Optical Pulse Compression Assisted by High‐Q Time‐Modulated Transmissive Metasurfaces

Abstract

In this paper, based on the recently introduced concept of time-varying media, an alternative approach is presented for controlling the compression ratio of an optical pulse in the near-infrared regime via two all-dielectric transmissive metasurfaces consisting of a zigzag array of silicon-based elliptical nanodisks. Upon introducing in-plane asymmetries and under normal incidence, the supported symmetry-protected bound-state in the continuum resonant mode collapses into two Fano resonances, which can be spectrally overlapped to satisfy the first Kerker's condition. To acquire an amplified signal, the desired chirp is applied to the incident pulse via a purely temporal waveform that modulates the optical response of the first layer, while the required group delay dispersion is imparted to the phase-modulated pulse by the second metasurface in order to compress its temporal distribution. Following such a configuration, the temporal duration of the output pulse decreases from 25 to 15 ps, leading to a peak intensity enhancement of 50%. On account of time-varying features of the first metasurface, the instantaneous frequency of the chirped light can be controlled dynamically, giving rise to the active tuning of the peak intensity from 0% up to 200%.

Manipulation of Scattering Spectra with Topology of Light and Matter

“…Complementary to recent experimental studies that addressed some aspects of the OAM beam interaction with spherical [98] and chiral nanostructures, [99] our study predicted the possibility of the excitation of various multipolar moments which are not accessible via unstructured light illumination and elucidated the role of the OAM in the scattering response of the alldielectric meta-atoms with arbitrary shapes and orientations, enabling new ways of manipulating their optical responses on demand and/or in time-modulated fashion. [100][101][102][103][104][105]…”

Increasing the stability margins using multi-pattern metasails and multi-modal laser beams

“…Nevertheless, both unitcells are designed to provide a wide phase span throughout the Doppler-broadened propulsion band. Based on the application, all-dielectric metasurfaces can operate both in reflective and transmissive regimes by offering a broad phase accumulation [37][38][39][40][41][42][43] . Moreover, sub-wavelength dielectric resonators enable the excitation of electric dipole (ED) and magnetic dipole (MD) resonances which can operate in the reflection with high efficiencies 38 .…”

Active Tunable Pulse Shaping Using MoS2‐Assisted All‐Dielectric Metasurface

“…Recently, metasurfaces (2D arrangements of subwavelength scatterers with the ability to control the constitutive properties of scattered light [ 11 ] ) were employed as pulse shapers. [ 12–16 ] Metasurfaces introduce more degrees of freedom compared to conventional spectral pulse shapers by providing fine‐grained control of the time‐domain properties of laser pulses. Since the minimum bandwidth of the resonant features of dielectric metasurfaces determines a lower limit on the bandwidth of a pulse, a resonance with a high Q‐factor and bandwidth well below that of the input pulses is needed for high wavelength selectivity.…”