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W. H. Burkett

Bio: W. H. Burkett is an academic researcher from University of Arkansas. The author has contributed to research in topics: Electromagnetically induced transparency & Laser linewidth. The author has an hindex of 7, co-authored 9 publications receiving 314 citations.

Papers
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Journal ArticleDOI
TL;DR: Cavity-linewidth narrowing in a ring cavity that is due to the high dispersion and reduced absorption produced by electromagnetically induced transparency in rubidium-atom vapor has been experimentally observed.
Abstract: Cavity-linewidth narrowing in a ring cavity that is due to the high dispersion and reduced absorption produced by electromagnetically induced transparency (EIT) in rubidium-atom vapor has been experimentally observed. The cavity linewidth with rubidium atoms under EIT conditions can be significantly narrowed. Cavity-linewidth narrowing was measured as a function of coupling beam power.

119 citations

Journal ArticleDOI
TL;DR: A maximal efficiency for generating the NDFWM signal exists for a moderate pump power in this double-L system of Rb atomic vapor.
Abstract: Nondegenerate four-wave mixing (NDFWM) in a double-? system of Rb atomic vapor was achieved for collinear pump fields. By comparison of different pump–probe configurations, direct experimental evidence of influence of coherent population trapping on the output power of the NDFWM signal was established. A maximal efficiency for generating the NDFWM signal exists for a moderate pump power in this double-? system.

118 citations

Journal ArticleDOI
TL;DR: In this article, a three-level $\ensuremath{\Lambda}$-type system of the rubidium $D1$ line is controlled by adjusting the linewidth of the pumping (coupling) laser.
Abstract: Resonance transmission in a three-level $\ensuremath{\Lambda}$-type system of the rubidium $D1$ line is controlled by adjusting the linewidth of the pumping (coupling) laser. With the change of pumping-laser linewidth from several MHz to about 100 MHz, the absorption reduction degrades from about 70% to less than 15%. The experimentally measured results are in good agreement with a simple theoretical calculation.

27 citations

Journal ArticleDOI
TL;DR: In this article, the spectral characteristics of a semiconductor laser are altered by injecting additional noise current into its current-drive port, and the conditions under which the line shape changes from a standard Lorentzian shape to a Gaussian shape as functions of laser power and noise current are investigated.
Abstract: The spectral characteristics of a semiconductor laser are altered by injecting additional noise current into its current-drive port. A continuously varying spectral linewidth from about 5 MHz to above 100 MHz is achieved experimentally in this semiconductor laser. The conditions under which the line shape changes from a standard Lorentzian shape to a Gaussian shape as functions of laser power and noise current are investigated and compared with an existing theoretical treatment.

18 citations

Journal ArticleDOI
TL;DR: In this paper, the authors made theoretical and experimental examinations of the cavity transmission with a highly dispersive intracavity multilevel atomic medium and found that the cavity linewidth can be made much narrower than the empty cavity linwidth.
Abstract: Atomic media inside an optical cavity can significantly alter the spectral response of the cavity. Both theoretical and experimental examinations are made of the cavity transmission with a highly dispersive intracavity multilevel atomic medium. It is found, owing to the reduced absorption and steep dispersion change accompanying electromagnetically induced transparency in such a multi-level atomic medium, that the cavity linewidth can be made much narrower than the empty cavity linewidth. Cavity linewidth narrowing is measured as a function of both the coupling beam power and the atomic density. These experimental results are in good agreement with the theoretical predictions.

16 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, a time-dependent analysis of four-wave mixing in an ultraslow-propagation regime was performed and the authors obtained the analytical expressions of pulsed probe laser, FWM-generated pulse, phase shifts and absorption coefficients, group velocities, and FWM efficiency.
Abstract: We perform a time-dependent analysis of four-wave mixing (FWM) in a double-$\ensuremath{\Lambda}$ system in an ultraslow-propagation regime and obtain the analytical expressions of pulsed probe laser, FWM-generated pulse, phase shifts and absorption coefficients, group velocities, and FWM efficiency. With these analytical expressions, we show that an efficiently generated FWM field can acquire the same ultraslow group velocity $({V}_{g}∕c\ensuremath{\sim}{10}^{\ensuremath{-}4}--{10}^{\ensuremath{-}5})$ and pulse shape of a probe pump and that the maximum FWM efficiency is greater than 25%, which is orders of magnitude larger than previous FWM schemes in the ultraslow-propagation regime.

