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Fiber Optics Speeds: Everything You Need to Know About

fiber optic test
Posted on Dec 31, 2020

Fiber Optics Speeds mainly depend on the fiber structure, the network’s equipment, the network design, and the regional constraints. Fiber optic is a dielectric waveguide that can have plastic or glass cores. Fiberglass core has fewer losses compared to plastic ones and is more expensive. Most plastic fibers are made of polymethylmethacrylate, polystyrene, or polycarbonate.

Plastic fibers’ superior features are low price, lightweight, and high flexibility, but they don’t perform well in extreme temperatures. Here we will discuss Fiber Optics Speeds and its contributing factors.

The fiber consists of a transparent core and a transparent metal cladding with refractive indexes of n1  and n2.

The shell refractive index is less than the core (with a one percent tolerance). Common and widely used refractive index values for core and fiber shell is 1.74 and 1.84, respectively.

The fiber structure’s cladding protects the core from absorbing contamination, directs light, and reflects light into the core.

Optical fibers are used in optic telecommunication systems like LANs to achieve high signal quality rates.

A picture containing light indicating fiber optic cables
Fiber Optics Speeds

Optical networks can offer high bandwidth due to fiber optic cable speed and capacity.

They reduce costs for various applications based on optical layers development in transmission networks.

The linear and nonlinear optical fibers’ properties are limiting factors to achieve 100 percent performance.

In the last two decades, optical telecommunications has become a significant competitor to present telecommunications systems.

With optical fibers’ ability to send/receive information with high capacity and low power, This trend will expand in the coming years.

Therefore, here, we will examine fiber optics speeds and the factors that attenuate light pulses.

Fiber Optics, The World’s Fastest Internet

Fiber-optic internet is one of the best-known internet services with the highest speed.

In this section, you will get acquainted with the concept and benefits of fiber optic internet and fiber optic vs cable internet speed.

Today, many countries in the world use fiber optic internet to provide high-speed internet services.

High-speed fiber optic cable allows virtual information to be transferred between data centers and the user very quickly.

The fiber optic cable bandwidth capacity reaches terabytes.

That’s why fiber optic cable internet speed will be higher than cable internet (ADSL) and dial-up.

The copper cable used electrical, modulated signals for transferring data, while fiber uses light pulses along the plastic or glass strands.

The speed of light transmission is not comparable to an electrical signal.

Even if the fiber quality is average, fiber optics speeds will be several times faster than copper.

Features of Fiber Optics in Providing Fiber Optics Speeds

Sending information with the highest possible speed, the lowest error, and the lowest energy resources consumption is one of telecommunication engineering’s primary goals.

Fiber optics are efficient tools in fast and quality information transmitting, which can receive or send the image, sound, and other information in the shortest time.

Entering the 21st century, the telecommunications industry and research centers paid more attention to this technology.

A picture contains a bunch of optical fibers

Wide Bandwidth And High Capacity

Optical communication employs a beam of modulated light to carry information from transmitter to receiver.

The optical frequency is usually close to an infrared ray and about one hundred thousand GHz.

The amount of transmitted digital and analog data by fiber optics is much more considerable than the best copper cables.

Interference Immunity

Noise, electromagnetic interference, and radiofrequency waves do not affect fiberglass or plastic optical fibers because they are insulated.

Interference immunity is one of the most considerable properties affecting fiber cable speed.


Security is one of the strengths of fiber optics. The light that passes through the optical fibers has no radiation, and no one can eavesdrop on the transmission path.

It is ideal for military purposes.

Low Attenuation

Low attenuation of optical fiber is important in providing higher speeds. We will discuss this in the following sections.

Due to these cables’ low attenuation, we need fewer repeaters along the route, so the repeaters’ distances are more than cable systems, which is cost-effective.

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What Are The Speed Limitations of Fiber Optic Internet?

Thanks to fiber optics, the world has current modern high-speed internet. It is interesting to know that you take its benefits even if you don’t subscribe to high speed fiber optic cable.

