Hannover 2010 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 67: Photonics IV
Q 67.5: Vortrag
Freitag, 12. März 2010, 15:00–15:15, F 128
Frequency Stable Fiber Ring Laser based on Whispering Gallery Modes — •Benjamin Sprenger, Harald G. L. Schwefel, and Lijun Wang — MPI für die Physik des Lichts, Günther-Scharowsky-Str. 1 / Bau 24, D-91058 Erlangen, Deutschland
We use high quality (Q) factor whispering gallery mode resonances in microspheres to stabilize a fiber loop laser. Microspheres are created by melting the tips of standard 1550 nm fibers, and can have Q factors up to 108. We evanescently couple into the high Q modes of such a sphere using a tapered fiber, and out using a fiber polished at a sharp angle. By including this frequency selective element into a fiber loop laser we manage to stabilize the laser to single-mode emission. The linewidth is determined to be 170 kHz, limited by the resolution of a heterodyne beat measurement with a grating stabilized diode laser. This corresponds to a Q factor of 109, and is five orders of magnitude larger than in the unstabilized regime. Additionally, we observe a red-shift with increasing pump intensity due to the thermo-refractive index inside the microsphere. Further experiments will focus on a more rigid coupling design to prevent the slight drift of the emission, as well as investigation of the linewidth and quantum behavior.