Development Of Laser Systems Research Articles

フィルムの両面にレーザ・波長検出器を実装した表面実装・全有機システムの開発(II)

フィルムの両面にレーザ・波長検出器を実装した表面実装・全有機システムの開発(II)

Development of two-color laser system for high-resolution polarization spectroscopy measurements of atomic hydrogen

We have developed a high-spectral-resolution laser system for two-photon pump, polarization spectroscopy probe (TPP-PSP) measurements of atomic hydrogen in flames. In the TPP-PSP technique, a 243-nm laser beam excites the two-photon 1S-2S transition, and excited n=2 atoms are then detected by polarization spectroscopy of the n=2 to n=3 transition using 656-nm laser radiation. The single-frequency-mode 243 and 656-nm beams are produced using injection-seeded optical parametric generators coupled with pulsed dye amplifiers. The use of single-mode lasers allows accurate measurement of signal line shapes and intensities even with significant pulse-to-pulse fluctuations in pulse energies. Use of single-mode lasers and introduction of a scheme to select nearly constant laser energies enable repeatable extraction of important spectral features in atomic hydrogen transitions.

Narrow linewidth laser system realized by linewidth transfer using a fiber-based frequency comb for the magneto-optical trapping of strontium

A narrow linewidth diode laser system at 689 nm is realized by phase-locking an extended cavity diode laser to one tooth of a narrow linewidth optical frequency comb. The optical frequency comb is phase-locked to a narrow linewidth laser at 1064 nm, which is frequency stabilized to a high-finesse optical cavity. We demonstrate the magneto-optical trapping of Sr using an intercombination transition with the developed laser system.

The development and application of femtosecond laser systems

Some background as well as recent progress in the development of femtosecond lasers are discussed together with a brief outline of a few representative emergent applications in biology and medicine that are underpinned by access to such sources. We also provide a short summary of other contributions in this focus issue.

Non-covalent interactions of coumarin dyes with cucurbit[7]uril macrocycle: modulation of ICT to TICT state conversion

Non-covalent interaction of coumarin laser dyes, namely coumarin-1 (C1), coumarin-481 (C481) and coumarin-6H (C6H), with a versatile macrocyclic host molecule cucurbit[7]uril (CB7), has been investigated in aqueous solution using photophysical methods. Steady-state and time-resolved fluorescence studies illustrate significant enhancements/modifications in the fluorescence yields, lifetimes and spectral features of C1, C481 and C6H on interaction with CB7, and are assigned to 1 : 1 complex formation between the dyes and the CB7 host. The complex formation is mainly driven by charge-dipole interaction, as evident from the binding constant values (K ~ 10(4)-10(5) M(-1)). The large changes in the excited state behaviour of C1 and C481 as compared to C6H in the presence of CB7 indicate that CB7 binds C1 and C481 through the encapsulation of the 7-N,N'-diethylamino group of the dyes and the structural rigidity imposed by this interaction dramatically alters the excited state properties of the dyes by preventing the conversion of their emissive intramolecular charge transfer (ICT) state to the non-radiative twisted intramolecular charge transfer (TICT) state. The present results direct towards the probable supramolecular approach using water soluble macrocyclic CB7, in the development of aqueous dye laser systems in the blue-green region.

A simple introduction to multiphoton microscopy

Multiphoton microscopy is a powerful technique based on complex quantum mechanical effects. Thanks to the development of turnkey mode-locked laser systems, multiphoton microscopy is now available for everyone to use without extreme complexity. In this short introduction, we describe qualitatively the important concepts underlying the most commonly used type of multiphoton microscopy (two-photon excitation). We elucidate how those properties lead to the powerful results that have been achieved using this technique. As with any technique, two-photon excitation microscopy has limitations that we describe, and we provide examples of particular classes of experiments where two-photon excitation microscopy is advantageous over other approaches. Finally, we briefly describe other useful multiphoton microscopy approaches, such as three-photon excitation and second harmonic generation imaging.

