Abstract-Terahertz generation in lithium niobate driven by Ti:sapphire laser pulses and its limitations

Xiaojun Wu, Sergio Carbajo, Koustuban Ravi, Frederike Ahr, Giovanni Cirmi, Yue Zhou, Oliver D. Mücke, and Franz X. Kärtner  »View Author Affiliations

http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-39-18-5403

Optics Letters, Vol. 39, Issue 18, pp. 5403-5406 (2014)
http://dx.doi.org/10.1364/OL.39.005403

We experimentally investigate the limits of 800-nm-to-terahertz (THz) energy conversion in lithium niobate at room temperature driven by amplified Ti:sapphire laser pulses with tilted pulse front. The influence of the pump central wavelength, pulse duration, and fluence on THz generation is studied. We achieved a high peak efficiency of 0.12% using transform limited 150 fs pulses and observed saturation of the optical-to-THz conversion efficiency at a fluence of 15  mJ/cm2 for this pulse duration. We experimentally identify two main limitations for the scaling of optical-to-THz conversion efficiencies: (i) the large spectral broadening of the optical pump spectrum in combination with large angular dispersion of the tilted pulse front and (ii) free-carrier absorption of THz radiation due to multi-photon absorption of the 800 nm radiation.

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