On-chip time-domain terahertz spectroscopy of superconducting films below the diffraction limit

Abstract

Free-space time domain THz spectroscopy accesses electrodynamic responses in a frequency regime ideally matched to interacting condensed matter systems. However, THz spectroscopy is challenging when samples are physically smaller than the diffraction limit of ~0.5 mm, as is typical, for example, in van der Waals materials and heterostructures. Here, we present an on-chip, time-domain THz spectrometer based on semiconducting photoconductive switches with a bandwidth of 200 GHz to 750 GHz. We measure the optical conductivity of a 7.5-$\mu$m wide NbN film across the superconducting transition, demonstrating spectroscopic signatures of the superconducting gap in a sample smaller than 2% of the Rayleigh diffraction limit. Our spectrometer features an interchangeable sample architecture, making it ideal for probing superconductivity, magnetism, and charge order in strongly correlated van der Waals materials.

References in corpus (16)

• Light-induced anomalous Hall effect in graphene
• An optically stimulated superconducting-like phase in K3C60 far above equilibrium Tc
• Electrodynamics of Correlated Electron Materials
• Moiré heterostructures as a condensed matter quantum simulator
• Infrared nanoscopy of Dirac plasmons at the graphene-SiO2 interface
• Optically enhanced coherent transport in YBa2Cu3O6.5 by ultrafast redistribution of interlayer coupling
• Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D topological insulator
• Ultrafast single-nanowire multi-terahertz spectroscopy with sub-cycle temporal resolution
• THz response and colossal Kerr rotation from the surface states of the topological insulator Bi${}_2$Se${}_3$
• Temporal correlations of superconductivity above the transition temperature in La${}_{2-x}$Sr${}_x$CuO${}_4$ probed by terahertz spectroscopy
• Ultrafast helicity control of surface currents in topological insulators with near-unity fidelity
• Locating the missing superconducting electrons in overdoped cuprates
• Anomalous gap edge dissipation in disordered superconductors on the brink of localization
• On-chip terahertz modulation and emission with integrated graphene junctions
• Nonlinear transport in a photo-induced superconductor
• Corrective Re-gridding Techniques for Non-Uniform Sampling in Time Domain Terahertz Spectroscopy

Cited by in corpus (9)

• Room-Temperature Plasmon-Assisted Resonant THz Detection in Single-layer Graphene Transistors
• A 2D van der Waals Material for Terahertz Emission with Giant Optical Rectification
• Cavity electrodynamics of van der Waals heterostructures
• On-Chip Terahertz Spectroscopy for Dual-Gated van der Waals Heterostructures at Cryogenic Temperatures
• Direct measurement of terahertz conductivity in a gated monolayer semiconductor
• Fundamental limits of few-layer NbSe${}_2$ microbolometers at terahertz frequencies
• Monolithic optoelectronic circuit design for on-chip terahertz applications
• Demonstration of an Integrated Planar Guided-wave Terahertz Synthesized Filter
• Proposal for an electrically controlled terahertz micro-oscillator