Fiber Optic Cable Distance: A Comprehensive Guide

Do you often receive questions like, “Where is the home fiber modem connected to the fiber?” or “What is the max distance of fiber optic cable?”

In this blog, I will discuss the fiber optic cable distance, the effect factors, how to choose the right fiber optic cables, and how to compare the transmission distances of single-mode and multimode fiber optic cables.

Let’s dive deeper together!

What Factors affect the fiber optic cable distance?

Many factors decide the fiber cable distance, but the key factors include the below six aspects.

#1. Attenuation

First is the attenuation of the optical fiber. Attenuation is the weakening of light as it comes in from the transmitting end of the fiber and out of the transmitting end. For some reason, some substance in the fiber blocks the transmission of the light signal inside the fiber.

Many factors cause attenuation in fiber optic cables: inherent loss, bending, impurities, refractive index, butt joints, and so on.

• Intrinsic loss: Rayleigh scattering, inherent absorption.
• Bending: The fiber is squeezed, and other reasons cause bending, which causes part of the light to be lost due to scattering, resulting in attenuation.
• Impurities: impurities within the fiber absorb and scatter the light propagating in the fiber.
• Refractive index: uneven refractive index of the fiber material causing loss.
• Docking: Losses occur when optical fibers are docked.

#2. Chromatic Dispersion

Dispersion of an optical fiber directly affects the bandwidth and distance capability of the fiber optic link and reduces its efficiency. The higher the dispersion, the lower the potential data rate and transmission distance.

Leading causes of optical fiber dispersion include the physical characteristics of the fiber (e.g., core diameter and refractive index), the wavelength of the propagating light, and the operating temperature. In multimode fibers, the different path lengths taken by the light can also contribute to dispersion.

#3. Optical Power

The more power coupled into the fiber, the longer the transmission distance. There are three main reasons for this:

• Firstly, the higher the power, the lower the loss of the optical signal as it travels through the fiber, allowing for longer distances.
• Secondly, the high input power increases the signal strength at the receiving end, and the signal-to-noise ratio increases under a relatively constant noise level, increasing the sensitivity at the receiving end and thus increasing the transmission distance.
• Finally, from a connector perspective, high optical power can allow more connectors to be used for the same receiver sensitivity, extending the transmission distance.

#4. Receiver Sensitivity

Higher receiver sensitivity means that it can detect weaker optical signals. Even if the optical signal power is low, the receiver can still detect and decode the signal correctly, extending the transmission distance of fiber optic communication.

Another consideration is that due to the lower received power, the optical signal can be transmitted longer distances in the fiber before it decays to the receiver’s minimum detection threshold.

#5. Bandwidth

Transmission distance decreases as the bandwidth increases. For example, a fiber optic cable with a distance of 1km supports a bandwidth of 500MHz, while a fiber optic cable with a distance of 2km can only support a bandwidth of 250MHz.

There are three main reasons for this:

• First, high-bandwidth signals are more susceptible to chromatic dispersion than low-bandwidth signals, so the transmission distance is shortened.
• Second, high-bandwidth optical signals are usually more lossy to the fiber.
• Finally, high-bandwidth signals contain a more comprehensive spectral range and are subject to more attenuation and absorption.

#6. Number of Splices and Connectors

Splices and connectors are inevitable in most fiber optic cable systems. When light passes through them, it inevitably causes loss.

How far is single mode fiber distance?

SMF, short for single-mode fiber, usually consists of a fiber core with a diameter of about 9 μm. Due to the small core, only one optical mode is allowed to be transmitted. This characteristic enables single-mode fibers to transmit signals over long distances with low mode dispersion (mode dispersion is the time delay caused by the propagation of light signals along different paths).

Single-mode fiber optic cables are more suitable for long-distance, high-speed transmission than multimode fiber optics. For most applications, the maximum distance of a single-mode cable is around 160 kilometers. However, the dispersion-compensating fibers can support more than 200 kilometers.

How far is the multimode fiber distance?

Unlike single-mode fiber optics (MMF), multimode fiber optics (MMF) allow transmitting and passing multiple light modes. Typically, these fibers consist of an oversized core with a diameter of about 50 μm or 62.5 μm.

In contrast to single mode, optical signals can be transmitted along different paths of the fiber, leading to the problem of mode dispersion. Therefore, multimode fibers are mainly used for short-distance signal transmission. The maximum distance that can be transmitted is not more than 2km for 100Mbps speed.

