Fiber Optic Cables | Technology Overview
In the realm of computer networks, connections between various devices are predominantly established using two types of network cables. Copper-based network patch cables are primarily utilized for shorter connections, extending up to 328 feet (100 meters). These cables facilitate connections between computers and network switches or routers, link wireless access points to the network, or establish an uplink from one network switch to another. However, for connections exceeding 100 meters, a different type of cable is required: the optical-fiber cable.
This guide discusses the fundamentals of fiber optic patch cables, also known as fiber optic jumper cables.
Key Advantages of Optical-Fiber cabling over copper RJ45 Ethernet cables
Higher Bandwidth and Speed: Fiber optic cables offer significantly higher bandwidth compared to copper cables, allowing for faster data transmission rates. This makes them ideal for high-speed internet connections, large-scale data transfer, and applications requiring high bandwidth.
Longer Distance: Fiber optic cables can transmit data over much longer distances without signal degradation. While copper cables are effective over short distances (up to 100 meters), fiber optics can maintain signal integrity over many kilometers, making them suitable for long-distance communication and large network infrastructures.
Immunity to Electromagnetic Interference: Fiber optic cables are immune to electromagnetic interference (EMI) and radio-frequency interference (RFI) because they transmit data as light rather than electrical signals. This makes them more reliable in environments with high interference and ensures a more stable and secure connection.
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Common Fiber Connector Types
| Connector Type | Description | Common Use | Popularity | Insertion Loss | Durability | Common Devices |
|---|---|---|---|---|---|---|
| LC | Lucent Connector, small form factor, push-pull connection | High-density applications, data centers | Very High | Low | High | SFP Transceivers, Switches |
| MTP®/MPO | Multi-fiber Termination Push-on, high-density, multi-fiber connector | Data centers, high-performance networks | Very High | Low | High | High-density switches, patch panels, transceivers |
| SC | Subscriber Connector, larger form factor, push-pull connection | General networking, telecommunications | High | Low | High | Fiber Media Converters, Switches |
| ST | Straight Tip, cylindrical with bayonet lock | Field installations, network patches | Moderate | Moderate | Moderate | Fiber Media Converters, Switches |
| MTRJ | Mechanical Transfer Registered Jack, small form factor, duplex connection | High-density, compact applications | Low | Low | High | Switches, routers, transceivers |
| FC | Ferrule Connector, threaded connection, typically metal | Telecommunications, measurement equipment | Low | Low | Very High | Fiber optic instruments, telecommunications equipment |
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Common Fiber Jacket Colors
Official fiber optica jacket colors are defined and approved by the Telecommunications Industry Association / Electronic Industries Alliance, or TIA/EIA for short.
Fiber optic jumper cables come in a variety of jacket colors, and each color serves an important purpose in helping users easily identify and organize their network infrastructure. The color of the jacket helps to distinguish between different types of fiber. For example, single-mode fibers typically have yellow jackets, while multimode fibers often have orange or aqua jackets.
| Jacket Color (Non-military Applications) | Fiber Type | Common Use | Wavelength (nm) | Connector Types |
|---|---|---|---|---|
| Yellow | Single-mode | Long-distance telecommunications, high-speed networks | 1310/1550 | LC, SC, ST, MTP |
| Orange | Multi-mode (OM1/OM2) | Short-distance data and audio/video applications | 850/1300 | LC, SC, ST, MTP |
| Aqua | Multi-mode (OM3/OM4) | High-speed data networks, data centers | 850 | LC, SC, ST, MTP |
| Erika Violet | Multi-mode (OM4) | Ultra high-speed data centers, SAN | 850 | LC, SC, ST, MTP |
| Lime Green | Multi-mode (OM5) | Next-generation data centers, extended reach | 850/953 | LC, SC, ST, MTP |
Why are there two colors for OM4 colors, and who is Erica?
OM4 cables were initially introduced introduced with aqua jackets, similar to OM3 cables. That EIA/TIA thought that was a good idea, because OM4 is merely an enhancement of OM3, with better performance characteristics.
As far as bad ideas go, this one was pretty high on the list.
Technicians and network installers rely on color coding to quickly identify the standard of an existing cable run. Having different colors for different fiber standards is therefore of vital importance. Over time, as OM4 became more widely adopted, the need to clearly differentiate it from OM3 grew. Erica Violet (also known as Heather Violet in the UK) was introduced as a distinct color to help quickly identify OM4 cables in environments where both OM3 and OM4 might be present. This differentiation helps avoid confusion and ensures that the correct cable is used for the required application.
