Basic knowledge of optical cable

1. The composition and classification of optical fiber
2. Optical fibers can be divided into silica optical fibers and plastic optical fibers according to their manufacturing materials. Silica optical fibers are commonly used optical fibers. Silica optical fibers are divided into single-mode optical fibers and multi-mode optical fibers according to their transmission modes. Plastic optical fibers are all made of plastic, and are usually used for multi-mode short-distance applications. They are still in their infancy and have not been used on a large scale.
3. The structure of silica optical fiber: silica optical fiber is composed of core, cladding and coating layer, and its structure is as shown in the figure:

The transmission of light in the optical fiber is carried out in the core. Because the refractive index of the cladding and the core silica is different, the light is totally reflected on the surface of the core and the cladding, so that the light is always transmitted in the core, while the plastic coating layer It plays the role of protecting the quartz fiber and increasing the strength of the fiber. Because the quartz is very brittle, it cannot be used in practice without plastic protection. Because of the structure of the fiber, the fiber is easy to break, but it has a certain tensile force.

3.

Classification of silica fiber

single mode fiber

G.652A (referred to as B1)

(referred to as B1)

G.652C()

()

G.655A optical fiber (B4) (for long-distance trunk lines)

Optical fiber (B4) (for long-distance trunk lines)

multimode fiber

50/125 (A1a referred to as A1)

125(A1b)

2. The structure of the optical cable
3. Outdoor optical cables mainly have three structures: central tube optical cable, layer stranded optical cable and skeleton optical cable. According to the use of optical fiber bundles and optical fiber ribbons, they can be divided into six types: ordinary optical cables and optical fiber ribbon cables. The structural characteristics of each optical cable:

① Central tube optical cable (executive standard: YD/T769-2003): The center of the optical cable is a loose tube, and the strengthening member is located around the loose tube. Small, usually below 12 cores.

② Stranded optical cable (executive standard: YD/T901-2001): the strengthening member is located in the center of the optical cable, and 5~12 loose tubes are stranded on the central core strength member in a twisted manner, usually SZ twisted combine. This type of optical cable, such as GYTS, etc., can obtain a larger number of optical cables through the combination of loose tubes. The color separation of stranded loose tubes usually uses red and green collars to distinguish colors, which is used to distinguish different loose tubes and different optical fibers. The number of cores of the layer-stranded optical cable can be relatively large. At present, the number of cores of the layer-stranded optical cable of our company can reach 216 cores or higher.

③ Skeleton optical cable: The strengthening member is located in the center of the optical cable, and there is a skeleton groove made of plastic on the strengthening member. The optical fiber or optical fiber ribbon is located in the skeleton groove. The optical fiber or optical fiber ribbon is not easy to be compressed, and the optical cable has good compression resistance. performance. This kind of structural optical cable is rare in China, and its proportion is small.

④ 8-shaped self-supporting structure, this kind of structure optical cable can be incorporated into the central tube type and layer stranding type optical cable, it is listed separately mainly because the structure of this optical cable is quite different from other optical cables. There are usually central tube type and layer twisted type 8 self-supporting optical cables.

5 Flame-retardant optical cable for coal mine (executive standard: Q/M01-2004 enterprise standard): Compared with ordinary optical The color of the sheath is blue to facilitate the identification of optical cables in mines. According to the structure, it can be divided into two types of structures: central tube optical cable and layer twisted optical cable.

2. Indoor optical cable

Indoor optical cables are classified according to the number of optical fiber cores, mainly including single-core, dual-core and multi-core optical cables. The indoor optical cable is mainly composed of tight-buffered optical fiber, spun fiber and PVC outer sheath. According to the type of fiber, it can be divided into two categories: single-mode and multi-mode. The color of the outer sheath of single-mode indoor cables is usually yellow, the color of the outer sheath of multi-mode indoor cables is usually orange, and the color of the outer sheath of some indoor cables is grey.

3. Naming method of optical cable model (YD/T908-2000)
4. The cable type consists of five parts
5. Indicates the type of optical cable

II.

GY——outdoor optical cable for communication

GJ——Indoor Optical Cable

MG——Optical cable for coal mine

Ⅱ. Reinforcement member type

(no model number) – metal reinforcement member

F——Non-metallic strengthening member

Ⅲ. Structural features

D——Fiber Ribbon Structure

(unsigned)——loose tube layer stranded structure

X——central tubular structure

G——skeleton structure

T – filled

Z——flame retardant structure

C8——8-shaped self-supporting structure

Ⅳ. Sheath

Y——polyethylene sheath

W——Steel-polyethylene bonded sheath with entrained steel wire

S—Steel-polyethylene bonded sheath

A——Aluminum-polyethylene bonded sheath

V——PVC sheath

Ⅴ. Outer sheath

53—Corrugated steel tape longitudinally wrapped armored polyethylene sheath

23—Wrapped Steel Tape Armored Polyethylene Sheath

33—fine steel wire wrapped armored polyethylene sheath

43—thick steel wire wrapped armored polyethylene sheath

333—Double-layer thin steel wire wrapped armored polyethylene sheath

2. Representation of optical cable specifications

The specification of the optical cable is expressed according to the number of optical fibers contained in the optical cable and the type of optical fiber.

