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A Tunable Mode-Locked Ytterbium-Doped Fiber Laser Based on Nonlinear Kerr Beam Clean-Up Effect
A tunable mode-locked ytterbium-doped fiber laser based on nonlinear Kerr beam clean-up effect Shanchao Ma,1 Baofu Zhang,2,* Qiurun He,1 Jing Guo,3 and Zhongxing Jiao1,* 1School of Physics, Sun Yat-sen University, Guangzhou 510275, China 2School of Materials Science and Engineering, Dongguan University of Technology, Dongguan 523808, China 3School of Opto-Electronics, Beijing Institute of Technology, Beijing 100081, China *Corresponding author: [email protected], [email protected] Abstract:We demonstrate a novel approach to achieve tunable ultrashort pulses from an all-fiber mode-locked laser with a saturable absorber based on nonlinear Kerr beam clean-up effect. This saturable absorber was formed by a single-mode fiber spliced to a commercial graded-index multimode fiber, and its tunable band-pass filter effect has been studied by an original numerical model. By adjusting the bending condition of graded-index multimode fiber, the laser could produce dissipative soliton pulses with their central wavelength tunable from1033 nm to 1063 nm. The pulse width of output laser could be compressed externally to 791 fs, and the signal to noise ratio of its radio frequency spectrum was measured to be 75.5 dB. This work provides a new idea for the design of tunable mode-locked laser which can be used as an attractive light source in optical communication system. 1. Introduction Wavelength tunable lasers are widely used in optical communication [1], detection [2], and remote sensing [3]. Compared to tunable continuous-wave lasers, tunable mode-locked lasers can generate ultra-short pulses with high peak power and wide bandwidth that enable many important advances, such as high-sensitivity optical absorption measurement [4], multi photon microscopy [5], and super-continuum light source used in dense wavelength division multiplexing [6]. -
Tunable Laser Absorption Spectroscopy for Human Spaceflight
49th International Conference on Environmental Systems ICES-2019-358 7-11 July 2019, Boston, Massachusetts Tunable Laser Absorption Spectroscopy for Human Spaceflight Christopher M Matty1 and Lance E Christensen2 National Aeronautics and Space Administration, Houston Texas 77058 and Pasadena California 91109 Human Spaceflight consistently has need for measurement of the major constituent gasses in a habitable cabin environment. Traditionally, this measurement has been performed using a mixture of mass spectrometry, electrochemical, and other traditional sensing methods. Tunable laser spectroscopy has been used in industry and research applications since the 1970s but has not been used in primary operational human spaceflight systems aside from a handful of experimental applications. Meanwhile, recent advances in the quality, size, and cost of semiconductor lasers has had a significant impact on the range of feasible applications for tunable laser spectroscopy. In 2018, work started on the Orion Laser Air Monitor (LAM), which is designed to be the primary major constituency monitoring system for the Orion Spacecraft. This paper covers the history leading up to the selection, design, and build of the Orion Laser Air Monitor as a primary major constituent analyzer for human spaceflight. Nomenclature TLDAS = Tunable Laser Diode Absorption Spectroscopy QC = Quantum Cascade IC = Interband Cascade TEC = Thermo Electric Cooler TRL = Technology Readiness Level SWAP = System Size Weight and Power IR = Infrared MCA = International Space Station Major Constituent Analyzer CAMS = Submarine Central Atmosphere Monitoring System AGA = Anomaly Gas Analyzer MGM = Multi Gas Monitor CPM = Combustion Product Monitor LAM = Laser Air Monitor SAFFIRE = Spacecraft Fire Experiement GaSb = Gallium Antimodide I. Introduction UNABLE Laser Diode Absorption Spectroscopy (TLDAS) is currently enjoying a period at the developmental Tforefront. -
Detection of Chemical Clouds Using Widely Tunable Quantum Cascade Lasers
