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Karl Friedrich Renk

Professor Emeritus
Physics

karl.renk@physik.uni-regensburg.de


Fakultät Physik
Universität Regensburg
Universitätsstraße 31
93053 Regensburg, Germany

Research areas

During his career, Professor Renk performed research mainly in the field of experimental solid state physics. The main interest concerned the study of low-energy excitations of solids by spectroscopic techniques and the development of spectroscopic devices for the far infrared. Among the low-energy excitations studied are optical phonons in alkali halides, electron spin resonance, antiferromagnetic resonance, and electronic excitations of high temperature superconductors. Further questions were dealing with nonequilibrium high frequency acoustic phonons and thermalization processes in crystals. Another area was the study of nonlinear electric transport based on Bloch oscillations of electrons in semiconductor superlattices. A recent study concerns the origin of gain of radiation in optical fibers. Spectroscopic tools were Fourier transform infrared spectroscopy and lasers. Among the devices developed are the Fabry-Perot interferometer for the far infrared, a high-pressure CO2 laser, optically pumped far infrared lasers, and the p-germanium laser. A large area dealt with devices based on Bloch oscillations of electrons in semiconductor superlattices, such as oscillators for millimeter waves, frequency multipliers, heterodyne detectors, and ultrafast detectors and autocorrelators for terahertz radiation pulses.

Education

Study of physics at the Universities Freiburg (Germany), Munich, and Frankfurt, 1957-62; Diploma, University Freiburg, 1962; PhD, University Freiburg, 1966

Positions

Senior Research Physicist, University Reading, Great Britain, 1966/1967; Wissenschaftlicher Assistent, Technical University Munich, 1967-1972; Professor of Physics, University Regensburg, 1972-2006; Professor Emeritus, 2006

Visiting appointments

Research Center Jülich, 1974; High-Field Magnet Laboratory of the Max-Planck Society, Grenoble, 1976; University of California, Los Angeles, 1980/1981; Université Scientific et Médicale de Grenoble, 1985/1986; University of Canterbury, New Zealand, 1992

Award

New Zealand Erskine Fellow, 1992

Membership

American Physical Society; Deutsche Physikalische Gesellschaft; Gesellschaft Deutscher Naturforscher und Ärzte

Book

Karl F. Renk, Basics of Laser Physics – For Students of Science and Engineering (Springer 2012)

Book Chapters

·   K. F. Renk, Detection of high-frequency phonons by phonon-induced fluorescence, in Nonequilibrium Phonons in Nonmetallic Crystals, Eds.: W. Eisenmenger, A. A. Kaplyanskii (Elsevier Science Publ. 1986), p. 277

·   K. F. Renk, Far-infrared spectroscopy of high temperature superconductors, in Studies of High Temperature Superconductors, vol. 10, Ed. A. Narlikar (Nova Science Publishers1992), p. 25-55

·   K. F. Renk, Infrared studies of thallium cuprate superconductors, in Tl-Based High Temperature Superconductors, Eds. A. M. Hermann, J. V. Yakhmi (Marcel Dekker 1994), p. 477-510

 

Journal Articles

·   K. F. Renk, B. I. Stahl, Operation of a semiconductor superlattice oscillator, Phys. Lett. A 375, 2644 (2011)

·   K. F. Renk, Role of excited-impurity quasiparticles for amplification of radiation in an erbium-doped glass fiber amplifier, Appl. Phys. Lett. 96, 131104 (2010)

·   A Rogl, K. F. Renk, B. I. Stahl, C. Reichl, D. Schuh, W. Wegscheider, Double-Resonance Semiconductor Superlattice Parametric Oscillator for Generation of Subterahertz radiation, Intern. Journ. Infrared and Millimeter Waves doi:101007/s10762-9392 (2008)

·   K. F. Renk, A Rogl, B. I. Stahl, M. Muthmann, H. Appel, M. Jain, A. Glukhowskoy, D. Schuh, W. Wegscheider, Semiconductor-Superlattice Parametric oscillator as a sub-terahertz and possible terahertz radiation source, Advances in OptoElectronics doi:10.1155/54042 (2007)

·   K. F. Renk, A. Rogl, B. I. Stahl, Semiconductor-superlattice parametric oscillator for generation of sub-terahertz and terahertz waves, J. Luminescence 125, 252 (2007)

