The Magneto-Optical Traps (MOTs) described in the following two articles are cooled by three DBR lasers tuned to a Rb transition.
After successfully miniaturizing both clocks and magnetometers based on the properties of individual atoms, NIST physicists have now turned to precision gyroscopes, which measure rotation.
Compact atom-interferometer gyroscope based on an expanding ball of atoms
S Riedl, G W Hoth, B Pelle, J Kitching and E A Donley, Time and Frequency Division, National Institute of Standards and Technology, Boulder, CO, USA
8th Symposium on Frequency Standards and Metrology 2015 IOP Publishing Journal of Physics: Conference Series 723 (2016) 012058. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd.
Abstract. We present a compact atom interferometer based on 87Rb atoms that can simultaneously measure rotations and accelerations with a single expanding ball of atoms in a 300 cm3 vacuum package.
Operating Atomic Fountain Clock using robust DBR Laser: Short-Term Stability Analysis
Sangmin Lee* **, Myoung-Sun Heo*, Taeg Yong Kwon*, Hyun-Gue Hong*, Sang-Bum Lee*, Ashby Hilton***, Andre N. Luiten***, John G. Hartnett***, and Sang Eon Park**
Proceedings of the 2016 Conference on Precision Electromagnetic Measurements, as published in CPEM digest, 2016, pp. 1-2
Abstract. We operate an atomic fountain clock KRISS-F1 using a laser system based on a DBR (Distributed Bragg Reflector) laser. We have found that there is no major difference in the fountain performance between laser systems with an ECDL (Extended-Cavity Diode Laser) and the DBR laser, even though spectral properties of the DBR is worse than that of ECDL. Moreover, quantum projection-noise limited stability is observed using DBR lasers. After replacing the ECDL to the DBR laser, laser system of the fountain clock became robust against acoustic and vibration noise mainly from mechanical shutters. Therefore, currently KRISS-F1 can be operated without failure of laser locking.
* S. Lee, M.-S Heo, T.Y. Kwon, H.G. Hong, S.-B Lee, and S.E. Park are supported by the Korea Research Institute of Standards and Science.
** S. Lee and S.E. Park are with the Science of Measurements, University of Science and Technology (UST), Daejeon 34113 Korea
***A. Hilton, A.N. Luiten and J.G. Hartnett are with the Institute of Photonics and Advanced Sensing, School of Chemistry and Physics, University of Adelaide, South Australia, Australia
Differential Absorption lidar demands high-power, narrowband DBR sources
Water vapor plays a role in many atmospheric processes and is a primary driver of weather. Atmospheric water-vapor concentrations span more than four orders of magnitude from the planetary boundary layer—where high-impact weather initiates—to lower levels in the upper troposphere and lower stratosphere, where water vapor has significant and long-term impacts on the Earth’s radiation budget. NASA Langley has been fielding airborne water-vapor differential-absorption lidar (DIAL) systems for more than 30 years in support of atmospheric chemistry, high-impact weather, and climate process studies, with an end goal of implementing a water-vapor DIAL system in space for weather and climate applications. In collaboration with the National Center for Atmospheric Research (NCAR) and Montana State University, NASA researchers are also working towards implementing a nationwide water-vapor-profiling network to improve weather forecasting and climate modeling with an automated,eye-safe, lowcost, and compact ground-based watervapor DIAL system. NASA recognizes that the airborne-, space-,and groundbased water-vapor DIAL systems share a common requirement for frequency-agile, narrowband, rugged seed lasers that are used to injection- seed higher-power pulsed lasers. A differential absorption lidar (DIAL) system has been developed by NASA using Photodigm distributed Bragg reflection (DBR) injection-seed lasers.
