TY - JOUR A1 - Jechow, Andreas A1 - Seefeldt, Michael A1 - Kurzke, Henning A1 - Heuer, Axel A1 - Menzel, Ralf T1 - Enhanced two-photon excited fluorescence from imaging agents using true thermal light JF - Nature photonics N2 - Two-photon excited fluorescence (TPEF) is a standard technique in modern microscopy(1), but is still affected by photodamage to the probe. It has been proposed that TPEF can be enhanced using entangled photons(2,3), but this has proven challenging. Recently, it was shown that some features of entangled photons can be mimicked with thermal light, which finds application in ghost imaging(4), subwavelength lithography(5) and metrology(6). Here, we use true thermal light from a superluminescent diode to demonstrate TPEF that is enhanced compared to coherent light, using two common fluorophores and luminescent quantum dots, which suit applications in imaging and microscopy. We find that the TPEF rate is directly proportional to the measured(7) degree of second-order coherence, as predicted by theory. Our results show that photon bunching in thermal light can be exploited in two-photon microscopy, with the photon statistic providing a new degree of freedom. Y1 - 2013 U6 - https://doi.org/10.1038/NPHOTON.2013.271 SN - 1749-4885 SN - 1749-4893 VL - 7 IS - 12 SP - 973 EP - 976 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Jechow, Andreas A1 - Lichtner, Mark A1 - Menzel, Ralf A1 - Radziunas, Mindaugas A1 - Skoczowsky, Danilo A1 - Vladimirov, Andrei G. T1 - Stripe-array diode-laser in an off-axis external cavity : theory and experiment N2 - Stripe-array diode lasers naturally operate in an anti-phase supermode. This produces a sharp double lobe far field at angles +/-alpha depending on the period of the array. In this paper a 40 emitter gain guided stripe-array laterally coupled by off-axis filtered feedback is investigated experimentally and numerically. We predict theoretically and confirm experimentally that at doubled feedback angle 2 alpha a stable higher order supermode exists with twice the number of emitters per array period. The theoretical model is based on time domain traveling wave equations for optical fields coupled to the carrier density equation taking into account diffusion of carriers. Feedback from the external reflector is modeled using Fresnel integration. Y1 - 2009 UR - http://www.opticsexpress.org/Issue.cfm U6 - https://doi.org/10.1364/OE.17.019599 SN - 1094-4087 ER - TY - JOUR A1 - Skoczowsky, Danilo A1 - Jechow, Andreas A1 - Stürmer, Herbert A1 - Poßner, Torsten A1 - Sacher, Joachim A1 - Menzel, Ralf T1 - Quasi-monolithic ring resonator for efficient frequency doubling of an external cavity diode laser N2 - A quasi-monolithic second-harmonic-generation ring resonator assembled with miniaturized components is presented. The ring contains a 10-mm-long bulk periodically poled lithium niobate crystal for second-harmonic generation, four plane mirrors and two gradient-index lenses. All parts are mounted on a glass substrate with an overall size of 19.5 mmx8.5 mmx4 mm. As pump source a broad-area laser diode operated in an external resonator with Littrow arrangement is utilized. This external cavity diode laser provides near diffraction limited, narrow-bandwidth emission with an optical output power of 450 mW at a wavelength of 976 nm. Locking of the diode laser emission to the resonance frequency of the ring cavity was achieved by an optical self-injection locking technique. With this setup more than 126 mW of diffraction-limited blue light at 488 nm could be generated. The opto-optical conversion efficiency was 28% and a wall plug efficiency better than 5.5% could be achieved. Y1 - 2010 UR - http://www.springerlink.com/content/100502 U6 - https://doi.org/10.1007/s00340-009-3802-7 SN - 0946-2171 ER - TY - JOUR A1 - Kappe, Philip A1 - Menzel, Ralf A1 - Ostermeyer, Martin T1 - Analysis of the