Fiber Optical Cabling Types and Considerations

In our blog “Unveiling the Power of Fiber Optical Cabling” we explored the basics of fiber optics, the difference between fiber optic and copper cables and looked at the different criteria to consider when implementing fiber optics. Here we’ll take a deeper look at the different types of fiber optic cables along with the different types of connectors, terminations and jackets. Understanding these different cable types and features, alongside factors such as cost and performance, is critical to selecting the most suitable cabling solution to use in different applications.

Types of Fiber Optic Cables

First of all, let’s take a look at some terminology that you will come across when selecting fiber optical cables for different scenarios.

Singlemode versus multimode, including the types of fiber optical cables
Simplex versus duplex

Singlemode versus Multimode

Singlemode and multimode are two types of optical fibers. As a general rule, singlemode fiber is suited to long distance transmission of data, while multimode is commonly used for shorter distance communications. Choosing between them will therefore depend on your application, required distance, data rates as well as compatibility with your existing infrastructure and budget. The key difference between singlemode and multimode fiber is their core size, which affects the way that light is propagated through them. Singlemode fiber has a smaller core and light is transmitted through a single wavelength of light, which lends it to transmission over long distances at high data rates, whereas multimode fiber has a larger core which can accommodate multiple wavelengths of light that are able to transmit effectively at lower data rates over short distance.

	Singlemode Fiber	Multimode Fiber
Fiber Cable Types	Optical Singlemode: OS1, OS2	Optical Multimode: OM1, OM2, OM3, OM4, OM5
Core Diameter	9 µm	50 to 62.5 µm
Propagation of Light	Singlemode of light.Supports wavelengths, such as 1310nm, 1490nm, 1550nm as well as Wavelength Division Multiplexing.	Multiple wavelengths. The larger fiber core suits multimode fiber to short wavelengths, such as 850nm and 1300nm.
Transmission Distance	Suited to long distances up to 180km due to less attenuation and mode dispersion. However, distance is determined by factors such as speed, selected wavelength, attenuation and dispersion.	Shorter distances, up to 550m. Distance is determined by speed, selected wavelength, attenuation and dispersion.
Attenuation	Minimal dispersion and attenuation. For example, maximum attenuation for OS2: 0.5 dB/km at 1310 nm 0.5 dB/km at 1550 nm	Higher levels of dispersion and attenuation. For example, maximum attenuation for OM1: 3.5 dB/km at 850 nm 1.5 dB/km at 1300 nm

Standard fiber optic cables are categorized into different types which show whether they are Optical Singlemode (OS1, OS2 for example) or Optical Multimode (OM1, OM2, OM3, OM4, OM5). The table below shows the differences between the cables and the bandwidths and distances that they can support.

Singlemode Fiber Cables:

Fiber Cable Type	Bandwidth	Transmission Distance	Attenuation	Wavelengths	Jacket
OS1	Max 10G	Max 10km	1dB/km	1310 nm, 1550 nm	Thick, tightly buffered. Suitable for shorter distance than OS2, indoor applications
OS2	Max 100G	Max 200km	0.4 dB/km	1310 nm, 1383 nm, 1550 nm Supports CWDM and DWDM.	Loose tubes, can be stretched and suitable for long distance, indoor and outdoor applications. Yellow color.

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Multimode Fiber Cables:

Fiber Cable Type	Laser	Bandwidth	Transmission Distance	Wavelengths	Jacket Color
OM1, OM2	LED	Up to 10G	Up to 300 metres (OM1), 600 meters (OM2)	Optimized for 850 nm and 1310nm	Orange
OM3	VCSEL	10G, 40G, 100G Modal Bandwidth: 2000 MHz-km	Up to 300 metres (10G), 100 metres (40G), 70 metres (100G)	Optimized for 850 nm	Aqua
OM4	VCSEL	10G, 40G, 100G Modal Bandwidth: 4700 MHz-km	Up to 550 metres (10G), 150 metres (40G, 100G)	Optimized for 850 nm	Aqua/Violet
OM5	VCSEL	40G, 100G, 200G, 400G	up to 550 metres (10G), 150 metres (40G, 100G)	Optimized between 850 nm and 953 nm. Supports SWDM Technology	Lime Green

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Simplex versus Duplex Fiber Optic Cables

Singlemode and multimode fiber cables are both also available in simplex and duplex formats. Simplex fiber cables consist of a single strand of fiber, which can either be used for data transmission in one direction over a single wavelength or set up for bidirectional transmission using wavelength division multiplexing. Duplex fiber optic cables have two fiber strands supporting simultaneous communication in two directions. Whether to choose simplex or duplex depends on transmission requirements, the network architecture, compatibility of networking equipment and the protocols being used.

Protocol	Simplex	Duplex	Application
Ethernet	X	X	LANs and WANs. Both simplex and duplex fiber optical cables can be used depending on the network topology, transmission distance and data rate requirements.
Fiber Channel		X	Used in high-speed storage area networks (SAN) to connect servers to storage arrays and other storage devices.
SONET/SDH		X	These protocols are designed for transmitting large volumes of data over optical fiber networks at high speed.
FDDI		X	Commonly used in LANs for high speed data transmission, FDDI networks use duplex for transmitting between network nodes and switches.
InfiniBand		X	A high speed interconnect technology used in high-performance computing (HPC) environments and datacenters between servers, storage systems and other network devices.
Parallel Optics		X	Parallel optics is a technology utilized in high speed data center networks to aggregate multiple data streams into multiple parallel fiber channels for high-bandwidth transmission between network switches and servers.

