Coherent Detection of Ultrabroadband Infrared Pulses Using a Single Crystal of Diamond

We coherently detected ultrabroadband infrared pulses generated through two-color pumped air plasma produced by hollow-fiber compressed 10 fs pulses in a spectral range of 1–100 THz using a biased single crystal of diamond as a nonlinear medium. The sensitivity was enhanced by two-orders of magnitude compared with the case of air in the probe energy range where saturation did not occur. Even when the probe pulse energy was 100 nJ, the spectral range reached 80 THz. Thus, diamond has reduced the energy of pulses required for realizing broadband coherent detection without sacrificing the advantage of gapless detection.