temporal and spectral output properties of a mode-locked and Q-switched laser oscillator with a nonlinear mirror based on stimulated Brillouin scattering N2 - The emission dynamics of a mode-locked laser oscillator with a nonlinear mirror based on stimulated Brillouin scattering (SBS) has been investigated with regard to its spectrum and to its intensity distribution. The investigation was carried out experimentally as well as by numerical simulations. The laser yields trains of pulses with measured durations of 410 ps and energies of the single pulse of up to 2 mJ. Two theoretical models describing the complex emission dynamics of a mode-locked SBS-laser oscillator are introduced. The first model consists of spectrally resolved laser rate equations and thus describes the mode locking in the frequency domain by the superposition of the longitudinal resonator modes. The SBS-Q-switch is incorporated by a phenomenological description of the time dependent SBS reflectivity. Numerical simulations based on this model yield the evolution of a few 100 longitudinal laser modes and the corresponding intensity distribution during the course of a Q-switch pulse with 10-ps resolution. The influences of the different components on the spectrum and thus on the pulse duration will be discussed. The second model describes all occurring dynamics in the time domain providing easy access to the study of misalignment on the output dynamics. Results of numerical simulations of both models and measurement results are compared Y1 - 2006 UR - http://pra.aps.org/ U6 - https://doi.org/10.1103/Physreva.74.013809 SN - 1050-2947 ER - TY - JOUR A1 - Jechow, Andreas A1 - Lichtner, Mark A1 - Menzel, Ralf A1 - Radziunas, Mindaugas A1 - Skoczowsky, Danilo A1 - Vladimirov, Andrei G. T1 - Stripe-array diode-laser in an off-axis external cavity : theory and experiment N2 - Stripe-array diode lasers naturally operate in an anti-phase supermode. This produces a sharp double lobe far field at angles ña depending on the period of the array. In this paper a 40 emitter gain guided stripe-array laterally coupled by off-axis filtered feedback is investigated experimentally and numerically. We predict theoretically and confirm experimentally that at doubled feedback angle 2a a stable higher order supermode exists with twice the number of emitters per array period. The theoretical model is based on time domain traveling wave equations for optical fields coupled to the carrier density equation taking into account diffusion of carriers. Feedback from the external reflector is modeled using Fresnel integration. Y1 - 2009 UR - http://www.opticsinfobase.org/oe/Issue.cfm U6 - https://doi.org/10.1364/OE.17.019599 SN - 1094-4087 ER - TY - JOUR A1 - Eichler, Hans Joachim A1 - Haase, Alfred A1 - Menzel, Ralf A1 - Schwartz, J. T1 - Depolarization treatment and optimization of high power double pass neodym-rod amplifiers with SBS mirror Y1 - 1994 ER - TY - JOUR A1 - Eichler, Hans Joachim A1 - Haase, Alfred A1 - Menzel, Ralf T1 - SBS-Phase Conjugation for Thermal Lens Compensation in 100 Watt Average Power Solid-State Lasers Y1 - 1994 ER - TY - JOUR A1 - Lueck, H. A1 - Menzel, Ralf A1 - Sander, Rolf T1 - Inherent sample heating and temperature calibration in excited state absorption (ESA) measurements between room temperature and 77 kelvin Y1 - 1994 ER - TY - JOUR A1 - Eichler, Hans Joachim A1 - Macdonald, R. A1 - Menzel, Ralf A1 - Sander, Rolf T1 - Excited state absorption of 5CB (4'-n-pentyl-4-cyanobiphenyl) in cyclohexane Y1 - 1995 ER - TY - JOUR A1 - Eichler, Hans Joachim A1 - Menzel, Ralf A1 - Sander, Rolf A1 - Schulzke, M. A1 - Schwartz, J. T1 - SBS at different wavelengths between 308 and 725 nm Y1 - 1995 ER - TY - JOUR A1 - Eichler, Hans Joachim A1 - Haase, Alfred A1 - Menzel, Ralf T1 - Power enhancement and application of a Nd:YALO rod amplifier with a phase conjugating mirror Y1 - 