Example: The cable specification of 4 single-mode optical fibers is expressed as or 4B1. If the same optical cable contains different types of optical fibers, they are connected with a ‘+’ sign in the middle of the specification.

If it contains 4 multimode 50/125 optical fibers, it is expressed as 4A1a or 4A1.

3. Description of commonly used models in our company

GYXTW——Metal strengthening member, central tube filling type, entrained steel wire, steel-polyethylene bonded sheath communication outdoor optical cable, suitable for pipeline and overhead laying.

GYXTW53——Metal strengthening member, central tube filling type, steel-polyethylene bonded sheath with steel wire entrained, longitudinally wrapped corrugated steel tape armored polyethylene sheath outdoor optical cable for communication, suitable for direct burial laying.

GYTA——Metal strengthening member, loose tube layer twisted filling type, aluminum-polyethylene bonded sheath communication outdoor optical cable, suitable for pipeline and overhead laying.

GYTS——Metal strengthening member, loose tube layer stranded filling type, steel-polyethylene bonded sheath communication outdoor optical cable, suitable for pipeline and overhead laying.

GYTY53——Metal strengthening member, loose tube layer stranding filling type, polyethylene sheath, longitudinally wrapped corrugated steel tape armor, polyethylene sheath outdoor optical fiber cable for communication, suitable for direct burial laying.

GYTA53——Metal strengthening member, loose tube layer stranded filling type, aluminum-polyethylene bonded sheath, longitudinally wrapped corrugated steel tape armor, polyethylene sheath outdoor optical cable for communication, suitable for direct burial laying.

GYTA33——Metal strengthening member, loose tube layer twisted filling type, aluminum-polyethylene bonded sheath, single thin round steel wire armor, polyethylene sheath outdoor optical cable for communication, suitable for direct burial and underwater laying.

GYFTY——Non-metallic strengthening member, loose-tube layer-twisted filling type, polyethylene sheath outdoor optical fiber cable for communication, suitable for pipeline and overhead laying, mainly used in occasions with strong electromagnetic hazards.

GYXTC8S——Metal reinforcement member, central tube filling type, 8-shaped self-supporting type, steel-polyethylene bonded sheath outdoor optical fiber cable for communication, suitable for self-supporting aerial laying.

GYTC8S——Metal reinforcement structure⑺Commercial impact SPAN >Twisted filling type, 8-shaped self-supporting type, steel-polyethylene bonded sheath outdoor optical fiber cable for communication, suitable for self-supporting aerial laying.

ADSS－PE——Non-metallic strengthening member, loose tube layer twisted filling type, circular self-supporting type, spun-strengthened polyethylene sheath outdoor optical fiber cable for communication, suitable for self-supporting overhead laying of high-voltage iron towers.

MGTJSV——Metal strengthening member, loose tube layer twisted filling type, steel polyethylene bonded sheath, PVC outer sheath flame-retardant communication optical cable for coal mines, suitable for laying underground in coal mines.

GJFJV——Non-metal strengthening member, tight-buffered optical fiber, PVC sheathed indoor communication optical cable, mainly used for laying in buildings and indoors or as optical cable jumpers.

Fourth, the use of optical cable and the main performance indicators

Application occasions of optical cables: In general, single-sheath optical cables are suitable for overhead and pipelines, while double-sheath optical cables are suitable for direct burial. Indoor optical cables are suitable for building and indoor use.

Main performance indicators of optical cable

① Attenuation: The attenuation index is an important index in the optical cable. The attenuation index is detected during the production process, and the problems existing in the production and process can be found.

Various types of fiber attenuation index requirements (A grade fiber):

(single mode): 1310nm≤km

1550nm≤km

B4 (single mode): 1550nm≤km

A1a (multimode 50/125): 850nm≤ km

1300nm≤km

A1b (multimode 125): 850nm≤km

1300nm≤km

② Other indicators of optical fiber

Single-mode fiber: mode field diameter, cut-off wavelength, dispersion, zero dispersion wavelength, zero dispersion slope, core-wrap concentricity error, cladding diameter, coating diameter, polarization mode dispersion coefficient (PMD), etc.

Multimode fiber: numerical aperture, bandwidth, core diameter, cladding diameter, cladding out-of-roundness, coating diameter, core-clad concentricity error, coating out-of-roundness, coating/cladding concentricity error, etc. .

③ Optical cable mechanical properties

Stretching, flattening, repeated bending, torsion, impact, etc.

④ Environmental performance of optical cable

Optical cable high and low temperature performance (-40°C~+60°C), water seepage performance, trickle performance.

⑤ other

Electrical conductivity of steel and aluminum strips, lap width of steel and aluminum strips, thickness of PE sheath, meter accuracy.

