Category: Fiber Transceivers

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Fiber-to-the-home (FTTH) fiber optic cabling is generally divided into the trunk part, distribution part, the introduction part, and access part from the base station to the user.

If the fiber link from the base station to the user passes through only one fiber cable segment (not counting the jump optical fiber), that is, each user has a direct cable to the board,What is the problem?

There are two main problems here. (1) The number of fiber optic cables connected to the base station is large, and the number of incoming fiber optic cables that can be tolerated by one base station is limited; (2) The distance for laying the fiber optical cable during installation is long, which is not convenient for installation. Limited by the above two aspects, such a base station can only allow dozens of users to access, and of course, there is no application set.

In order to solve the above problems, we made 2 improvements

(1) The fiber optical cable is out of the way with a large-core fiber optical cable, and then the fiber cable splice closure is divided into a plurality of small-core optical cables. It should be noted that if a fiber optic cable has too many branch points, it will affect the life and transmission indicators of the cable.

(2) Set the fiber distribution box at the location where the user is concentrated, as the branch point between the project and the loading. When the user puts the device, it is only necessary to put a small cable from the fiber distribution box to the user.

It is estimated that there are 10 fiber optical cables in one office, 6 to 12 fiber distribution boxes in each optical cable, and 8 users in each fiber distribution box. The number of service users in one office is 480 to 960. At this point, the fiber optic cable line from the office to the user has become two cable segments: Base station – distribution box, distribution box- user. Since the connection relationship of the optical fiber is fixed at the optical cable splice closure, and the attenuation is small, the cable splice closure is generally not used as the starting point of the segment.

Compared with Figure 1, the number of service users in the office in Figure 2 has increased several times, but the capacity is still too small. In addition, the user’s development is dynamic. If a location needs to add a fiber distribution box, it needs to be re-laying fiber cables from the base station.

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As can be seen from the comparison of Fig. 3 and Fig. 2, from the perspective of reducing the number of outgoing optical cables and facilitating the loading, the capacity of the lifting station can be realized by adding branch points on the optical cable. There are two types of fiber optic cable branch points: fiber cable distribution box and fiber optical splice closure.

Through the optical cable distribution, one optical cable can be divided into multiple optical cables, and the number of different branches can be mainly limited by the laying conditions of the optical cable; the connection relationship between the optical cables is flexible. But it will increase the loss of active connections and make core management more difficult.

The number of cables that can be branched through the fiber spice closure is small, generally no more than 6 (1 into 5). There are generally cables left on both sides of the fiber splice box. If there are more cables in a splice closure box, the cable will appear messy and unsightly. Therefore, in general, the number of fiber splice closure to divergent fiber cables will be controlled within 4 (1 into 3).

By adding a fiber cable distribution box as fig. 5 shows, the number of service users in a distribution box is 480 to 960, and the number of service users in one transfer box is 8 to 12, and 6 to 12 fiber feeders are placed in each of the fiber-optic cables.

So how many fiber cable branches can a base station set? With 10 optical cables out of one base station and 3 optical connections per optical cable, 30 optical connections can be set. In this way, the capacity of a base station is about 14400-28800; such a large capacity can basically meet the needs of a large number of field.

The construction of the project will be limited by the construction conditions. For example, if the fiber optical cable network is to cover a residential area, the optical communication is preferably set in the residential area. However, when constructing a backbone optical cable base station, most of the residential properties will not be allowed to be constructed in their communities. When the market department and a certain community negotiated the conditions for engineering construction, the backbone optical cable project has already been completed.

The demand for engineering construction in residential areas, commercial buildings, and other cluster markets in the city are uncertain, and the construction of trunk optical cables must be completed within a certain period of time (generally within 2 to 3 months). In order to solve this contradiction, in the construction of the backbone optical cable, the trunk ONU is placed in a location close to the potential user group, convenient for the cable to be laid, and the installation conditions.

When there are construction conditions in residential quarters, commercial buildings, and other cluster markets, installing distribution ONU and wiring fiber cables from trunk ONU to distribution ONU as shown in Figure 6. Thus, the optical cable line from the base station to the user is divided into the following: the trunk section, the wiring section, the lead-in section, and the home section.

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The advantage of optical cable is the necessary condition for the realization and development of optical cable transmission. Relative to the copper wire rate of 1.54MHZ per second, the operating speed of the fiber optic cable network has reached 2.5GB per second. 