Because when you use international services, Internet exchange points (IXP) will connect your system to global services with fiber optics.

Of course, if older generation cables make all or part of your connection, your data transfer speed will be reduced, but in an FTTH network, all the connection is provided by optical cables at very high speed.

There are two limitations for fiber optic internet:

  • The cost of providing fiber optic internet is higher than cable internet, and that is why it is not yet widespread. Many users are satisfied with their Internet speed at the download speed of 20 to 100 MB per second. So, they do not want to buy higher speed fiber optic cable services.
  • Fiber optic cables provide very high download speeds, but fiber optic cable internet speed depends on the servers that offer website services; the lower the download link’s quality, the slower the download speed.
    For example, when you want to download a 20 GB game by your fiber optics speeds of 1 GB per second, your download should be done in a few seconds. But the download speed may be slow due to the quality of the link, and the time will be longer than expected.

Single Mode And Multimode Fiber Optic Cable Speeds

As mentioned in Fiber Internet How It Works – Get A Quick Guide to Fiber Optic, Fiber optic cables have two categories:

  1. Single mode
  2. Multi mode

Single Mode Fiber Optic Cable Speeds

Light passes directly and without refraction in the Single mode category. The core diameter of these cables is very small and equal to 9 micrometers (µm).

The main difference between these two fibers is their structure.

speedtest shows high speed of fiber optic speeds

single-mode optical fibers have an ultra-narrow core that can only send one beam of light.

So this beam will have the least expansion and is suitable for sending over very long distances. The core diameter in single mode fibers is between 8 and 10 microns.

The data transfer rate is not related to the thickness of the single-mode fibers. The important factor that directly affects the speed is the refractive index.

The exact calculation of the refractive index depends on the cladding or sheath around the core, which has a higher refractive index. In single mode fibers, the core diameter is very thin, which allows light to be emitted directly.

Hence, the light is less attenuated and does not require repeaters over long distances.

Single mode fibers are mostly used at 1310 wavelength. As mentioned, these types of fibers are very responsive over long distances.

Multi Mode Fiber Optic Cable Speeds

In the continuation of fiber optics speeds, the first and most important difference between single-mode and multi mode optical fibers is the core diameter.

The core diameter of multimode fibers ranges from 50 to 62.5 microns, while in single mode fibers, it is between 8 and 10 microns.

The bigger diameter allows multiple light signals to pass through the core simultaneously.

This creates several modes of diffusion or scattering. Scattering reduces bandwidth, which reduces transmission distance in multimode fibers.

Another difference is the type of equipment used in these fibers. Single mode fibers require special equipment such as a laser to focus light and fine-tune it due to the core’s smaller diameters.

Multi mode fibers support shorter distances due to their larger core diameters and use LEDs to create light pulses. So, the final cost is cheaper than the single-mode based network.

Telecommunication engineers use single mode fiber optics in long-distance infrastructures to gain less pulse attenuation.

Although single-mode fiber optics reduces bandwidth over long distances, it is much better than obligatory installing expensive repeaters at certain distances to amplify the signal. Multimode fibers are widely used in computer networks, high-speed telecommunications, and the military and aerospace industries.

Factors Contributing to Optical Fiber Losses And Fiber Optics Speeds

Light waves can travel long distances due to the mirror coating layer around the core that does not absorb light.

READ THIS  What Is Symmetrical Internet?

However, some optical signals are attenuated as they travel along with the fiber. Attenuation is mainly due to some impurities inside the glass.

So, signal attenuation level depends on the purity of the glass used inside the fiber and the traveling signal wavelength.

the picture illustrates decreasing internet speed - fiber optics speeds

Optical fiber losses sources are:

1- Boundary Losses

This loss is due to the unevenness of the boundary between the core and the fiber sheath.