Design and construction of Q-switched Nd:YAG laser system for LIBS measurements

A passive, Q-switched pulsed, Nd:YAG laser system was designed and built, which can provide a potential compact robust laser source for portable laser induced breakdown spectroscopy systems. The developed laser system operates at 1064 nm. Each laser shot contains a train of pulses having maximum total output energy of 170 mJ. The number of pulses varies from 1–6 pulses in each laser shot depending on the pump energy. The pulse width of each pulse ranges from 20 to 30 ns. The total duration of the output pulse train is within 300 μs. The multi-pulse nature of the laser shots was employed to enhance the LIBS signal. To validate the system, LIBS measurements and analysis were performed on ancient ceramic samples collected from Al-Fustat excavation in Old Cairo. The samples belong to different Islamic periods in Egypt history. The results obtained are highly indicative that useful information can be provided to archeologists for use in restoring and repairing of precious archeological objects.

Waveguide lasers based on dielectric materials

Fifty years since the invention of the laser have been witness of the development of many different laser systems and designs. Among them, miniaturized versions of solid sate lasers based on rare-earth-doped dielectric materials have been proposed and demonstrated during the last 20 years. They are based on confined radiation provided by optical waveguide structures. Although many materials and techniques have been studied for producing planar and channel waveguides, only a few of them have shown to be adequate routes for fabricating waveguide lasers. Here we summarize the theory and specific technologies developed for characterizing waveguide structures, and we present some common fabrication techniques already successfully applied to fabricate dielectric waveguide lasers, where relevant examples of demonstrated working devices are outlined.

Laser interferometer for measuring the mass velocity of condensed substances in shock-wave experiments on the TWAC-ITEP proton-radiographic facility

The results of development of a laser interferometer designed for measuring the mass velocity of condensed substances in shock-wave experiments in the field of high-energy-density physics are presented. The interferometer is incorporated in the measuring complex of the TWAC-ITEP proton-radiographic facility. The developed laser system allows measurements of the velocity of free surfaces of samples in shock-wave experiments with an error no worse than 10 m/s for the entire range of velocities attained experimentally. The time resolution of measurements is limited by the response speed of the used PMTs and amounts to 2.5 ns. Combined investigations of shock-wave loading of metal targets and scabbing-fracture and jet-formation processes on free metal surfaces were performed by the proton-radiography and laser-interferometry methods.

Loop laser cavities with self-pumped phase-conjugate mirrors in low-gain active media for phase-locked multichannel laser systems

It is proved that lasers with different loop cavities with self-pumped phase-conjugate mirrors in low-gain active media can operate under injection of external laser radiation and can be used for the development of diode-pumped phase-locked multichannel neodymium laser systems operating both on the fundamental laser transition with the wavelength λ = 1.06 μm and on the transition with λ = 1.34 μm. The phase-conjugate oscillation thresholds in the case of injection of an external signal are determined for a multiloop cavity configuration and an increased number of active elements in the cavity. It is shown that phase-conjugate oscillation can occur even if the single-pass gain of the active element is as low as only ∼2. Under high-power side diode pumping of a multiloop Nd:YAG laser, single-mode output radiation was achieved at λ = 1.064 μm with a pulse energy up to 0.75 J, a pulse repetition rate up to 25 Hz, an average power up to 18.3 W, and an efficiency up to 20%. In a multiloop Nd:YAG laser with three active elements in the cavity, single-mode radiation at λ = 1.34 μm was obtained with a pulse energy up to 0.96 J, a pulse repetition rate up to 10 Hz, and an average power up to 8.5 W.

Simulation of medical Q-switch flash-pumped Er:YAG laser

Er: YAG laser, the wavelength is 2940nm, can be absorbed strongly by water. The absorption coefficient is as high as 13000 cm−1. As the water strong absorption, Erbium laser can bring shallow penetration depth and smaller surrounding tissue injury in most soft tissue and hard tissue. At the same time, the interaction between 2940nm radiation and biological tissue saturated with water is equivalent to instantaneous heating within limited volume, thus resulting in the phenomenon of micro-explosion to removal organization. Different parameters can be set up to cut enamel, dentin, caries and soft tissue. For the development and optimization of laser system, it is a practical choice to use laser modeling to predict the influence of various parameters for laser performance. Aim at the status of low Erbium laser output power, flash-pumped Er: YAG laser performance was simulated to obtain optical output in theory. the rate equation model was obtained and used to predict the change of population densities in various manifolds and use the technology of Q-switch the simulate laser output for different design parameters and results showed that Er: YAG laser output energy can achieve the maximum average output power of 9.8W under the given parameters. The model can be used to find the potential laser systems that meet application requirements.

