We report the application of electric-field-induced optical second-harmonic generation as a new technique for measuring the field of freely propagating terahertz radiation. Using silicon as the nonlinear medium, we demonstrate subpicosecond time resolution and a sampling signal that varies linearly with the terahertz electric field. This approach, which is attractive for centrosymmetric media, permits a significantly broadened class of materials to be exploited for free-space sampling measurements.
© 1998 Optical Society of America
(190.2620) Nonlinear optics : Harmonic generation and mixing
(240.4350) Optics at surfaces : Nonlinear optics at surfaces
(320.7110) Ultrafast optics : Ultrafast nonlinear optics
(350.5610) Other areas of optics : Radiation
Ajay Nahata and Tony F. Heinz, "Detection of freely propagating terahertz radiation by use of optical second-harmonic generation," Opt. Lett. 23, 67-69 (1998)