High-Quality, Inn-Based, Saturable Absorbers for Ultrafast Laser Development
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Demonstration of Inp-On-Si Self-Pulsating DFB Laser Diodes for Optical Microwave Generation Volume 9, Number 4, August 2017
Open Access Demonstration of InP-on-Si Self-Pulsating DFB Laser Diodes for Optical Microwave Generation Volume 9, Number 4, August 2017 Keqi Ma M. Shahin, Student Member, IEEE A. Abbasi, Member, IEEE G. Roelkens, Member, IEEE G. Morthier, Senior Member, IEEE DOI: 10.1109/JPHOT.2017.2724840 1943-0655 © 2017 IEEE IEEE Photonics Journal Demonstration of InP-on-Si Self-Pulsating DFB Laser Demonstration of InP-on-Si Self-Pulsating DFB Laser Diodes for Optical Microwave Generation Keqi Ma,1 M. Shahin,2,3 Student Member, IEEE, A. Abbasi,2,3 Member, IEEE, G. Roelkens,2,3 Member, IEEE, and G. Morthier,2,3 Senior Member, IEEE 1Centre for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China 2Photonics Research Group, Department of Information Technology (INTEC), Ghent University–IMEC, Gent B-9000, Belgium 3Center for Nano-and Biophotonics, Ghent University, Gent B-9000, Belgium DOI:10.1109/JPHOT.2017.2724840 1943-0655 C 2017 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 June 9, 2017; revised July 5, 2017; accepted July 5, 2017. Date of publication July 11, 2017; date of current version July 26, 2017. This work was supported by the Methusalem program of the Flemish Government. (Keqi Ma and M. Shahin contributed equally to this work.) Corresponding author: M. Shahin (e-mail: [email protected]). Abstract: We demonstrate self-pulsating heterogeneously integrated III-V-on-SOI two- section distributed feedback laser diodes, with a wide range of self-pulsation frequencies between (but not limited to) 12 and 40 GHz. -
FY20 National Laser Users' Facility Program
FY20 NATIONAL LASER USERS’ FACILITY PROGRAM FY20 National Laser Users’ Facility Program M. S. Wei Laboratory for Laser Energetics, University of Rochester During FY19, the National Nuclear Security Administration (NNSA) and Office of Science jointly completed a funding opportu- nity announcement (FOA), review, and selection process for National Laser Users’ Facility (NLUF) experiments to be conducted at the Omega Facility during FY20 and FY21. After peer review by an independent proposal review committee for scientific and technical merit and the feasibility review by the Omega Facility team, NNSA selected 11 proposals for funding and Omega shot allocation with a total of 22.5 and 23.5 shot days for experiments in FY20 and FY21, respectively. During the first half of the FY20, LLE completed a one-time solicitation, review, and selection process for Academic and Industrial Basic Science (AIBS) experiments to utilize the remaining NLUF shot allocation in FY20–FY21. Ten new projects were selected for AIBS shot alloca- tion (a total of 11 and 10 shot days) for experiments staring in Q3FY20 and throughout FY21. FY20 was the first of a two-year period of performance for these 21 NLUF including AIBS projects (Table I). Fifteen NLUF and AIBS projects obtained a total of 232 target shots during FY20, which are summarized in this section. A critical part of the NNSA-supported NLUF program and the DOE Office of Fusion Energy Sciences (FES)-supported Laser- NetUS program is the education and training of graduate students in high-energy-density (HED) physics. In addition, graduate students can also access the Omega Laser Facility to conduct their theses research through collaborations with national labora- tories and LLE. -
A Programmable Mode-Locked Fiber Laser Using Phase-Only Pulse Shaping and the Genetic Algorithm