From the perspective of bandwidth, the great advantage is that the optical fiber has a large information capacity, which means that it is possible to use a small-sized electronic cable without having to update or enhance the signal in the fiber cable transmission.Fiber-optic cables have a large impedance to electromagnetic noise such as radios, motors, or other adjacent cables, making them immune to electrical noise. From a long-term maintenance perspective, the maintenance cost of the fiber optic cable will be very low. 

Optical fiber transmission has the advantages of small attenuation, frequency bandwidth, strong anti-interference, high safety performance, small size, and light weight, so it has unparalleled advantages in long-distance transmission and special environments. The transmission medium is an important factor that determines the transmission loss. It determines the distance required to relay the signal. Optical fiber as a transmission medium for optical signals has the characteristics of low loss. The frequency band of optical fiber can reach more than 1.0GHz. The bandwidth of general images is only 8MHz. The image of one channel is more than enough to transmit with a core optical fiber, and it is more advantageous in transmitting voice, control signals or contact signals. 

The carrier wave in optical fiber transmission is light wave, which is an electromagnetic wave with extremely high frequency, which is much higher than the frequency used in radio wave communication, so it is not interfered. Moreover, the glass material used in the optical fiber is non-conductive and does not generate sparks due to disconnection, lightning strikes, etc., so it has strong safety and is particularly suitable for flammable and explosive situations.

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The Relationship Between Optical Fiber and Optical Cable

In this world with developed networks, fiber optic cables are an inevitable trend to replace other communication tools. However, many people who are not in contact with the communications industry think that optical fibers and optical cables sound the same, and they will think that they are the same product. In fact, optical fibers are not equal to optical cables. Today, fiber-mart.com will introduce to you the relationship between optical fiber and optical cable, hoping to help friends who are not in contact with optical fiber and cable.

The optical fiber is made of pure silica (glass) by a special process to be drawn into a glass tube thinner than a hair with a medium in the middle, which can transmit a huge amount of information in a short time. The diameter of the fiber core originally produced is very small, and the current standard is only 0.125 mm. Optical fiber factories will cover the surface of the core with a resin protective coating with a diameter of 0.25 mm or 0.9 mm. Generally, the fiber with a diameter of 0.25 mm after the first coating, we usually call it a bare fiber. In some cases, the bare fiber will be re-coated according to the needs of the cable to make a relatively thick tight-buffered fiber with a diameter of 0.9 mm.

The characteristics of optical fiber are: fast transmission speed, long distance, large content, and it is not electromagnetic interference, not afraid of lightning, it is difficult to eavesdrop on the outside, it is not conductive, and there is no trouble of grounding between devices.

The current international standards divide optical fibers into two types: single-mode optical fibers and multi-mode optical fibers. Single-mode fiber can only transmit one mode of light. Because of its small inter-mode dispersion, single-mode fiber has a transmission distance of hundreds of kilometers and is suitable for long-distance communication. Most of the fiber optic cables that have been laid in networks that used single-mode fiber. Multi-mode fiber is mainly used in local area networks and is not suitable for long-distance transmission. The transmission distance of multi-mode fiber is relatively short, generally only 2 kilometers.

Due to the small diameter and easy break of the optical fiber, it cannot be directly used on the construction site. In order to allow the optical fiber to be used in various fields (expressways, airports, residential areas, mountains, sea lows, etc.), according to different construction sites, optical fiber companies make optical fibers into different types of optical cables. Usually can be divided into indoor fiber optic cable, outdoor fiber optic cable, direct buried fiber optic cable, photoelectric hybrid cable and so on. Optical cables are generally made of optical fiber, grease, aluminum tape, steel wire, aramid, glass yarn, high-strength yarn, PE, LSZH, FRP and other materials through precision machining to make optical cables.

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Nowadays, more and more people live in apartment buildings, dormitories and other multi-dwelling units (MDU), and with the increasing demand for high-bandwidth applications such as high-definition televisions, fiber to the home (FTTH) has become an irreversible trend, UnitekFiber will talk about how to lay a fiber to the home (FTTH) network in a multi-dwelling unit (MDU)?

The factors to be considered when laying fiber-to-the-home (FTTH) network in a multi-dwelling unit (MDU)

Before laying, we should first design a reasonable optical fiber network architecture for the multi-dwelling unit (MDU). The following factors should be considered when designing:

1. How old is a multi-dwelling unit (MDU)?

This factor is very important. If a multi-dwelling unit (MDU) is newly built, its structure is more suitable for modern network access, and it is easier to design a fiber-to-the-home (FTTH) network; if the multi-dwelling unit (MDU) already has in a certain age, its network access infrastructure may be outdated, and some are not even suitable for access to fiber optic networks. Then there will be many restrictions when laying fiber to the home (FTTH) network, and even consume a lot of manpower and material resources.

