Fiber patch cords, couplers, fiber optic terminal boxes, fiber optic cable splice boxes

1. Optical fiber jumper

Fiber Jumper

1. Introduction to fiber optic patch cords

Optical fiber jumpers (also known as optical fiber connectors) refer to the connector plugs installed on both ends of the optical cable to realize the active connection of the optical path; the plugs on one end are called pigtails. Fiber patch cords (Optical Fiber Patch Cord/Cable) are similar to coaxial cables, but without a mesh shield. At the center is the glass core where light travels. In a multimode fiber, the diameter of the core is 50 μm to 65 μm, which is roughly the thickness of a human hair. The diameter of the single-mode fiber core is 8 μm~10 μm. The core is surrounded by a glass envelope with a lower refractive index than the core to keep the fiber within the core. On the outside is a thin plastic jacket that protects the envelope.

2. Classification of optical fiber jumpers

Optical fiber jumpers can be divided into common silicon-based optical fiber single-mode and multi-mode jumpers according to different transmission media, and other optical fiber jumpers such as plastic as the transmission medium; according to the structure of the connector, it can be divided into: FC Jumper, SC jumper, ST jumper, LC jumper, MTRJ jumper, MPO jumper, MU jumper, SMA jumper, FDDI jumper, E2000 jumper, DIN4 jumper, D4 jumper, etc. form. The more common fiber jumpers can also be divided into FC-FC, FC-SC, FC-LC, FC-ST, SC-SC, SC-ST, etc.

Single-mode fiber (Single-mode Fiber): Generally, the fiber jumper is shown in yellow, and the connector and protective sleeve are in blue; the transmission distance is longer.

Multi-mode fiber (Multi-mode Fiber): Generally, the fiber patch cord is indicated in orange, and some are indicated in gray, and the connector and protective sleeve are in beige or black; the transmission distance is short.

3. Precautions for the use of optical fiber jumpers

The transceiver wavelengths of the optical modules at both ends of the fiber jumper must be the same, that is to say, the two ends of the optical fiber must be optical modules with the same wavelength. In general, short-wave optical modules use multimode fibers (orange fibers), and long-wave optical modules use single-mode fibers (yellow fibers) to ensure the accuracy of data transmission.

Do not bend and loop the optical fiber excessively during use, which will increase the attenuation of light during transmission.

After using the optical fiber jumper, it is necessary to protect the optical fiber connector with a protective sleeve. Dust and oil will damage the coupling of the optical fiber.

If the optical fiber connector is dirty, you can use a cotton swab dipped in alcohol to clean it, otherwise the communication quality will be affected.

1. Before use, the ceramic ferrule and the end face of the fiber jumper must be wiped clean with alcohol and absorbent cotton.

2. The minimum bending radius of the optical fiber is less than 30mm.

3. Protect the ferrule and the end face of the ferrule to prevent bumps and pollution, and put on a dust cap in time after disassembly.

4. Do not look directly at the fiber end face when the laser signal is transmitted.

5. The damaged fiber jumper should be replaced in time in the event of man-made and other force majeure damage.

6. Read the manual carefully before installation, and carry out installation and debugging under the guidance of the engineer of the manufacturer or dealer.

7. If the optical fiber network or system is abnormal, the troubleshooting method can be used to test one by one. When testing or troubleshooting the jumper, you can do the on-off test first. Usually, you can use a visible laser pointer to judge the entire fiber link. Or further use a precision optical fiber insertion loss and return loss instrument to test its various indicators. If the indicators are within the qualified range, the jumper indicates normal, otherwise it is unqualified.

4. Characteristics of fiber optic patch cords

1. Low insertion loss

2. Good repeatability

3. Large return loss

4. Good inter-plug performance

5. Good temperature stability

6. Strong tensile properties

5. Application of optical fiber jumper

Optical fiber jumper products are widely used in: communication room, fiber-to-the-home, local area network, optical fiber sensor, optical fiber communication system, optical fiber connection transmission equipment, national defense combat readiness, etc. It is suitable for cable television network, telecommunication network, computer optical fiber network and optical test equipment. The subdivision is mainly used in several aspects.

1. Optical fiber communication system

2. Optical fiber access network

3. Optical fiber data transmission

4. Optical fiber CATV

5. Local Area Network (LAN)

6. Test equipment

7. Fiber Optic Sensors

6. Selection of fiber jumpers

There are three main types of fiber jumpers according to the termination type: ST-ST, SC-SC, ST-SC. According to the type of fiber, there are mainly two types of single-mode fiber and multi-mode fiber. The specifications of the jumper length are 0.5m, 1m, 2m, 3m, 5m, 10m and so on. According to the cable outer sheath material, it can be divided into ordinary type, ordinary flame-retardant type, low-smoke halogen-free type (LZSH), low-smoke halogen-free flame-retardant type, etc.

According to the fire rating of the building and the fire resistance requirements of the materials, corresponding measures should be taken for the integrated wiring system. When laying cables or optical cables in flammable areas and building shafts, flame-retardant cables and optical cables should be used; in large public places, flame-retardant, low-smoke, low-toxic cables or optical cables should be used; adjacent equipment or transfer rooms Flame retardant wiring equipment should be used.