Detection of chemical clouds using widely tunable quantum cascade lasers Anish K. Goyal*, Petros Kotidis, Erik R. Deutsch, Ninghui Zhu, Mark Norman, Jim Ye, Kostas Zafiriou, and Alex Mazurenko Block Engineering/MEMS, 377 Simarano Drive, Marlborough, MA 01752 ABSTRACT Widely tunable quantum cascade lasers (QCLs) spanning the long-wave infrared (LWIR) atmospheric transmission window and an HgCdTe detector were incorporated into a transceiver having a 50-mm-diameter transmit/receive aperture. The transceiver was used in combination with a 50-mm-diameter hollow retro-reflector for the open-path detection of chemical clouds. Two rapidly tunable external-cavity QCLs spanned the wavelength range of 7.5 to 12.8 m. Open-path transmission measurements were made over round-trip path-lengths of up to 562 meters. Freon-132a and other gases were sprayed into the beam path and the concentration-length (CL) product was measured as a function of time. The system exhibited a noise-equivalent concentration (NEC) of 3 ppb for Freon-132a given a round-trip path of 310 meters. Algorithms based on correlation methods were used to both identify the gases and determine their CL- products as a function of time. Keywords: atmospheric sensing, open-path spectroscopy, gas detection, vibrational spectroscopy, infrared spectroscopy, quantum cascade lasers, chemical detection 1. INTRODUCTION Open-path atmospheric spectroscopy is used to measure the gas concentration along an optical path. There are many such systems and they operate within one or more of the atmospheric transmission bands that exist between the ultraviolet (UV) and mid-infrared (MIR) portions of the optical spectrum [1-4]. -
NS14 ASSOCIATION NATIONAL BOAT REGISTER Sail No. Hull
NS14 ASSOCIATION NATIONAL BOAT REGISTER Boat Current Previous Previous Previous Previous Previous Original Sail No. Hull Type Name Owner Club State Status MG Name Owner Club Name Owner Club Name Owner Club Name Owner Club Name Owner Club Name Owner Allocated Measured Sails 2070 Midnight Midnight Hour Monty Lang NSC NSW Raced Midnight Hour Bernard Parker CSC Midnight Hour Bernard Parker 4/03/2019 1/03/2019 Barracouta 2069 Midnight Under The Influence Bernard Parker CSC NSW Raced 434 Under The Influence Bernard Parker 4/03/2019 10/01/2019 Short 2068 Midnight Smashed Bernard Parker CSC NSW Raced 436 Smashed Bernard Parker 4/03/2019 10/01/2019 Short 2067 Tiger Barra Neil Tasker CSC NSW Raced 444 Barra Neil Tasker 13/12/2018 24/10/2018 Barracouta 2066 Tequila 99 Dire Straits David Bedding GSC NSW Raced 338 Dire Straits (ex Xanadu) David Bedding 28/07/2018 Barracouta 2065 Moondance Cat In The Hat Frans Bienfeldt CHYC NSW Raced 435 Cat In The Hat Frans Bienfeldt 27/02/2018 27/02/2018 Mid Coast 2064 Tiger Nth Degree Peter Rivers GSC NSW Raced 416 Nth Degree Peter Rivers 13/12/2017 2/11/2013 Herrick/Mid Coast 2063 Tiger Lambordinghy Mark Bieder PHOSC NSW Raced Lambordinghy Mark Bieder 6/06/2017 16/08/2017 Barracouta 2062 Tiger Risky Too NSW Raced Ross Hansen GSC NSW Ask Siri Ian Ritchie BYRA Ask Siri Ian Ritchie 31/12/2016 Barracouta 2061 Tiger Viva La Vida Darren Eggins MPYC TAS Raced Rosie Richard Reatti BYRA Richard Reatti 13/12/2016 Truflo 2060 Tiger Skinny Love Alexis Poole BSYC SA Raced Skinny Love Alexis Poole 15/11/2016 20/11/2016 Barracouta -
On the Instabilities of Tropical Cyclones Generated by Cloud Resolving Models
SERIES A DYANAMIC METEOROLOGY Tellus AND OCEANOGRAPHY PUBLISHED BY THE INTERNATIONAL METEOROLOGICAL INSTITUTE IN STOCKHOLM On the instabilities of tropical cyclones generated by cloud resolving models By DAVID A. SCHECTERÃ, NorthWest Research Associates, Boulder, CO, USA (Manuscript received 30 May 2018; in final form 29 August 2018) ABSTRACT An approximate method is developed for finding and analysing the main instability modes of a tropical cyclone whose basic state is obtained from a cloud resolving numerical simulation. The method is based on a linearised model of the perturbation dynamics that distinctly incorporates the overturning secondary circulation of the vortex, spatially inhomogeneous eddy diffusivities, and diabatic forcing associated with disturbances of moist convection. Although a general formula is provided for the latter, only parameterisations of diabatic forcing proportional to the local vertical velocity perturbation and modulated by local cloudiness of the basic state are implemented herein. The instability analysis is primarily illustrated for a mature tropical cyclone representative of a category 4 hurricane. For eddy diffusivities consistent with the fairly conventional configuration of the simulation that generates the basic state, perturbation growth is dominated by a low azimuthal wavenumber instability having greatest asymmetric kinetic energy density in the lower tropospheric region of the inner core of the vortex. The characteristics of the instability mode are inadequately explained by nondivergent 2D dynamics. Moreover, the growth rate and modal structure are sensitive to reasonable variations of the diabatic forcing. A second instability analysis is conducted for a mature tropical cyclone generated under conditions of much weaker horizontal diffusion. In this case, the linear model predicts a relatively fast high-wavenumber instability that is insensitive to the parameterisation of diabatic forcing. -
