Terahertz field induced second harmonic generation in biomolecules

We report the THz field-induced-second-harmonic generation in various biomolecules including amino acids, proteins and sugars. The THz field induced optical second harmonic (SH) signal depends on the strength of THz beam and on the relative polarizations of optical and THz beam. The THz waveform is coherently retrieved from the time dependent SH signal.