THz generation from liquid water under two-color excitation . (a) Two THz waveforms are obtained when the relative phase is and . Inset: THz electric field as a function of the phase delay. (b) THz wave energy with a tuned phase between 800 nm and 400 nm pulses. The THz energy was monitored by a Golay cell. (c) Normalized THz energy from liquid water as a function of the total laser pulse energy. Blue squares show the THz energy calculated from the temporal integral of the THz waveform measured by EOS. Blue dots indicate modulated THz energy measured by a Golay cell. Red circles present unmodulated THz energy measured by the Golay cell.