There was a brief period when the ports on the back of some TVs were a nightmare. Specifically I'm thinking of the period shortly after HDMI became available, but when many people still had component or even composite accessories they needed to hook up, usually DVD or VHS players. If you weren't that familiar with AV gear, some port assemblies were so complicated that it was entirely possible to plug something into the wrong place and wonder why it didn't work.
What is the optical port on my TV for?
A relic from a (recently) forgotten age
What you're looking at is sometimes known as a TOSLINK or S/PDIF connector. The first term stems from the format's creator, Toshiba, which originally developed it in 1983 as a way of delivering PCM (pulse-code modulated) audio from its CD players to its receivers. S/PDIF stands for Sony/Philips Digital Interface, which also refers to a separate copper cable type that's fallen out of favor. As you've no doubt guessed, TOSLINK is short for Toshiba Link.
The technology eventually made its way beyond Toshiba and into the home theater space, becoming a preferred option for enthusiasts. That's because it uses fiber optics, enabling not just high-speed data transfer, but immunity from issues that plagued earlier cable types, including RF interference and ground loops (a source of hum and other unwanted noise).
The format's creator, Toshiba, originally developed it in 1983 as a way of delivering PCM audio from its CD players to its receivers.
Functionally, the format supports two channels of uncompressed PCM audio, as well as several compressed surround formats, such as DTS and Dolby Digital. If you want to go all-out, it's powerful enough to handle a 7.1-channel surround system.
Aside from TVs, CD players, and speaker equipment, you'll also find optical ports on some cable boxes, DVD players, Blu-ray players, and game consoles. You might even find it on some computers, although I can't recall ever seeing that myself.
So what's wrong with optical audio?
An evolutionary dead-end
Optical has been eclipsed by HDMI, or rather an associated technology, ARC (Audio Return Channel). This eliminates the need for dedicated audio cables, and lets you output audio from any device connected to your TV. It can potentially greatly simplify your setup, for instance letting you connect your console and Blu-ray player to your soundbar, which then connects to your TV -- no receiver needed.
Another ARC advantage is support for CEC control. That means your regular remote can not only turn speakers on and off, but adjust their volume as if you were controlling the TV's internal sound. Optically-based speakers may need a separate remote, or "training" to recognize IR blasts.
Optical connections are limited to 384Kbps, which just isn't enough to handle the data needs of something like Atmos.
As if that weren't enough, the best version of ARC -- eARC -- offers dramatically better bandwidth, up to 37Mbps (megabits per second). This enables uncompressed surround formats like DTS-HD and Dolby TrueHD, as well as object-based 3D formats like DTS:X and Dolby Atmos. You won't necessarily notice the difference versus compressed and uncompressed tracks, but only 3D formats can project sounds over your head. Optical connections are limited to 384Kbps, which just isn't enough to handle the data needs of something like Atmos.
A comparatively minor issue is the range and fragility of optical cables. Cheaper plastic ones are ineffective beyond 10 meters (about 32.8 feet), and just about anything you buy will be ultra-thin, making it all too easy to crimp or bend in a way that blocks light signals. I've always felt like I've had to treat optical cables like I would fine china.
Why optical still has a place in my home
You don't always need the best of the best
The fact is that in my own home, my audio needs aren't complicated. I do consider myself a cinephile, but many of my favorite movies were mixed in Dolby Surround, if not plain-old stereo or mono. Dolby Atmos may be technically impressive -- but I hardly need it to enjoy myself. I'm far more concerned with fidelity and bass response. I want to clearly discern dialogue, and feel the thump of explosions or a bombastic soundtrack. 3D audio often feels like a pure gimmick to me, something that shows off a sound system, rather than contributing to immersion. There's a better argument to be made for including it in games, but I'm better off using headphones if I care whether an enemy is above or below me.
All this is to say that optical audio is potentially a better value. When I was shopping for a soundbar last year, I deliberately chose a Sonos Ray instead of the eARC-equipped Beam, since I cared more about what I could do with the extra $200 than 3D effects. The Ray has been frustrating sometimes, I'll admit. But that's only because it drops off Wi-Fi whenever I update my router, and because I have to disable Bluetooth on my TV if I want to use my remote's IR blaster for volume. I'll eventually get around to fixing the second problem by buying a second remote for a lot less than $200.
There are already TVs without optical ports, and it seems inevitable that the entire industry will follow suit at some point.
For some of you, the advantage might be the ability to buy or reuse older "legacy" speakers. If you can find one, a system from the '90s or 2000s is not only going to be cheap, but potentially just as impressive as anything new if you don't care about where it sounds like a starfighter is coming from. I might've gone that route myself if I'd had the time to browse the local used market.
Really, my only serious concern is the future of the format. The writing is on the wall. There are already TVs without optical ports, and it seems inevitable that the entire industry will follow suit at some point, for the same reason that you'll have a hard time finding a 4K TV with component hookups. HDMI is the superior technology, full stop, so it's just a question of whether my Ray will become obsolete the next time I upgrade the screen it's attached to. I'm crossing my fingers that both devices will be good until 2035 -- by which point I may be more interested in watching movies with AR glasses than bothering with anything as archaic as cables. I suppose we'll see if companies like Apple, Meta, and Samsung can make good on their promises of delivering cinema quality on something I'm willing to wear for two or three hours.