EGAS41 - Swansea University

41 st EGAS CP 59 Gdańsk 2009
Injection locking of a single ion regenerative oscillator
S. Knünz 1,∗ , M. Herrmann 1 , V. Batteiger 1 , G. Saathoff 1 , Th. Udem 1 , K. Vahala 2 ,
T.W. Hänsch 1
1 Max-Planck-Institut für Quantenoptik 85748 Garching, Germany
2 California Institute of Technology, Pasadena, CA 91125
∗ Corresponding author: sknuenz@mpq.mpg.de,
Injection locking (or entrainment) of oscillators has important and widespread technological
applications. We present a study of injection locking in a particulary clean and
well controlled representation of an oscillator, a regeneratively oscillating single trapped
ion. In a first step we optically excite a regenerative oscillation of a 24 Mg + ion [1] using
both a blue and a red detuned laser beam. By controlling the detunings and intensities
of the beams we can vary the oscillation amplitude and quality factor of this oscillator.
In a second step we inject a RF signal using an auxillary electrode and phase-sensitively
detect fluorescence photons by gating our single photon camera accordingly. The phase
sensitive images allow to directly measure the average phase-lag of the ion relative to the
injected signal. We studied the locking range and relative phases for a variety of parameters
and find excellent agreement with the Adler [2] equations that describes injection
locking, both inside and outside the locking range.
0,50
Avg. Phase shift
0,25
0,00
-0,25
-0,50
48,5 49,0 49,5 50,0 50,5 51,0 51,5 52,0
Drive Frequency [kHz]
Figure 1: Average phase of a regenerative oscillating ion vs the injected frequency. Note the
locking range enclosed by the two extrema.
References
[1] M. Herrmann et al., PRL 102 (2009)
[2] R. Adler, Proc. IRE 34, 351-357 (1946)
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