@article{EichlerHaaseMenzel1995, author = {Eichler, Hans Joachim and Haase, Alfred and Menzel, Ralf}, title = {100 watt average output power 1.2*diffraction limited beam from pulsed neodym single rod amplifier with SBS- phaseconjugation}, year = {1995}, language = {en} } @article{OstermeyerHeuerMenzel1998, author = {Ostermeyer, Martin and Heuer, Axel and Menzel, Ralf}, title = {27 Watt average output power with 1.2*DL beam quality from a single rod Nd:YAG-Laser with phase conjugating SBS- mirror}, year = {1998}, language = {en} } @article{OstermeyerMenzel1997, author = {Ostermeyer, Martin and Menzel, Ralf}, title = {34 Watt flash lamp pumped single rod ND:YAG laser with 1.2 * DL beam quality via special resonator design}, year = {1997}, language = {en} } @article{OstermeyerMenzel1999, author = {Ostermeyer, Martin and Menzel, Ralf}, title = {50 Watt average output power with 1.2*DL beam quality from a single rod Nd:YALO laser with phase-conjugating SBS mirror}, year = {1999}, language = {en} } @article{MenzelHeuerPuhlmannetal.2013, author = {Menzel, Ralf and Heuer, Axel and Puhlmann, Dirk and Dechoum, K. and Hillery, M. and Spaehn, M. J. A. and Schleich, W. P.}, title = {A two-photon double-slit experiment}, series = {Journal of modern optics}, volume = {60}, journal = {Journal of modern optics}, number = {1}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {0950-0340}, doi = {10.1080/09500340.2012.746400}, pages = {86 -- 94}, year = {2013}, abstract = {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.}, language = {en} } @article{KappeOstermeyerMenzel2005, author = {Kappe, Philip and Ostermeyer, Martin and Menzel, Ralf}, title = {Active mode locking of a phase-conjugating SBS-laser oscillator}, issn = {0946-2171}, year = {2005}, abstract = {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}, language = {en} } @article{KappeOstermeyerMenzel2005, author = {Kappe, Philip and Ostermeyer, Martin and Menzel, Ralf}, title = {Active mode locking of a phase-conjugating SBS-laser oscillator}, issn = {0946-2171}, year = {2005}, language = {en} } @article{UnterhuberPovazayBizhevaetal.2004, author = {Unterhuber, Angelika and Povazay, B. and Bizheva, K. and Hermann, B. and Sattmann, Harald and Stingl, A. and Le, Trang and Seefeldt, Michael and Menzel, Ralf and Preusser, Matthias and Budka, Herbert and Schubert, Christian and Reitsamer, H. and Ahnelt, Peter Kurt and Morgan, J. E.}, title = {Advances in broad bandwidth light sources for ultrahigh resolution optical coherence tomography}, issn = {0031-9155}, year = {2004}, abstract = {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}, language = {en} } @article{KappeMenzelOstermeyer2006, author = {Kappe, Philip and Menzel, Ralf and Ostermeyer, Martin}, title = {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}, issn = {1050-2947}, doi = {10.1103/Physreva.74.013809}, year = {2006}, abstract = {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}, language = {en} } @article{SpitzvonSeggernGrunwaldtetal.2002, author = {Spitz, Christian and von Seggern, David and Grunwaldt, Gisela and Menzel, Ralf}, title = {Biochemical Diagnostics by Excited State Absorption Spectroscopy}, isbn = {0-8194-4365-4}, year = {2002}, language = {en} } @article{ZinkNiebuhrJechowetal.2014, author = {Zink, Christof and Niebuhr, Mario and Jechow, Andreas and Heuer, Axel and Menzel, Ralf}, title = {Broad area diode laser with on-chip transverse Bragg grating stabilized in an off-axis external cavity}, series = {Optics express : the international electronic journal of optics}, volume = {22}, journal = {Optics express : the international electronic journal of optics}, number = {12}, publisher = {Optical Society of America}, address = {Washington}, issn = {1094-4087}, doi = {10.1364/OE.22.014108}, pages = {14108 -- 14113}, year = {2014}, abstract = {The emission characteristics of a novel, specially designed broad area diode laser (BAL) with on-chip transversal Bragg resonance (TBR) grating in lateral direction were investigated in an off-axis external cavity setup. The internal TBR grating defines a low loss transversal mode at a specific angle of incidence and a certain wavelength. By providing feedback at this specific angle with an external mirror, it is possible to select this low loss transverse mode and stabilize the BAL. Near diffraction limited emission with an almost single lobed far field pattern could be realized, in contrast to the double lobed far field pattern of similar setups using standard BALs or phase-locked diode laser arrays. Furthermore, we could achieve a narrow bandwidth emission with a simplified setup without external frequency selective elements. (C) 2014 Optical Society of America}, language = {en} } @article{MittlerLorenzMenzel1999, author = {Mittler, Kay and Lorenz, Dieter and Menzel, Ralf}, title = {Broadband operation of a gain-switched Ti:sapphire laser for measurements with the coherence radar}, issn = {0277-786X}, year = {1999}, language = {en} } @article{LorenzMenzel1998, author = {Lorenz, Dieter and Menzel, Ralf}, title = {Broadband operation of frequency doubled Cr4+:YAG laser with high beam quality}, year = {1998}, language = {en} } @article{GarzSandmannRadingetal.2012, author = {Garz, Andreas and Sandmann, Michael and Rading, Michael and Ramm, Sascha and Menzel, Ralf and Steup, Martin}, title = {Cell-to-cell diversity in a synchronized chlamydomonas culture as revealed by