Broadband THz detection using GaSe crystals

We report the experimental results of using GaSe crystals for the tunable broadband detection of terahertz (THz) waves from 100 GHz to 30 THz. The results indicate that a GaSe crystal is a good sensor crystal for broadband THz waves with a 10 fs laser system. In comparison, the THz wave field amplitude measured with a GaSe crystal exceeds that detected by a ZnTe crystal with comparable detection bandwidth. The central frequency of THz pulses detected by the GaSe crystal is tunable by tilting the angle about the vertical axis, which is perpendicular to the direction of the probe beam. This suggests that GaSe can be also used as a narrowband detector.