TY - GEN A1 - Menzel, Ralf A1 - Heuer, Axel A1 - Milonni, Peter W. T1 - Entanglement, complementarity, and vacuum fields in spontaneous parametric down-conversion T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Using two crystals for spontaneous parametric down-conversion in a parallel setup, we observe two-photon interference with high visibility. The high visibility is consistent with complementarity and the absence of which-path information. The observations are explained as the effects of entanglement or equivalently in terms of interfering probability amplitudes and also by the calculation of a second-order field correlation function in the Heisenberg picture. The latter approach brings out explicitly the role of the vacuum fields in the down-conversion at the crystals and in the photon coincidence counting. For comparison, we show that the Hong–Ou–Mandel dip can be explained by the same approach in which the role of the vacuum signal and idler fields, as opposed to entanglement involving vacuum states, is emphasized. We discuss the fundamental limitations of a theory in which these vacuum fields are treated as classical, stochastic fields. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1077 KW - complementarity KW - vacuum fields KW - entanglement KW - Hong-Ou-Mandel effect KW - spontaneous parametric down-conversion Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-473542 SN - 1866-8372 IS - 1077 ER - TY - JOUR A1 - Menzel, Ralf A1 - Heuer, Axel A1 - Milonni, Peter W. T1 - Entanglement, Complementarity, and Vacuum Fields in Spontaneous Parametric Down-Conversion JF - Atoms N2 - Using two crystals for spontaneous parametric down-conversion in a parallel setup, we observe two-photon interference with high visibility. The high visibility is consistent with complementarity and the absence of which-path information. The observations are explained as the effects of entanglement or equivalently in terms of interfering probability amplitudes and also by the calculation of a second-order field correlation function in the Heisenberg picture. The latter approach brings out explicitly the role of the vacuum fields in the down-conversion at the crystals and in the photon coincidence counting. For comparison, we show that the Hong-Ou-Mandel dip can be explained by the same approach in which the role of the vacuum signal and idler fields, as opposed to entanglement involving vacuum states, is emphasized. We discuss the fundamental limitations of a theory in which these vacuum fields are treated as classical, stochastic fields. KW - complementarity KW - vacuum fields KW - entanglement KW - Hong-Ou-Mandel effect KW - spontaneous parametric down-conversion Y1 - 2019 U6 - https://doi.org/10.3390/atoms7010027 SN - 2218-2004 VL - 7 IS - 1 PB - MDPI CY - Basel ER - TY - JOUR A1 - Menzel, Ralf A1 - Heuer, Axel A1 - Puhlmann, Dirk A1 - Dechoum, K. A1 - Hillery, M. A1 - Spaehn, M. J. A. A1 - Schleich, W. P. T1 - A two-photon double-slit experiment JF - Journal of modern optics N2 - We employ a photon pair created by spontaneous parametric down conversion (SPDC) where the pump laser is in the TEM01 mode to perform a Young's double-slit experiment. The signal photon illuminates the two slits and displays interference fringes in the far-field while the idler photon measured in the near-field in coincidence with the signal photon provides us with which-slit' information. We explain the results of these experiments with the help of an analytical expression for the second-order correlation function derived from an elementary model of SPDC. Our experiment emphasizes the crucial role of the mode function in the quantum theory of radiation. KW - complementarity KW - wave-particle dualism KW - Young's double-slit experiment KW - spontaneous parametric down conversion KW - TEM01 mode Y1 - 2013 U6 - https://doi.org/10.1080/09500340.2012.746400 SN - 0950-0340 VL - 60 IS - 1 SP - 86 EP - 94 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Menzel, Ralf A1 - Marx, Robert A1 - Puhlmann, Dirk A1 - Heuer, Axel A1 - Schleich, Wolfgang T1 - The photon BT - the role of its mode function in analyzing complementarity JF - Journal of the Optical Society of America : B, Optical physics N2 - We investigate the role of the spatial mode function in a single-photon experiment designed to demonstrate the principle of complementarity. Our approach employs entangled photons created by spontaneous parametric downconversion from a pump mode in a TEM01 mode together with a double slit. Measuring the interference of the signal photons behind the double slit in coincidence with the entangled idler photons at different positions, we select signal photons of different mode functions. When the signal photons belong to the TEM01-like double-hump mode, we obtain almost perfect visibility of the interference fringes, and no "which slit" information is available in the idler photon detected before the slits. This result is remarkable because the entangled signal and idler photon pairs are created each time in only one of the two intensity humps. However, when we break the symmetry between the two maxima of the signal photon mode structure, the paths through the slits for these additional photons become distinguishable and the visibility vanishes. It is the mode function of the photons selected by the detection system that decides if interference or "which slit" information is accessible in the experiment. Y1 - 2019 U6 - https://doi.org/10.1364/JOSAB.36.001668 SN - 0740-3224 SN - 1520-8540 VL - 36 IS - 6 SP - 1668 EP - 1675 PB - Optical Society of America CY - Washington 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 - Menzel, Ralf A1 - Puhlmann, Dirk A1 - Heuer, Axel T1 - Complementarity in single photon interference – the role of the mode function and vacuum fields JF - Journal of the European Optical Society-Rapid N2 - Background In earlier experiments the