{'fraction_non_alphanumeric': 0.03210272873194221, 'fraction_numerical': 0.012841091492776886, 'mean_word_length': 5.117647058823529, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 1, '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}}
Narrowband 1.5-μm Bragg filter based on a polymer waveguide with a laser-written refractive-index grating

We report the fabrication of narrowband frequency-selective filters for the 1.5-μm telecom window, which include a single-mode polymer waveguide with a submicron Bragg grating inscribed by a helium-cadmium laser. The filters have a reflectance R > 98 % and a nearly rectangular reflection band with a bandwidth Δλ≈0.4nm. They can be used as components of optical multiplexers/demultiplexers for combining and separating signals in high-speed dense wavelength-division multiplexed optical fibre communication systems.