2. Types of multi-dwelling units (MDU)

The type of multi-dwelling unit (MDU) is another factor that needs to be considered, that is, different types of multi-dwelling units (MDU) are suitable for different fiber to the home (FTTH) structures. In general, there are three types of multi-dwelling units (MDU).The low-rise multi-dwelling unit (MDU) has 3 floors and a maximum of 12 households. The fiber access point is usually outside the building, which is suitable for each household to use a separate fiber.

The middle-level multi-dwelling unit (MDU) has a maximum of 10 floors, and the number of households is between 12 and 128. The fiber access point is set inside the building, and multiple users can share a fiber interface.

The high-rise multi-dwelling unit (MDU) usually exceeds 10 floors, and the number of households is more than 128. The network architecture of FTTx terminal business is usually distributed vertically, and the network wiring is spread over multiple floors and areas of the high-rise multi-dwelling unit (MDU) to ensure Every household can enjoy an efficient and reliable fiber-to-the-home (FTTH) network.

3. Types of Optical Network Terminal (ONT)

In a fiber to the home (FTTH) network, the type and location of the optical network terminal (ONT) play an important role in the maintenance and operation of the network. There are two types of optical network terminals (ONT): single-dwelling unit optical network terminals (ONT) and multi-dwelling unit optical network terminals (ONT); among them, single-dwelling unit optical network terminals (ONT) can be used in single-dwelling units and It can be used in multi-dwelling units, and multi-dwelling unit optical network terminals (ONT) are only used in multi-dwelling units.

In general, the cost of installing a single-dwelling unit optical network terminal (ONT) will be higher because the related equipment is exclusive to a single household. The multi-dwelling unit optical network terminal (ONT) is that the residents of a unit building share related equipment, but if the number of end users is large, since the end users are connected through copper cables and the optical network terminal (ONT), the number of copper cables required at this time is also Many, the cost will increase. In addition, we should also consider network speed and security. The broadband speed and security provided by single-unit optical network terminals (ONT) will undoubtedly be higher. The following are examples of installing two types of optical network terminals (ONT) in a mid-to-high-rise multi-dwelling unit (MDU).

High-rise multi-dwelling unit (MDU) fiber access solution

Due to the large number of residents in high-rise multi-dwelling units (MDU), a variety of optical fiber hardware equipment such as optical fiber cables, optical fiber distribution frames, and optical cable terminal boxes need to be used when laying fiber-to-the-premises (FTTP) networks. In order to better explain how to lay the optical fiber access network in the high-rise multi-dwelling unit (MDU), the following is an intuitive expression in the form of a legend.

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MTP/MPO fiber cables are widely used in data centers. In recent years, the demand for bandwidth of data center optical fiber transmission systems has shown a trend of high growth. Therefore, the use of a new generation of optical fibers and optic transceiver modules can continue to explore the potential of optical fiber network bandwidth growth. Because multi mode MTP/MPO fiber cable has great advantages in cost, there are absolute advantages in data center applications.

Driven by the continuous application and promotion of network media in the cloud computing environment, multi mode MTP/MPO fiber cable is also constantly developing. From OM1 to OM2, and from OM3 to OM4, the VCSEL laser optimization technology used, and bandwidth requirements continue to grow. The introduction of the new category OM4 multimode MTP/MPO fiber cable standard EIA/TIA492AAAD provides a better transmission method for the wide application of multi mode fiber in the future. This article will provide an ideal communication solution for your data center, server, network switch, telecommunication switching center and many other embedded application systems that require high-speed data transmission.

In 40G/100G data transmission applications, transmission port connection equipment, such as QSFP optical transceiver modules, will be directly connected through MTP/MPO fiber cable regardless of the fiber connections used by the fiber channel, and regardless of the type of fiber connection. Because the 40G/100G data transmission application device and the channel connection between the device need to form a special mode, so that the channel of the transmitting end and the receiving end of the device correspond to each other, which requires the MTP/MPO fiber cable to complete the connection.

MTP/MPO fiber cables can provide various applications for all networks and devices that require 100G modules. They adopt the MT series casing design of the high-density multimode fiber optic connector system industry. MTP/MPO fiber cables use UPC and APC polished end faces, and support both multi-mode and single-mode applications. With VCSEL laser and LED light source, 10G OM3/OM4 MTP/MPO fiber cables can provide 10Gbps data transmission rate in high bandwidth applications. They are 5 times faster than standard 50um fiber optic patch cords.

