler; Look at the other end for visible light? If there is visible light, it indicates that the optical cable is not broken.
b. Optical fiber connection on-off detection: use laser flashlight, sunlight, etc. to illuminate one end of the optical fiber jumper; Look at the other end for visible light? If there is visible light, it indicates that the optical fiber jumper is not broken.