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HL: Halbleiterphysik
HL 41: Ultrakurzzeitph
änomene II
HL 41.11: Talk
Friday, March 30, 2001, 14:00–14:15, S9/10
Increased THz emitter efficiency by coherent superposition in a high repetition rate resonator — •C. Janke1, P. Haring Bolivar1, A. Bartels1, H. Kurz1, and H. Künzel2 — 1Institut für Halbleitertechnik II, RWTH Aachen, D-52074 Aachen — 2Heinrich-Hertz-Institut für Nachrichtentechnik, D-10587 Berlin
The wide range of attractive applications of time domain THz sensing is strongly hampered by the low conversion efficiency of optically excited THz emitters. Considerable amount of interest is therefore directed towards possible ways of increasing the THz emitter efficiency. We follow the approach of exposing the emitter to a coherent phasematched THz background field during the emission process in order to radiate more energy before dephasing occurs, thereby amplifying the amount of coherently emitted THz radiation [1]. In this presentation we discuss recent experiments where a surface field emitter is placed in a high repetition rate THz resonator and synchronously pumped with a high repetition rate (1 GHz) Ti:sapphire laser source [2]. In contrast to previous approaches [3], the oberserved efficiency increase overcomes the resonator losses and outcoupling ratio an hence yields a net extra-cavity efficiency increase for the first time. We estimate that by optimizing resonator and emitter design a further enhancement of the emitter efficiency by at least one order of magnitude is feasible.
[1] R. Martini,F. Hilbk-Kortenbruck, P. Haring Bolivar, H. Kurz in Sixth Int. Conf. on THz Electr. Proc., IEEE, New York, 1998
[2] A. Bartels, T. Dekorsy, H. Kurz, Opt. Lett. 24, 996 (1999)
[3] P. Haring Bolivar, R. Martini, H. Kurz, SPIE vol. 3828, 228 (1999)