Laser systems for ablative fractional resurfacing

Ablative fractional resurfacing (AFR) creates microscopic vertical ablated channels that are surrounded by a thin layer of coagulated tissue, constituting the microscopic treatment zones (MTZs). AFR induces epidermal and dermal remodeling, which raises new possibilities for the treatment of a variety of skin conditions, primarily chronically photodamaged skin, but also acne and burn scars. In addition, it is anticipated that AFR can be utilized in the laser-assisted delivery of topical drugs. Clinical efficacy coupled with minimal downtime has driven the development of various fractional ablative laser systems. Fractionated CO2 (10,600-nm), erbium yttrium aluminum garnet, 2940-nm and yttrium scandium gallium garnet, 2790-nm lasers are available. In this article, we present an overview of AFR technology, devices and histopathology, and we summarize the current clinical possibilities with AFR incorporating our personal experience. AFR is still in the exploratory era, and systematic investigations of clinical outcomes related to various system settings are needed.

Development of ultra-short pulse VUV laser system for nanoscale processing

We have developed intense vacuum ultraviolet (VUV) radiation sources for advanced material processing, such as photochemical surface reactions and precise processing on a nanometer scale. We have constructed a new VUV laser system to generate sub-picosecond pulses at the wavelength of 126 nm. A seed VUV pulse was generated in Xe as the 7th harmonic of a 882-nm Ti:sapphire laser. The optimum conversion was achieved at the pressure of 1.2 Torr. The seed pulse will be amplified by the $\mathrm{Ar}_{2}^{*}$ media generated by an optical-field-induced ionization Ar plasma produced by the Ti:sapphire laser. We have obtained a gain coefficient of g=0.16 cm−1. Our developing system will provide VUV ultra-short pulses with sub-μJ energy at a repetition rate of 1 kHz.

Development of Ultrahigh-power Laser System for Relativistic Laser-Matter Interactions

물리학과 첨단기술 April 2010 19 저자약력 정태문 박사는 한국과학기술원 이학박사(1999)로서 한국원자력연구소(1998 -2000), 삼성전자(2000-2002), 로체스터 대학교(2002-2005)를 거쳐 2005 년부터 광주과학기술원 고등광기술연구소에서 재직 중이며 레이저 연구실장 으로 펨토초 페타와트 레이저 개발에 참여하고 있다. (jeongtm@gist.ac.kr) 성재희 박사는 한국과학기술원 이학박사(2005)로서 2005년부터 광주과학 기술원 고등광기술연구소에서 재직 중으로 극초단 페타와트 레이저 개발 에 참여하고 있다. (sungjh@gist.ac.kr) 이성구 박사는 한국과학기술원 이학박사(2005)로서 2005년부터 광주과학 기술원 고등광기술연구소에서 재직 중으로 펨토초 페타와트 레이저 개발 에 참여하고 있다. (lsk@gist.ac.kr) 유태준 박사 약력은 2쪽 참조. 이종민 교수 약력은 2쪽 참조. 상대론적 레이저-물질 상호작용 연구를 위한 초고출력 레이저

Modeling laser wakefield accelerator experiments with ultrafast particle-in-cell simulations in boosted frames

The development of new laser systems at the 10 Petawatt range will push laser wakefield accelerators to novel regimes, for which theoretical scalings predict the possibility to accelerate electron bunches up to tens of GeVs in meter-scale plasmas. Numerical simulations will play a crucial role in testing, probing, and optimizing the physical parameters and the setup of future experiments. Fully kinetic simulations are computationally very demanding, pushing the limits of today’s supercomputers. In this paper, the recent developments in the OSIRIS framework [R. A. Fonseca et al., Lect. Notes Comput. Sci. 2331, 342 (2002)] are described, in particular the boosted frame scheme, which leads to a dramatic change in the computational resources required to model laser wakefield accelerators. Results from one-to-one modeling of the next generation of laser systems are discussed, including the confirmation of electron bunch acceleration to the energy frontier.

SilviLaser: applications of laser systems for forest assessment and inventory

In recent years, there has been rapid development and uptake of laser systems operating on a principal of Light Detection And Ranging (LiDAR) in the inventory, assessment and monitoring of forests....

Tiefes chemisches Peeling mit Phenol – Renaissance eines Goldstandards?

