Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

In the late 1980ies the photoconductive switch revolutionized science and technology in the previously underdeveloped terahertz spectral range [1]. With these devices it was for the first time possible to produce picosecond coherent pulses and to characterize them in amplitude and phase. We discuss how photoconductive THz emitters profit from the rapid development of femtosecond laser sources: Initially dye lasers were used, in the 1990ies Ti:sapphire lasers became the workhorse in many laboratories and GaAs-based photoconductive fitted perfectly to these sources. Later, fiber lasers operating at 1550 nm allowed for more compact systems while amplified lasers can provide high THz field amplitudes. We present large area antennas [2, 3] that circumvent the issue of saturation by screening which limits the performance of single dipole antennas. Furthermore, we discuss the role of the photoconductive material for THz generation. In particular, we show that the non-polar material Ge is suitable for generating ultrabroadband pulses ranging up to 70 THz without a gap region [4, 5].
[1] Ch. Fattinger and D. Grischkowsky, Appl. Phys. Lett. 53, 1460 (1988).
[2] A. Dreyhaupt, S. Winnerl, T. Dekorsy, and M. Helm, Appl. Phys. Lett. 86, 121114 (2005).
[3] S. Winnerl, J Infrared Milli Terahz Waves 33, 431 (2012).
[4] A. Singh, A. Pashkin, S. Winnerl, M. Helm and H. Schneider ACS Photonics 5, 2718 (2018).
[5] A. Singh, A. Pashkin, S. Winnerl, M. Welsch, C. Beckh, P. Sulzer, A. Leitenstorfer, M. Helm and H. Schneider, Light: Science & Applications 9, 30 (2020).