1995 ER - TY - JOUR A1 - Menzel, Ralf A1 - Eichler, Hans Joachim A1 - Geinitz, E. A1 - Haase, Alfred A1 - Scherrer, R. T1 - Neodymium-laser with SBS phase conjugation for high beam quality Y1 - 1995 ER - TY - JOUR A1 - Eichler, Hans Joachim A1 - Haase, Alfred A1 - Menzel, Ralf T1 - Power enhancement and application of a Nd:YALO rod amplifier with a phase conjugating mirror Y1 - 1995 ER - TY - JOUR A1 - Eichler, Hans Joachim A1 - Haase, Alfred A1 - Menzel, Ralf T1 - 100 watt average output power 1.2*diffraction limited beam from pulsed neodym single rod amplifier with SBS- phaseconjugation BT - Onehundred watt average output 1.2*diffraction limited beam from pulsed neodym single rod amplifier with SBS- phaseconjugation T2 - Hundred watt average output power 1.2*diffraction limited beam from pulsed neodym single rod amplfier with SBS- phaseconjugation Y1 - 1995 ER - TY - JOUR A1 - Heuer, Axel A1 - Menzel, Ralf A1 - Ostermeyer, Martin T1 - Power tunable Nd-oscillators with diffraction limited beams via SBS phase conjugation Y1 - 1996 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Heuer, Axel A1 - Menzel, Ralf T1 - Q-switching of Nd-lasers with high repetition rates by SBS phase conjugation Y1 - 1996 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Heuer, Axel A1 - Watermann, V. A1 - Menzel, Ralf T1 - Resonators with phase conjugating SBS-mirror for solid state lasers with high output powers Y1 - 1996 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Heuer, Axel A1 - Watermann, V. A1 - Menzel, Ralf T1 - Single rod Nd:laser with phase conjugating SBS-mirror and large transversal mode for average output powers above 20 Watts Y1 - 1996 ER - TY - JOUR A1 - Sander, Rolf A1 - Herrmann, V. A1 - Menzel, Ralf T1 - Transient absorption spectra and bleaching of 4'-n-Pentyl-4-Cyanoterphenyl in Cyclohexane : determination of cross sections and recovery times Y1 - 1996 ER - TY - JOUR A1 - Eichler, Hans Joachim A1 - Haase, Alfred A1 - Menzel, Ralf T1 - High beam quality of a single rod neodym amplifier by SBS-phase conjugation up to 140 watt average output Y1 - 1996 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Menzel, Ralf T1 - 34 Watt flash lamp pumped single rod ND:YAG laser with 1.2 * DL beam quality via special resonator design BT - Vierunddreißig Watt flash lamp pumped single rod ND:YAG laser with 1.2 * DL beam quality via special resonator design Y1 - 1997 ER - TY - JOUR A1 - Heuer, Axel A1 - Hodgson, N. A1 - Lorenz, Dieter A1 - Ostermeyer, Martin A1 - Menzel, Ralf T1 - Solid state lasers with high brightness via optical phase conjugation for micromachining Y1 - 1997 ER - TY - JOUR A1 - Mittler, Kay A1 - Ostermeyer, Martin A1 - Heuer, Axel A1 - Menzel, Ralf T1 - Longitudinal mode structure of Nd-lasers with phase conjugating mirrors based on stimulated Brillouin scattering in different materials Y1 - 1997 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Lorenz, Dieter A1 - Menzel, Ralf T1 - Nd-laser oscillators with phase-conjugating SBS mirrors for high average output powers and fundamental mode operation Y1 - 1997 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Lorenz, Dieter A1 - Hodgson, N. A1 - Menzel, Ralf T1 - Transverse Modes in Laser Resonators with Phase Conjugating Mirror Based on Stimulated Brillouin Scattering (SBS) Y1 - 1997 ER - TY - JOUR A1 - Lorenz, Dieter A1 - Menzel, Ralf T1 - Broadband operation of frequency doubled Cr4+:YAG laser with high beam quality Y1 - 1998 ER - TY - JOUR A1 - Menzel, Ralf A1 - Ostermeyer, Martin T1 - Fundamental mode determination for guaranteeing diffrraction limited beam quality of lasers with high output powers Y1 - 1998 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Heuer, Axel A1 - Menzel, Ralf T1 - 27 Watt average output power with 1.2*DL beam quality from a single rod Nd:YAG-Laser with phase conjugating SBS- mirror BT - Siebenundzwanzig Watt average output power