Presumably OP has surround sound because he references Phillips Home Theater. Optical out usually doesn't preserve 5.1 surround (though there are select exceptions), instead outputting only stereo sound even if it is a 5.1 program.
Based on very little information from OP, I'm still guessing an HDMI splitter is going to be the way to go: HDMI video to TV, HDMI audio to Phillips HT equipment. OR if OP has or buys a receiver, it will likely cover the same base even better.
I made an assumption that "Phillips Home Theatre" was a receiver. From your comment, maybe it is a sound bar that takes an HDMI input and it's connected directly from the TV.
I have a more conventional setup with a Denon receiver/amp acting as an HDMI switcher, with outputs to the TV, passive sound bar, and passive rear speakers. I use an optical cable to get sound back to the Denon from the TV on the rare, rare occasion that I use the TV as a source. It's a "smart TV" but not very new - it's one of the last of the Samsung plasmas. I don't watch on-air, and I don't use it to watch Netflix, etc. as I use Apple TV instead. I honestly don't remember why I used the optical cable instead of ARC as it was so many years ago - oh, maybe the active HTMI cable I used to connect the receiver to the TV doesn't support ARC.
If it's one of those new-fangled HDMI sound-bar thingies, I don't know why you wouldn't just use the TV as an HDMI switcher, plug the Apple TV into any available HDMI input on the TV, and the TV will pass sound on to the speakers. Again, you don't need an ARC port.
Make/model of TV, model of "Phillips Home Theatre", and how you currently have them hooked-up, so that we aren't guessing.