To understand the types of optical fibers, optical cables, jumpers, connectors, and adapters, you first need to know the relationship between these products.

Optical fiber
The optical fiber is drawn from silica glass through a complicated process, it is a highly transparent glass filament, which is also called optical fiber.

Optical fiber type
Optical fiber is divided into single mode fiber and multimode fiber according to the transmission mode. Light enters the optical fiber at a specific angle of incidence, and full emission occurs between the optical fiber and the cladding. When the diameter is small, only one direction of light is allowed to pass through, which is a single-mode optical fiber; when the diameter of the optical fiber is large, light can be allowed to inject and propagate at multiple angles of incidence, that is a multimode fiber.

Single mode optical fiber
Normally, there are two types of optical fiber: single mode and multi mode. Single-mode fiber is a single glass fiber strand used to transmit a single mode or ray of light. Single mode fiber with a relatively narrow diameter, through which all signals travel straight down the middle without bouncing off the edges. Single-mode fiber features only one transmission mode. Single Mode Fiber with a relatively narrow diameter of 8.5 to 9.5μm, through which only one mode will propagate typically 1310 or 1550nm.

Multimode optical fiber
Multi mode fiber is an optical fiber that allows multiple guided modes to be transmitted. Multi-mode fiber has a larger diameter core, typically 50 or 62.5μm. This larger core allows multiple modes of light to propagate. The standard wavelengths of the multimode are 850 nm and 1300 nm. Multimode fiber is available in four classifications: OM1 (62.5/125 µm), OM2, OM3, OM4 (50/125 µm). There’s also a new multimode fiber standard known as WBMMF (wideband multimode fiber) which uses the wavelengths between 850nm and 953nm.

Both single mode fiber and multimode fiber have a cladding diameter of 125μm.

G652，G657 fiber
According to the ITU standard, there are seven kinds of fibers: G651, G652, G653, G654, G655, G656, G657, and G652 and G657 are commonly used.

G652 fiber is the most widely used fiber in the metropolitan area network. It is a standard single-mode fiber with a zero-point dispersion of 1300nm. G652 fiber is subdivided into four types: G652A, G652B, G652C and G652D. The main difference lies in PMD. Among them, G652D is more commonly used. Because of its low fiber dispersion at 1300nm operating wavelength, the transmission distance of the system is only limited by loss.

G657 is a bending loss-insensitive fiber, and it is the most commonly used fiber optic cable for FTTH because of its better performance. But G657 fiber is more expensive than G652D.

G651 is a multi-mode optical fiber, mainly used in multi-tenant, residential buildings, and enterprise networks in FTTH networks. Its bending radius is half that of G652 fiber. It is suitable for indoor and FTTH cabling.

OS1, OS2, OM1, OM2, OM3, OM4, OM5
OS1 and OS2 are both single-mode optical fibers. OS1: the ordinary single-mode optical fiber used earlier; OS2: the ordinary optical fiber in use now, the low-water peak optical fiber. In general, OM1 is conventional 62.5/125μm; OM2 is conventional 50/125μm; OM3 is 850nm laser-optimized 50μm core multimode fiber, and in 10Gb/s Ethernet with 850nm VCSEL, the fiber transmission distance can reach 300m; OM4 is an upgraded version of OM3. OM4 multimode fiber optimizes the differential mode delay (DMD) generated by OM3 multimode fiber during high-speed transmission. Therefore, the transmission distance is greatly improved, and the fiber transmission distance can reach 550m; OM5 is a new standard for fiber patch cords defined by TIA and IEC with a fiber diameter of 50/125μm. Compared to OM3 and OM4 fiber patch cords, OM5 fiber patch cords can be used for higher bandwidth applications. The bandwidth and maximum distance are different for different levels of transmission.

Optical cable
The optical fiber is drawn from pure quartz with a special process into a glass tube thinner than a hair with a few mediums in the middle. Its texture is brittle and fragile, so an additional protective layer is needed. The outer layer of the optical fiber is combined with a plastic protective tube and a plastic sheath to form an optical cable.

Optical cables include fibers. Broadly speaking, optical fibers are optical cables, which are all transmission media. But they are also difference. The difference between optical fiber and optical cable: optical fiber is a thin and soft medium that transmits light beams. Most optical fibers must be covered by several layers of protective structures before use, and the covered cables including fibers are called optical cables. Therefore, the optical fiber is the core part of the optical cable, and the optical fiber forms the optical cable through the protection of some components and the auxiliary protective layer.

