@article{AfshaarvahidHeuerMenzeletal.2001, author = {Afshaarvahid, Shahraam and Heuer, Axel and Menzel, Ralf and Munch, Jesper}, title = {Temporal structure of stimulated-Brillouin-scattering reflectivity considering transversal-mode development}, year = {2001}, language = {en} } @article{ElsnerPuhlmannPieplowetal.2015, author = {Elsner, Robert and Puhlmann, Dirk and Pieplow, Gregor and Heuer, Axel and Menzel, Ralf}, title = {Transverse distinguishability of entangled photons with arbitrarily shaped spatial near- and far-field distributions}, series = {Journal of the Optical Society of America : B, Optical physics}, volume = {32}, journal = {Journal of the Optical Society of America : B, Optical physics}, number = {9}, publisher = {Optical Society of America}, address = {Washington}, issn = {0740-3224}, doi = {10.1364/JOSAB.32.001910}, pages = {1910 -- 1919}, year = {2015}, abstract = {Entangled photons generated by spontaneous parametric downconversion are ubiquitous in quantum optics. In general, they exhibit a complex spatial photon count distribution. This spatial structure is responsible for seemingly surprising results concerning, e.g., complementarity such as the apparent simultaneous observation of interference fringes V and which-way information D at a double slit, as recently reported by Menzel et al. [Proc. Natl. Acad. Sci. USA 109, 9314 (2012)]. We implement a complete quantitative model of the SPDC interaction that fully incorporates the effects of crystal anisotropies, phase matching, and the pump beam structure and allows for arbitrary manipulations of the SPDC light in the near and far fields. This enables us to establish an upper bound D-2 + V-2 <= 1.47 for the experimental parameters reported by Menzel et al. We report new experimental results that agree excellently with these theoretical predictions. The new model enables a detailed quantitative analysis of this surprising result and the fair sampling interpretation of biphotons passing a double slit. (C) 2015 Optical Society of America}, language = {en} } @article{ElsnerUllmannHeueretal.2012, author = {Elsner, Robert and Ullmann, Roland and Heuer, Axel and Menzel, Ralf and Ostermeyer, Martin}, title = {Two-dimensional modeling of transient gain gratings in saturable gain media}, series = {OPTICS EXPRESS}, volume = {20}, journal = {OPTICS EXPRESS}, number = {7}, publisher = {OPTICAL SOC AMER}, address = {WASHINGTON}, issn = {1094-4087}, doi = {10.1364/OE.20.006887}, pages = {6887 -- 6896}, year = {2012}, abstract = {A transient two-dimensional model describing degenerate four-wave mixing inside saturable gain media is presented. The new model is compared to existing one-dimensional models with their qualitative results confirmed. Large quantitative differences with respect to peak reflectivity and optimum pump fluence are observed. Furthermore, the influence of the beam focus size, the transverse position and the crossing angle on the reflectivity of the grating is investigated using the improved model. It is demonstrated that the phase conjugate reflectivity depends sensitively on the transverse features of the interacting beams with a transverse shift in the position of the pump beams yielding a threefold improvement in reflectivity. (C) 2012 Optical Society of America}, language = {en} } @phdthesis{Heuer1998, author = {Heuer, Axel}, title = {Phasenkonjugierende Spiegel auf Basis der stimulierten Brillouin-Streuung in optischen Wellenleitern}, pages = {92 S. : Ill.}, year = {1998}, language = {de} } @article{HeuerHodgsonLorenzetal.1997, author = {Heuer, Axel and Hodgson, N. and Lorenz, Dieter and Ostermeyer, Martin and Menzel, Ralf}, title = {Solid state lasers with high brightness via optical phase conjugation for micromachining}, year = {1997}, language = {en} } @article{HeuerHodgsonMenzel1998, author = {Heuer, Axel and Hodgson, N. and Menzel, Ralf}, title = {Efficient, low-threshold phase conjugation in a tapered optical fiber}, year = {1998}, language = {en} } @article{HeuerHaenischMenzel2003, author = {Heuer, Axel and H{\"a}nisch, Christoph and Menzel, Ralf}, title = {Low-power phase conjugation based on stimulated Brillouin scattering in fiber amplifiers}, year = {2003}, language = {en} } @article{HeuerHaenischMenzel2003, author = {Heuer, Axel and H{\"a}nisch, Christoph and Menzel, Ralf}, title = {New concept for low threshold optical phase conjugation via SBS in a fiber amplifier}, isbn = {0-8194-4772-2}, year = {2003}, language = {en} } @book{HeuerHaenischOstermeyeretal.2002, author = {Heuer, Axel and H{\"a}nisch, Christoph and Ostermeyer, Martin and Menzel, Ralf}, title = {Low Power Threshold Phase Conjugating Mirrors by SBS in Yb-doped Fiber