How Does Fiber-Optic Internet Work?

Get fiber internet access and download all the things at light speed.

Catherine McNally
Dec 13, 2023
Icon Time To Read5 min read

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A fiber connection lets you hop online thanks to fiber-optic cables, which use light signals to send data to and from your computer.

Because of the newer technology behind it, fiber internet far surpasses DSL and cable internet in terms of internet connection speed and reliability.

Still curious? Here’s more on how fiber internet works, why it's worth the money—and how to get a fiber connection of your own.

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What is fiber-optic internet?

Fiber internet uses fiber-optic cables instead of copper wires. Fancy.

We mentioned before that fiber internet lets you surf the web thanks to fiber-optic cables filled with glass filaments. Those cables send data back and forth thanks to lasers and light signals. (Cue dramatic echo.)

An illustration of a fiber-optic cable

But that may be too simple of a definition for the tech-savvy among us, so let’s dig in a little more.

“Fiber-optic cable carries light very well over relatively long distances with low attenuation and distortion of the light signal,” says Frank Cornett, a retired electrical engineer for Intel.

What is attenuation?
Info Box

In terms of your internet connection, attenuation means the strength of the signal sent to your computer gets weaker over time. That change makes the signal harder for your computer to process overall. With fiber, the signal stays stronger so you get faster wireless internet access and better streaming. Zoom.

That light signal uses binary to communicate with your computer. “. . . The presence of light might indicate a binary one and the absence of light would indicate a binary zero,” says Frank. Pretty cool.

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Differences between fiber, cable, and DSL internet

Fiber connections don't get as distorted over long distances like copper-wire connections do.

You might now be wondering why fiber is so much better at transmitting data than cable or DSL internet connections. Well, the answer lies in the types of cables used.

How does cable internet work?
Pin

Curious to learn more about cable internet? Check out our guide here.

DSL and cable internet both rely on copper wires to transmit data—the same kind of wires that transmit your voice over a telephone line. That goes to show you just how long this technology has been around.

“In contrast to fiber-optic cable, which carries light with relatively low attenuation and distortion, copper wires significantly attenuate and distort the voltage signals they carry,” Frank explains.

That’s a bad thing, and it gets worse.

Distance is a big problem for cable and DSL

The problem of attenuation and distortion for copper wires gets worse the longer those wires get—so the farther away from your neighborhood node and internet service provider (ISP) you live, the worse your signal could get. Attenuation and distortion also get worse with your internet speed. (That’s why DSL and cable internet can only go so fast.)

That’s why “a link made up of fiber can provide much faster data transfer than copper,” Frank says. That means faster load times, higher-quality streaming, and less mashing of the reload button when your favorite website won’t load fast enough. (Yes, we’re button mashers and we’re proud.)

"Fiber transfers data faster than copper wiring. That means faster load times, higher-quality streaming, and less mashing of the website reload button."

Your internet speed also depends on how much data the infrastructure can handle.

Like we mentioned, fiber-optic internet lines transfer data using modulated light instead of electricity. That gives them much higher bandwidth capacity, since they’re not bound by the physical limitations of electricity conducting through metal.

Here’s a quick look at how quickly you can download files with fiber internet versus DSL and cable.

How fast is fiber-optic internet?1,2
Approximate file size
1,000 Mbps fiber connection
100 Mbps cable connection
25 Mbps DSL connection

4-minute song

4 MB

0.03 sec.

0.03 sec.

1 sec.

9-hour audiobook

110 MB

0.9 sec.

9 sec.

36 sec.

45-minute TV show

200 MB

1 sec.

16 sec.

1 min. 7 sec.

2-hour movie

1.5 GB

12 sec.

2 min. 8 sec.

8 min. 35 sec.

2-hour HD movie

4.5 GB

38 sec.

6 min. 26 sec.

25 min. 46 sec.

Speed/time examples are estimates.

Fiber internet compared to DSL

Fiber internet connections work at speeds up to 1 gigabit per second—literally 100 times faster than those old copper wire connections. Providers like AT&T, Frontier, and Ziply Fiber use this kind of connection.

Traditional copper wires used by DSL and cable internet were originally intended to transmit voice only, though, so they’re limited in the amount of data they can handle.

But both DSL and cable internet speeds got better over the years, so you may not readily see the difference when you compare these types of internet plans.

Some companies only offer one type of connection, but some providers like CenturyLink Internet and Xfinity Internet offer DSL, fiber, and cable options.

Here's a quick look at some fiber, cable, and DSL internet plans to compare.

Fiber internet compared to DSL and cable
Provider
Monthly price
Download speeds
Connection Type
Learn more
AT&T Fiber$55–$225*300-5000 MbpsFiber
CenturyLink Internet$50-$75100-940 MbpsDSL/Fiber
Frontier Fiber Internet$44.99-$154.99500-5000 MbpsFiber
Spectrum Internet®$19.99-$89.9930-1000 Mbps^Cable
WOW! Internet$30-$185°100-5000 MbpsCable
Xfinity Internet$19.99-$120**75-2000 MbpsCable/Fiber
Ziply Fiber$20-$300††100-10000 MbpsFiber
Data as of 04/05/2023. Offers and availability vary by location and are subject to change.
* Price after $5/mo Autopay & Paperless bill discount (w/in 2 bills). Plus taxes $ fees. Limited availability. May not be available in your area.
Speed may not be available in your area. Paperless billing or prepay required. Additional taxes, fees, and surcharges apply.
Requires Auto Pay or $5/mo. fee applies. Beginning April 2022, a printed bill fee of $2.99/mo. will apply, NY, PA and select customers excluded. A $10 fee applies when Internet is disconnected. Equipment return required at disconnection, up to $150 per device if not returned. Multi-Device Security covers up to 10 devices. Other applicable charges and additional services are extra. Service subject to availability. Cannot be combined with other offers. Other restrictions, Frontier policies and service terms apply.
^ Limited time offer; subject to change; valid to qualified residential customers who have not subscribed to any services within the previous 30 days and who have no outstanding obligation to Charter.
° With AutoPay & paperless billing. Equipment, taxes, data allowance, and other fees extra. Other restrictions apply to usage-based plans.
** Pricing for some packages are for the first 12 months. Some packages require a 1- or 2-year contract.
†† For new residential customers only. No annual contract required. Prices shown are before taxes and fees and require autopay and paperless billing. Standard month to month pricing.

