{'fraction_non_alphanumeric': 0.02230151650312221, 'fraction_numerical': 0.0008920606601248885, 'mean_word_length': 4.783505154639175, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Using single-mode infrared fibers for interferometry: progress report

With the recent availability of low-loss single-mode fluoride glass fibers, it becomes possible to consider interferometric beam recombination with fibers at infrared wavelengths. After a brief description of their present performances, specific aspects of the use of single-mode fibers in the infrared are studied here. In an astronomical interferometer thermal emission from the fibers will limit the sensitivity if they are not cooled. It is interesting to use the fibers at large X/? ratios: the beam is wider inside the fiber, most of the energy being routed by the cladding, and the coupling to starlight is eased because it can be done at slower f-ratios. This is true as long as X/X<2; beyond, evanescent field leaks through the fiber coating at the bends become too strong and prevent any practical use of the fiber. Far field beam profiles have been measured in the K and L bands. A project for a laboratory demonstration interferometer is presented: fringes were obtained in the visible and an extension to longer wavelengths is under way.