Bulletin of the American Physical Society
40th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 54, Number 7
Tuesday–Saturday, May 19–23, 2009; Charlottesville, Virginia
Session L2: Focus Session: Laser Frequency Combs and Applications |
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Sponsoring Units: GPMFC Chair: Jun Ye, JILA Room: Gilmer Hall 130 |
Thursday, May 21, 2009 2:00PM - 2:30PM |
L2.00001: Laser frequency combs for precision astrophysical spectroscopy Invited Speaker: Precision astrophysical spectroscopy is a crucial tool for cosmology and the search for extrasolar planets, but is currently limited by the stability and precision of existing wavelength calibration sources. I will describe our realization of a near-IR laser comb with up to 40 GHz line-spacing, generated from a 1-GHz repetition-rate source comb and Fabry-Perot filtering cavity; the ongoing integration and testing of this ``astro- comb'' with a telescope and precision spectrograph at the Whipple Observatory, directed at searches for extrasolar planets; and efforts toward development of astro- combs operating in the visible. Astro-combs should allow more than an order-of- magnitude improvement in sensitivity to changes in Doppler-shifts and cosmological redshifts, with significant impact on many fields. [Preview Abstract] |
Thursday, May 21, 2009 2:30PM - 3:00PM |
L2.00002: Fibers and combs: weaving a portable frequency reference in the near-IR Invited Speaker: Ten years after the advent of femtosecond optical frequency combs, they are now used for many applications. Here, we use near infrared combs to characterize and develop portable frequency references based on gas-filled hollow optical fibers. We explore the accuracy and stability of saturated absorption features in acetylene gas confined inside both 10 micron core diameter photonic bandgap fibers and $\sim $60 micron core diameter kagome-structured photonic crystal fibers. A cw fiber laser referenced to these features has resulted in stabilities of $\sim $10$^{-11}$ in 1 s, competitive with iodine-stabilized HeNe lasers. Most of these studies have been performed using a femtosecond fiber laser that relies on a carbon nanotube saturable absorber. However, we have also explored Cr:forsterite femtosecond lasers with intracavity prisms, which reveal dramatic narrowing of the carrier-envelope offset beat when a knife edge is inserted in the cavity. Such observations and subsequent noise dynamics studies will lead to a better understanding of noise in these solid state combs, making Cr:forsterite laser combs more competitive for spectroscopy and other applications. [Preview Abstract] |
Thursday, May 21, 2009 3:00PM - 3:12PM |
L2.00003: Experimental Progress on the NIST $^{27}$Al$^{+}$ Optical Clock Chin-wen Chou, David B. Hume, Jeroen C.J. Koelemeij, Till Rosenband, James C. Bergquist, Dave J. Wineland A recent measurement of the frequency ratio between single-ion optical clocks based on $^{27}$Al$^{+}$ and $^{199}$Hg$^{+}$ at NIST showed a combined statistical and systematic uncertainty of 5.2 $\times $ 10$^{-17}$[1]. Here we report progress on improving both the accuracy and stability of the $^{27}$Al$^{+}$ optical clock. We have developed a new trap and laser systems that enable the use of $^{25}$Mg$^{+}$ for sympathetic cooling and clock-state detection of $^{27}$Al$^{+}$. These developments should reduce time-dilation shifts caused by harmonic motion of the ions and thus lower the dominant systematic uncertainty below 10$^{-17}$. In the new clock apparatus we have demonstrated spectroscopy of the $^{27}$Al$^{+}$ $^{1}$S$_{0}$ to $^{3}$P$_{0}$ transition with a quality factor of Q = 3.5 $\times $ 10$^{14}$ and simultaneously a contrast approaching unity. In addition, we have developed techniques for the sympathetic laser cooling and quantum logic spectroscopy of multiple aluminum ions with the goal of further improving measurement stability [2]. *supported by ONR and NIST [1] T. Rosenband et al., Science \textbf{319}, 1808 (2008) [2] D. B. Hume et al., Phys. Rev. Lett. \textbf{99}, 120502 (2007) [Preview Abstract] |
Thursday, May 21, 2009 3:12PM - 3:24PM |
