Broadband and narrowband terahertz generation and detection in GaSe1−x S x crystals

Terahertz wave generation through optical rectification of femtosecond laser pulses and its detection in GaSe and GaSe1−x S x crystals with a relatively low (x = 0.04) and high (x = 0.29) content of sulfur was studied. The decrease of terahertz generation and detection efficiency at an increase of sulfur content in GaSe1−x S x was observed. The phase-matching conditions for electro-optical sampling in GaSe and GaSe1−x S x crystals were analyzed. The arising possibility to achieve the narrowing of terahertz detection bandwidth using thicker GaSe crystals was experimentally confirmed.