7. The difference between fiber jumpers and fiber pigtails

Fiber patch cords are used to make patch cords from equipment to fiber optic cabling links. There is a thicker protective layer, which is generally used for the connection between the optical transceiver and the terminal box.

Pigtail, also known as pigtail, has only one end with a connector, and the other end is a broken end of a fiber optic cable core. It is connected to other fiber optic cable cores by welding. It often appears in fiber optic terminal boxes. (couplers, jumpers, etc. are also used between them).

Optical fiber connector is a device for detachable (active) connection between optical fiber and optical fiber. It precisely connects the two end faces of optical fiber, so that the light energy output by the transmitting fiber can be coupled to the receiving fiber to the maximum extent. And minimize the impact on the system due to its involvement in the optical link, which is the basic requirement of fiber optic connectors. To a certain extent, fiber optic connectors also affect the reliability and performance of optical transmission systems.

Grinding method

"/" indicates the cross-section process of the optical fiber connector, that is, the grinding method.

"PC" is most widely used in telecom operators' equipment, and its connector section is flat.

"SC" indicates that the pigtail connector model is SC connector. The optical interface on the side of transmission equipment in the industry generally uses the SC connector. The SC connector is made of engineering plastic, which has the advantages of high temperature resistance and is not easy to be oxidized; the optical interface on the ODF side generally uses the FC connector. It is a metal connector, but ODF will not have high temperature problems. At the same time, the number of pluggable and unpluggable metal connectors is more than that of plastic, and the maintenance of ODF pigtails is more than that of optical board pigtails. Other common connector types are: ST, DIN, FDDI.

"PC" represents the fiber optic connector cross-section process, and PC is the most common. The APC model is widely used in radio and television and early CATV. The pigtail head adopts an end face with an inclination angle (8 degrees), and the inclination is generally invisible, which can improve the quality of the TV signal. The main reason is that the TV signal is an analog light modulation. When the coupling surface of the connector is vertical, the reflected light is Return to the original path. Due to the uneven distribution of the refractive index of the fiber, it will return to the coupling surface again. Although the energy is very small at this time, the noise cannot be completely eliminated by the analog signal, so it is equivalent to superimposing a weak signal with time delay on the original clear signal. The performance on the screen is ghosting. The inclination of the pigtail headband prevents the reflected light from returning along the original path. General Digital signals generally do not have this problem.

There is also a "UPC" process, which has a smaller attenuation than PC. Generally, the flanges of equipment with special needs are generally FC/UPC. Foreign manufacturers' ODF racks use FC/UPC to improve the index of the ODF equipment itself.

8. How to check whether the fiber jumper is qualified

Use an insertion and return loss tester. First, use a light-passing pen to test whether the jumper is clear to make sure that the fiber is not broken. Measured indicators General carrier-level indicators: insertion loss is less than 0.3dB, return loss is greater than 45dB.

The performance testing of optical fiber jumpers is divided into:

1. Optical performance testing, including return loss/insertion loss testing. The test instrument can use FibKey 7602 return loss/insertion loss integrated tester.

2. End face geometry test, the test parameters include curvature radius, vertex offset, fiber height, etc. The test instrument is an interferometer, and many people use NorlandAC/NC3000 or CC6000 for testing. Especially the CC6000 interferometer is used by more and more factories because of its superior cost performance.

3. Optical fiber end face scratch detection, use video optical fiber magnifier for observation, such as many factories use FibView FV-400PA for inspection. The instrument gives the clearest images and is extremely easy to operate. Some customers also use the FibKey-5600 variable magnification magnifier for testing. The instrument integrates 400x, 200x, and 80x magnifiers, which can clearly and conveniently observe the fiber end face and the ferrule end face. Of course, you can also use the relevant software to automatically check.

4. Optical fiber tensile test, it is necessary to test the tensile force that the optical fiber connector can withstand.

5. For the ambient temperature experiment, it is necessary to test the performance indicators of the optical fiber connector under different ambient temperature conditions.

There are also relatively few people using PoE for power supply. On the contrary, in some civilian and package markets, PoE applications are very common in small projects.

9. Optical fiber jumper interface - diagram

The common interface types of fiber jumpers are FC, SC, ST, PC, APC, and LC. Fiber jumpers with FC connectors are mostly used on patch panels, while fiber jumpers with SC connectors are mostly used on routers and switches. In addition, there are various forms of optical fiber interface types such as MTRJ, MPO, MU, SMA, FDDI, E2000, and D4.

The meanings of several common fiber jumper interface types are as follows:

FC round with thread, commonly used in optical transceivers and other equipment

ST snap-on round type Commonly used in terminal box equipment

SC snap-on type Commonly used in fiber optic transceivers

PC microsphere grinding and polishing

APC is at an 8-degree angle and is ground and polished with microspheres

product you want.

