Spectral Interferometric Microscopy for Fast and Broadband Phase Characterization

Abstract

The rapid growth in the development of new optical materials such as 2D materials, layered heterostructures, active phase changing materials, optical metasurfaces, and metamaterials, requires new methods which enable accurate, broadband, and real‐time microscopic characterization of their optical and physical properties. Here, this necessity is addressed and a novel method is presented to dynamically and accurately obtain the spectral phase of a microscopic sample, either in reflection or transmission. The method is based on a designed optical relay that couples the output port of a typical microscope setup to an imaging spectrometer. By post‐processing the acquired images, a stable, accurate, and easy‐to‐align broadband spectral microscopic interferometer is obtained. This approach is experimentally demonstrated by measuring the spectral phase response of two different types of metasurfaces in reflection and in transmission and also by accurately measuring the dispersion of a thick glass slab in transmission. Moreover, the method's applicability to broadband dynamic measurements is demonstrated by real‐time tracking the phase response of optically driven nematic to isotropic and isotropic to nematic phase transitions of a liquid crystal. Altogether this method enables accurate, dynamic, and easy microscopic phase characterization and can become widely used for materials characterization.

Rayleigh anomaly induced phase gradients in finite nanoparticle chains

“…So far, we have investigated how the RA induces anomalous phase gradients of the particle's excitation. However, although these gradients can be probed by interferometric measurements, 60,61 their notable implication are the associated angular anomalies. Specifically, we show that the light reflected and diffracted from the chain deviates from the grating equation (eqn (8)) for infinite chains.…”

Femtosecond laser-induced damage threshold of nematic liquid crystals at 1030 nm

“…A spectrometer (Avantes, 0.07 nm resolution) is employed to monitor the interferogram pattern. Spectral-domain interferometry combined with Fourier analysis is a powerful tool for metrology [22,23], with numerous practical applications, such as optical index and/or group index, or phase response of metasurfaces measurements [24][25][26][27]. In practice, a Fourier Transform of each acquired spectrum is followed by temporal filtering in the Fourier space.…”

An All‐Optically Controlled Liquid‐Crystal Plasmonic Metasurface Platform

“…[ 31 ] For applications of all‐optical switching, light‐induced nematic‐to‐isotropic (N–I) phase transition via local heating (i.e., change in refractive index and order parameter), has been proposed and studied. [ 31–37 ]…”