Significant advancements in short-pulse generation have propelled the evolution of terahertz and mid-infrared field sampling techniques over the past decades. The ability to generate high-peak-power, few-cycle femtosecond pulses has now extended direct electric field sampling to near-petahertz frequencies. While such measurements were previously confined to vacuum-based methods like attosecond streaking, recent breakthroughs have enabled direct field detection in ambient air. This has opened new possibilities for high-precision spectroscopy and metrology, offering unprecedented insights into material composition and molecular interactions.
Field-resolved spectroscopy has primarily been limited to gas-phase studies in the mid-to-long-wave infrared region. However, the near-infrared (NIR) range holds great potential for biological applications due to its sensitivity to molecular vibrations, superior spatial resolution, and reduced water absorption. In this talk, I introduce Fieldoscopy, a novel field-resolved spectroscopy technique that bridges the technological gap in NIR spectroscopy. Using coherent excitation and electro-optic sampling, Fieldoscopy enables high-sensitivity detection of molecular responses. A proof-of-concept study on aqueous samples demonstrates the first field-sensitive detection of water-ethanol combination bands, expanding the potential for biological spectro-microscopy with enhanced sensitivity and temporal resolution.