Time Domain diffuse correlation spectroscopy
Jason Sutin, Bernhard Zimmerman, Danil Tyulmankov, Davide Tamborini, Kuan Cheng Wu, Juliette Selb, Angelo Gulinatti, Ivan Rech, Alberto Tosi, David A. Boas, and Maria Angela Franceschini
Optica 3, 1006-1013 (2016)
Physiological monitoring of oxygen delivery to the brain has great significance for improving the management of patients at risk for brain injury. Diffuse correlation spectroscopy (DCS) is a rapidly growing optical technology able to non-invasively assess the blood flow index (BFi) at the bedside. The current limitations of DCS are the contamination introduced by extracerebral tissue and the need to know the tissue’s optical properties to correctly quantify the BFi. To overcome these limitations, we have developed a new technology for time-resolved diffuse correlation spectroscopy. By operating DCS in the time domain (TD-DCS), we are able to simultaneously acquire the temporal point-spread function to quantify tissue optical properties and the autocorrelation function to quantify the BFi. More importantly, by applying time-gated strategies to the DCS autocorrelation functions, we are able to differentiate between short and long photon paths through the tissue and determine the BFi for different depths. Here, we present the novel device and we report the first experiments in tissue-like phantoms and in rodents. The TD-DCS method opens many possibilities for improved non-invasive monitoring of oxygen delivery in humans.
© 2016 Optical Society of America
Christoph Przeszlakowski of Hanel-Photonics in Berlin has surveyed manufacturers of single frequency lasers and reports their range of powers over the 400 to 2800 nm range. Check out his review on this link
Sequentially Shifted Excitation Raman Spectroscopy: Novel Algorithm and Instrumentation for Fluorescence-Free Raman Spectroscopy in Spectral Space
John B. Cooper, Mohamed Abdelkader, Kent L. Wise
Applied Spectroscopy 67:973 (2013)
A novel Raman spectrometer is presented in a handheld format. The spectrometer utilizes a temperature-controlled, distributed Bragg reflector diode laser, which allows the instrument to operate in a sequentially shifted excitation mode to eliminate fluorescence backgrounds, fixed pattern noise, and room lights, while keeping the Raman data in true spectral space. The cost-efficient design of the instrument allows rapid acquisition of shifted excitation data with a shift time penalty of less than 2 s. The Raman data are extracted from the shifted excitation spectra using a novel algorithm that is typically three orders of magnitude faster than conventional shifted-excitation algorithms operating in spectral space. The superiority of the instrument and algorithm in terms of background removal and signal-to-noise ratio is demonstrated by comparison to FT-Raman, standard deviation spectra, shifted excitation Raman difference spectroscopy (SERDS), and conventional multiple-shift excitation methods.
Spatially compressed dual-wavelength excitation Raman spectrometer
John B. Cooper, Sarah Marshall, Richard Jones, Mohamed Abdelkader, and Kent L. Wise
Applied Optics, Vol. 53, Issue 15, pp. 3333-3340 (2014)
The design and operation of a novel dual-laser excitation Raman instrument is described. The use of two lasers of differing wavelengths allows for a Raman spectrum covering all fundamental modes of vibration to be collected while minimizing fluorescence and allowing for spatial compression of the spectrum on an imaging detector. The use of diode lasers with integrated distributed Bragg reflector gratings facilitates the use of an integrated thermoelectric cooler to allow collection of shifted excitation spectra for both of the lasers, further enhancing the rejection of fluorescence. An example is given, which uses seven excitation wavelengths for each laser to reconstruct the Raman spectrum of a solvent in the presence of a highly fluorescent dye by using a sequentially shifted excitation Raman reconstruction algorithm.
Sequentially Shifted Excitation Raman Spectroscopy
John B. Cooper, Kent L. Wise, Richard W. Jones, Sarah Marshall
A method for removing fluorescence-induced backgrounds from Raman spectra using sequentially shifted excitation (SSE) is described. The SSE method generates Raman spectra in true spectral space and does not require the generation (and subsequent reconstruction) of derivative spectra used in shifted excitation Raman difference spectroscopy (SERDS). This feature of SSE Raman spectroscopy results in improved signal-to-noise ratios compared to traditional fluorescence rejection methods while providing instrument-limited bandwidth resolution. In this work, a temperature-tuned, distributed Bragg reflector diode laser is used to produce the multiple excitation spectra required to implement the SSE algorithm. Examples applying the SSE method to analysis of motor oils and edible oils are given.
