Digital Optical Connection - What It Is And How To Use It

Digital Optical Cable Tip and Connection Example
Digital Optical Cable Tip and Connection Example. Images by Robert Silva

What A Digital Optical Connection Is

A digital optical connection is a type of physical connection that uses light (fiber optics) to transfer audio data digitally from a compatible source device to a compatible playback device using a specially designed cable and connector.

The audio data is converted from electrical pulses to light pulses on the transmission end, and then back to electrical sound pulses on the receiving end.

The electrical sound pulses then travel through a compatible device that amplifies them so that they can be heard through speakers or headphones.

Contrary to popular belief, the light is not generated by a laser - but is the result of a small LED that emits the needed light source on the transmission end, which can be sent through the fiber optical cable to a compatible connection on the receiving end.

Digital Optical Connection Applications

In home audio and home theater, digital optical connections are used for transferring specific types of digital audio signals.

Devices that may provide this connection option include DVD players, Blu-ray Disc players, Media Streamers, Cable/Satellite Boxes, Home Theater Receivers, most sound bars, and, in some cases CD players and newer Stereo Receivers.

It is important to note that although digital optical connections may be included in DVD/Blu-ray disc players or media streamers, they are not designed to transfer video signals.

This means that when connecting a DVD/Blu-ray/Media streamer and you want to use the digital optical connection option, that is for audio only. For video, you need to make a separate, different, type of connection.

The types of digital audio signals that can be transferred by a digital optical connection include two-channel stereo PCM, Dolby Digital/Dolby Digital EX, DTS Digital Surround, and DTS ES.

It is important to note that digital audio signals, such as 5.1/7.1 multi-channel PCM, Dolby Digital Plus, Dolby TrueHD, Dolby Atmos, DTS-HD Master Audio, and DTS:X cannot be transferred via Digital Optical connections - These formats require HDMI connections.

The reason for this difference is that when the digital optical connection was developed, it was made to comply with digital audio standards at the time (mainly 2-channel CD playback), which did not include 5.1/7.1 channel PCM, Dolby Digital Plus, Dolby TrueHD, Dolby Atmos, DTS-HD Master Audio, or DTS:X. In other words, digital optical cables do not have the bandwidth capability to handle some of the newer home theater surround sound formats.

It is also important to point out that although all Home Theater Receivers, DVD players, most Media Streamers, Cable/Satellite Boxes, and even some Stereo Receivers have a Digital Optical connection option, there are some Blu-ray Disc players that eliminated Digital Optical connection as one of the audio connection options, opting for an HDMI output only connection for both audio and video.

On the other hand, Ultra HD Blu-ray players, usually include a digital optical audio output option, but it is up to the manufacturer - it is not a required feature.

In other words, if you have a home theater receiver that has the Digital Optical connection option, but does not provide the HDMI connection option, make sure that when you are shopping for a newer Blu-ray Disc player, that it does, indeed offer, a Digital Optical connection option for audio.

NOTE: Digital Optical connections are also referred to as TOSLINK connections. Toslink is short for "Toshiba Link", since Toshiba was company that invented and introduced it into the consumer market. The development and implementation of the digital optical (Toslink) connection paralleled the introduction of the CD audio format, where it was first used in high-end CD players, before it expanded into its current role as part of the home theater audio landscape.

More Info

To dig deeper into the history, construction, and technical specifications of Digital Optical/Toslink connections refer to TOSLINK Interconnect History & Basics (via Audioholics).

There is another digital audio connection that is available that has the same specifications as Digital Optical, and that is Digital Coaxial, which transfers digital audio signals over a traditional wire, rather than light. For more on this connection, including a photo, refer to my article: Digital Coaxial Connection - Definition and Explanation.