hv photonics Article A Programmable Mode-Locked Fiber Laser Using Phase-Only Pulse Shaping and the Genetic Algorithm Abdullah S. Karar 1,* , Raymond Ghandour 1 , Ibrahim Mahariq 1 , Shadi A. Alboon 1,2, Issam Maaz 1, Bilel Neji 1 and Julien Moussa H. Barakat 1 1 College of Engineering and Technology, American University of the Middle East, Kuwait; [email protected] (R.G.); [email protected] (I.M.); [email protected] (S.A.A.); [email protected] (I.M.); [email protected] (B.N.); [email protected] (J.M.H.B.) 2 Electronics Engineering Department, Hijjawi Faculty for Engineering Technology, Yarmouk University, Irbid 21163, Jordan * Correspondence: [email protected] Received: 24 July 2020; Accepted: 2 September 2020; Published: 4 September 2020 Abstract: A novel, programmable, mode-locked fiber laser design is presented and numerically demonstrated. The laser programmability is enabled by an intracavity optical phase-only pulse shaper, which utilizes the same linearly chirped fiber Bragg grating (LC-FBG) from its two opposite ends to perform real-time optical Fourier transformation. A binary bit-pattern generator (BPG) operating at 20-Gb/s and producing a periodic sequence of 32 bits every 1.6 ns, is subsequently used to drive an optical phase modulator inside the laser cavity. Simulation results indicate stable programmable intensity profiles for each optimized user defined 32 code words. The laser operated in the self-similar mode-locking regime, enabling wave-breaking free operation. The programmable 32 bit code word targeting a specific intensity profile was determined using 100 generations of the genetic algorithm. -
MRI-Guided Laser Ablation Surgery of Hypothalamic Hamartomas
NEUROSURGERY MRI-Guided Laser Ablation Surgery of Hypothalamic Hamartomas HOW DOES THE TEAM DECIDE IF A PATIENT IS A CANDIDATE FOR MRI-GUIDED LASER ABLATION? A careful review of each patient’s medical records is the first step, including MR imaging of the brain and any applicable neurology or neurosurgery records. Patients with Hypothalamic Hamartomas (HH) typically have gelastic seizures, which are characterized by emotionless laughing, although variations including abnormal movements or staring spells are also common. Every patient’s case is handled individually, and it may be necessary for a patient to come to Texas Children’s Hospital for further testing to determine if they are a candidate for MRI-guided laser ablation surgery. WHAT HAPPENS DURING MRI-GUIDED LASER ABLATION SURGERY? After being placed under general anesthesia, a head frame, or a set of markers, is fitted to the patient’s skull. A CT scan is completed to orient the brain to the frame in 3 dimensions. With the help of computer software, a safe pathway that goes through the brain to the HH is calculated for the laser. The neurosurgeon then makes a small incision and drills a small hole through the skull (3.2 mm wide). The laser applicator, a small tube about the width of a strand of spaghetti, is inserted and guided through the brain into the HH. Once the laser applicator is inserted into the brain, the head frame is removed, and the patient is transported to the MRI scanner. After confirming proper placement of the laser applicator and setting safety markers, the surgeon performs a small test firing using the laser. -
Short Pulse Generation Using Multisegment Mode-Locked
2186 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 28, NO. 10, OCTOBER 1992 Short Pulse Generation Using Multisegment - . * T Mode-Locked Semconductor Lasers Dennis J. Derickson, Member, IEEE, Roger J. Helkey, Member, IEEE, Alan Mar, Judy R. Karin, Student Member, IEEE, John G. Wasserbauer, Student Member, IEEE, and John E. Bowers, Senior Member, IEEE Invited Paper Abstract-Mode-locked semiconductor lasers which incorpo- SectionC SedionB SeetionA rate multiple contacting segments are found to give improved performance over single-segment designs. The functions of gain, saturable absorption, gain modulation, repetition rate tuning, wavelength tuning, and electrical pulse generation can be integrated on a single semiconductor chip. The optimization of the performance of multisegment mode-locked lasers in terms va 7F of material parameters, waveguiding parameters, electrical parasitics, and segment length is discussed experimentally and theoretically. ExternalI Cavity I. INTRODUCTION EMICONDUCTOR lasers are important sources of Sshort optical and electrical pulses. Semiconductor la- sers are small in size, use electrical pumping, are easy to operate, and consequently short optical pulses can now be (b) used in applications that were previously infeasible or un- SedionC SedionA economical. These pulses are used in high-speed optical fiber communication systems using time-division multi- Gain-Switch plexing for transmitters and for demultiplexing at the re- Q-SllitCh ceiver [l], [2]. Short optical pulses are also being used for optoelectronic measurement applications such as elec- trooptic sampling [3], analog to digital (A-D) conversion [4], and impulse response testing of optical components. (C) This paper concentrates on advances in the short pulse Fig. 1. Multisegment structures for generating short optical and electrical generation field that are a result of using multiple-segment pulses. -
