{'fraction_non_alphanumeric': 0.018292682926829267, 'fraction_numerical': 0.004878048780487805, 'mean_word_length': 5.568, '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}}
Formation of uniform two-dimensional subwavelength structures by delayed triple femtosecond laser pulse irradiation.

The fabrication of subwavelength two-dimensional (2D) structures on metals is of paramount importance to modern nanophotonics. Here we report a method to fabricate 2D conic structures on nickel surfaces using a single beam with three temporally delayed pulses. The 2D structures are fabricated over the entire irradiated region with relatively high uniformity. By controlling the delay between the three pulses, we control the effect of each pulse in creating laser-induced periodic surface structures which enables the control of the 2D structure features, namely, the period and structure dimensions. We explain the results based on the surface plasmon polariton-femtosecond laser interference model.