with 1.2*DL beam quality from a single rod Nd:YAG-Laser with phase conjugating SBS-mirror Y1 - 1998 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Hodgson, N. A1 - Menzel, Ralf T1 - High-power, fundamental mode Nd:YALO laser using a phase-conjugate resonator based on SBS Y1 - 1998 ER - TY - JOUR A1 - Heuer, Axel A1 - Hodgson, N. A1 - Menzel, Ralf T1 - Efficient, low-threshold phase conjugation in a tapered optical fiber Y1 - 1998 ER - TY - JOUR A1 - Heuer, Axel A1 - Menzel, Ralf T1 - Phase conjugating SBS-mirror for low powers and reflectivities above 90 % in an internally tapered optical fiber Y1 - 1998 ER - TY - JOUR A1 - Heuer, Axel A1 - Schultheiss, J. A1 - Hodgson, N. A1 - Kurths, Jürgen A1 - Menzel, Ralf A1 - Raab, Volker T1 - Transverse effects in phase conjugate laser mirrors based on stimulated brillouin scattering Y1 - 1999 ER - TY - JOUR A1 - Lorenz, Dieter A1 - Brandenburg, Ingo A1 - Menzel, Ralf T1 - Spectral broadening of the laser spectrum of gain-switched Ti:sapphire laser with nonlinear absorbers Y1 - 1999 ER - TY - JOUR A1 - Mittler, Kay A1 - Lorenz, Dieter A1 - Menzel, Ralf T1 - Broadband operation of a gain-switched Ti:sapphire laser for measurements with the coherence radar Y1 - 1999 SN - 0277-786X ER - TY - JOUR A1 - Mittler, Kay A1 - Lorenz, Dieter A1 - Menzel, Ralf T1 - Time-resolved measurements of the spectra of a broadband laser used as light source for the coherence radar Y1 - 1999 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Mittler, Kay A1 - Menzel, Ralf T1 - Q switch and longitudinal modes of a laser oscillator with a stimulated-Brillouin-scattering mirror Y1 - 1999 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Menzel, Ralf T1 - Single rod efficient Nd:YAG and Nd:YALO-lasers with average output powers of 46 and 47 W in diffraction limited beams with M2 < 1.2 and 100 W with M2 < 3.7 Y1 - 1999 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Menzel, Ralf T1 - 50 Watt average output power with 1.2*DL beam quality from a single rod Nd:YALO laser with phase-conjugating SBS mirror BT - Fünfzig Watt average output power with 1.2*DL beam quality from a single rod Nd:YALO laser with phase- conjugating SBS mirror Y1 - 1999 ER - TY - JOUR A1 - Mittler, Kay A1 - Lorenz, Dieter A1 - Menzel, Ralf T1 - Time resolved emission spectra of a broadband ns-laser with 0.5 W average output power used as light source for the coherence radar Y1 - 1999 ER - TY - JOUR A1 - Lorenz, Dieter A1 - Mittler, Kay A1 - Brandenburg, Ingo A1 - Menzel, Ralf T1 - Enhanced coherence radar measurements with spectrally broadened Ti:sapphire laser using nonlinear absorber N2 - D. Lorenz, K. Mittler, I. Brandenburg, R. Menze Y1 - 2000 SN - 08194-3546-5 ER - TY - JOUR A1 - Heuer, Axel A1 - Menzel, Ralf T1 - Temporal features of SBS phase conjugation Y1 - 2000 SN - 0-8194-3545-7 ER - TY - JOUR A1 - Heuer, Axel A1 - Menzel, Ralf T1 - Low threshold SBS phase conjugation for quasi-cw laser systems Y1 - 2000 ER - TY - JOUR A1 - Raab, Volker A1 - Ullner, Ekkehard A1 - Menzel, Ralf T1 - Novel External Resonators for High Power Diode Lasers with Improved Beam Quality Y1 - 2000 ER - TY - JOUR A1 - Menzel, Ralf A1 - Raab, Volker A1 - Lorenz, Dieter A1 - Heuer, Axel T1 - Efficient phase conjugating mirror with a low threshold in a tapered optical fiber Y1 - 2000 ER - TY - JOUR A1 - Klemz, Guido A1 - Kubina, P. A1 - Ostermeyer, Martin A1 - Menzel, Ralf T1 - Diode pumped high power TEM_00 Nd:YAG rod laser with birefringence compensation Y1 - 2001 ER - TY - JOUR A1 - Hänisch, Christoph A1 - Heuer, Axel A1 - Menzel, Ralf T1 - Threshold reduction of stimulated Brillouin scattering (SBS) using fiber loop schemes Y1 - 2001 ER - TY - JOUR A1 - Afshaarvahid, Shahraam A1 - Heuer, Axel A1 - Menzel, Ralf A1 - Munch, Jesper T1 - Temporal structure of stimulated-Brillouin-scattering reflectivity considering transversal-mode development Y1 - 