Precision measurement of ultralow losses of an asymmetric optical microcavity
ABSTRACT The losses of the transmission, absorption, and scattering of optical mirrors govern the extraction efficiency of a nonclassical state that is generated inside a cavity. By measuring the reflectivities and transmittances and the matching factors from both sides of a super-mirror-made microcavity at various mode-matching efficiencies, the transmission losses and the unwanted losses, including the absorption and scatter losses, of the left and right cavity mirrors were both determined at the parts-per-million level.
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ABSTRACT: We propose an experimental method with which all the following quantities can be determined separately: the intracavity loss and individual cavity-mirror transmittances of a monolithic Fabry-Perot cavity and furthermore the coupling efficiency between the cavity mode and the incident light. It is notable that the modified version of this method can also be applied to whispering-gallery-mode cavities. Using this method, we measured the intracavity losses of monolithic Fabry-Perot cavities made of Pr3+:Y2SiO5 at room temperature. The knowledge of the intracavity losses is very important for applications of such cavities, e.g., to quantum information technologies. It turns out that fairly high losses (about 0.1%) exist even for a sample with extremely low dopant concentration (2×10(-5) at. %). The experimental results also indicate that the loss may be mainly due to the bulk loss of Y2SiO5 crystal. The bulk loss is estimated to be 7×10(-4) cm(-1) (0.003 dB/cm) or lower.Optics Express 11/2010; 18(23):23763-75. DOI:10.1364/OE.18.023763 · 3.49 Impact Factor
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ABSTRACT: We demonstrate the trajectory measurement of the single neutral atoms deterministically using a high-finesse optical microcavity. The single atom strongly couples to the high-order transverse vacuum TEM10 mode, instead of the usual TEM00 mode, and the parameters of the system are (g10,κ,γ)=2π×(20.5,2.6,2.6) MHz. The atoms simply fall down freely from the magneto-optical trap into the cavity modes, and the trajectories of the single atoms are linear. The transmission spectra of atoms passing through the TEM10 mode are detected by single-photon counting modules and are well fitted. Thanks to the tilted cavity transverse TEM10 mode, which is inclined to the vertical direction ~45°, it helps us to eliminate the degenerate trajectory of the single atom falling through the cavity and to obtain a unique atom trajectory. An atom position with a high precision of 0.1 μm in the off-axis direction (axis y) is obtained, and a spatial resolution of 5.6 μm is achieved in a time interval of 10 μs along the vertical direction (axis x). The average velocity of the atoms is also measured from the atom transits, which determines independently the temperature of the atoms in a magneto-optical trap, 186±19 μK.Physical Review A 03/2011; 83(3). DOI:10.1103/PhysRevA.83.031804 · 2.81 Impact Factor
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ABSTRACT: Based on the real sense of the time-of-flight , we demonstrate an alternative method of measuring the temperature of cold atoms in magneto-optical traps (MOTs) using a high-finesse optical microcavity, which acts as a pointlike single-atom counter. A cloud of atoms trapped in magneto-optical traps is positioned about 5 mm above the cavity, and the atoms fall freely down through the cavity. The temperature of the cold atoms in the MOT is determined by counting the exact arrival times of the single atoms. A theoretical model based on a ballistic expansion of a cloud of trapped atoms falling in the earth’s gravitational field is used to fit the probability distribution of atom arrivals, and the fittings agree very well with the experimental results. This method could be used for systems with little room, where an extra probe beam is hard to involve, or with fewer atoms initially.Journal of the Optical Society of America B 03/2011; 28(4):667-670. DOI:10.1364/JOSAB.28.000667 · 1.97 Impact Factor