Amplifiers}, year = {2002}, language = {en} } @article{HeuerMenzel2004, author = {Heuer, Axel and Menzel, Ralf}, title = {Principles of Phase Conjugating Brillouin Mirrors}, isbn = {0-471-43957-6}, year = {2004}, language = {en} } @article{HeuerMenzel1998, author = {Heuer, Axel and Menzel, Ralf}, title = {Phase conjugating SBS-mirror for low powers and reflectivities above 90 \% in an internally tapered optical fiber}, year = {1998}, language = {en} } @article{HeuerMenzel2000, author = {Heuer, Axel and Menzel, Ralf}, title = {Low threshold SBS phase conjugation for quasi-cw laser systems}, year = {2000}, language = {en} } @article{HeuerMenzel2000, author = {Heuer, Axel and Menzel, Ralf}, title = {Temporal features of SBS phase conjugation}, isbn = {0-8194-3545-7}, year = {2000}, 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{HeuerMenzelOstermeyer1996, author = {Heuer, Axel and Menzel, Ralf and Ostermeyer, Martin}, title = {Power tunable Nd-oscillators with diffraction limited beams via SBS phase conjugation}, year = {1996}, language = {en} } @article{HeuerRaabeMenzel2014, author = {Heuer, Axel and Raabe, S. and Menzel, Ralf}, title = {Phase memory across two single-photon interferometers including wavelength conversion}, series = {Physical review : A, Atomic, molecular, and optical physics}, volume = {90}, journal = {Physical review : A, Atomic, molecular, and optical physics}, number = {4}, publisher = {American Physical Society}, address = {College Park}, issn = {1050-2947}, doi = {10.1103/PhysRevA.90.045803}, pages = {4}, year = {2014}, abstract = {Spontaneous parametric down-conversion (SPDC) in a nonlinear crystal generates two single photons (signal and idler) with random phases. Thus, no first-order interference between them occurs. However, coherence can be induced in a cascaded setup of two crystals if, e.g., the idler modes of both crystals are aligned to be indistinguishable. Due to the effect of phase memory it is found that the first-order interference of the signal beams can be controlled by the phase delay between the pump beams. Even for pump photon delays much larger than the coherence length of the SPDC photons, the visibility is above 90\%. The high visibilities reported here prove an almost perfect phase memory effect across the two interferometers for the pump and the signal photon modes.}, language = {en} } @article{HeuerSagahtiJechowetal.2012, author = {Heuer, Axel and Sagahti, A. and Jechow, Andreas and Skoczowsky, D. and Menzel, Ralf}, title = {Multi-wavelength, high spatial brightness operation of a phase-locked stripe-array diode laser}, series = {Laser physics}, volume = {22}, journal = {Laser physics}, number = {1}, publisher = {Pleiades Publ.}, address = {New York}, issn = {1054-660X}, doi = {10.1134/S1054660X12010057}, pages = {160 -- 164}, year = {2012}, abstract = {Stable continuous wave multi-wavelength operation of a stripe-array diode laser with an externalcavity spectral beam combining geometry is presented. In this setup each emitter of the stripe-array is forced to operate at a different wavelength, which leads to a decoupling between the usually phase-locked emitters. With a reflective diffraction grating with a period of 300 lines per mm, 33 equidistant laser lines around a center wavelength of 978 nm were realized, spanning a spectral range of 26 nm. With this novel approach near-diffraction limited emission with a beam quality of M (2) < 1.2 and an output power of 450 mW was achieved. This laser light source can be used for applications requiring low temporal but high spatial coherence.}, language = {en} } @article{HeuerSchultheissHodgsonetal.1999, author = {Heuer, Axel and Schultheiss, J. and Hodgson, N. and Kurths, J{\"u}rgen and Menzel, Ralf and Raab, Volker}, title = {Transverse effects in phase conjugate laser mirrors based on stimulated brillouin scattering}, year = {1999}, language = {en} } @article{HaenischHeuerMenzel2001, author = {H{\"a}nisch, Christoph and Heuer, Axel and Menzel, Ralf}, title = {Threshold reduction of stimulated Brillouin scattering (SBS) using fiber loop schemes}, year = {2001}, language = {en} } @article{JechowSeefeldtKurzkeetal.2013, author = {Jechow, Andreas and Seefeldt, Michael and Kurzke, Henning and Heuer, Axel and Menzel, Ralf}, title = {Enhanced two-photon excited fluorescence from imaging agents using true thermal light}, series = {Nature photonics}, volume = {7}, journal = {Nature photonics}, number = {12}, publisher = {Nature Publ. Group}, address = {London}, issn = {1749-4885}, doi = {10.1038/NPHOTON.2013.271}, pages = {973 -- 976}, year = {2013}, abstract = {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.}, language = {en} }