Second Harmonic Generation Microscopy for Quantitative Analysis
PROTOCOL Second harmonic generation microscopy for quantitative analysis of collagen fibrillar structure Xiyi Chen1, Oleg Nadiarynkh1,2, Sergey Plotnikov1,2 & Paul J Campagnola1 1Department of Biomedica l Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA. 2Present addresses: Department of Physics, University of Utrecht, Utrecht, The Netherlands (O.N.); US National Institutes of Health, Heart, Lung and Blood Institute, Bethesda, Maryland, USA (S.P.). Correspondence should be addressed to P.J.C. ([email protected]). Published online 8 March 2012; doi:10.1038/nprot.2012.009 Second-harmonic generation (SHG) microscopy has emerged as a powerful modality for imaging fibrillar collagen in a diverse range of tissues. Because of its underlying physical origin, it is highly sensitive to the collagen fibril/fiber structure, and, importantly, to changes that occur in diseases such as cancer, fibrosis and connective tissue disorders. We discuss how SHG can be used to obtain more structural information on the assembly of collagen in tissues than is possible by other microscopy techniques. We first provide an overview of the state of the art and the physical background of SHG microscopy, and then describe the optical modifications that need to be made to a laser-scanning microscope to enable the measurements. Crucial aspects for biomedical applications are the capabilities and limitations of the different experimental configurations. We estimate that the setup and calibration of the SHG instrument from its component parts will require 2–4 weeks, depending on the level of the user′s experience. INTRODUCTION Over the past decade, the nonlinear optical method of SHG micros on the harmonophores and their assembly that can be imaged, as copy has emerged as a powerful tool for visualizing the supra the environment must be noncentrosymmetric on the size scale molecular assembly of collagen in tissues at an unprecedented level of of λSHG; otherwise, the signal will vanish. -
Practical Tips for Two-Photon Microscopy
Appendix 1 Practical Tips for Two-Photon Microscopy Mark B. Cannell, Angus McMorland, and Christian Soeller INTRODUCTION blue and green diode lasers. To provide an alignment beam to which the external laser can be aligned, light from this reference As is clear from a number of the chapters in this volume, 2-photon laser needs to be bounced back through the microscope optical microscopy offers many advantages, especially for living-cell train and out through the external coupling port: studies of thick specimens such as brain slices and embryos. CAUTION: Before you switch on the reference laser in this However, these advantages must be balanced against the fact that configuration make sure that all PMTs are protected and/or commercial multiphoton instrumentation is much more costly than turned off. the equipment used for confocal or widefield/deconvolution. Given Place a front-surface mirror on the stage of the microscope and these two facts, it is not surprising that, to an extent much greater focus onto the reflective surface using an air objective for conve- than is true of confocal, many researchers have decided to add a nience (at sharp focus, you should be able to see scratches or other femtosecond (fs) pulsed near-IR laser to a scanner and a micro- mirror defects through the eyepieces). The idea of this method is scope to make their own system (Soeller and Cannell, 1996; Tsai to cause the reference laser beam to bounce back through the et al., 2002; Potter, 2005). Even those who purchase a commercial optical train and emerge from the other laser port. -
State-Of-The-Art Fiber Optics for Short Distance Frequency Reference Distribution
