Quantum-probe Field Microscope (QFIM) films THz-Nearfield Evolutions

We demonstrate a novel ultrafast electric field microscopy for sub-wavelength and sub-cycle imaging of nearfield waveforms at THz frequencies. Based on the fluorescence of semiconductor quantum-dots as local field probes, we acquire ultrafast movies of dynamic electric field evolutions inside broadband THz-antennas and of propagating THz-excitations in metallic waveguides using an optical microscope. This flexible scheme allows for local time-domain spectroscopy more than 100x below the diffraction limit and provides field-resolved access to field-driven and strong-field dynamics inside active metamaterials.