Single mode vs multimode fiber distance

Cable type	Fiber jacket color	Distance	Wavelength	Maximum attenuation	Minimum overfilled modal bandwidth length	Minimum effective modal bandwidth length
OM1 62.5-/125-micron multimode fibre	Orange	2000m (100Mbps) 275m (1Gbps 33m (10Gbps)	850-nm	3.5 dB/km	200 MHz-km	Not required
			1300-nm	1.5 dB/km	500 MHz-km	Not required
OM2 50-/125-micron multimode fibre	Orange	2000m (100Mbps) 550m(1Gbps) 82m (10Gbps)	850-nm	3.5 dB/km	500 MHz-km	Not required
			1300-nm	1.5 dB/km	500 MHz-km	Not required
OM3 50-/125-micron multimode fibre	Aqua	2000m (100Mbps) 550m (1Gbps) 300m (10Gbps) 100m (40Gbps) 100m(100Gbps) 100m(400Gbps)	850-nm	3.0 dB/km	1500 MHz-km	2000 MHz-km
			1300-nm	1.5 dB/km	500 MHz-km	Not required
OM4 50-/125-micron multimode fibre	Aqua	2000m (100Mbps) 550m (1Gbps) 400m (10Gbps) 150m (40Gbps) 150m (100Gbps) 100m((400Gbps)	850-nm	3.0 dB/km	3500 MHz-km	4700 MHz-km
			1300-nm	1.5 dB/km	500 MHz-km	Not required
OM5 50-/125- micron multimode fibre	Green	2000m (100Mbps) 550m (1Gbps) 400m (10Gbps) 300m (40Gbps) 300m (100Gbps) 100m(400Gbps) 100m (800Gbps)	850-nm	3.0 dB/km	3500 MHz-km	4700 MHz-km
			953-nm	2.3 dB/km	1850 MHz-km	2470 MHz-km
			1300-nm	1.5 dB/km	500 MHz-km	Not required
SINGLE-MODE FIBRE	Yellow	180km (100Mbps) 180km (1Gbps) 100km (10Gbps) 80km (40Gbps) 80km (100Gbps) 80km (400Gbps) 80km (800Gbps)	1310-nm	0.5 dB/km	N/A	N/A
			1383-nm	0.5 dB/km	N/A	N/A
			1550-nm	0.5 dB/km	N/A	N/A

What fiber optic cable range do you need?

Mainly consider the following factors.

#1. The fiber optic cable length you need

If it is too short, moving the equipment in the future will be impossible; if it is too long, it will also be a waste of cost. If you need a fiber optic cable that transmits over a distance more significant than the fiber optic cable length you purchased, you may need to repurchase it.

#2. Bandwidth requirement

How much bandwidth do you need now? How much bandwidth will you need in the future?

#3. Budget

Single-mode fiber optic cables are cheaper to manufacture but more expensive to wire, while multimode fiber is cheaper but less expensive.

#4. Application Scenarios

Multimode cables are widely used in LANs, enterprises, cloud computing, and data centers. Single-mode cables are suitable for medium—and long-distance applications such as telecom, datacom, and CATV networks.

#5. Future-oriented

Multimode fiber optic cables are upgraded faster and constantly undergo technological innovation. However, they are costly to upgrade and require the removal of existing cables.

single-mode fiber optic technology may move toward reconfigurability and flexibility in the future. This means optical fibers can be dynamically adapted to different application scenarios based on various transmission requirements.

FAQ

Q: How far can single-mode fiber go?
A: For most applications, the maximum distance of a single-mode cable is around 160 kilometers. However, the dispersion-compensating fibers can support more than 200 kilometers.

Q: How far can multimode fiber go?
A: It varies with the data speed and fiber type. Take the common OM2 as an example. It supports a maximum of 550m at 1Gbps and 82m at 10Gbps. However, the maximum distance for all multimode fibers will be less than 2km.

Q: Can I use single-mode fiber for a short distance?
A: Yes, it may be. However, you must add appropriate optical attenuation to avoid overloading or damaging the receiver.

Q: Which fiber type should I choose, multimode vs. single-mode fiber?
A: The choice between single-mode and multimode fiber depends on several factors, such as link distance, bandwidth requirements, and budget constraints.

Multimode fiber is usually sufficient for shorter distances and lower bandwidth requirements. However, single-mode fiber is recommended for longer distances and higher bandwidth requirements.

Q: What applications are multimode fiber commonly used for?
A: Multimode fiber is commonly used for shorter-distance applications such as local area networks (LANs), data centers, and campus networks. It is also suitable for audio/video transmission, security, and industrial control systems.

Q: What factors affect fiber optic cable max length?
A: The transmission distance of fiber optic cables depends on many factors, including the type of fiber optic, the wavelength of the light used, the signal amplification and regeneration equipment used, and the bandwidth.

Conclusion

The type, transmission rate, fiber material, and other factors affect the maximum transmission distance of fiber optic cable. This article also compares the maximum transmission distance, structure, and bandwidth of single-mode fiber optic and multimode fiber optic cables. You can also determine what factors to consider when choosing a fiber optic cable.

How far is the fiber optic cable distance? The answer is in the future, and we can look forward to it with you.

Reference

• Single Mode vs Multimode Fiber, What is The Difference?
• https://www.blackbox.co.uk/gb-gb/page/28533/Resources/Technical-Resources/Black-Box-Explains/Fibre-Optic-Cable/Multimode-vs-Singlemode-Fibre
• https://en.wikipedia.org/wiki/Multi-mode_optical_fiber