single-cell analyses}, series = {Biophysical journal}, volume = {103}, journal = {Biophysical journal}, number = {5}, publisher = {Cell Press}, address = {Cambridge}, issn = {0006-3495}, doi = {10.1016/j.bpj.2012.07.026}, pages = {1078 -- 1086}, year = {2012}, abstract = {In a synchronized photoautotrophic culture of Chlamydomonas reinhardtii, cell size, cell number, and the averaged starch content were determined throughout the light-dark cycle. For single-cell analyses, the relative cellular starch was quantified by measuring the second harmonic generation (SHG). In destained cells, amylopectin essentially represents the only biophotonic structure. As revealed by various validation procedures, SHG signal intensities are a reliable relative measure of the cellular starch content. During photosynthesis-driven starch biosynthesis, synchronized Chlamydomonas cells possess an unexpected cell-to-cell diversity both in size and starch content, but the starch-related heterogeneity largely exceeds that of size. The cellular volume, starch content, and amount of starch/cell volume obey lognormal distributions. Starch degradation was initiated by inhibiting the photosynthetic electron transport in illuminated cells or by darkening. Under both conditions, the averaged rate of starch degradation is almost constant, but it is higher in illuminated than in darkened cells. At the single-cell level, rates of starch degradation largely differ but are unrelated to the initial cellular starch content. A rate equation describing the cellular starch degradation}, language = {en} } @article{PuhlmannHenkelHeueretal.2016, author = {Puhlmann, Dirk and Henkel, Carsten and Heuer, Axel and Pieplow, Gregor and Menzel, Ralf}, title = {Characterization of a remote optical element with bi-photons}, series = {Physica scripta : an international journal for experimental and theoretical physics}, volume = {91}, journal = {Physica scripta : an international journal for experimental and theoretical physics}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0031-8949}, doi = {10.1088/0031-8949/91/2/023006}, pages = {113 -- 114}, year = {2016}, abstract = {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.}, language = {en} } @article{vonSeggernModrakowskiSpitzetal.2004, author = {von Seggern, David and Modrakowski, Claudia and Spitz, Christian and Schl{\"u}ter, A. D. and Menzel, Ralf}, title = {Charge transfer initiated by optical excitation in diester substituted biphenylpyrene as a function of the solvent characterized by excited state absorption spectroscopy}, year = {2004}, abstract = {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}, language = {en} } @article{SeefeldtHeuerMenzel2003, author = {Seefeldt, Michael and Heuer, Axel and Menzel, Ralf}, title = {Compact white-light source with an average output power of 2.4 W and 900 nm spectral bandwidth}, year = {2003}, language = {en} } @article{HeuerMenzelMilonni2015, author = {Heuer, Axel and Menzel, Ralf and Milonni, P. W.}, title = {Complementarity in biphoton generation with stimulated or induced coherence}, series = {Physical review : A, Atomic, molecular, and optical physics}, volume = {92}, journal = {Physical review : A, Atomic, molecular, and optical physics}, number = {3}, publisher = {American Physical Society}, address = {College Park}, issn = {1050-2947}, doi = {10.1103/PhysRevA.92.033834}, pages = {8}, year = {2015}, abstract = {Coherence can be induced or stimulated in parametric down-conversion using two or three crystals when, for example, the idler modes of the crystals are aligned. Previous experiments with induced coherence [Phys. Rev. Lett. 114, 053601 (2015)] focused on which-path information and the role of vacuum fields in realizing complementarity via reduced visibility in single-photon interference. Here we describe experiments comparing induced and stimulated coherence. Different single-photon interference experiments were performed by blocking one of the pump beams in a three-crystal setup. Each counted photon is emitted from one of two crystals and which-way information may or not be available, depending on the setup. Distinctly different results are obtained in the induced and stimulated cases, especially when a variable transmission filter is inserted between the crystals. A simplified theoretical model accounts for all the experimental results and is also used to address the question of whether the phases of the signal and idler fields in parametric down-conversion are correlated.}, language = {en} } @article{MenzelPuhlmannHeuer2017, author = {Menzel, Ralf and Puhlmann, Dirk and Heuer, Axel}, title = {Complementarity in single photon interference - the role of the mode function and vacuum fields}, series = {Journal of the European Optical Society-Rapid}, volume = {13}, journal = {Journal of the European Optical Society-Rapid}, publisher = {Springer}, issn = {1990-2573}, doi = {10.1186/s41476-017-0036-x}, pages = {7}, year = {2017}, abstract = {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.}, language = {en} } @misc{MenzelPuhlmannHeuer2017, author = {Menzel, Ralf and Puhlmann, Dirk and Heuer, Axel}, title = {Complementarity in single photon interference - the role of the mode function and vacuum fields}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-395210}, pages = {7}, year = {2017}, abstract = {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.}, language = {en} }