2- Input And Output Losses

3- Absorption Losses

Absorption occurs under the influence of these factors:

  • Intrinsic properties of glass
  • Impurities such as OH ions
  • Atomic defects in glass

4- Dispersion Losses Due to Heterogeneity of Fiber Core Refractive Index

In addition to fiber constituents, dispersion losses depend on fiber non-uniformity. It can decrease the speed of fiber optic cables.

These losses are mainly due to minor density changes, fluctuations in volume, and the composition of materials and fiber optics structural heterogeneities during fabrication.

5- Losses Due to Fiber Optic Bending

The passage of light through a sharp bend with a tiny radius causes the loss of light radiation. Fiber optic bending while the installation process is two types:

  1. Bends whose radius is larger than the fiber’s diameter: such as bends occur through different paths.
    Radiation losses of such curves are very small and not significant due to the fiber optics installation conditions.
  2. Microscopic bends usually occur when the fiber is placed into the cable and during the production process.
    These bends make a significant loss.  

6- Losses At The Joints And Fiber Optics Speeds

For long-distance transmission, it is necessary to connect the optical fibers at the junctions.

So technician cut the fibers to connect them to the other equipment or other fiber strands.

All the coming out light of the first optical fiber does not enter the second one at the intersection, and it causes connection losses.

a fiber optic technician is performing fiber optic cabling and connect the optical fibers at the junctions which is important in fiber optics speeds

7- Connectors

The optical signal is a modulated light (contains information) and is coupled to the optical fiber by a connector or coupler to propagate.

Connecting fibers is one of the most challenging issues in this technology. In the fiber network establishing process, technicians need to use these tools to connect fiber to a transmitter, receiver, or other fibers.

This connection needs to provide the lowest loss possible.

Connectors are located at the beginning and end of a fiber optic cable and include different types:

  1. SC Connector: This connector is used in single mode and multi mode fibers. SC connectors have high transmission speed, high security, high efficiency, low loss, low return reflection, and reasonable price.
  2. FC Connector: FC connector is also used in single mode and multi mode fibers like the sc connector. This connector is mostly used in high-speed telephone and communication networks and fiber optic systems that require high strength and stability.
  3. LC Connectors: LC Connectors’ loss is low and is used in both single mode and multi mode fibers. Connecting fiber to system devices is one of the most important characteristics in determining the final loss rate and fiber optics speeds. Insertion loss and return loss are indicators in evaluating connectors’ quality.

8- Fusions

A method called “fusion” is used in long distances to connect two optical fibers or to replace a new optical fiber with a damaged one.

This method melts the core of two optical fibers together with a strong electric arc.

The two fiber cores should be matched to reduce power losses at the fusion junction.

Incorrect fusion will slow down the internet.

the picture depicts the act of fusion fiber optic cables.

Max Speed Of Fiber Optic Cable

Most ISPs have a maximum fibre optic cable bandwidth capacity of 1Gbit/s,  which is the typical fiber optic max speed. Fiber optics is the fastest network offering symmetric upload and download speeds in gigabit scales (up to 10 gigabit per second).

Note that the internet bandwidth is increasing continuously; we can expect improvement in the fiber optic cable max speed at a range of 100 Gbps.

Fiber Optic Vs Cable Speed Test

Broadband internet users want to know what is the exact speed of their internet connection.

Has the ISP delivered the promised fiber optics speeds? Fortunately, there are many ways to test your personal connection at any time, even on a cellphone or tablet device.

We introduce two websites, and you can find more by searching on google.

  1. Stop all downloads and uploads
  2. Disconnect your VPN application
READ THIS  Fiber Internet How It Works – Get A Quick Guide to Fiber Optic Internet


You can create an account in Speedtest and pick a server in the country from a list and save it.

You can also access your fiber optic cable speed test history and monitor its change.

Which can help you decide to keep, cancel, upgrade, or downgrade your service.

You can share the speed test result easily. This website also measures ping, which is the required time to send and receive data packets between your computer and server.


Xfinity has a well-designed website with an excellent graphical design and user experience.

