Naïvely, glass is made from sand and copper is mined. And I can already recycle glass from my house, but not copper. So it looks like an environmental win to me. There may be something I'm missing.
Don't get hung up on the "green" characteristics of just the active component. You have to look at the whole picture, including packaging and manufacturing. It's not like the choice is between melting a little sand or an old bottle and digging a big hole in the ground to extract copper.
- There's a lot of plastic involved, for either medium
- optical stuff is pretty exacting to manufacture. It's easily possible that it's more energy-intensive to refine the materials, make the lasers, draw the fibers and so on than it is to make the copper equivalent
Copper is pretty trivially recyclable, which is why you get reports of drug addicts stealing copper piping from people's houses to sell on the black market.
I think the real account is in the phenomenal energy costs to convert the mines material to a final form. The glass is going to be mined as well, as even the cheap soda lime glass we see everywhere has many ingredients, and I would be surprised if the typical fiber was made of such cheap material (went and checked, and the optical fibers are likely to be doped and tuned to the application). A furnace consumes huge amounts of energy, for both refineries and glass plants (I worked at a glass plant, and the size of the natural gas line running to it 24/7 full open was shocking). Recycling helps (since the material stores some of the original energy), but there still needs to be a process to remove impurities.
As a sibling comment noted, green energy probably isn't what we would hope it to be.
- There's a lot of plastic involved, for either medium
- optical stuff is pretty exacting to manufacture. It's easily possible that it's more energy-intensive to refine the materials, make the lasers, draw the fibers and so on than it is to make the copper equivalent