Terahertz Technology – Pulsed THz Generation
Principle of time domain terahertz generation. The laser pulse has a spectral width of approx. 10 nm or 5 THz.
Pulsed Terahertz Generation
- Optical rectification or photoconductive switches
- TOPTICA’s ultrafast fiber lasers: 780 and 1560 nm, < 100 fs
- 50 kW peak power, up to 350 mW average power
- Optional: ECOPS technique, replacing mechanical delay line
Pulsed terahertz radiation is generated with femtosecond lasers. The ultrashort laser pulses are focused on an antenna device, generating a fast current transient. This leads to the emission of electromagnetic wave packets with a broad spectrum in the terahertz range.
The most established emitter technologies are based on GaAs or InP antennae, requiring laser wavelengths around 800 nm or 1550 nm, respectively. Another common generation mechanism is optical rectification in nonlinear crystals, such as GaP, ZnTe or DAST.
All required wavelengths are conveniently accessible with TOPTICA’s FemtoFiber pro series. The Erbium based fiber lasers deliver more than 50 kW peak power and pulse widths well below 100 fs. 1560 nm and 780 nm outputs are available from one unit.
In time-domain spectroscopy, a terahertz pulse is sampled with a time-delayed copy of the excitation pulse. TOPTICA’s technique of electronically controlled optical sampling (ECOPS) offers a means for fast and accurate scanning, without any mechanical delay stage.
5 THz spectrum, acquired with the FemtoFiber pro laser. The dips are absorption lines of water vapor (courtesy of Otsuka Electronics).