At the same time, multimode MTP/MPO fiber cables are also a more economical choice for most of the most common fiber optic communication systems. Single mode MPO/MTP fiber optic patch cords are mainly used in long-distance data transmission systems. MPO/MTP backbone fiber cables are specially designed for data center applications. Generally, single mode and multimode MTP/MPO fiber cables are designed as round cables with an outer diameter of 3mm or 4.5mm.At present, MPO/MTP high-density fiber cables are mainly used in three aspects: high-density cabling data centers, fiber to the home, and connection applications with optical splitters, 40G/100G QSFP+, SFP+ and other optical transceiver modules. Today, there are already a series of high-density parallel optical interconnection products that can adapt to the optical fiber transmission of modern data centers, such as custom MTP/MPO fiber cables, multi-mode fiber loop backs and QSFP+ high-speed cable.

The development of server virtualization and cloud computing, as well as the development trend of network integration, has brought about the development of faster and more efficient data center networks. At present, the 10G switch composed of 48 10G channels is mainly limited to use SFP+ transceiver modules to realize the connection. In order to meet higher bandwidth requirements, users can use high-density QSFP+ high-speed cables to complete the connection, and increase the data transmission rate of each channel and increase the port density to meet the customer’s high bandwidth requirements.

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Optical fiber jumper (also known as optical fiber patchcord) refers to the fact that both ends of the optical cable are equipped with fiber optical connectors, which are used to realize the connection of the optical path. Optical fiber jumper (Optical Fiber Patch Cord / Cable) is similar to coaxial cable, except that there is no mesh shield. At the center is a glass core for signal transmission. In multimode fiber, the diameter of the core is 50μm~65μm, which is roughly equivalent to the thickness of human hair. The diameter of single-mode fiber core is 8μm~10μm. The fiber core is surrounded by a glass envelope with a lower refractive index than the core to keep the optical fiber in the core. The Kevlar and outer jacket( LSZH or PVC) is used to protect fiber core.

The types of Fiber Optical Jumper

LC fiber jumper is developed by BELL (Bell) Research Institute. The connector is similar to SC and smaller than SC. The modular jack latch with convenient operation is adopted, and the size of the pin and the sleeve is 1.25mm, which is half of the size used by ordinary SC and FC. LC fiber patch cord connect to the SFP optical transceiver modules which commonly used in routers. To a certain extent, it can increase the density of fiber optic connectors in the fiber distribution frame.

SC optical fiber jumper is developed by Japan NTT. The structure and size of its pin and coupling sleeve are exactly the same as FC type. The fastening method of the plug lock, does not need to be rotated, and is often used as the connector of the GBIC optical transceiver module, which is often used on the router. It has the characteristics of low price and small fluctuation of access loss and commonly used for 100G BASE-FX connection.

FC fiber jumper was first developed by Japan NTT. FC is the abbreviation of English Ferrule Connector. The external protective sleeve is a metal sleeve, and the fastening method is a screw buckle. FC fiber jumper is generally installed in the ODF box. It has the advantages of strong fastening and anti-dust.

ST optical fiber jumper: the shell is round, the fastening method is screw buckle and the fiber core is exposed. The plug is fixed by a bayonet half a rotation after insertion. It is often used as a 10BASE-F connector and is mostly used in fiber distribution frames.

MPO (Multi-fiber Push On) fiber optic patchcord is one of the MT series patchcord. The two guide holes with a diameter of 0.7 mm on the left and right of the ferrule end face are accurately connected with the guide pin. MPO connectors and fiber optic cables can be processed to produce various forms of MPO patch cords.

The difference between single-mode and multi-mode fiber optic patchcord

The concept of single-mode and multi-mode is to classify optical fiber into multi-mode fiber and single-mode fiber according to the propagation mode. In the field of optical fiber data transmission, the term “mode” is used to describe the propagation mode of optical signals in the optical fiber glass core, that is, the mode is the propagation path of light. Therefore, in single-mode fiber, light travels along one path, in multimode fiber, light travels in multiple paths.

Transmission distance: The transmission distance of single-mode fiber is not less than 5km, which is generally used for remote communication. Multimode fiber can only reach about 2km, suitable for short-distance communication in buildings or campuses.

Light source: because the LED light source is more dispersed and can produce multiple modes of light. It is mostly used for multimode fiber. While the laser light source is close to a single mode, so it is usually used for single mode fiber.