Hannover 2010 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 67: Photonics IV
Q 67.6: Talk
Friday, March 12, 2010, 15:15–15:30, F 128
Directional emission from Terahertz whispering gallery mode resonators — •Harald G. L. Schwefel1, Sascha Preu1, Sebastian T. Bauerschmidt1, Stefan Malzer1, Gottfried H. Döhler1, Hong Lu2, Arthur C. Gossard2, and Lijun Wang1 — 1MPI für die Physik des Lichts, Erlangen — 2Materials Department, Univ. of California, Santa Barbara, USA
High quality (Q) whispering gallery mode (WGM) resonators are known to feature extremely narrow frequency selectivity. Their azimuthal symmetry dictates however non-directional spatial emission. Theoretical studies predict that an inclusion of a finite scatterer inside the WGM resonator leads to directional emission [1]. In the THz domain, with millimeter wavelength, the accuracy requirements for fabricating such resonators are chiefly relaxed. Resonators in the optical domain, for comparison, require (sub-) nanometer accuracy. We report strong directional emission with a minimal loss in the Q factor from a 10 mm poly-ethylene disk including a 1 mm scatterer. For characterizing the resonator properties and emission pattern we use continuous-wave, room temperature operating Terahertz n-i-pn-i-p superlattice photomixer sources, pumped by two frequency off-set diode lasers operating at the telecommunication wavelength. The THz radiation is coupled into the resonators through the evanescent field of a thin dielectric waveguide and collected in the far-field with a Golay cell. Qualitative agreement of experiment and theoretical expectation will be reported.
[1] J. Wiersig and M. Hentschel, Phys. Rev. A 73, 031802 (2006).