·   B. I. Stahl, A. Rogl, K. F. Renk, A theoretical study of operation conditions for a terahertz superlattice parametric oscillator, Phys. Lett. A 359, 512 (2006)

·   K. F. Renk, B. I. Stahl, A. Rogl, T. Janzen, D. G. Pavel‘ev, Yu. I. Koschurinov, V. Ustinov, A. Zhukov, Subterahertz superlattice parametric oscillator, Phys. Rev. Lett. 95, 126801 (2005)

·   F. Klappenberger, K. F. Renk, Proposal of a microwave-driven semiconductor superlattice oscillator for generation of THz radiation, Intern. Journ. of Infrared and Millimeter Waves 25, 429-438 (2004)

·   F. Klappenberger, K. F. Renk, P. Renk, B. Rieder, Yu. I. Koschurinov, D. G. Pavel‘ev, V. Ustinov, A. Zhukov, N. Maleev, A. Vasilyev, Semiconductor-superlattice frequency multiplier for generation of submillimeter waves, Appl. Phys. Lett. 84, 3924 (2004)

·   F. Klappenberger, K. F. Renk, R. Summer, L. Keldysh, B. Rieder, W. Wegscheider, Electric-field-induced reversible avalanche breakdown in a GaAs microcrystal due to cross band gap impact ionization, Appl. Phys. Lett. 83, 704 (2003)

·   F. Klappenberger, A.A. Ignatov, S. Winnerl, E. Schomburg, W. Wegscheider, K.F. Renk, Broadband Semiconductor Superlattice Detector for THz Radiation, Appl. Phys. Lett. 78, 1673 (2001)

·   S. Winnerl, E. Schomburg, S. Brandl, O. Kus, K. F. Renk, M.C. Wanke, S. J. Allen, A.A. Ignatov, V. Ustinov, A. Zhukov, P. S. Kop‘ev, Frequency doubling and tripling of terahertz radiation in a GaAs/AlAs superlattice due to frequency modulation of Bloch oscillations, Appl. Phys. Lett. 77, 1762 (2000)

·   E. Schomburg, T. Blomeier, K. Hofbeck, J. Grenzer, S. Brandl, I. Lingott, A. A. Ignatov, K. F. Renk, D. G. Pavel'ev, Yu. Koschurinov, B. Ya. Melzer, V. Ustinov, S. Ivanov, A. Zhukov, P. S. Kop'ev, Current oscillation in superlattices with different miniband widths, Phys. Rev. B 58, 4035-4038 (1998)

·   S. Winnerl, W. Seiwerth, E. Schomburg, J. Grenzer, K. F. Renk, C. J. G. M. Langerak, A. F. G. van der Meer, D. G. Pavel'ev, Yu. Koschurinov, A. A. Ignatov, B. Melzer, V. Ustinov, S. Ivanov, P. S. Kop'ev, Ultrafast detection and autocorrelation of picosecond THz radiation pulses with a GaAs/AlAs superlattice, Appl. Phys. Lett. 73, 2983 (1998)

·   K. Hofbeck, E. Schomburg, J. Grenzer, K. F. Renk, D. G. Pavel'ev, Yu. Koschurinov, B. Melzer, S. Ivanov, P. S. Kop'ev, Frequency-locked GaAs/AlAs superlattice oscillator for tunable narrowband microwave generation, IEEE Microwave and Guided Wave Letters 8, 427 (1998)

·   S. Winnerl, E. Schomburg, J. Grenzer, H.-J. Regl, A. A. Ignatov, A. D. Semenov, K. F. Renk, Quasistatic and dynamic interaction of high-frequency fields with miniband electrons in semiconductor superlattices, Phys. Rev. B 56, 10303 (1997)

·   E. Schomburg, A. A. Ignatov, J. Grenzer, K. F. Renk, D. G. Pavel'ev, Yu. Koschurinov, B. Ja. Melzer, S. Ivanov, S. Schaposchnikov, P. S. Kop'ev, Suppression of current through an Esaki-Tsu GaAs/AlAs superlattice by millimeter wave irradiation, Appl. Phys. Lett. 68, 1096 (1996)

·   D. Semenov, Yu. P. Gousev, R. S. Nebosis, K. F. Renk, Heterodyne detection of THz radiation with a superconducting hot-electron bolometer mixer, Appl. Phys. Lett. 69, 260 (1996)