N89-27878 January-March 1989 TDA Progress Report 42-97 State-of-the-Art Fiber Optics for Short Distance Frequency Reference Distribution G. Lutes and L. Primas Communications Systems Research Section A number of recently developed fiber-optic components that hem the promise of unprecedented stability for passively stabilized frequency distribution links are character- ized. These components include a fiber-optic transmitter, an optical isolator, and a new type of fiber-optic cable. A novel laser transmitter exhibits extremely low sensitivity to intensity and polarization changes of reflected light due to cable flexure. This virtually eliminates one of the shortcomings in previous laser transmitters. A high-isolation, low- loss optical isolator has been developed which also virtually eliminates laser sensitivity to changes in intensity and polarization of reflected light. A newly developed fiber has been tested. This fiber has a thermal coefficient of delay of less than 0.5 parts per million per °C, nearly 20 times lower than the best coaxial hardline cable and 10 times lower than any previous fiber-optic cable. These components are highly suitable for distribution systems with short extent, such as within a Deep Space Communications Complex. In this article these new components are described and the test results presented. I. Introduction mary causes of degradation. These effects are caused by distri- bution system noise, which reduces the SNR, and variations in The transmitter exciter, local oscillator, and receiver delay the environmental temperature, which cause delay changes. calibration system in a Deep Space Station (DSS) require The degree of delay change is dependent on the Thermal Coef- stable frequency references. -
Improved Laser Based Photoluminescence on Single-Walled Carbon Nanotubes
Improved laser based photoluminescence on single-walled carbon nanotubes S. Kollarics,1 J. Palot´as,1 A. Bojtor,1 B. G. M´arkus,1 P. Rohringer,2 T. Pichler,2 and F. Simon1 1Department of Physics, Budapest University of Technology and Economics and MTA-BME Lend¨uletSpintronics Research Group (PROSPIN), P.O. Box 91, H-1521 Budapest, Hungary 2Faculty of Physics, University of Vienna, Strudlhofgasse 4., Vienna A-1090, Austria Photoluminescence (PL) has become a common tool to characterize various properties of single- walled carbon nanotube (SWCNT) chirality distribution and the level of tube individualization in SWCNT samples. Most PL studies employ conventional lamp light sources whose spectral dis- tribution is filtered with a monochromator but this results in a still impure spectrum with a low spectral intensity. Tunable dye lasers offer a tunable light source which cover the desired excitation wavelength range with a high spectral intensity, but their operation is often cumbersome. Here, we present the design and properties of an improved dye-laser system which is based on a Q-switch pump laser. The high peak power of the pump provides an essentially threshold-free lasing of the dye laser which substantially improves the operability. It allows operation with laser dyes such as Rhodamin 110 and Pyridin 1, which are otherwise on the border of operation of our laser. Our sys- tem allows to cover the 540-730 nm wavelength range with 4 dyes. In addition, the dye laser output pulses closely follow the properties of the pump this it directly provides a time resolved and tunable laser source. -
Electrically Tunable Mode-Locked Lasers Based on Time-To-Wavelength Mapping for Optical Communications
Laser Original Electrically Tunable Mode-Locked Lasers Based on Time-to-Wavelength Mapping for Optical Communications Kohichi R. TAMURA NTT Corporation, NTT Network Innovation Laboratories, 1-1 Hikari-no-oka, Yokosuka, Kanagawa 239-0847 (Received August 20, 2001) The tunable mode-locked laser based on time-to-wavelength mapping is a relatively unexplored alternative to tunable sources that can be applied to transmission and wavelength switching in optical networks. These lasers have the advantages of a simple tuning mechanism, good wavelength reproducibility, and simple cavity design. The state of research is discussed. Key Words: Tunable laser, Mode-locked laser, Fiber Bragg grating, Arrayed waveguide grating 1. Introduction ment to make a cavity with a length that depends on wavelength. The oscillation wavelength is selected by changing a single elec- Compact and tunable lasers are considered to be key compo- trical control signal - the RF frequency. The dependence of the nents for realizing advanced functionality in optical communi- oscillation wavelength on RF frequency