The digital optical audio connection is one of the two audio-only connection types (along with coaxial audio) required to convey multichannel surround sound between audio/video components. This connection type (and its corresponding cables) is also known as TOSLINK (short for Toshiba-Link, who first developed it, or S/PDIF for Sony/Philips Digital Interface). Devices such as Blu-ray/DVD players, cable/satellite set-top receiver boxes and HDTVs often feature an optical audio output to connect to a surround sound receiver, utilising its optical fibre design to deliver crystal-clear digital audio.
Ensure that the component(s) you wish to connect to your home theatre system offer an optical audio output. The output port is shaped a bit like a home plate on a baseball field, to provide an exact fit with the connector points of the optical audio cable. The port will be located near the other input/output ports on the rear of the device and likely labelled "Optical Audio Out" or "SPDIF."
Purchase an optical audio cable of sufficient length to comfortably span the distance between the component and the home theatre receiver.
Remove any protective plastic caps from the ends of the cable, and insert one end of the cable into the device's optical audio output, aligning the connector to fit into the jack. The port may have a plug or hatch covering the opening; remove the plug or slide the hatch to enable the cable to be inserted.
Connect the other end of the cable to an optical audio input on your home theatre receiver. Select the appropriate input device setting on the receiver, and set that input to the "Digital" setting if necessary, to access the digital audio when viewing content from that device.