The type of fiber optic cable
There are many classification methods to categorize fiber optic cables, such as:
Classified by material: LSZH, PVC, HYTREL 7246, HYTREL 7237, PE, TPU
According to the outer diameter: φ0.9, φ2.0, φ3.0……
Divided by mode field: single mode (9/125), multimode (50/125, 62.5/125)
Divided by color: single mode is yellow, multimode is orange (OM1/OM2), OM3 is aqua blue, OM4 is aqua blue or violet, OM5 is lime green.
According to the structure, it can be divided into: generally simplex or duplex, duplex in single-tube, mini multicore, branch cable
Optical fiber brands: Corning, YOFC, Fujikura, Sumitomo, OFS, etc.

Type of patch cord
The 0.9, 2.0, and 3.0 of the optical fiber jumper are used to distinguish the outer diameter of the optical cable. 0.9 means the outer diameter of the optical cable is 0.9mm, 2.0 means the outer diameter of the optical cable is 2mm, and 3.0 means the outer diameter of the optical cable is 3mm.

There are also single-mode fiber jumpers and multi-mode fiber jumpers. Single mode is indicated by yellow, and the transmission distance is longer; multimode is indicated by orange, and the transmission distance is shorter.

Pigtail
Only one end of the pigtail has a connector, and the other end is a broken end of an optical cable core, which is connected to other optical cable cores through fusion splicing. It often appears in the optical fiber terminal box and is used to connect the optical cable to the optical transceiver.

Type of connector
Divided by the connection mode: FC, SC, ST, MU, LC, MT, E2000, MTRJ
Divided by fiber end face: PC, UPC, APC, SPC
According to the number of cores of the optical cable, it can be divided into: single core, double core (with clip)
Commonly used connectors: FC/PC, SC/PC, SC/APC, LC/PC
According to the tail sleeve structure, it can be divided into: round tail sleeve, square tail sleeve, conventional tail sleeve, short tail sleeve

Why should the fiber end face be divided into PC,UPC,APC
There are many reasons to caused fiber loss caused during fiber connections, such as: different axis (single-mode fiber coaxiality is required to be less than 0.8μm), the end face is not perpendicular to the axis, the end face is not flat, the butt core diameter is not matched, and the splicing quality is poor.

In order to make the end faces of the two optical fibers better contact, the end faces of the ferrule of the fiber jumper are usually ground into different structures. Common grinding methods are mainly: PC, APC, UPC. PC/APC/UPC represents the front surface structure of the ceramic ferrule.

Different fiber end face finishes
PC (Physical Contact).The two end faces are polished to be slightly curved or microspherical, and the fiber core is at the highest point of the bending. This eliminates the air gap and forces the fibers into physical contact.

UPC (Ultra Physical Contact) is based on the PC to optimize the end face polishing and surface finish, the end face looks more dome-shaped. The end face of the UPC connector is not entirely flat, and there is a slight arc to achieve more accurate connecting.

APC (Angled Physical Contact). The end face of APC is usually polishing into an 8-degree angle. The 8° angled bevel makes the fiber end face tighter and reflects light through its beveled angle to the cladding instead of returning directly to the source, providing better connection performance.

The APC fiber optic connector is usually green. UPC/PC connectors are easily identified by their blue color on the connector boot.

Type of adapter
Optical fiber adapters are used to convert various optical fiber equipment and optical fiber connection methods. With the wide application of fiber optic adapters in fiber optic connections, there are various fiber optic adapters with different interfaces to choose from to adapt to different environmental installation requirements. Common types of adapters are: LC adapter, FC adapter, SC adapter, ST adapter, E2000 adapter, MTP / MPO adapter, etc.

HYC is a leading passive optical component OEM/ODM manufacturer, focusing on providing customers with efficient manufacturing, high-quality products and in-depth research and development. The main products are: fiber optic connectors (high-density optical connectors for data centers), WDM wavelength division multiplexers, PLC optical splitters, MEMS optical switches and other four core optical passive basic devices, which are widely used in fiber to the home , 4G/5G mobile communications, Internet data centers, national defense communications and other fields.
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