2001 ER - TY - JOUR A1 - Menzel, Ralf T1 - Photonics : Linear and nonlinear interactions of laser light and matter Y1 - 2001 SN - 3-540-67074-2 PB - Springer CY - Berlin ER - TY - JOUR A1 - Spitz, Christian A1 - von Seggern, David A1 - Grunwaldt, Gisela A1 - Menzel, Ralf T1 - Biochemical Diagnostics by Excited State Absorption Spectroscopy Y1 - 2002 SN - 0-8194-4365-4 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Klemz, Guido A1 - Menzel, Ralf T1 - Double rod Nd:YAG laser with 180 W average output and diffraction limited beam quality via path-matched birefringence compensation Y1 - 2002 SN - 0-8194-4368-9 ER - TY - JOUR A1 - Raab, Volker A1 - Menzel, Ralf T1 - Phase-locked array of 25 broad-area lasers Y1 - 2002 SN - 0-8194-4368-9 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Klemz, Guido A1 - Heuer, Axel A1 - Menzel, Ralf T1 - High Brightness Double and Single Rod Nd:YAG Laser Oscillators with up to 180 W and M2 < 1.2 Y1 - 2002 ER - TY - BOOK A1 - Heuer, Axel A1 - Hänisch, Christoph A1 - Ostermeyer, Martin A1 - Menzel, Ralf T1 - Low Power Threshold Phase Conjugating Mirrors by SBS in Yb-doped Fiber Amplifiers Y1 - 2002 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Klemz, Guido A1 - Kubina, P. A1 - Menzel, Ralf T1 - Quasi-continuous-wave birefringence-compensated single- and double-rod Nd : YAG lasers Y1 - 2002 ER - TY - JOUR A1 - Raab, Volker A1 - Menzel, Ralf T1 - External resonator design for high-power laser diodes that yields 400 mW of TEM00 power Y1 - 2002 ER - TY - JOUR A1 - Heuer, Axel A1 - Hänisch, Christoph A1 - Menzel, Ralf T1 - New concept for low threshold optical phase conjugation via SBS in a fiber amplifier Y1 - 2003 SN - 0-8194-4772-2 ER - TY - JOUR A1 - Raab, Volker A1 - Skoczowsky, Danilo A1 - Menzel, Ralf T1 - Tuning high-power diodes with as much as 0.38 W of power and M2 = 1.2 over a range of 32 nm with 3-GHz bandwidth Y1 - 2003 ER - TY - JOUR A1 - Heuer, Axel A1 - Hänisch, Christoph A1 - Menzel, Ralf T1 - Low-power phase conjugation based on stimulated Brillouin scattering in fiber amplifiers Y1 - 2003 ER - TY - JOUR A1 - Seefeldt, Michael A1 - Heuer, Axel A1 - Menzel, Ralf T1 - Compact white-light source with an average output power of 2.4 W and 900 nm spectral bandwidth Y1 - 2003 ER - TY - JOUR A1 - von Seggern, David A1 - Modrakowski, Claudia A1 - Spitz, Christian A1 - Schlüter, A. D. A1 - Menzel, Ralf T1 - Charge transfer initiated by optical excitation in diester substituted biphenylpyrene as a function of the solvent characterized by excited state absorption spectroscopy N2 - Cross-sections for ground and excited state absorptions of the charge transfer system 3-(3-tert- butoxycarbonylamino-propyl)-4'-pyren-1-yl-biphenyl-2,5-dicarbo xylicacid dimethyl ester (Py-C) are determined from nonlinear absorption and fluorescence measurements as a function of solvent. While in non-polar solvents no stable charge transfer (CT) state occurs after optical excitation, in polar solvents the CT state is stabilized. (C) 2004 Elsevier B.V. All rights reserved Y1 - 2004 ER - TY - JOUR A1 - Tedeschi, Concetta A1 - Li, L. A1 - Möhwald, Helmuth A1 - Spitz, Christian A1 - von Seggern, David A1 - Menzel, Ralf A1 - Kirstein, Stefan T1 - Engineering of layer-by-layer coated capsules with the prospect of materials for efficient and directed electron transfer N2 - We show a Lefschetz fixed point formula for holomorphic functions in a bounded domain D with smooth boundary in the complex plane. To introduce the Lefschetz number for a holomorphic map of D, we make use of the Bergman kernel of this domain. The Lefschetz number is proved to be the sum of the usual contributions of fixed points of the map in D and contributions of boundary fixed points, these latter being different for attracting and repulsing fixed points Y1 - 2004 ER - TY - JOUR A1 - Unterhuber, Angelika A1 - Povazay, B. A1 - Bizheva, K. A1 - Hermann, B. A1 - Sattmann, Harald A1 - Stingl, A. A1 - Le, Trang A1 - Seefeldt, Michael A1 - Menzel, Ralf A1 - Preusser, Matthias A1 - Budka, Herbert A1 - Schubert, Christian A1 - Reitsamer, H. A1 - Ahnelt, Peter Kurt A1 - Morgan, J. E. T1 - Advances in broad bandwidth light sources for ultrahigh resolution optical coherence tomography N2 - Novel ultra-broad bandwidth light sources enabling unprecedented sub-2 pm axial resolution over the 400 nm-1700 nm wavelength range have been developed and evaluated with respect to their feasibility for clinical ultrahigh resolution optical coherence tomography (UHR OCT) applications. The state-of-the-art light sources described here include a compact Kerr lens mode locked Ti:sapphire laser (lambda(c) = 785 nm, Deltalambda = 260 nm, P-out = 50 mW) and different nonlinear fibre-based light sources with spectral bandwidths (at full width at half maximum) up to 350 nm at lambda(c) = 1130 nm and 470 nm at lambda(c) = 1375 run. In vitro UHR OCT imaging is demonstrated at multiple wavelengths in human cancer cells, animal ganglion cells as well as in neuropathologic and ophthalmic biopsies in order to compare and optimize UHR OCT image contrast, resolution and penetration depth Y1 - 2004 SN - 0031-9155 ER - TY - JOUR A1 - Menzel, Ralf T1 - Metrological Applications Y1 - 2004 SN - 3-540-20114-9 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Menzel, Ralf T1 - Laser resonators with brillouin mirrors JF - Phase conjugate laser optics Y1 - 2004 SN - 0-471-43957-6 PB - Wiley CY - Hoboken, NJ ER - TY - JOUR A1 - Heuer, Axel A1 - Menzel, Ralf T1 - Principles of Phase Conjugating Brillouin Mirrors Y1 - 2004 SN - 0-471-43957-6 ER - TY - BOOK A1 - Ostermeyer, Martin A1 - Kappe, Philip A1 - Menzel, Ralf A1 - Sommer, S. A1 - Dausinger, Friedrich T1 - Laser drilling in thin materials with bursts of ns-pulses generated by stimulated Brillouin scattering (SBS) N2 - A passively Q-switched laser with a nonlinear mirror on the basis of stimulated Brillouin scattering (SBS), generates bursts of pulses with a few 10 ns pulse duration and a separation between 20-90 mu s. Percussion drilling and trepanning are performed in different materials with 1 mm thickness. The optimum parameter set of these pulse trains with regard to the burr height and ablation rate is investigated. Differences in the processing results between single pulse and multi pulse structures are discussed. In addition the laser allowed for transiently mode locked operation. Results for mode locked and merely Q-switched operation were compared Y1 - 2005 ER - TY - BOOK A1 - Ostermeyer, Martin A1 - Kappe, Philip A1 - Menzel, Ralf A1 - Wulfmeyer, Volker T1 - Diode-pumped Nd : YAG master oscillator power amplifier with high pulse energy, excellent beam quality, and frequency-stabilized master oscillator as a basis for a next-generation lidar system N2 - A pulsed, diode-laser-pumped Nd:YAG master oscillator power amplifier (MOPA) in rod geometry, frequency stabilized with a modified Pound-Drever-Hall scheme is presented. The apparatus delivers 33-ns pulses with a maximum pulse energy of 0.5 J at 1064 nm. The system was set up in two different configurations for repetition rates of 100 or 250 Hz. The beam quality was measured to be 1.5 times the diffraction limit at a pulse energy of 405 mJ and a repetition rate of 100 Hz. At 250 Hz with the same pulse energy, the M-2 was better than 2.1. The radiation is frequency converted with an efficiency of 50% to 532 nm. This MOPA system will be the pump laser of transmitters for a variety of high-end, scanning lidar systems. (C) 2005 Optical Society of America Y1 - 2005 ER - TY - JOUR A1 - Kappe, Philip A1 - Ostermeyer, Martin A1 - Menzel, Ralf T1 - Active mode locking of a phase-conjugating SBS-laser oscillator N2 - We present a flashlamp-pumped Nd: YAG laser simultaneously emitting pulse structures on microsecond, nanosecond