DBR Lasers in Action

Recent articles describing work enabled by Photodigm DBR Lasers 


Atomic Sensors

Multiaxis atom interferometry with a single-diode laser and a pyramidal magneto-optical trap

Abstract:  Atom interferometry as become one of the most powerful technologies for precision measurements.  To develop simple, precise, and versatile atom interferometers for inertial sensing, we demonstrate an atom interferometer measuring acceleration, rotation, and inclination by pointing Raman beams toward individual faces of a pyramidal mirror.  Only a single-diode laser is used for all functions, including atom trapping, interferometry, and detection.  ...  This work paves the way toward deployable multiaxis atom interferometers for geodesy, geology, or intertial navigation.  

Xuejian Wu1, Fei Zi1,2, Jordan Dudley1, Ryan J. Bilotta1, Philip Canoza1, and Holger Muller1,3, Optica, 4:1545 (2017).  https://doi.org/10.1364/OPTICA.4.001545

1.  Department of Physics, University of California, Berkeley, California 94720, USA

2.  Institute of Optics, Department of Physics, Zhejiang University, Hangzhou 310058, China

3.  Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California 94720.  

The Magneto-Optical Traps (MOTs) described in the following two articles are cooled by three DBR lasers tuned to a Rb transition.  

NIST's Compact Gyroscope May Turn Heads

Abstract. 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.

-- Photonics OnLine News, August 23, 2016. 

Compact atom-interferometer gyroscope based on an expanding ball of atoms

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. 

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)   

Operating Atomic Fountain Clock using robust DBR Laser:  Short-Term Stability Analysis

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.

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

* 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

Atmospheric Monitoring of Water Vapor Profiles using Differential Absorprtion Lidar (DIAL)

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).

Differential Absorption lidar demands high-power, narrowband DBR sourcesPhotodigm Water Vapor DIAL - Laser Focus World.jpg

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, low cost, and compact ground-based water vapor DIAL system. NASA recognizes that the airborne-, space-,and ground based 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.

Gail Overton, Laser Focus World, September 2016, page 14

Diode-laser-based water vapor differential absorption lidar (DIAL) profiler evaluation

Background. We are evaluating the performance of an eye-safe, low-cost, diode-laser-based, water vapor differential absorption lidar. This class of instrument may be capable of providing continuous water vapor and aerosol backscatter profiles at high vertical resolution in the atmospheric boundary layer for periods of months to years.The technology potentially fills a national long term observing facility gap and could greatly benefit micro- and meso-meteorology, water cycle, carbon cycle and, more generally, biosphere-hydrosphere-atmosphere interaction research at both weather and climate variability time scales.

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.  ePoster, AGU Fall Meeting, 2012 

Progress toward an Autonomous Field Deployable Diode-Laser-Based Differential Absorption Lidar (DIAL) for Profiling Water Vapor in the Lower Troposphere

Abstract. A laser transmitter has been developed and incorporated into a micro-pulse differential absorption lidar (DIAL) for water vapor profiling in the lower troposphere as an important step towards long-term autonomous field operation. The laser transmitter utilizes two distributed Bragg reflector (DBR) diode lasers to injection seed a pulsed tapered semiconductor optical amplifier (TSOA), and is capable of producing up to 10 mJ of pulse energy with a 1 ms pulse duration and a 10 kHz pulse repetition frequency. The on-line wavelength of the laser transmitter can operate anywhere along the water vapor absorption feature centered at 828.187 nm (in vacuum) depending on the prevailing atmospheric conditions, while the off-line wavelength operates at 828.287 nm. This laser transmitter has been incorporated into a DIAL instrument utilizing a 35.6 cm Schmidt-Cassegrain telescope and fiber coupled avalanche photodiode (APD) operating in the photon counting mode. The performance of the DIAL instrument was demonstrated over a ten-day observation period. During this observation period, data from radiosondes were used to retrieve water vapor number density profiles for comparisons with the number density profiles retrieved from the DIAL data.