is determined by the cation networks.1) A variety of designs exist, and, currently, sev- delay element and should be stable over time if a stable wave- eral of them are in the early stages of commercialization. The length-selective element is used. Inherent drawbacks to ETMLs first application of tunable lasers will be as temporary sources are the changing repetition rate with wavelength and the broad for DWDM terminals, which eliminates the need for stocking optical spectrum that results from mode-locking. Even so, as spare parts at each wavelength. While the tuning speed is not we describe below, these lasers may find applications in optical critical in this case, more advanced applications call for speeds switching within nodes or for short distance transmission in ranging from millisecond-to-nanosecond time scales. -
Coupled-Ring-Resonator-Mirror-Based Heterogeneous III–V Silicon Tunable Laser Volume 7, Number 3, June 2015
Coupled-Ring-Resonator-Mirror-Based Heterogeneous III–V Silicon Tunable Laser Volume 7, Number 3, June 2015 S. Srinivasan M. Davenport T. Komljenovic J. Hulme D. T. Spencer J. E. Bowers, Fellow, IEEE DOI: 10.1109/JPHOT.2015.2428255 1943-0655 Ó 2015 IEEE IEEE Photonics Journal Heterogeneous III–V Silicon Tunable Laser Coupled-Ring-Resonator-Mirror-Based Heterogeneous III–V Silicon Tunable Laser S. Srinivasan, M. Davenport, T. Komljenovic, J. Hulme, D. T. Spencer, and J. E. Bowers, Fellow, IEEE Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106 USA DOI: 10.1109/JPHOT.2015.2428255 1943-0655 Ó 2015 IEEE. Translations and content mining are permitted for academic research only. Personal use is also permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. Manuscript received February 6, 2015; revised April 21, 2015; accepted April 23, 2015. Date of current version May 26, 2015. This work was supported by the DARPA EPHI Program. The work of T. Komljenovic was supported by NEWFELPRO under Grant 25. Corresponding author: S. Srinivasan (e-mail: [email protected]). Abstract: We show theoretical and experimental results from a tunable laser, with its center wavelength in the C-band, designed using coupled-ring resonator mirrors. The effective cavity length enhancement and negativeopticalfeedbackobtainedfromtheres- onators helps to narrow the laser linewidth in a small form factor. We report a linewidth of 160 kHz and a side-mode suppression ratio of 9 40 dB over the full tuning range. Index Terms: Tunable lasers, coupled resonators, semiconductor lasers, silicon photonics. -
A Polarization-Insensitive Recirculating Delayed Self-Heterodyne Method for Sub-Kilohertz Laser Linewidth Measurement
hv photonics Communication A Polarization-Insensitive Recirculating Delayed Self-Heterodyne Method for Sub-Kilohertz Laser Linewidth Measurement Jing Gao 1,2,3 , Dongdong Jiao 1,3, Xue Deng 1,3, Jie Liu 1,3, Linbo Zhang 1,2,3 , Qi Zang 1,2,3, Xiang Zhang 1,2,3, Tao Liu 1,3,* and Shougang Zhang 1,3 1 National Time Service Center, Chinese Academy of Sciences, Xi’an 710600, China; [email protected] (J.G.); [email protected] (D.J.); [email protected] (X.D.); [email protected] (J.L.); [email protected] (L.Z.); [email protected] (Q.Z.); [email protected] (X.Z.); [email protected] (S.Z.) 2 University of Chinese Academy of Sciences, Beijing 100039, China 3 Key Laboratory of Time and Frequency Standards, Chinese Academy of Sciences, Xi’an 710600, China * Correspondence: [email protected]; Tel.: +86-29-8389-0519 Abstract: A polarization-insensitive recirculating delayed self-heterodyne method (PI-RDSHM) is proposed and demonstrated for the precise measurement of sub-kilohertz laser linewidths. By a unique combination of Faraday rotator mirrors (FRMs) in an interferometer, the polarization-induced fading is effectively reduced without any active polarization control. This passive polarization- insensitive operation is theoretically analyzed and experimentally verified. Benefited from the recirculating mechanism, a series of stable beat spectra with different delay times can be measured simultaneously without changing the length of delay fiber. Based on Voigt profile fitting of high- order beat spectra, the average Lorentzian linewidth of the laser is obtained. The PI-RDSHM has advantages of polarization insensitivity, high resolution, and less statistical error, providing an Citation: Gao, J.; Jiao, D.; Deng, X.; effective tool for accurate measurement of sub-kilohertz laser linewidth.