Ultrabroadband detection of multi-terahertz field transients with GaSe electro-optic sensors:: Approaching the near infrared

Field-resolved detection of ultrabroadband infrared pulses is implemented with GaSe crystals. Via phase matching, we extend the detectable frequency range toward the near infrared (lambda=2.5 mum) and directly record transform-limited pulses as short as 28 fs with a 3 dB bandwidth of 41 THz. The continuous tunability of the center frequency over a wide interval ranging from 31 THz to the far-infrared is demonstrated using thick sensors. (C) 2004 American Institute of Physics.