You can easily check optic fiber cable speed without any app or software on mobile and desktop.

It will provide you a report that shows what your internet is appropriate for or not.

For example, is it good for stream HD video, stream 4K video, or speedy downloads?

Fiber Optic Speed Chart

In this table, you can see fiber internet and cable speed provided by different ISPs.

ISPFiber optic internetCable internet
Cox1000 Mbps10-940 Mbps
Mediacom1000 Mbps60-1000 Mbps
Optimum300-940 Mbps
Xfinity25-2000 Mbps
SuddenLink100-1000 Mbps100-1,000 Mbps
Verizon Fios200-940 Mbps
Windstream1000 Mbps
Spectrum100-940 Mbps
Shentel 50-1,000 Mbps

 In the following fiber optic speed chart, you can see the range of bandwidth:

fiber optic speed chart prepared at CFBTEL

Fiber Optics Speeds: FAQ

How Much Fiber Optics Speeds Do I Need?

The amount of fiber optic cable speed Mbps depends on you. You must specify what you need it for.

Do you want it for gaming? High speed downloading? Or just check your email? Use the following amounts as a minimum limit:

Online ActivityBandwidth – speed
Email1-2 Mbps
Web surfing3- 4 Mbps
Stream HD Videoup to 5 Mbps
Stream 4K Video25 Mbps

What Is An Optical Amplifier?

As the name implies, an optical amplifier is responsible for amplifying the input signal and increasing the power when it exits.

Erbium doped fiber amplifier,  EDFA, is one of the most widely used amplifiers in optical telecommunications.

What Are The Three Wavelengths of PON Networks?

PON networks use three wavelengths of 1310 nm, 1490 nm, and 1550 nm. 1550 nm is used to send video, and 1490 to transmit voice and data to the user (Downstream).

These two wavelengths are multiplexed in a device called Wavelength Division Multiplexer (DWM) and sent to the user.

The 1310 wavelength is also used to send voice and data from the user side to the center (Upstream).

What Is GPON, The New Generation of The PON Network?

The new generation of PON network used in various optical networks is Gigabit PON or GPON.

GPON networks can achieve a maximum data transfer rate of 2488 downstream and 2488 data upstream.

What Is An Asymmetric Internet Connection?

An asymmetric internet connection provides different upload and download speeds, and the bandwidth is shared between downloading and uploading.

Home Internet users typically use asymmetric bandwidth that has faster download speeds than upload speeds.

This option is not suitable for commercial affairs because organizations need features such as audio and video conferencing, speedy file sharing, VoIP phone system, cloud facilities, online fax, etc., which is not possible without high upload speed.

However, asymmetric internet connection has lower costs than symmetric bandwidth; that is why most home internet users use asymmetric bandwidth.

If you do not need to upload large files, asymmetric bandwidth will be a cost-effective and convenient choice for you.

What Is The Symmetrical Internet Connection?

A symmetrical internet connection provides equal upload and download speeds and special download and upload bandwidth at the same time.

The symmetrical connection enables fast data transmission in both directions.

It is the best choice for large or small businesses where several people are simultaneously connected to the Internet and transmitting data.

You will have a better internet experience than asymmetric internet by spending more money and buying symmetric bandwidth services.

As a result, if you are a business that uploads many high-quality files, you have many employees simultaneously, and You have many users use the Internet, it is better to purchase symmetric bandwidth.

Also, if you use cloud-based features, symmetrical bandwidth is the best choice for you.

What Are P2P Fiber Optics Speeds?

Optical fiber networks employ one of two basic architectures:

point-to-point (P2P) or point-to-multi-point (P2MP) systems, which are usually referred to as passive optical networks (PONs).

P2P provides direct connections between server and user and is a dedicated fiber link that offers private, high-speed fiber connection with more than 1 Gbps download and upload fiber optics speeds.

In experimental trials, transmission values of more than 69 Terabits per second have been recorded.


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