and picosecond time scales. Within a microsecond flashlamp pump pulse a nonlinear reflector based on stimulated Brillouin scattering (SBS) generates several Q-switch pulses. The phase-conjugating effect of the SBS reflector provides a compensation of phase distortions generated inside the laser rod, resulting in transverse fundamental mode operation. Additional acousto-optic loss modulation inside the resonator leads to mode locking. As a result, each Q-switch pulse is subdivided into several picosecond pulses. Energies of up to 2 mJ for the mode-locked pulses with durations between 220 and 800 ps are demonstrated. The wide variability of the laser's temporal output parameters as well as its high beam quality make it a splendid tool for fundamental research in laser materials processing Y1 - 2005 SN - 0946-2171 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Kappe, Philip A1 - Menzel, Ralf A1 - Wulfmeyer, Volker T1 - Diode-pumped Nd : YAG master oscillator power amplifier with high pulse energy, excellent beam quality, and frequency-stabilized master oscillator as a basis for a next-generation lidar system N2 - In the original publication [Ostermeyer et al., Appl. Opt., 44, 582-590 (2005)], Fig. 5 appeared twice as Figs. 4 and 5. This inaccuracy is corrected here. (c) 2005 Optical Society of America Y1 - 2005 SN - 0003-6935 ER - TY - JOUR A1 - Li, L. A1 - Möhwald, Helmuth A1 - Spitz, Christian A1 - von Seggern, David A1 - Mucke, M. A1 - Menzel, Ralf T1 - Long-lived photoinduced charge separation inside polarity gradient capsules Y1 - 2005 ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Klemz, Guido A1 - Kubina, P. A1 - Menzel, Ralf T1 - Enhanced brightness and extraction efficiency of Nd:YAG rod lasers resulting in 180 W output power with M2<1.2 Y1 - 2005 SN - 1-557-52697-4 ER - TY - JOUR A1 - Kappe, Philip A1 - Ostermeyer, Martin A1 - Menzel, Ralf T1 - Active mode locking of a phase-conjugating SBS-laser oscillator Y1 - 2005 SN - 0946-2171 ER - TY - JOUR A1 - Skoczowsky, Danilo A1 - Jechow, Andreas A1 - Menzel, Ralf A1 - Paschke, Katrin A1 - Erbert, Götz T1 - Efficient second-harmonic generation using a semiconductor tapered amplifier in a coupled ring-resonator geometry N2 - A new approach for efficient second-harmonic generation using diode lasers is presented. The experimental setup is based on a tapered amplifier operated in a ring resonator that is coupled to a miniaturized enhancement ring resonator containing a periodically poled lithium niobate crystal. Frequency locking of the diode laser emission to the resonance frequency of the enhancement cavity is realized purely optically, resulting in stable, single-frequency operation. Blue light at 488 nm with an output power of 310 mW is generated with an optical-to-optical conversion efficiency of 18%. Y1 - 2010 UR - http://www.opticsinfobase.org/ U6 - https://doi.org/10.1364/OL.35.000232 SN - 0146-9592 ER - TY - JOUR A1 - Jechow, Andreas A1 - Raab, Volker A1 - Menzel, Ralf T1 - High cw power using an external cavity for spectral beam combining of diode laser-bar emission N2 - In extension to known concepts of wavelength-multiplexing diode laser arrays, a new external cavity is presented. The setup simultaneously improves the beam quality of each single emitter of a standard 25 emitter broad-area stripe laser bar and spectrally superimposes the 25 beams into one. By using this external resonator in an "off-axis" arrangement, beam qualities of M-slow(2) < 14 and M-fast(2) < 3 with optical powers in excess of 10 W in cw operation are obtained. Y1 - 2006 UR - http://www.opticsinfobase.org/ao/browse.cfm U6 - https://doi.org/10.1364/AO.45.003545 SN - 0003-6935 ER - TY - JOUR A1 - Menzel, Ralf T1 - Photonics : linear and nonlinear interactions of laser light and matter Y1 - 2007 SN - 978-540-67074-2 PB - Springer CY - Berlin ER - TY - JOUR A1 - Rätzel, Dennis A1 - Wilkens, Martin A1 - Menzel, Ralf T1 - Gravitational properties of light BT - the gravitational field of a laser pulse JF - New journal of physics : the open-access journal for physics N2 - The gravitational field of a laser pulse of finite lifetime, is investigated in the framework of linearized gravity. Although the effects are very small, they may be of fundamental physical interest. It is shown that the gravitational field of a linearly polarized light pulse is modulated as the norm of the corresponding electric field strength, while no modulations arise for circular polarization. In general, the gravitational field is independent of the polarization direction. It is shown that all physical effects are confined to spherical shells expanding with the speed of light, and that these shells are imprints of the spacetime events representing emission and absorption of the pulse. Nearby test particles at rest are attracted towards the pulse trajectory by the gravitational field due to the emission of the pulse, and they are repelled from the pulse trajectory by the gravitational field due to its absorption. Examples are given for the size of the attractive effect. It is recovered that massless test particles do not experience any physical effect if they are co-propagating with the pulse, and that the acceleration of massless test particles counter-propagating with respect to the pulse is four times stronger than for massive particles at rest. The similarities between the gravitational effect of a laser pulse and Newtonian gravity in two dimensions are pointed out. The spacetime curvature close to the pulse is compared to that induced by gravitational waves from astronomical sources. KW - gravity KW - general relativity KW - laser pulses KW - electromagnetic radiation KW - linearized gravity KW - pp-wave solutions Y1 - 2016 U6 - https://doi.org/10.1088/1367-2630/18/2/023009 SN - 1367-2630 VL - 18 SP - 1 EP - 16 PB - IOP Science CY - London ER - TY - GEN A1 - Rätzel, Dennis A1 - Wilkens, Martin A1 - Menzel, Ralf T1 - Gravitational properties of light BT - the gravitational field of a laser pulse N2 - The gravitational field of a laser pulse of finite lifetime, is investigated in the framework of linearized gravity. Although the effects are very small, they may be of fundamental physical interest. It is shown that the gravitational field of a linearly polarized light pulse is modulated as the norm of the corresponding electric field strength, while no modulations arise for circular polarization. In general, the gravitational field is independent of the polarization direction. It is shown that all physical effects are confined to spherical shells expanding with the speed of light, and that these shells are imprints of the spacetime events representing emission and absorption of the pulse. Nearby test particles at rest are attracted towards the pulse trajectory by the gravitational field due to the emission of the pulse, and they are repelled from the pulse trajectory by the gravitational field due to its absorption. Examples are given for the size of the attractive effect. It is recovered that massless test particles do not experience any physical effect if they are co-propagating with the pulse, and that the acceleration of massless test particles counter-propagating with respect to the pulse is four times stronger than for massive particles at rest. The similarities between the gravitational effect of a laser pulse and Newtonian gravity in two dimensions are pointed out. The spacetime curvature close to the pulse is compared to that induced by gravitational waves from astronomical sources. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 222 KW - electromagnetic radiation KW - general relativity KW - gravity KW - laser pulses KW - linearized gravity KW - pp-wave solutions Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-90553 ER -