Lecture 9 and 10: Pulsed Lasers and Mode-Locking
Lecture 9 and 10: Pulsed lasers and mode-locking 1. Ultrashort pulses Ultrashort pulse shorter than 1 ps (10-12 s) Shortest pulses generated from lasers: Type of laser Pulse duration Fiber laser ~35 - 50 fs Solid-state laser (e.g. Yb) ~40-50 fs Ti:Sapphire laser ~ 3 fs – 7 fs The shortest possible pulse of a given wavelength is one light cycle long: 1550 nm 4.3 fs 800 nm 2.7 fs Shorter wavelength shorter pulses 2. Measurement of ultrashort pulses Techniques: • Optical autocorrelation • FROG (Frequency Resolved Optical Gating) Improved version: GRENOULLIE • SPIDER (Spectral Phase Interferometry for Direct Electric-field Reconstruction) Autocorrelator Interferometric autocorrelation trace: FROG Source: Rick Trebino, Frequency Resolved Optical Gating SPIDER 3. Mode-locked lasers a) Difference between a CW and mode-locked laser: A mode-locked laser: Emits a train of equally-spaced, ultrashort pulses (femtosecond) - down to almost single- cycle Output spectrum is broad (tens-hundreds of nanometers)/ Broader spectrum shorter pulses In the frequency domain, the output consists of thousands/millions of narrow lines (comb- like structure) b) Relation between the number of synchronized modes and the pulse duration: More synchronized modes shorter pulse. c) Passive mode-locking and saturable absorber In order to achieve passive mode-locking we need a device called saturable absorber. The saturable absorber: - Blocks any CW radiation in the cavity - It forces the laser to synchronize the modes and generate pulses - Only high-intensity pulse -
Mid-Infrared Ultra-Short Mode-Locked Fiber Laser Utilizing Topological
Mid-infrared ultra-short mode-locked fiber laser utilizing topological insulator BiR2RTeR3R nano-sheets as the saturable absorber 1 1,2,3 1 1 1,2 1,4 Ke YinP ,P Tian JiangP ,P Hao YuP ,P Xin ZhengP ,P Xiangai ChengP ,P Jing HouP 1 P CollegeP of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, P.R.China; 2 P StateP key laboratory of High Performance Computing, National University of Defense Technology, Changsha 410073, P.R.China; 3 P P [email protected] U 4 PU hUP [email protected] Abstract: The newly-emergent two-dimensional topological insulators (TIs) have shown their unique electronic and optical properties, such as good thermal management, high nonlinear refraction index and ultrafast relaxation time. Their narrow energy band gaps predict their optical absorption ability further into the mid-infrared region and their possibility to be very broadband light modulators ranging from the visible to the mid-infrared region. In this paper, a mid-infrared mode-locked fluoride fiber laser with TI Bi2Te3 nano-sheets as the saturable absorber is presented. Continuous wave lasing, Q-switched and continuous-wave mode-locking (CW-ML) operations of the laser are observed sequentially by increasing the pump power. The observed CW-ML pulse train has a pulse repetition rate of 10.4 MHz, a pulse width of ~6 ps, and a center wavelength of 2830 nm. The maximum achievable pulse energy is 8.6 nJ with average power up to 90 mW. This work forcefully demonstrates the promising applications of two-dimensional TIs for ultra-short laser operation and nonlinear optics in the mid-infrared region. -
With Short Pulse • About 7% Coupling Significantly Less Than the Osaka Experiment
