{'fraction_non_alphanumeric': 0.025022341376228777, 'fraction_numerical': 0.005361930294906166, 'mean_word_length': 5.746987951807229, '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}}
Ultrafast Optical Modulation of Harmonic Generation in Two-Dimensional Materials.

The modulation of optical harmonic generation in two-dimensional (2D) materials is of paramount importance in nanophotonic and nano-optoelectronic devices for their applications in optical switching and communication. However, an effective route with ultrafast modulation speed, ultrahigh modulation depth, and broad operation wavelength range is awaiting a full exploration. Here, we report that an optical pump can dynamically modulate the third harmonic generation (THG) of a graphene monolayer with a relative modulation depth above 90% at a time scale of 2.5 ps for a broad frequency ranging from near-infrared to ultraviolet. Our observation, together with the real-time, time-dependent density functional theory (TDDFT) simulations, reveals that this modulation process stems from nonlinear dynamics of the photoexcited carriers in graphene. The superior performance of the nonlinear all-optical modulator based on 2D materials paves the way for its potential applications including nanolasers and optical communication circuits.