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Dynamic localization (DL) refers to a wavefunction confinement effect of electrons in periodic lattices under an ac electric field driving. Recent studies have transplanted DLs from electronic to photonic systems using periodically curved waveguide lattices, where the ac electric field is mimicked by the waveguide's bending curvature. However, due to the severe limitations of bending losses and poor tunability for highly curved, arbitrarily shaped waveguides, present studies mainly focus on DL under the simplest sinusoidal‐wave driving; its extension to an arbitrary‐wave driving remains challenging. Here, by constructing a synthetic temporal lattice with a coupled fiber‐loop circuit, the limitations of spatially curved waveguides are circumvented and generalized DLs are experimentally demonstrated under arbitrary‐wave driving. First, by applying band‐collapse criteria, the general conditions for the driving field's symmetry to achieve DLs are revealed. Then, two representative even‐function driving fields of square‐ and triangle‐waveforms are chosen, and wave‐packet revivals are observed as signatures of DLs. As a counter‐example, the breakdown of DL is also verified using odd‐function driving field of sawtooth‐waveform. The work reveals the conditions for realizing generalized DLs and experimentally verifies them using synthetic lattice schemes. This paradigm may find potential applications in versatile temporal‐waveform reshaping, pulse manipulations for optical communications, and signal processing. [ABSTRACT FROM AUTHOR]

Abstract: The near‐field features of graphene plasmons (GPs) using a recently developed photo‐induced force microscopy (PiFM) technique are characterized here. The GPs are excited by a mid‐infrared laser beam obliquely incident on graphene suspended over a metallic grating with a dielectric spacer. The PiFM records the optical force yielded by the interaction between the electric field of GPs in the normal direction and dipoles in a metallic tip. The magnitude of the optical force is proportional to the field intensity of the GPs. By detecting the interference pattern of GPs on the grating trenches, the wavelength and propagation distance of GPs can be obtained. The PiFM technique demonstrated here provides a powerful tool to precisely characterize GPs in a deeply subwavelength scale and aid in the design of nanoscale optical devices based on graphene. [ABSTRACT FROM AUTHOR]