Electron/proton generation from solid targets and applications Farhat Beg University of California, San Diego This work was performed under the auspices of the U.S. DOE under contracts No.DE-FG02-05ER54834, DE-FC0204ER54789 and DE-AC52-07NA27344. We greatly acknowledge support of Institute for Laser Science Applications, LLNL. Committee on Atomic, Molecular and Optical Sciences Meeting The National Academy of Sciences Washington DC, April 5, 2011 1 Summary ü Short pulse high intensity laser solid interactions create matter under extreme conditions and generate a variety of energetic particles. ü There are a number of applications from fusion to low energy nuclear reactions. 10 ns ü Fast Ignition Inertial Confinement Fusion is one application that promises high gain fusion. ü Experiments have been encouraging but point towards complex issues than previously anticipated. ü Recent, short pulse high intensity laser matter experiments show that low coupling could be due to: - prepulse - electron source divergence. ü Experiments on fast ignition show proton focusing spot is adequate for FI. However, conversion efficiency has to be increased. 2 Outline § Short Pulse High Intensity Laser Solid Interaction - New Frontiers § Extreme conditions with a short pulse laser § Applications § Fast Ignition - Progress - Current status § Summary Progress in laser technology 10 9 2000 Relativistic ions 8 Nonlinearity of 10 Vacuum ) Multi-GeV elecs. V 7 1990 Fast Ignition e 10 ( e +e- Production y 6 Weapons Physics g 10 Nuclear reactions r e 5 Relativistic -
Chapter 20 SOFT LASER DESORPTION IONIZATION - MALDI, DIOS and NANOSTRUCTURES
Chapter 20 SOFT LASER DESORPTION IONIZATION - MALDI, DIOS AND NANOSTRUCTURES Akos Veites Department of Chemistry, Institute for Proteomics Technology and Applications, The George Washington University, Washington DC 20052 1. INTRODUCTION In 1948, Ame Tiselius won the Nobel Prize in chemistry for the discovery of electrophoresis and its application to analyze large molecules, specifically complex serum proteins. During the following decades, gel electrophoresis and its derivative techniques became a central method for molecular biology. They allowed for the identification of molecular mass with an accuracy of ~1 kDa, i.e., a thousand atomic mass units. Although this method enabled the separation of thousands of proteins from biological samples, the determination of the actual molecular weight, and with it finding the true identity of many substances, remained unachievable. When it came to accurate mass determination of small molecules, mass spectrometry was the method of choice. However, for the accurate mass analysis of large molecules, their low volatility presented a fundamental obstacle. Typically, the larger the molecule, the harder it is to transfer it into the gas phase without degradation. Depositing the energy necessary for volatilization initiates other competing processes that elevate the internal energy of the adsorbate and results in its fragmentation. This competition between evaporation (or desorption) and fragmentation was recognized early on and the method of rapid heating was proposed to minimize the latter (Beuhler, et al., 1974). Lasers with submicrosecond pulse length were appealing tools for rapid heating but the initial results indicated limitations with respect to the ultimate size of the biomolecules (m/z < 1,500) that could 506 Laser Ablation and its Applications be successfully analyzed (Posthumus ,et al., 1978). -
Laser Ablationablation
LaserLaser AblationAblation FundamentalsFundamentals && ApplicationsApplications Samuel S. Mao Department of Mechanical Engineering Advanced Energy Technology Department University of California at Berkeley Lawrence Berkeley National Laboratory March 10, 2005 University of California at Berkeley Q Lawrence Berkeley National Laboratory LaserLaser AblationAblation What is “Laser Ablation”? Mass removal by coupling laser energy to a target material University of California at Berkeley Q Lawrence Berkeley National Laboratory ion lat ab er IsIs itit important?important? las ) Film deposition substrate * oxide/superconductor films material * nanocrystals/nanotubes plume target mass spectrometer ) Materials characterization * semiconductor doping profiling plasma lens * solid state chemical analysis target optical spectrometer ) Micro structuring * direct wave guide writing * 3D micro fabrication