{'fraction_non_alphanumeric': 0.022486772486772486, 'fraction_numerical': 0.005291005291005291, 'mean_word_length': 6.20952380952381, 'pattern_counts': {'":': 0, '<': 0, '<?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}}
1 x 8 Supergrating wavelength-division demultiplexer in a silica planar waveguide.

Wavelength-division demultiplexing by superimposed gratings (supergrating) in a planar waveguide is modeled, accounting for intergrating coupling, and a theoretical decoupling criterion that serves as a guideline for practical design is presented. Superimposed gratings were formed by direct photoinscription in a photosensitive silica planar waveguide, which is a promising method for practical optical circuit applications. A 1x8 channel wavelength-division multiplexer is demonstrated experimentally as a proof-of-concept study. The effects on experimental performance of wavelength-selectivity broadening and finite photosensitive index-modulation depth are discussed.