role of the vacuum fields could be demonstrated as the source of complementarity with respect to the temporal properties (Heuer et al., Phys. Rev. Lett. 114:053601, 2015). Methods Single photon first order interferences of spatially separated regions from the cone structure of spontaneous parametric down conversion allow for analyzing the role of the mode function in quantum optics regarding the complementarity principle. Results Here the spatial coherence properties of these vacuum fields are demonstrated as the physical reason for complementarity in these single photon quantum optical experiments. These results are directly connected to the mode picture in classical optics. Conclusion The properties of the involved vacuum fields selected via the measurement process are the physical background of the complementarity principle in quantum optics. KW - Quantum optics KW - Complementarity KW - Mode function KW - Vacuum fields Y1 - 2017 U6 - https://doi.org/10.1186/s41476-017-0036-x SN - 1990-2573 VL - 13 PB - Springer ER - TY - GEN A1 - Menzel, Ralf A1 - Puhlmann, Dirk A1 - Heuer, Axel T1 - Complementarity in single photon interference – the role of the mode function and vacuum fields N2 - Background In earlier experiments the role of the vacuum fields could be demonstrated as the source of complementarity with respect to the temporal properties (Heuer et al., Phys. Rev. Lett. 114:053601, 2015). Methods Single photon first order interferences of spatially separated regions from the cone structure of spontaneous parametric down conversion allow for analyzing the role of the mode function in quantum optics regarding the complementarity principle. Results Here the spatial coherence properties of these vacuum fields are demonstrated as the physical reason for complementarity in these single photon quantum optical experiments. These results are directly connected to the mode picture in classical optics. Conclusion The properties of the involved vacuum fields selected via the measurement process are the physical background of the complementarity principle in quantum optics. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 333 KW - Complementarity KW - Mode function KW - Quantum optics KW - Vacuum fields Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-395210 ER - TY - JOUR A1 - Menzel, Ralf A1 - Puhlmann, Dirk A1 - Heuer, Axel A1 - Schleich, Wolfgang P. T1 - Wave-particle dualism and complementarity unraveled by a different mode JF - Proceedings of the National Academy of Sciences of the United States of America N2 - The precise knowledge of one of two complementary experimental outcomes prevents us from obtaining complete information about the other one. This formulation of Niels Bohr's principle of complementarity when applied to the paradigm of wave-particle dualism-that is, to Young's double-slit experiment-implies that the information about the slit through which a quantum particle has passed erases interference. In the present paper we report a double-slit experiment using two photons created by spontaneous parametric down-conversion where we observe interference in the signal photon despite the fact that we have located it in one of the slits due to its entanglement with the idler photon. This surprising aspect of complementarity comes to light by our special choice of the TEM01 pump mode. According to quantum field theory the signal photon is then in a coherent superposition of two distinct wave vectors giving rise to interference fringes analogous to two mechanical slits. Y1 - 2012 U6 - https://doi.org/10.1073/pnas.1201271109 SN - 0027-8424 VL - 109 IS - 24 SP - 9314 EP - 9319 PB - National Acad. of Sciences CY - Washington 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 - 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 - 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 - 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 - 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 - Niebuhr, Mario A1 - Zink, Christof A1 - Jechow, Andreas A1 - Heuer, Axel A1 - Glebov, Leonid B. A1 - Menzel, Ralf T1 - Mode stabilization of a laterally structured broad area diode laser using an external volume Bragg grating JF - Optics express : the international electronic journal of optics N2 - An external volume Bragg grating (VBG) is used for transverse and longitudinal mode stabilization of a broad area diode laser (BAL) with an on-chip transverse Bragg resonance (TBR) grating. The internal TBR grating defines a transverse low-loss mode at a specific propagation angle inside the BAL. Selection of the TBR mode was realized via the angular geometry of an external resonator assembly consisting of the TBR BAL and a feedback element. A feedback mirror provides near diffraction limited and spectral narrow output in the TBR mode albeit requiring an intricate alignment procedure. If feedback is provided via a VBG, adjustment proves to be far less critical and higher output powers were achieved. Moreover, additional modulation in the far field distribution became discernible allowing for a better study of the TBR concept. (C) 2015 Optical Society of America Y1 - 2015 U6 - https://doi.org/10.1364/OE.23.012394 SN - 1094-4087 VL - 23 IS - 9 SP - 12394 EP - 12400 PB - Optical Society of America CY - Washington 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - Puhlmann, Dirk A1 - Henkel, Carsten A1 - Heuer, Axel A1 - Pieplow, Gregor A1 - Menzel, Ralf T1 - Characterization of a remote optical element with bi-photons JF - Physica scripta : an international journal for experimental and theoretical physics N2 - We present a simple setup that exploits the interference of entangled photon pairs. 