microstructure target transparent solid University of California at Berkeley Q Lawrence Berkeley National Laboratory ion lat ab er IsIs itit important?important? las ) Film deposition * oxide/superconductor films * nanocrystals/nanotubes ) Materials characterization * semiconductor doping profiling * solid state chemical analysis 100 µm ) Micro structuring * direct wave guide writing * 3D micro fabrication University of California at Berkeley Q Lawrence Berkeley National Laboratory ion lat ab er DoDo wewe reallyreally understand?understand? las laser beam “Laser ablation … is still largely unexplored at the plasma fundamental level.” J. C. Miller & -
MRI-Guided Laser Ablation Surgery for Epilepsy
MRI-Guided Laser Ablation Surgery for Epilepsy In August 2010, Texas Children’s Hospital became the first hospital in the world to use real-time MRI-guided thermal imaging and laser technology to destroy epilepsy-causing lesions in the brain that are too deep inside the brain to safely access with usual neurosurgical methods. To date, our team has performed more than 100 of these procedures on patients who have traveled to Houston and Texas Children’s from around the globe. This technology has become a standard of care and is now being used in many adult and pediatric centers across the United States. The advantages of the MRI-guided laser surgery procedure include: • A safer, significantly less-invasive alternative to open brain surgery with a craniotomy, which is the traditional technique used for the surgical treatment of epilepsy. • No hair is removed from the patient’s head. • Only a 3 mm opening is needed for the laser. It is closed with a single suture resulting in less scarring and pain for the patient. • A reduced risk of complications and a faster recovery time for the patient. Most patients are discharged the day after surgery. MRI-guided laser surgery is changing the face of epilepsy treatment and provides a life-altering option for many epilepsy surgery candidates. The benefits of this new approach in reducing risk and invasiveness may open the door for more epilepsy patients to see surgery as a viable treatment option. Epilepsy today • Approximately 1 in 10 people will have at least one seizure during their lifetime. -
Numerical Simulation of Passively Q-Switched Solid State Lasers
Chapter 14 Numerical Simulation of Passively Q-Switched Solid State Lasers I. Lăncrănjan, R. Savastru, D. Savastru and S. Micloş Additional information is available at the end of the chapter http://dx.doi.org/10.5772/47812 1. Introduction Short laser light pulses have a large number of applications in many civilian and military applications [1-10]. To a large percentage these short laser pulses are generated by solid state lasers using various active media types (crystals, glasses or ceramic) operated in Q- switching and/or mode-locking techniques [1-10]. Among the short light pulses laser generators, those operated in Q-switching regime and emitting pulses of nanosecond FWHM duration occupy a large part of civilian (material processing - for example: nano- materials formation by using ablation technique [3,7]) and military (projectile guidance over long distances and range finding) applications. Basically, Q-switching operation relies on a fast switching of laser resonator quality factor Q from a low value (corresponding to large optical losses) to a high one (representing low radiation losses). Depending on the proposed application, two main Q-switching techniques are used: active, based on electrical (in some cases operation with high voltages up to about 1 kV being necessary) or mechanical (spinning speeds up to about 1 kHz being used) actions on an optical component at least, coming from the outside of the laser resonator, and passive relying entirely on internal to the laser resonator induced variation of one optical component transmittance. 2. Theory Figure 1 displays a general schematic of electronic energy levels of laser active centers embedded in an active medium and of saturable absorption centers embedded into solid state passive optical Q-switch cell laser oscillator operated in passive optical Q-switching regime [11-18,26].