·  Yu. Gousev, A. D. Semenov, E. V. Pechen, A. V. Varlashkin, R. S. Nebosis, K. F. Renk, Coupling of Terahertz Radiation to a High- Tc Superconducting Hot Electron Bolometer Mixer, Appl. Phys. Lett. 69, 691 (1996)

·   A. Ignatov, E. Schomburg, J. Grenzer, K. F. Renk, E. P. Dodin, THz-field induced nonlinear transport and dc voltage generation in a semiconductor superlattice due to Bloch oscillations, Z. Phys. B 98, 187-195 (1995)

·   J. Grenzer, A. A. Ignatov, E. Schomburg, K. F. Renk, D. G. Pavel'ev, Yu. Koschurinov, B. Melzer, S. Ivanov, S. Schaposchnikov, P. S. Kop'ev, Microwave oscillator based on Bloch oscillations of electrons in a semiconductor superlattice, Annalen der Physik 4, 184-1990 (1995)

·   J. Grenzer, E. Schomburg, A. A. Ignatov, K. F. Renk, D. G. Pavel'ev, Yu. Koschurinov, B. Ja. Melzer, S. Ivanov, S. Schaposchnikov, P. S. Kop'ev, Frequency multiplication of microwave radiation in a semiconductor superlattice by electrons capable to perform Bloch oscillations, Annalen der Physik 4, 265-271 (1995)

·   D. Semenov, R. S. Nebosis, Yu. P. Gousev, M. A. Heusinger, K. F. Renk, Analysis of the nonequilibrium photoresponse of superconducting films to pulsed radiation by use of a two-temperature model, Phys. Rev. B 52, 581-590 (1995)

·   A. Ignatov, E. Schomburg, K. F. Renk, W. Schatz, J. F. Palmier, F. Mollot, Response of a Bloch oscillator to a THz-field, Annalen der Physik 3, 137-144 (1994)

·   Yu. P. Gousev, G. N. Gol'tsman, A. D. Semenov, E. M. Gershenzon, R. S. Nebosis, M. A. Heusinger, K. F. Renk, Broadband ultrafast superconducting NbN detector for electromagnetic radiation, J. Appl. Phys. 75, 3695-3697 (1994)

·   A.A. Ignatov, K. F. Renk, E. P. Dodin, Esaki-Tsu Superlattice Oscillator: Josephson-Like Dynamics of Carriers, Phys. Rev. Lett. 70, 1996-1999 (1993)

·   W. Schatz, M. A. Heusinger, R. S. Nebosis, K. F. Renk, P. T. Lang, 100-ps far-infrared laser pulses from optically pumped D2O, Infrared Phys. 34, 339-344 (1993)

·   V. Bespalov, A. Schilz, W. Prettl, W. W. Fischer, K. F. Renk, Nonlinear magnetic field dependence of the emission frequency and bandwidth of a far-infrared p-type Ge cyclotron laser, Phys. Rev. B 47, 6312 (1993)

·   V. Bespalov, A. Schilz, W. Prettl, W. W. Fischer, K. F. Renk, Nonlinear magnetic field dependence of the emission frequency and bandwidth of a far-infrared p-type Ge cyclotron laser, Phys. Rev. B 47, 6312 (1993)

·   A.D. Semenov, G. N. Gol'tsman, I. G. Gogidze, A. V. Sergeev, E. M. Gershenzon, P. T. Lang, K. F. Renk, Subnanosecond photoresponse of a YBa2Cu3O7 thin film to infrared and visible radiation by quasiparticle induced suppression of superconductivity, Appl. Phys. Lett. 60, 903 (1992)

·   W. Schatz, P. T. Lang, T. Kass, M. A. Heusinger, K. F. Renk, Determination of the spectral width of raman gain regions for different far infrared laser gases using a metal mesh Fabry-Perot interferometer, Int. J. of Infrared and Millimeter Waves 13, 853-867 (1992)

·   W. Schatz, T. Kass, A. D. Semenov, K. F. Renk, Generation of far-infrared laser pulses in CH3 gas by stimulated Raman scattering resonantly enhanced at fundamental and overtone transitions, Opt. Communications 89, 233-239 (1992)