5. Optical cable process
6. The process flow of the main optical cable is as follows:
7. Optical fiber coloring process

The purpose of the coloring process production line is to color the optical fiber with bright, smooth, stable and reliable colors, so that the optical fiber can be easily identified during the production process of the optical cable and during the use of the optical cable. The main raw materials used in the coloring process are optical fibers and coloring inks. Coloring ink colors are divided into 12 types according to industry standards. Among them, the chromatographic arrangement according to the radio and television industry standards and the standards of the Ministry of Information Industry is different. The chromatographic arrangement of the radio and television standards is as follows: (White), red, yellow, green, gray, black, blue, orange, brown, purple, pink, turquoise, the industry standard chromatographic arrangement of the Ministry of Information Industry is as follows: blue, orange, green, brown, gray, original (white) , red, black, yellow, purple, pink, green. The use of natural colors instead of white is permitted provided that identification is not affected. The chromatographic arrangement adopted by our company is carried out according to the radio and television standard, and it can also be arranged according to the standard chromatographic arrangement of the Ministry of Information Industry at the request of users. When the user requires more than 12 fibers per tube, different colors can be used to distinguish the fibers according to different proportions.

The optical fiber should meet the requirements of the following aspects after coloring:

1. The color of the colored optical fiber does not migrate and does not fade (the same is true for wiping with methyl ethyl ketone or alcohol).
2. The optical fiber cable is neat and smooth, not messy or crimped.
3. The fiber attenuation index meets the requirements, and the OTDR test curve has no steps.

The equipment used in the optical fiber coloring process is an optical fiber coloring machine. The optical fiber coloring machine is composed of an optical fiber pay-off part, a coloring mold and an ink supply system, an ultraviolet curing furnace, a traction, an optical fiber take-up and an electrical control part. The main principle is that the UV-curable ink is coated on the surface of the optical fiber through a coloring mold, and then fixed on the surface of the optical fiber after being cured by an ultraviolet curing oven to form an optical fiber that is easy to separate colors. The ink used is UV curable ink.

3. Two sets of optical fiber technology

The secondary coating process of optical fiber is to select suitable polymer materials, adopt the method of extrusion, and under reasonable process conditions, put a suitable loose tube on the optical fiber, and at the same time, fill a chemical compound between the tube and the optical fiber. Long-term stable physical properties, suitable viscosity, excellent waterproof performance, good long-term protection performance for optical fibers, and fully compatible with the sleeve material Special ointment for optical fibers.

The second set of process is the key process in the optical cable process, and the main indicators of control are:

1. Optical fiber excess length control.
2. Outer diameter control of loose tube.
3. Wall thickness control of loose tube.
4. The fullness of the oil in the tube.
5. For the color separation beam tube, the color should be bright, consistent and easy to separate.

The equipment used in the optical fiber secondary coating process is the optical fiber secondary coating machine. It is composed of cooling water tank, drying device, on-line caliper, belt traction, wire storage device, double-disc take-up and electrical control system.

4. Cabling process

The cabling process, also known as the stranding process, is an important process in the manufacturing process of optical cables. The purpose of cabling is to increase the flexibility and bendability of the optical cable, improve the tensile capacity of the optical cable and improve the temperature characteristics of the optical cable, and at the same time produce optical cables with different numbers of cores by combining different numbers of loose tubes.

The process indicators mainly controlled by the cabling process are:

1. Cable pitch.
2. Yarn pitch, yarn tension.
3. Pay-off and take-up tension.

The equipment used in the cabling process is an optical cable cabling machine. The equipment consists of a reinforcing member pay-off device, a bundle tube pay-off device, an SZ twisting table, a front and back binding device, a double-wheel traction, a lead wire and an electrical control system.

5. Sheath process

According to the different laying conditions of the optical cable, different sheaths are added to the cable core to meet the mechanical protection of the optical fiber under different conditions. As a protective layer for optical cables against various special and complex environments, the optical cable sheath must have excellent mechanical properties, environmental resistance, and chemical corrosion resistance.

Mechanical performance means that the optical cable must be stretched, laterally pressed, impacted, twisted, repeatedly bent, and bent by various mechanical external forces during laying and use. The optical cable sheath must be able to withstand these external forces.

Environmental resistance means that the optical cable must be able to withstand the normal external radiation, temperature changes, and moisture erosion from the outside during its service life.

Chemical corrosion resistance refers to the ability of the optical cable sheath to withstand the corrosion of acid, alkali, oil, etc. in a special environment. For special properties such as flame retardancy, special plastic sheaths must be used to ensure performance.

The process indicators to be controlled by the sheath process are:

1. The gap between steel, aluminum strip and cable core is reasonable.
2. The overlapping width of steel and aluminum strips meets the requirements.
3. The thickness of the PE sheath meets the process requirements.
4. The printing is clear and complete, and the meter standard is accurate.
5. The receiving and arranging lines are neat and smooth.

The equipment used in the sheath process is an optical cable sheath extruder, which consists of a cable core pay-off device, a steel wire pay-off device, a steel (aluminum) longitudinal wrapping tape embossing device, an ointment filling device, and a feeding and drying device. device, 90 extrusion host, cooling water tank, belt traction, gantry take-up device and electrical control system.