Different types of fiber internet

Fiber internet comes in three types, and fiber to the home (FTTH) is the best.
fiber internet, how it works

There are three types of fiber internet—and not all are made equal.

Fiber to the home or premises (FTTH or FTTP) means your fiber internet connection goes straight into your home. If your home isn’t already set up to receive a fiber connection, you may need your ISP to drill holes or even dig nearby. This is the holy grail of fiber connections.

Fiber to the curb (FTTC) means your fiber connection goes to the nearest pole or utility box—not an actual concrete curb. After that, coaxial cables will send signals from the “curb” to your home. This means your connection is made up of part fiber-optic cables, part copper wires.

Fiber to the node or neighborhood (FTTN) provides a fiber connection to hundreds of customers within a one-mile radius of the node. The remaining connection from the node to your home is often a DSL line that uses existing telephone or cable lines.

For FTTN fiber internet, this is where things get tricky. The farther you live from the node, the longer the DSL line needs to be to reach your house—and the longer the line, the more attenuation and distortion you get, causing slower wireless internet access.

“With FTTN, the DSL link from the node to the home amounts to a bottleneck in the overall link,” says Frank. We don’t know about you, but bottlenecks and internet don’t sound like a match made in heaven.

Who is fiber internet best for?

Fiber internet benefits everyone, and it can even come at a reasonable price.

Is fiber internet right for you? We say yes.

Fiber internet uses a newer technology, and therefore tends to be more reliable and faster. You may not need 1,000 Mbps download speeds, but even if you grab a 100 Mbps fiber internet plan, you'll likely see fewer outages and overall faster speeds than you would with a 100 Mbps cable or DSL plan.

One other thing fiber internet offers that cable and DSL don’t is symmetrical download and upload speeds—meaning your upload fiber speed is the same as your download fiber speed.

So if you pay for a 300 Mbps fiber connection, your upload speed should also be 300 Mbps. (With cable and DSL, upload speeds normally only rev up to an average of 10–15 Mbps.) Faster upload speeds are a huge boon to anyone who deals with large files or jumps into a lot of video calls.

How to get fiber internet

Fiber internet still isn't widely available, but networks are expanding to new cities.

While fiber sounds amazing if you’re a lover of all things internet, the reality is it’s still not widely available.

Right now, fiber is mostly available on the East Coast and in big cities—though there are a few small ISP startups offering fiber elsewhere. ALLO in Nebraska and Colorado and Endeavor Communications in Indiana are two that come to mind—and both scored in the top 10 in our fastest ISPs analysis.

Here's a quick look at some of the larger fiber internet providers in the US:

Fiber internet providers in the US
Provider
Monthly price
Download speeds
Connection Type
Learn more
AT&T Fiber$55–$225*300-5000 MbpsFiber
Google Fiber$70–$150‡‡1000-8000 MbpsFiber
MetroNet$29.95-$69.9^^100-1000 MbpsFiber
Verizon Fios Home Internet$49.99-$89.99°°300-2300 MbpsFiber
Ziply Fiber$20-$300††100-10000 MbpsFiber
Data as of 04/05/2023. Offers and availability vary by location and are subject to change.
* Price after $5/mo Autopay & Paperless bill discount (w/in 2 bills). Plus taxes $ fees. Limited availability. May not be available in your area.
‡‡ Plus taxes and fees. Upload/download speed and device streaming claims are based on maximum wired speeds. Actual Internet speeds are not guaranteed and may vary based on factors such as hardware and software limitations, latency, packet loss, etc.
^^ Offers available to new residential customers only and may not be combined with other offers. MetroNet reserves the right to revoke or modify offers at any time. Taxes, fees, and other terms apply.
°° Price per month with Auto Pay & without select 5G mobile plans. Fios plan prices include taxes & fees
†† For new residential customers only. No annual contract required. Prices shown are before taxes and fees and require autopay and paperless billing. Standard month to month pricing.
Pro tip: Check reviews before you buy
Megaphone

The best way to find out if these ISPs are worth their salt is to see what real customers have to say and compare performance and pricing. We’ve got all that and more—check out our AT&T Fiber, Verizon Fios Home Internet, Frontier Fiber, and Google Fiber reviews.

If you’re lucky enough to have fiber internet in your area, here’s how the five best fiber ISPs compare.

Also check out the full Metronet review.

Now that you know how fiber internet works, check these out next.
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Enter your ZIP code to find fiber internet plans near you.
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See our picks for the best fiber internet providers.

Catherine McNally
Written by
Catherine McNally
Catherine has a degree in journalism and an MBA, and has spent the last 10+ years writing everything from Okinawa travel guides to stories on Medium. She’s been online since AOL CDs were a thing and is an unapologetic PC gamer. She believes the internet is a necessity, not a luxury, and writes reviews and guides to help everyone stay connected. You can also find her on Twitter: @CMReviewsIt.

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