402 citations

Journal ArticleDOI
05 Apr 2012-Nature
TL;DR: In this paper, the authors demonstrate a Raman super-radiant laser source in which spontaneous synchronization of more than one million rubidium-87 atomic dipoles is continuously sustained by less than 0.2 photons on average inside the optical cavity.
Abstract: The spectral purity of an oscillator is central to many applications, such as detecting gravity waves, defining the second, ground-state cooling and quantum manipulation of nanomechanical objects, and quantum computation. Recent proposals suggest that laser oscillators which use very narrow optical transitions in atoms can be orders of magnitude more spectrally pure than present lasers. Lasers of this high spectral purity are predicted to operate deep in the 'bad-cavity', or superradiant, regime, where the bare atomic linewidth is much less than the cavity linewidth. Here we demonstrate a Raman superradiant laser source in which spontaneous synchronization of more than one million rubidium-87 atomic dipoles is continuously sustained by less than 0.2 photons on average inside the optical cavity. By operating at low intracavity photon number, we demonstrate isolation of the collective atomic dipole from the environment by a factor of more than ten thousand, as characterized by cavity frequency pulling measurements. The emitted light has a frequency linewidth, measured relative to the Raman dressing laser, that is less than that of single-particle decoherence linewidths and more than ten thousand times less than the quantum linewidth limit typically applied to 'good-cavity' optical lasers, for which the cavity linewidth is much less than the atomic linewidth. These results demonstrate several key predictions for future superradiant lasers, which could be used to improve the stability of passive atomic clocks and which may lead to new searches for physics beyond the standard model.

361 citations

Proceedings Article
12 May 1991
TL;DR: In this article, the probe energy is increased to 150 n3 (10" W/cm ) and the absorption cross section at the transmission maximum increases by a factor of approximately 2.
Abstract: As stated in the text, Figs. 3 and 4 (transmission versus probe laser detuning) were taken at an energy of 10 nJ in a 0.5-mm-diam beam. We should have noted that when the probe energy is increased to 150 n3 (— 10" W/cm ) the absorption cross section at the transmission maximum increases by a factor of approximately 2. At this energy density, with or without the coupling laser present, transmitted probe energy is no longer linear with incident probe energy.

331 citations

Journal ArticleDOI
TL;DR: The LTRS system combines optical trapping and near-infrared Raman spectroscopy for manipulation and identification of single biological cells in solution and may provide a valuable tool for the study of fundamental cellular processes and the diagnosis of cellular disorders.
Abstract: We report on the development and testing of a compact laser tweezers Raman spectroscopy (LTRS) system. The system combines optical trapping and near-infrared Raman spectroscopy for manipulation and identification of single biological cells in solution. A low-power diode laser at 785 nm was used for both trapping and excitation for Raman spectroscopy of the suspended microscopic particles. The design of the LTRS system provides high sensitivity and permits real-time spectroscopic measurements of the biological sample. The system was calibrated by use of polystyrene microbeads and tested on living blood cells and on both living and dead yeast cells. As expected, different images and Raman spectra were observed for the different cells. The LTRS system may provide a valuable tool for the study of fundamental cellular processes and the diagnosis of cellular disorders.

311 citations

Journal Article
TL;DR: A Raman superradiant laser source is demonstrated in which spontaneous synchronization of more than one million rubidium-87 atomic dipoles is continuously sustained by less than 0.2 photons on average inside the optical cavity, and isolation of the collective atomic dipole from the environment is demonstrated by cavity frequency pulling measurements.

271 citations