·   G. N. Gol'tsman, A. D. Semenov, Y. P. Gousev, M. A. Zorin, I. G. Gogidze, E. M. Gershenzon, P. T. Lang, W. J. Knott, K. F. Renk, Sensitive Picosecond NbN Detector for Radiation from Millimeter Wavelengths to Visible Light, Supercond. Science & Techn. 4, 453-456 (1991)

·   P. T. Lang, W. Schatz, K. F. Renk, Generation of subnanosecond far-infrared laser pulses in a large spectral range with a Raman D2O laser optically pumped by a continously tunable CO2 laser, Opt. Commun. 84, 29 (1991)

·   V. Bespalov, G. N. Gol’tsman, A. D. Semenov, K. F. Renk, Determination of the far-infrared emission characteristic of a cyclotron p-germanium laser by use of a superconducting Nb detector, Solid State Commun. 80, 506 (1991)

·   K. F. Renk, B. Gorshunov, J. Schün, A. PrüB. Brunner, J. Betz, S. Orbach, N. Klein, G. Mü H. Piel , Far-infrared and microwave intragap absorption in a YBa2Cu3O7 thin film at low temperature, Europhys. Lett. 15, 661 (1991)

·   M. Mü S. Basun, S. Glaser, K. F. Renk, Study of the submillimeter absorptivity of high-Tc superconductors by photothermal interference spectroscopy, Appl. Phys. Lett. 59, 3476 (1991)

·   V. Bespalov, G. N. Gol’tsman, A. D. Semenov, K. F. Renk, Determination of the far-infrared emission characteristic of a cyclotron p-germanium laser by use of a superconducting Nb detector, Solid State Commun. 80, 506 (1991)

·   V. Bespalov, P. T. Lang, J. Betz, K. F. Renk, Use of high temperature superconductors for resonators of far-infrared p-germanium lasers, Appl. Phys. Lett. 58, 2030 (1991)

·   P. T. Lang, W. J. Knott, I. Leipold, K. F. Renk, A. D. Semenov, G. N. Gol'tsman, Generation and detection of tunable ultrashort infrared and far-infrared radiation pulses of high intensity, Intern. J. Infrared and Millimeter Waves 12, 1135 (1991)

·   P. L. Lang, W. Schatz, K. F. Renk, Observation of tunable far-infrared emission from optically pumped D2O with a 17 GHz tuning range, Optics Letters 15, 1449 (1990)

·   K. F. Renk, J. Betz, J. Schün, A. PrüB. Brunner, H. Lengfellner, Use of high-Tc superconductors for far-infrared fabry perot resonators, Appl. Phys. Lett. 57, 2148 (1990)

·   T. Zetterer, M. Franz, J. Schün, W. Ose, K. F. Renk, Anamalous behavior of phonons in superconducting Tl2Ba2Ca2Cu3O10 detected by far-infrared spectroscopy, Phys. Rev. B. 41, 9499-9501 (1990)

·   P. T. Lang, F. Sessler, U. Werling, K. F. Renk, Generation of widely tunable intense far-infrared radiation pulses by stimulated Raman transitions in methylfluoride gas, Appl. Phys. Lett. 55, 2576 (1989)

·   J. Schün, W. Ose, J. Keller, K. F. Renk, B. Roas, L. Schultz, G. Saemann-Ischenko, Far-infrared reflectivity and dynamical conductivity of an epitaxial YBaCuO thin film, Europhys. Lett. 8, 679 (1989)

·   T. Zetterer, W. Ose, J. Schün, H. H. Otto, P. E. Obermayer, N. Tasler, H. Lengfellner, G. Lugert, J. Keller, K. F. Renk, Preparation, characterization and far infrared study of ceramic high-Tc superconductors, J. Opt. Soc. Am. B 6, 420-435 (1989)

·   H. H. Otto, T. Zetterer, K. F. Renk, Crystal structure of the high-Tc superconductor Tl2Ba2Ca2Cu3O10, Naturwissenschaften 75, 509-510 (1988)

·   W. Ose, P. E. Obermayer, H. H. Otto, T. Zetterer, H. Lengfellner, J. Keller, K. F. Renk, Far-infrared reflectivity of sintered YBa2Cu3O7 in the normal and superconducting state, Z. Physik B - Condensed Matter 70, 307-316 (1988)

·   T. Zetterer, H. H. Otto, G. Lugert, K. F. Renk, Crystal chemistry of the Tl2-xBa2CanCun+1O2n+6 (n = 0, 1, 2) high Tc superconductors, Z. Phys. B - Condensed Matter 73, 321-328 (1988)