①FC type optical fiber jumper: The external strengthening method is a metal sleeve, and the fastening method is a turnbuckle. Generally used on the ODF side (the most used on the patch panel)

②SC type optical fiber jumper: the connector connecting the GBIC optical module, its shell is rectangular, and the fastening method is the plug-and-pull type, which does not need to be rotated. (Most used on router switches)

③ST-type optical fiber jumper: commonly used in optical fiber distribution frame, the outer shell is round, and the fastening method is turnbuckle. (For 10Base-F connections, the connectors are usually ST type. Often used in fiber optic distribution frames)

④LC-type fiber jumper: a connector for connecting SFP modules, it is made with a modular jack (RJ) latch mechanism that is easy to operate. (commonly used by routers)

⑤MT-RJ type optical fiber jumper: a square optical fiber connector with integrated transceiver, one dual-fiber transceiver integrated

ST, SC connector joints are often used in general networks. After the ST head is inserted, it is fixed with a bayonet in half a circle, but the disadvantage is that it is easy to break; the SC connector is directly inserted and unplugged, which is very convenient to use, but the disadvantage is that it is easy to fall out; It is reliable and dust-proof, but the disadvantage is that the installation time is slightly longer. MTRJ type fiber optic patch cord consists of two high-precision plastic molded connectors and fiber optic cables. The outer parts of the connector are precision plastic parts, including a push-pull plug-in clamping mechanism. Suitable for indoor applications in telecommunication and data network systems.

Optical fiber modules: generally support hot swap, the optical fiber interface used by GBIC is mostly SC or ST type; SFP, namely: small package GBIC, the optical fiber used is LC type.

2. Optical fiber coupler/flange

1. Introduction to fiber optic coupler/flange

Optical fiber coupler (Coupler), also known as splitter (Splitter), connector, adapter, flange, is a component used to realize optical signal splitting/combining, or used to extend optical fiber links, belonging to the field of optical passive components , in telecommunication network, cable television network, subscriber loop system, local area network will be applied.

Optical fiber couplers can be divided into standard couplers (belonging to waveguide type, double branch, unit 1×2, that is, the optical signal is divided into two powers), direct-connected couplers (connect two optical fibers of the same or different types of optical fiber interfaces, to Extended fiber link), star/tree coupler, and wavelength multiplexer (WDM, if the wavelength is high-density separation, that is, the wavelength spacing is narrow, it belongs to DWDM), and the production methods include sintering (Fuse), micro Optical (Micro Optics), optical waveguide (Wave Guide) three, and the sintering method of production accounts for the majority (about 90%). The production method of the sintering method is to melt and stretch the two optical fibers together, so that the cores are aggregated together to achieve optical coupling, and the most important production equipment is the optical fiber fusion splicer, which is also an important step. Some important steps can be manufactured by machine, but after sintering, people still need to work to inspect the packaging, so the labor cost accounts for about 10-15%. In addition, manual inspection and packaging must ensure the consistency of quality, which is also the reason for mass production. It must be overcome, but the technical difficulty is not as high as that of DWDM modules and optical active components. Therefore, most of the manufacturers who want to enter the optical fiber industry in the early stage will start with optical couplers, and the gross profit is 20-30%.

fiber optic coupler

2. Classification of fiber optic couplers

According to the difference of the coupled fibers, they are classified as follows:

SC fiber optic coupler: applied to SC fiber optic interface, it looks very similar to RJ-45 interface, but SC interface is flatter, the obvious difference is the contacts inside, if it is 8 thin copper contacts, then It is an RJ-45 interface, and if it is a copper column, it is an SC fiber interface.

LC fiber optic coupler: A connector used in LC fiber optic interfaces to connect SFP modules, it is made with a modular jack (RJ) latch mechanism that is easy to operate. (commonly used by routers)

FC fiber optic coupler: applied to FC fiber optic interface, the external strengthening method is a metal sleeve, and the fastening method is a turnbuckle. Generally used on the ODF side (the most used on the patch panel)

ST fiber optic coupler: used in ST fiber optic interface, commonly used in fiber optic distribution frame, the outer shell is round, and the fastening method is turnbuckle. (For 10Base-F connections, the connectors are usually ST type. Often used in fiber optic distribution frames)

3. Principle of fiber optic coupler

Optical fiber coupler is a device for detachable (active) connection between optical fiber and optical fiber. It precisely butts the two end faces of optical fiber, so that the light energy output from the transmitting fiber can be coupled to the receiving fiber to the maximum extent. And make it intervene in the optical link to minimize the impact on the system. For a waveguide fiber coupler, it is generally a component with a Y-shaped branch, and the optical signal input by a fiber can be equally divided by it. When the opening angle of the branch circuit of the coupler increases, the light leaking into the cladding will increase to increase the excess loss, so the opening angle is generally within 30°, so the length of the waveguide fiber coupler cannot be too short.

4. The role of fiber optic couplers

The optocoupler consists of two parts: a light source and a light receiver. The light-emitting source and the light-receiver are assembled in the same closed casing, and are isolated from each other by a transparent insulator. The pin of the light-emitting source is the input end, and the pin of the light receiver is the output end.