Chemische Peelingverfahren zur Hautverjüngung haben in der Geschichte der Medizin eine lange Tradition. Bereits im Papyrus Ebers wurden vor 3500 Jahren erste chemische Peels beschrieben. Das Phenol-Peeling wurde in den 40er-Jahren des letzten Jahrhunderts von Laienoperateuren in den USA durchgeführt. Baker und Gordon modifizierten die Lösung und der wissenschaftliche Durchbruch mit Anerkennung der Methode erfolgte in den 60er-Jahren. Seither ist es eine Standardmethode der Hautverjüngung. Mit Einführung der Lasertechnologie wurde das Phenol-Peeling zurückgedrängt. Mit einiger Erfahrung nach CO2-Laser skin resurfacing wurde allerdings auch diese Methode wegen der Nebenwirkungen und der teils unbefriedigenden kosmetischen Ergebnisse wieder verlassen. Einige neue Lasersysteme sind zurzeit auf dem Markt, müssen sich aber erst bewähren und ihr Stellenwert wird sich erst in einigen Jahren zeigen. Das tiefe Peeling mit Phenol bietet sehr gute und verlässliche Ergebnisse, die darüber hinaus lang anhaltend sind. Es handelt sich hierbei aber um eine dermatologische, invasive Maßnahme, die Erfahrung und einer intensiven Patientenführung bedarf. Die kosmetischen Ergebnisse sind überzeugend und führen zu einer hohen Patientenzufriedenheit.

Fractional laser skin therapy

Modern treatment of chronically photodamaged skin provides new, minimally invasive methods for laser intervention, using fractional, non-ablative thermal energy for an induction of dermal remodeling. The clinical efficacy coupled with a minimum "down time" for the patient has directed the development of fractional ablative laser systems. Recently introduced systems are based on CO(2) and heated Er:YAG laser systems. The clinical efficacy has been tested on one prototype each and verified their effects at a microscopic level. Initial reports suggest the results are comparable to those achieved with fractional ablative systems. We review the current possibilities incorporating our personal experience. Systematic investigations of clinical outcomes with various system settings are still needed. The possible combination of ablative and non-ablative fractional technology may also lead to increased efficacy and safety of the procedure.

Principles of laser–plasma accelerators

Abstract The continuing development of powerful laser systems has permitted to extend the interaction of laser beams with matter far into the relativistic domain in which extremely high electric and magnetic fields are generated. Thanks to these tremendous fields, that only plasma can support and sustain, new and compact approaches for producing energetic particle beams have been recently achieved. The incredible progress of these laser–plasma accelerators has allowed physicists to produce high quality beams of energetic radiation and particles. These beams have interesting properties such as shortness, brightness and spatial quality, and could lend themselves to applications in many fields, including medicine (radiotherapy, proton therapy, imaging), radiation biology (short-time-scale), chemistry (radiolysis), physics and material science (radiography, electron and photon diffraction), security (material inspection), and of course accelerator science. Stimulated by the advent of compact and powerful lasers, with moderate costs and high repetition rate, this research field has witnessed considerable growth in the past few years, and the promises of laser–plasma accelerators are in tremendous progress. The recent years in particular have seen spectacular progress in the acceleration of electrons and of ions, both in terms of energy and in terms of quality of the beams. To cite this article: V. Malka, P. Mora, C. R. Physique 10 (2009).

Laser electron acceleration with 10 PW lasers

Abstract The development of new laser systems, in the 10 PW range, will push Laser Wakefield Accelerators (LWFA) to a new qualitative regime, where different configurations, approaches, and parameters can be explored. Based on the design parameters to be expected for some of these systems (e.g. the future Vulcan 10 PW OPCPA laser system), we have explored the optimal parameters for a single LWFA stage, using the theoretical scalings for these parameters (pulse duration ≈30 fs, energy ≈300 J). The scalings predict the possibility to accelerate electron bunches to energies close to the energy frontier, with self-injected electrons in excess of 10 GeV, and above 50 GeV bunches with externally-injected electrons. We have used these parameters as a baseline for 3D full scale simulations, confirming self-guiding of 10 PW lasers over distances in excess of 10 cm, and 12 GeV self-injected beams, in agreement with theoretical predictions for the maximum energy gain and the injected charge. In externally guided configurations, our simulations confirm the accelerating gradients and the stability of the laser guided propagation for the long distances required to reach the energy frontier. To cite this article: L.O. Silva et al., C. R. Physique 10 (2009).