L2.00004: A Spin-1/2 Optical Lattice Clock based on Yb Atoms Nathan Lemke, Andrew Ludlow, Zeb Barber, Yanyi Jiang, Tara Fortier, Scott Diddams, Chris Oates The $^{1}$S$_{0}-^{3}$P$_{0}$ transition in lattice-confined alkaline earth-(like) atoms has become a prime candidate for the next generation of optical frequency standards. To date, the work on lattice clocks has centered on bosonic atoms with no angular momentum (I=0) and on fermionic atoms with high angular momentum (I=9/2). Here we report on a different type of fermionic system, $^{171}$Yb (I=1/2). Such a system has several advantages over higher angular momentum systems, including its simple structure and straightforward manipulation of the nuclear spin state, while not suffering from spectroscopic field shifts that may limit the accuracy of clocks based on bosonic atoms. We have completed a frequency evaluation of the clock transition in $^{171}$Yb with a systematic uncertainty of 3.6 x 10$^{-16}$. [Preview Abstract] |
Thursday, May 21, 2009 3:24PM - 3:36PM |
L2.00005: Novel high power femtosecond laser system and progress towards improved EUV fs frequency combs Jason Jones, Jane Lee, Justin Paul The development of femtosecond frequency combs has had a dramatic impact in ultrafast science and optical frequency metrology. Recent work has demonstrated that the coherent comb-like structure can be extended into the vacuum and extreme ultraviolet regimes utilizing fs enhancement cavities and intracavity high harmonic generation. This offers the potential to open the field of precision frequency metrology to previously unexplored regimes. The development of higher power fs comb sources can greatly alleviate the design constraints on the fs enhancement cavities and aid in greatly improving the efficiency of this approach. We generate a record 7 Watts average power from a Ti:s fs frequency comb by optical injection-locking an amplification cavity, enabling efficient power scaling of fs frequency combs in bulk solid-state systems. We will present our current progress in utilizing this source with modified designs for a fs enhancement cavity to generate fs frequency in the EUV utilizing intracavity high harmonic generation. [Preview Abstract] |
Thursday, May 21, 2009 3:36PM - 3:48PM |
L2.00006: Cesium atom ground state coherence created by an optical frequency comb laser Wang-Yau Cheng, Tsung-Han Wu, Sheng-Huei Lu Quantum interference resolved by the coherent laser modes from a mode-locked laser is significant in demonstrating femtosecond-laser based high resolution spectroscopy. Moreover, the high Q frequency discriminator resulted from quantum interference phenomenon could possibly serve for comb laser repetition rate stabilization. We discovered a 5-Hz width transparent window when the repetition rate of our optical frequency comb laser [1] was adjusted to be on resonance of cesium atom ground state hyperfine transition. We showed that cesium atom ground state coherence might be created by the comb laser modes, based on the observation of Zeeman effects. We performed our experiment with 8700 Pascal Neon buffer gas and 100$^{\circ}$C (1 mK instability) wall temperature. Frequency shift by wall temperature and the other effects will be presented.\\[3pt] [1] Appl. Phys. B \textbf{92}, 13-18 (2008). [Preview Abstract] |
Thursday, May 21, 2009 3:48PM - 4:00PM |
L2.00007: Optical frequency comb control of Raman transitions in the presence of decoherence Svetlana Malinovskaya Theoretical studies are presented on the optical frequency comb interaction with the three-level $\lambda$-system in the presence of decoherence caused by vibrational energy relaxation and collisional dephasing. The exact numerical solutions are obtained without taking into account the rotating wave approximation and adiabatic elimination of transitional states. The resonant and nonresonant Raman scattering is analysed. The interplay of the frequency comb parameters and the properties of the material system is revealed showing the conditions for predetermined population dynamics. The control parameters of the frequency comb include the single pulse duration, the pulse train period, the single-photon detuning and the phase variation across an individual pulse in various forms. [Preview Abstract] |
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