'Signal' photons are sent through a Mach–Zehnder-like interferometer, while 'idlers' are detected in a variable polarization state. Two-photon interference (in coincidence detection) is observed with very high contrast and for significant time delays between signal and idler detection events. This is explained by quantum erasure of the polarization tag and a delayed choice protocol involving a non-local virtual polarizer. The phase of the two-photon fringes is scanned by varying the path length in the signal beam or by rotating a birefringent crystal in the idler beam. We exploit this to characterize one beam splitter of the signal photon interferometer (reflection and transmission amplitudes including losses), using only information about coincidences and control parameters in the idler path. This is possible because our bi-photon state saturates the Greenberger–Yelin–Englert inequality between contrast and predictability. KW - quantum optics KW - quantum eraser KW - entanglement KW - bi-photons Y1 - 2016 U6 - https://doi.org/10.1088/0031-8949/91/2/023006 SN - 0031-8949 SN - 1402-4896 VL - 91 SP - 113 EP - 114 PB - IOP Publ. Ltd. CY - Bristol 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 - 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 - 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 - 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 - Raetzel, Dennis A1 - Wilkens, Martin A1 - Menzel, Ralf T1 - Gravitational properties of light: The emission of counter-propagating laser pulses from an atom JF - Physical review : D, Particles, fields, gravitation, and cosmology Y1 - 2017 U6 - https://doi.org/10.1103/PhysRevD.95.084008 SN - 2470-0010 SN - 2470-0029 VL - 95 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Rätzel, Dennis A1 - Wilkens, Martin A1 - Menzel, Ralf T1 - Effect of polarization entanglement in photon-photon scattering JF - Physical review : A, Atomic, molecular, and optical physics N2 - It is found that the differential cross section of photon-photon scattering is a function of the degree of polarization entanglement of the two-photon state. A reduced general expression for the differential cross section of photon-photon scattering is derived by applying simple symmetry arguments. An explicit expression is obtained for the example of photon-photon scattering due to virtual electron-positron pairs in quantum electrodynamics. It is shown how the effect in this explicit example can be explained as an effect of quantum interference and that it fits with the idea of distance-dependent forces. Y1 - 2017 U6 - https://doi.org/10.1103/PhysRevA.95.012101 SN - 2469-9926 SN - 2469-9934 VL - 95 IS - 1 PB - American Physical Society CY - College Park 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 - 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 - JOUR A1 - Rätzel, Dennis A1 - Wilkens, Martin A1 - Menzel, Ralf T1 - Gravitational properties of light-the gravitational field of a laser pulse JF - NEW JOURNAL OF 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 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Rätzel, Dennis A1 - Wilkens, Martin A1 - Menzel, Ralf T1 - The effect of entanglement in gravitational photon-photon scattering JF - epl : a letters journal exploring the frontiers of physics N2 - The differential cross-section for gravitational photon-photon scattering calculated in perturbative quantum gravity is shown to depend on the degree of polarization entanglement of the two photons. The interaction between photons in the symmetric Bell state is stronger than between not entangled photons. In contrast, the interaction between photons in the anti-symmetric Bell state is weaker than between not entangled photons. The results are interpreted in terms of quantum interference, and it is shown how they fit into the idea of distance-dependent forces. Copyright (C) EPLA, 2016 Y1 - 2016 U6 - https://doi.org/10.1209/0295-5075/115/51002 SN - 0295-5075 SN - 1286-4854 VL - 115 SP - S12 EP - S13 PB - EDP Sciences CY - Mulhouse 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 - Sandmann, Michael A1 - Garz, Andreas A1 - Menzel, Ralf T1 - Physiological response of two different Chlamydomonas reinhardtii strains to light-dark rhythms JF - Botany N2 - Cells of a cell-wall deficient line (cw15-type) of Chlamydomonas reinhardtii and of the corresponding wild type were grown during repetitive light-dark cycles. In a direct comparison, both lines showed approximately the same relative biomass increase during light phase but the cw-line produced significantly more, and smaller, daughter cells. Throughout the light period the average cellular starch content, the cellular chlorophyll content, the cellular rate of dark respiration, and the cellular rate of photosynthesis of the cw-line was lower. Despite this, several non-cell volume related parameters like the development of starch content per cell volume were clearly different over time between the strains. Additionally, the chlorophyll-based photosynthesis rates were 2-fold higher in the mutant than in the wild-type cells, and the ratio of chlorophyll a to chlorophyll b as well as the light-saturation index were also consistently higher in the mutant cells. Differences in the starch content were also confirmed by single cell analyses using a sensitive SHG-based microscopy approach. In summary, the cw15-type mutant deviates from its genetic background in the entire cell physiology. Both lines should be used in further studies in comparative systems biology with focus on the detailed relation between cell volume increase, photosynthesis, starch metabolism, and daughter cell productivity. KW - cell wall deficient mutant KW - diurnal rhythm KW - nonlinear microscopy KW - photosynthesis KW - single-cell analysis Y1 - 2016 U6 - https://doi.org/10.1139/cjb-2015-0144 SN - 1916-2790 SN - 1916-2804 VL - 94 SP - 53 EP - 64 PB - NRC Research Press CY - Ottawa 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 - 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 - 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 - 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 -