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 differential absorption lidar (DIAL) for profiling water vapor

Abstract. A field-deployable water vapor profiling instrument that builds on the foundation of the preceding generations of diode-laser-based differential absorption lidar (DIAL) laboratory prototypes was constructed and tested. Significant advances are discussed, including a unique shared telescope design that allows expansion of the outgoing beam for eye-safe operation with optomechanical and thermal stability; multistage optical filtering enabling measurement during daytime bright-cloud conditions; rapid spectral switching between the online and offline wavelengths enabling measurements during changing atmospheric conditions; and enhanced performance at lower ranges by the introduction of a new filter design and the addition of a wide field-of-view channel. Performance modeling, testing, and intercomparisons are performed and discussed. In general, the instrument has a 150 m range resolution with a 10 min temporal resolution; 1 min temporal resolution in the lowest 2 km of the atmosphere is demonstrated. The instrument is shown capable of autonomous long-term field operation – 50 days with a > 95% uptime – under a broad set of atmospheric conditions and potentially forms the basis for a ground-based network of eye-safe autonomous instruments needed for the atmospheric sciences research and forecasting communities.

S.M. Spuler, K.S. Repasky, B. Morley, D. Moen, M. Hayman, and A.R. Nehrir, Atmos. Meas.Tech., 8, 1073-1087, 2015

 See the Image Gallery from the NCAR/UCAR Earth Observing Laboratory showing water vapor DIAL in the field. 

Quantitative Profiling of Clouds and Aerosols

Demonstration of a diode-laser-based High Spectral Resolution Lidar (HSRL) for quantitative profiling of clouds and aerosols

Matthew Hayman and Scott Spuler, Optics Express 25, A1096-A1110  (2017)


We present a demonstration of a diode-laser-based high spectral resolution lidar.  It is capable of performing calibrated retrievals of aerosols and cloud optical properties at a 150 m range resolution ... over an approximate range of 12 km...The instrument operates at 780 nm, a wavelength that is well established for reliable semiconductor lasers and detectors.  ... A heated vapor reference cell of isotopic rubidium 87 is used as an effective and reliable aerosol signal blocking filter in the instrument. ...

Laser-Induced Fluorescence of Sulfur Dioxide in the Atmosphere

A laser-induced fluorescence instrument for aircraft measurements of sulfur dioxide in the upper troposphere and lower stratosphere

Andrew W. Rollins, Troy D. Thornberry, Steven J. Ciciora, Richard J. McLaughlin, Laurel A. Watts, Thomas F. Hanisco, Esther Baumann, Fabrizio R. Giorgetta, Thaopaul V. Bui, David W. Fahey, and Ru-Shan Gao, Atmos. Meas. Tech. 9, 4601-4613 (2016)


This work describes the development and testing of a new instrument for in situ measurements of sulfur dioxide (SO2) on airborne platforms in the upper troposphere and lower stratosphere.  The instrument is based on the laser-induced fluorescence technique and uses the fifth of a tunable fiber amplified semiconductor diode laser system at 1084.5 nm to excite SO2 at 216.9 nm.  ...

Physiological Monitoring of Oxygen Delivery to the Brain

Development and characterization of a multi distance and multi wavelength diffuse correlation spectroscopy system

Davide Tamborini, Parisa Farzam, Bernard Zimmermann, Kuan-Cheng Wu,  David A. Boas, and Maria Angela Franceschini

 Neurophoton. 5(1), 011015 (2017)

doi: 10.1117/1.NPh.5.1.011015

Abstract. This paper presents a multidistance and multiwavelength diffuse correlation spectroscopy (DCS)approach and its implementation to simultaneously measure the optical proprieties of deep tissue as well asthe blood flow. The system consists of three long coherence length lasers at different wavelengths in thenear-infrared, eight single-photon detectors, and a correlator board. With this approach, we collect both lightintensity and DCS data at multiple distances and multiple wavelengths, which provide unique information tofit for all the parameters of interest: scattering, blood flow, and hemoglobin concentration. We present the characterizationof the system and its validation with phantom measurements. © The Authors. Published by SPIE under a CreativeCommons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication,including its DOI. [DOI: 10.1117/1.NPh.5.1.011015]

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)

doi: 10.1364/OPTICA.3.001006

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

Survey of  DBR/DFB Lasers, 400 to 2800 nm

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)

DOI: 10.1366/12-06852

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.

Linewidth Narrowing

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 low-frequency 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.  

Atomic Physics

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

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