CW Type-II Second Harmonic Generation without Temperature Control

Setup of the build-up cavity. By placing a lambda/2 plate inside the cavity, the cavity is only closed after the second round trip.


Y. Emery, A. Fleischhauer, Th. Walther and E.S. Fry, Angle Tuned, type-II, external cavity frequency doubling without temperature stabilization, Appl. Opt. 38 (1999) 972

CW Type-I Second Harmonic Generation

We routinely frequency double and quadruple (via two consecutive SHG) the output radiation of our home built laser systems such as fiber amplified ECDL sources.


Efficiency and Output Power of our fiber amplified ECDL at 1028 nm frequency doubled to 514 nm (left) Latest generation of our SHG cavities - in this case it is a build up cavity for 870 nm light and a KNbO3 crystal.


By a customized, very compact design of our frequency conversion unit we achieved high conversion efficiencies for second harmonic, third harmonic and fourth harmonic generation. Dual-wave plates (acting as lambda waveplates for the fundamental and lambda/2-plates for the harmonic) are placed in between non-linear crystals in order to use type-I processes in each step.

Output of our multiple frequency conversion unit for 8-ns laser pulses at 789.2 nm. The output is dispersed with a prism showing the fundamental, the second harmonic, the third-harmonic (SFG of the fundamental and the second-harmonic) and the fourth harmonic (SFG of the third harmonic and the fundamental). (Photograph by T. Beck)


T. Beck, Master Thesis, Darmstadt, 2009

C. Tian, Th. Walther, R. Nicolaescu, X.J. Pan, Y. Liao and E.S. Fry, Synchronous, dual-wavelength, injection-seeded amplification of 5 ns pulses in a flashlamp-pumped Ti:sapphire laser, Opt. Lett. 24 (1999) 1496-1498

D. Depenheuer, J. Kohl-Landgraf, H. Gläßer, Th. Walther, A pulsed laser system with large spectral coverage by nonlinear frequency conversion, appeared Applied Physics B (2009)



Prof. Dr. Thomas Walther

Laser und Quantenoptik
Institut für Angewandte Physik
Fachbereich 05 - Physik
Technische Universität Darmstadt
Schlossgartenstr. 7
D-64289 Darmstadt

+49 6151 16-20831 (Sekretariat)

+49 6151 16-20834 (Fax)




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