The fundamental design of optical fibers is that the fiber is typically broken into 3 layers three layers: the core, the cladding layer, and the coating layer.

The fiber cladding and the core consist of glass that has different refractive indexes, with an index of the high refractive body (germanium-doped silica) in the middle and silica with a low refractive index in the glass layer (pure silica) in the middle. Light is directed into the fiber at a particular angle of incidence. Total emission occurs between the core and the cladding (since the refractive index of the cladding is less than that of the core), allowing it to travel throughout the fiber.

The primary purpose of cladding is to protect the fiber from external damages and also to improve the fibrous’s flexibility. As we said earlier, the cladding and the core are made from glass, a non-bending material that cannot be broken or bent, while the coating is utilized for safeguarding and prolonging the fiber’s lifespan. The exterior of the fiber that is not bare will include a layer of the outer sheath. In addition to serving as a shield, the various shades of the outer sheath may also be used to identify between different optical fibers.

Optical fiber is classified as Single-Mode Fiber and MulTI Mode Fiber based on transmission mode. Light is injected into the fiber at a certain angle of incidence. The total emission occurs in the space between the fiber and the outer cladding in the case of a small diameter and allows only one direction for light to pass through, i.e., single-mode fiber. When the diameter of the fiber is more significant, that allows light to be injected into different angles of incidence and propagation. Then it’s called multimode fiber.

The characteristics of optical fiber transmission

Optical fibers possess two primary transmission characteristics that are losses and dispersion. The loss of optical fibers is the amount of attenuation for each unit of length in decimal dB/km. The degree of loss to the fiber directly impacts the distance at which the fiber is transmitted by the fiber optic communication system or how far relay stations are. Fiber dispersion is the transmission of the thread. It is shared by various frequency components, mode components, frequency components, and modes that make up the transmission speed, which increases the distortion.

Fiber dispersion is classified into material dispersion, waveguide, and mode dispersion. The two first types of distribution result from signals that don’t have the same frequency. The third type can be caused by signals that do not exist in the single mode. Any movement that isn’t only a single mode can cause mode dispersion. Single-mode fibers only transmit in one fundamental way, which means there is only material dispersion and dispersion of the waveguide, which is not mode dispersion. Multimode fibers, on the other hand, feature intermodal dispersion. The distribution of fiber does not only impacts the transmission capacity of the thread. However, it also restricts the distance at which fiber relays are transmitted in fiber optic communication systems.

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What is the Single Mode Fiber (SM Fiber)?

Singlemode and Multimode Fiber

Single Mode Fiber: light entering the fiber is emitted at a certain angle of incidence. The total light emission occurs in the area between the fiber and the cladding in the case of a small diameter that allows the light to only pass into the fiber, i.e., single mode fiber. Single mode fibers have a thin glass core in the center, the diameter of the body is usually 8.5 or 9.5 millimeters, and operates at wavelengths between 1310 and 1550 nm.

What is the Multimode fiber (MM Fiber)?

MT-D1000 LC-LC multimode Simplex fiber optic patch cord

Multi-Mode Fiber is an optical fiber that permits multiple modes of transmission. The diameter of the core of multimode fibers is typically 50mm/62.5mm. Because of the massive central diameter in multimode fibers can accommodate different types of light transmission through one thread. The most common frequencies for the multimode fiber are 850nm and 1300nm, respectively. Additionally, a new multimode fiber technology called WBMMF (Wideband Multimode Fiber) uses wavelengths ranging from 850nm to 953nm.

Multimode fiber and Single-mode Fiber have a cladding diameter of around 125mm.

Transmission distance

A smaller single-mode fiber allows for better reflections and only one type of light to travel, enabling light signals to go further. The smaller number of light reflections when light passes through the core minimizes attenuation and results in further signal propagation. Since it has neither or extremely low inter-mode dispersion, single-mode fiber transmits for 40 kilometers or more without affecting the signal. Therefore, single-mode fiber is commonly employed for long-distance data transmission and is extensively used by telecom companies, cable companies, colleges, and universities.

Multimode fibers have more giant diameter cores and can transmit multiple types of light. When the multimode transmission is used, the intermodal dispersion gets more extensive because of the larger core size, meaning that light “spreads” more quickly. Quality of signal affected over long distances Multimode fiber is generally utilized for shorter distances, audio/video and Local Area Networks (LANs), and multimode fiber OM3/OM4/OM5 can be used to support high-speed data transmission.

MT-D1000 ST-ST multimode Duplex fiber optic patch cord

Bandwidth and Capacity

The term “bandwidth” refers to the capacity to transmit information. The most significant factor influencing the speed of optical fiber transmissions is dispersion among the various modes. Of these, modes dispersions are the most important. Single-mode fiber has a tiny distribution, which means it can transmit light for long distances over a wide range. Multimode fiber is a source of interference as well as interference and other complicated issues. Its bandwidth and capacity are less when compared to single-mode. The most recent generation in multimode fiber’s bandwidth OM5 is set at 28000 MHz per km, whereas the one-mode bandwidth of single-mode is higher.


If single mode fiber has more bandwidth and a longer transmission distance, why do we require multimode fiber? The cost could be the primary factor in this issue. Since the diameter of single mode fiber is small, it’s difficult to control the beam’s transmission. Therefore, it is necessary to use a laser as the light source. Since optical terminators are expensive, using single-mode fibers is more costly than multimode optic cables. This is why most data centers utilize multimode fiber to cut costs.

The type of fiber to utilize depends on the specific applications. HYC offers a variety and types of optical patch cords. HYC is a leading national high-tech company focused on R&D production, sales, and support of passive core components for visual communications. The main products offered by the company are fiber optic connectors (data center high-density optical connectors) and wavelength division multiplexers optical splitters, as well as other Three optical passive infrastructure components which are used extensively in fiber-to-the-home mobile communications, 4G/5G, Internet Data Centers, Defense Communications, and various other areas.