I will try to link to this explanation for situations I come across in the future. It's very well argued. For what it's worth to future readers, I went ahead a

I will try to link to this explanation for situations I come across in the future. It's very well argued. For what it's worth to future readers, I went ahead and found examples of optical fiber rated for use up to 385C[0] (20km). There's research into fiber optic cables which may be able to withstand up to 1000C or more, but I couldn't find any products like that. Maximum drilling temperatures currently top out at around 250C/500F[1]. 0: https://www.leoni-fiber-optics.com/en/products-and-services/fibers/high-temperature-fibers/ https://www.leoni-fiber-optics.com/en/products-and-services/... 1: https://pubs.spe.org/en/jpt/jpt-article-detail/?art=1052 https://pubs.spe.org/en/jpt/jpt-article-detail/?art=1052