Single shot linear detection of 0.01-10 THz electromagnetic fields: EElectro-optic sampling with a supercontinuum in balanced detection

We demonstrate widely tunable and broadband single shot electro-optic detection of THz waveforms with a linear response to the electric field over a wide range. The THz field is encoded to the temporally dispersed spectrum of a supercontinuum whose polarization state is analyzed in balanced detection. With the probe bandwidth corresponding to a Fourier Transform-limited duration below 5 fs, the time window can easily be adjusted in the fs to 100 ps range to be several times longer than the THz pulse without signal distortion. Thanks to a laser fluctuation-free design, the phase retardation (Γ) is measured under shot noise limited conditions with a rms noise below 0.005 over the whole spectral (i.e., temporal) window. The method allows the direct determination of the absolute amplitude of the THz field for the first time in a single shot EO-experiment. The performance of the diagnostic can be achieved with state-of-the-art fs to ps laser sources.