Understanding Single-mode Fibre Optic Patch Cord

Background Introduction

    Optical fibre is a fine and flexible medium for transmitting light beams. In the process of high-speed network development, optical fibre is widely used in the field of fibre optic communication by virtue of its fast transmission rate and large transmission capacity. Fibre patch cords, also known as fibre optic connectors, are used to achieve the emitting, transmitting and receiving of optical signals, and are one of the most widely used transmission media in optical transmission. The centre of a fibre optic patch cord is the fibre optic core made of quartz glass, surrounded by a layer of Kevlar as a protective film from damage, and then the outside is a plastic outer jacket to strengthen the insulating properties. According to the different forms of optical wave transmission in the fibre, fibre optic patch cords can be divided into single-mode fibre and multi-mode fibre.

Structural Characteristics of Single-mode Fibre

    Single-mode fibre is generally represented in yellow, with blue connectors and protective sleeves. Compared with multi-mode fibre, there is a smaller core diameter of 8μm to 10μm in single-mode fibre, which prevents the waste of optical energy.

Advantages of Single-mode Fibre

    ①Longer transmission distance: Single-mode fibre can support data transmission over longer distances because of their lower attenuation. For example, multi-mode fibre generally has a maximum transmission distance of several hundred meters, while single-mode fibre can reach more than 100km.

    ②Higher bandwidth capacity: Single-mode fibre can provide higher bandwidth than multi-mode fibre, enabling high-speed data transmission.

    ③No inter-mode dispersion: Single-mode fibre only transmits one mode of light, so there is no inter-mode dispersion, effectively avoiding optical energy loss in the connector.

    ④Higher transmission rate: due to the absence of inter-mode dispersion, mode noise and some other effects, single-mode fibre optic patch cords are resistant to interference and can transmit signals at a higher rate and with more stable quality.

Disadvantages of Single-mode Fibre

    ①Coupling is more difficult: Because the core diameter of single-mode fibre is smaller, it is more difficult to couple light into single-mode fibre than into multi-mode fibre.

    ②Higher cost of production: The light source is a laser beam, and an optical transceiver is needed, both of which are much more expensive hardware devices. Therefore the cost of using a single-mode fibre will be higher than that of a multi-mode fibre.

    ③More demanding technology: Manufacturing and handling single-mode fibre is more difficult than multi-mode fibre.

    ④High installation requirements: The requirements for the installation environment are relatively high. Once installed improperly, it will cause the interface does not meet the requirements, so special attention needs to be paid during installation.

Application of Single-mode Fibre

    We should take both the actual transmission distance and cost into consideration when choosing either single-mode fibre or multi-mode fibre . Single-mode fibre can only transmit a mode of light with inter-mode dispersion, suitable for long-distance communication. While multi-mode fibre can transmit multiple modes of light signal but with larger inter-mode dispersion. If the transmission distance does not exceed 550 meters, multi-mode fibre has the same performance as single mode fibre at a lower cost. For distances of several thousand metres or more, single-mode fibre is the best choice.