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Fiber Optic Cable Types
Fiber optic networks use different types of cables, each designed to meet specific performance requirements. Here’s a detailed comparison of OM1, OM2, OM3, OM4, OM5, and OS2 fiber optic cables:
| Type | Core Diameter (µm) | Jacket Color | Bandwidth | Max Distance (10 Gigabit Ethernet) | Max Distance (40/100 Gigabit Ethernet) | Common Applications |
|---|---|---|---|---|---|---|
| OM1 | 62.5 | Orange | 200 MHz·km at 850 nm | Up to 33 meters | - | Short-distance, lower-speed networks like small offices |
| OM2 | 50 | Orange | 500 MHz·km at 850 nm | Up to 82 meters | - | Medium-distance, higher-speed networks, such as office buildings and small data centers |
| OM3 | 50 | Aqua | 2000 MHz·km at 850 nm | Up to 300 meters | Up to 100 meters | Higher-speed networks in data centers and enterprise environments |
| OM4 | 50 | Aqua or Erica Violet | 4700 MHz·km at 850 nm | Up to 550 meters | Up to 150 meters | Very high-speed networks with greater distance support |
| OM5 | 50 | Lime Green | Supports WBMMF, optimized for WDM over 850-950 nm | Up to 550 meters | Up to 150 meters | Advanced data centers with future-proofing for WDM technologies |
| OS2 | 9 | Yellow | Unlimited theoretical bandwidth | Up to 40 kilometers | Up to 10 kilometers | Long-distance telecommunications and high-speed data networks |
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Common Wavelengths in Fiber Optic Network Transmissions
Common wavelengths used to transmit data over fiber optic cables are essential for understanding how different types of fiber operate. Here are the most commonly used wavelengths (NM = Nanometers):
- 850 nm
Usage: Primarily used in multimode fiber (OM1, OM2, OM3, OM4, OM5).
Applications: Short-range communication, typically within buildings or campus environments. - 1310 nm
Usage: Used in both singlemode and multimode fibers.
Applications: Medium-range communication, often used for metropolitan area networks and some long-range applications. - 1550 nm
Usage: Primarily used in singlemode fiber (OS2).
Applications: Long-range communication, including long-haul telecommunication networks and undersea cables. - 1625 nm
Usage: Used in singlemode fibers for certain specialized applications.
Applications: Long-range and high-capacity networks, often used in dense wavelength division multiplexing (DWDM) systems.
| Wavelength (nm) | Fiber Type | Common Applications |
|---|---|---|
| 850 | Multimode (OM1-OM5) | Short-range, intra-building or campus communication |
| 1310 | Singlemode, Multimode | Medium-range, metropolitan networks, some long-range |
| 1550 | Singlemode (OS2) | Long-range, long-haul telecommunication, undersea cables |
| 1625 | Singlemode | Specialized long-range, high-capacity networks (DWDM) |
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Polishing Styles: Difference between PC, UPC and APC connectors
PC, UPC, and APC refer to different types of connector end-face finishes. These are often referred to as "PC Polish", "UPC Polish" and "APC Polish".
The polish type directly defines the quality of the fiber optic transmission, which is expressed by the terms "optical return loss" and "optical insertion loss".
PC (Physical Contact)
The PC finish involves slightly curving the fiber end-face, which brings the fiber cores into more direct contact. This reduces the air gap between fibers and minimizes back reflections.Applications: PC connectors are commonly used in general networking applications where low back reflection is acceptable but not critical, such as in most data communications OM1 and OM2 multimode fiber networks and telecommunications systems.
UPC (Ultra Physical Contact)
The UPC finish outperforms the PC finish, with a more precisely polished and slightly curved end-face, resulting in even lower back reflection and insertion loss.Applications: Found in OS2 singlemode fiber cables, UPC connectors are commonly used in digital, CATV, and telephony systems that require high performance. They are also widely used in data centers and high-speed networks.
APC (Angled Physical Contact)
Usage: The APC finish uses an 8-degree angled end-face, which significantly reduces back reflection by directing it into the cladding of the fiber rather than back into the core. This is the highest performing type of connector in terms of back reflection.Applications: APC connectors are essential in applications where very low back reflection is crucial, such as in RF and analog fiber optic systems, including FTTx (Fiber to the x), PON (Passive Optical Networks), and high-precision optical measurement systems.
| Connector Type | Description | Optical Return Loss (dB) | Optical Insertion Loss (dB) |
|---|---|---|---|
| PC (Physical Contact) | Slightly curved fiber end-face, reducing air gap and minimizing back reflections | -30 to -40 | ≤ 0.3 |
| UPC (Ultra Physical Contact) | More precisely polished, slightly more curved end-face for lower back reflection | -50 to -55 | ≤ 0.2 |
| APC (Angled Physical Contact) | 8-degree angled end-face significantly reduces back reflection | -60 to -65 | ≤ 0.2 |
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