Interband transitions in InP biased with THz fields of 4 MV/cm

Here we develop a THz bias NIR probe setup based on our high-field THz laser system. This scheme allows us to monitor the ultrafast interband dynamics of bulk semiconductors in electric fields as high as 8 MV/cm. We simultaneously detect the inherently phase-locked THz field and the field-induced NIR absorption change in the sample with two optically synchronized NIR pulses as short as 7 fs. Thus, the relative timing jitter between the THz transient and the probe pulse is known on the attosecond timescale.