Long-external-cavity distributed Bragg reflector laser with subkilohertz intrinsic linewidth
Qian Lin, Mackenzie A. Van Camp, Hao Zhang, Branislav Jelenković, and Vladan Vuletić
Optics Letters 37:1989 (2012)
We report on a simple, compact, and robust 780 nm distributed Bragg reflector laser with subkilohertz intrinsic linewidth. An external cavity with optical path length of 3.6 m, implemented with an optical fiber, reduces the laser frequency noise by several orders of magnitude. At frequencies above 100 kHz the frequency noise spectral density is reduced by over 33 dB, resulting in an intrinsic Lorentzian linewidth of 300 Hz. The remaining lowfrequency noise is easily removed by stabilization to an external reference cavity. We further characterize the influence of feedback power and current variation on the intrinsic linewidth. The system is suitable for experiments requiring a tunable laser with narrow linewidth and low high-frequency noise, such as coherent optical communication, optical clocks, and cavity QED experiments.
Photodigm DBR laser value proposition: "The DIAL technique requires a pulsed laser with high spectral fidelity and frequency agility, capable of operating at two separate wavelengths" (Spuler et al., 2015).
See the Image Gallery from the NCAR/UCAR Earth Observing Laboratory showing water vapor DIAL in the field.
Diode-laser-based water vapor differential absorption lidar (DIAL) profiler evaluation
Scott Spuler, Tammy Weckwerth, and Richard Carbone: National Center for Atmospheric Research (NCAR), Boulder, Colorado; Kevin Repansky: Montana State University (MSU), Bozeman, Montana; Amin Nehrir: National Aeronautics and Space Administration (NASA) Langley Research Center, Hampton, Virginia.
Progress toward an Autonomous Field Deployable Diode-Laser-Based Differential Absorption Lidar (DIAL) for Profiling Water Vapor in the Lower Troposphere
Kevin S. Repasky and Drew Moen: Electrical and Computer Engineering, Montana State University, Bozeman, MT; and Scott Spuler: National Center for Atmospheric Research (NCAR), Boulder, Colorado; Amin R. Nehrir: National Aeronautics and Space Administration (NASA) Langley Research Center, Hampton, Virginia; and John L. Carlsten: Physics Department, Montana State University, Bozeman, MT.
Remote Sens. 2013, 5, 6241; doi: 10.3390/rs5126241
Field-deployable diode-laser-based diferential absorption lidar (DIAL) for profiling water vapor
S.M. Spuler, K.S. Repasky, B. Morley, D. Moen, M. Hayman, and A.R. Nehrir, Atmos. Meas.Tech., 8, 1073-1087, 2015; www. atmos-meas-tech.net/8/1073/2015/
Progress on a Miniature Cold-Atom Frequency Standard
Scherer, David R., Lutwak, Robert, Mescher, Mark, Stoner, Richard, Timmons, Brian, Rogomentich, Fran, Tepolt, Gary, Mahnkopf, Sven, Noble, Jay, Chang, Sheng, Taylor, Dwayne, "Progress on a Miniature Cold-Atom Frequency Standard," Proceedings of the 46th Annual Precise Time and Time Interval Systems and Applications Meeting, Boston, Massachusetts, December 2014, pp. 154-163. arXiv:1411.5006v1
Measurement of hyperfine splitting and determination of hyperfine structure constant of cesium 8S1/2 state by using of ladder-type EIT
Jie Wang, Junmin Wang, Huifeng Liu, Baodong Yang, and Jun He: Shan Xi University, Tai Yuan, China.
Proc. of SPIE Vol. 89773 877311-1 doi:10.1117/12.2016842