Not exactly sure what you mean by "optical" out. But maybe this will help:
I use a thunderbolt to HDMI adapter (great prices and fast delivery at monoprice.com) to use a 32" Vizio HDTV as a second screen for my MBA. This works really well when retouching in Aperture, because I can have just the photo very large on the Vizio, and all palettes on the laptop. Cost me about 5 bucks. You can expand real estate, as I have, or mirror the displays.
And if you have a digital monitor you should also be able to adapt to that. Of course a T-bolt display would work (if anyone had one or could afford one).
I think you can also adapt thunderbolt to SVGA, although that is going digital to analog, so the adapters may cost more because of the DAC needed. I am not sure, but it seems as if T-bolt is backwards compatible with mini display port, so it connects to a lot of things.
Are any of these what you have in mind? Regardless, if you go to monoprice and search for the type of adapter for the output and target monitor you have, this will give you an idea what is possible (not to mention a great source for the adapter).
<edit> My apologies; now I understand you are looking for an optical audio adapter. The listed item will work, but my question is why? If you need to do this to get it into a format to connect to a particular target device, that makes sense. If you are doing it because you assume the quality will be better, it may not be, and it may be inconvenient since there are not a lot of optical interconnections available on most consumer equipment.
As Monkeyat indicates, you should check SI, but it may only mean that the chip is multipurpose one-size-fits-all and only has it onboard; whether it is implemented as an output is still a question, and what connector might that output be on anyway? There is no optical connector. The 1/8" connector might do S/PDIF, which is really the same protocol over copper.