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Fiber Optic Cable Connectors and Terminations

Fiber Optic Cable Connector Types:

There are a range of connectors used with fiber optic cables. The most common termination types are ST (Straight Tip), SC (Subscriber Connector), LC (Lucent Connector), MPO/MTP (Multi-Fiber Push-on/Pull-off), as well as the latests CS Connectors which have been designed for 200G and 400G applications. Detailed descriptions of the connectors are provided in the table below, and we will be covering more about MPO/MTP cables and other pre-assembled solutions in our next blog.

Polishing – APC and UPC Connectors:

The connector type, for example “LC” is usually followed by the designations APC or UPC, e.g. LC/APC or LC/UPC. APC stands for Angled Physical Contact and UPC stands for Ultra Physical Contact. These refer to the polish type.

UPC connectors are designed with a flat (non-angled) polish on the fiber end face which improves the physical contact and are commonly used in data systems as they provide a good compromise between reduced optical return loss (of -50dB or higher) and affordability.

APC connectors are designed with an 8-degree angled polish on the fiber end face to minimize any back reflections with better optical return loss than other connectors (-60dB or higher), and are used with higher optical wavelength ranges (above 1500 nm) in applications where real-time audio and video need to work flawlessly.

The easiest way of telling APC and UPC connectors apart is their colour. APC are green and UPC are blue.

Fiberoptisk kabel med SC/APC- och LC/UPC-anslutningar >

Connector Type	Features	Application
ST (Straight Tip)	Bayonet style connector with straight, cylindrical ferrule. Ferrule Diameter: 2.5 mm	Used in older networking equipment and legacy installations.	OM3 Fiber Patch Cord Duplex LC to ST connectors
SC (Subscriber Connector)	Push-pull coupling mechanism. Known for low insertion loss and high precision alignment. Ferrule Diameter: 2.5 mm	Data communications, Telecommunications networks, FTTH.	OS2 Fiber Patch Cord. Duplex. SC to SC connectors
LC (Lucent Connector)	Small form-factor connectors with push-pull connector similar to SC connectors. Excellent performance. Suitable for singlemode and multimode fibers. Ferrule Diameter: 1.25 mm	High-density installations in data centers, enterprise networks or where space is limited.	OM5 Fiber Patch Cord. Duplex. LC to LC connectors
CS Connectors (High Density Fiber Connector)	A 40% horizonal size reduction over LC duplex. Compatible with QDD and OSFP transceivers.	Next generation connector for 200G and 400G.	CS Connector. Duplex.

Connectors For Tight Areas – Short Boot versus Standard Boot Fiber Optic Cables

The length of the connector itself can have an impact on where the cable can be used. The boot length is the connector, plus the cable strain relief which gives additional protection. Long boot connectors are typically used in applications where additional strain relief and protection is need to help prevent damage from bending, pulling or twisting, and are often used in outdoors, in harsh environments or where they are handled frequently.

Short boot fiber optical cables are designed to minimize the overall footprint of the connector and are ideal for installations where space is limited or where connects are closely spaced. Short boot connectors are used in high-density environments such as data centers, in patch panels and equipment racks, and are available for LC, SC and MPO/MTP connector types.

The standard length of an LC connector, for example, is 49.5 mm, whereas short boot options are available at 33mm.

Fiber Optical Cable Jackets

Materials – Fiber optical cable jackets are made in a range of materials suitable for different environments. Low cost, fire resistant PVC (polyvinychloride) is generally used, but for confined spaces thermoplastic is used in more expensive LSZH (Low Smoke Zero Halogen) jackets, which produces little smoke or toxic fumes when burning. PE (Polyethylene) is used in outdoor applications where cables need to be resistant to moisture and UV and can be subject to a wide range of temperatures.

Colors – Jackets also come in a range of colors which designate the cable type, and are listed in our table on fiber optical cable types above as they relate to the OS and OM types.

Bend radius and bend-insensitive cable options.

Tight bends in fiber optical cables can cause micro cracks in the glass fibers as well as signal attenuation losses and potential performance issues.

Bend radius – The optical minimum bend radius is 10 times the outer jacket diameter of the cable. For example a cable with an outer jacket of 2mm in diameter can be bent up to 20 mm.

Bend-insensitive cables – For singlemode and multimode are designed and manufactured using special techniques to reduce the effect of bending to ensure signal integrity is maintained. For example in FTTx installations or any space where tight bends and flexibility is needed in the data center.

Choosing the Right Fiber Optic Cable

There are a range of considerations to make when selecting a fiber optic cable for your installation. Understanding what distance and attenuation you have and what network speed you require is a good basis for choosing cabling and optics. For example, if you require a large amount of data to be transferred over a relatively short distance of less than 300 meters, then multimode fiber might be an option, whereas if longer distance is the key requirement, then singlemode fiber might be more suitable. Added to that there is selection of the right type of connector based on your existing or new network environment and cable jacket depending on the environment where the cabling will be placed.

Selecting fiber optical cabling can be complex, so if in doubt, give our experts a call >