·   U. Happek, Y. Ayant, R. Buisson, K. F. Renk, Spontaneous-decay cascade of high-frequency acoustic phonons, Europhysics Letters 3, 1001 (1987)

·   U. Happek, T. Holstein, K. F. Renk, Energy transfer by phonons undergoing resonance-elastic and inelastic scattering in an infinite medium, Phys. Rev. B 34, 8898 (1986)

·   U. Werling, K. F. Renk, Wan Chong-Yi, Tuning characteristics of a high pressure CO2 laser pumped CH­3F raman laser, Intern. J. Infrared and Millimeter Waves 7, 881 (1986)

·   U. Werling, Wan Chong-Yi, K. F. Renk, Efficiency of a high pressure CO2 laser pumped CH3F raman laser, IEEE J. Quantum Electronics QE 22, 1024 (1986)

·   U. Werling, Wan Chong-Yi, K. F. Renk, Tuning characteristics of a uv preionized 20-atmosphere CO2 laser, Intern. J. Infrared and Millimeter Waves 6, 449 (1985)

·   Wan Chong-Yi, U. Werling, K. F. Renk, Study of broadband emission of a ultraviolet preionized 20-atm CO2 laser, J. Appl. Phys. 57, 990 (1985)

·   U. Happek, T. Holstein, K. F. Renk, Spectral-spatial diffusion of resonantly trapped phonons, Phys. Rev. Letters 54, 2091 (1985)

·   G. Busse, K. F. Renk, Spectroscopic depth analysis by thermal wave transmission for nondestructive evaluation, Appl. Phys. Lett. 42, 366 (1983)

·   R. Baumgartner, M. Engelhardt, K. F. Renk, Spectral distribution of high-frequency phonons generated by nonradiative transitions, Phys. Lett. A 94, 55 (1983)

·   R. Baumgartner, M. Engelhardt, K. F. Renk, Spontaneous decay of high frequency acoustic phonons in CaF2, Phys. Rev. Lett. 47, 1403 (1981)

·   H. Wolfrum, K. Lanzinger, K. F. Renk, Spin-lattice relaxation by the direct process in optically excited Er3+ in LaF3, Optics Letters 5, 294 (1980)

·   W. Eisfeld, K. F. Renk, Tunable optical detection and generation of terahertz-phonons in CaF2 and SrF2,, Appl. Phys. Lett. 34, 481 (1979)

·   G. Busse, K. F. Renk, Use of the opto-acoustic effect for far-infrared gas-lasers, Infrared Physics 18, 517 (1978)

·   G. Pauli, K. F. Renk, Spectral diffusion of resonantly trapped 29 cm-1 phonons in ruby, Phys. Lett. A 67, 410 (1978)

·   H. Lengfellner, K. F. Renk, Zeemann spectroscopy on the excited Cr3+ in Al2O3 with a far-infrared laser, Semiconductors and Insulators 3, 113 (1978)

·   K. F. Renk, H. Sixl, H. Wolfrum, Spin lattice relaxation in triplet states of naphthalene crystals at very high magnetic fields, Chem. Phys. Lett. 52, 98 (1977)

·   K. F. Renk, J. Deisenhofer, Imprisonment of resonant phonons observed with a new technique for the detection of 1012 Hz phonons, Phys. Rev. Lett. 26, 764 (1971)

·   F. Keilmann, K. F. Renk, Visual observation of submillimeter wave laser beams, Appl. Phys. Lett. 18, 452 (1971)

·   K. F. Renk, P. Grosse, Cyclotron resonance and relaxation time in tellurium at 890 GHz, Solid State Comm. 9, 1175 (1971)

·   H. Brunner, K. F. Renk, Antiferromagnetic resonance in CoF2 at 1012 Hz, J. Appl. Phys. 41, 2250 (1970)

·   J. Boettcher, K. Dransfeld, K. F. Renk, Far-infrared high resolution spectroscopy on EPR lines with a laser, Phys. Lett. 26 A, 146 (1968)

·   L. Genzel, K. F. Renk, R. Weber, Calculation of the impurity-induced lattice mode absorption, phys. stat. sol. 12, 639 (1965)

·   K. F. Renk, L. Genzel, Interference filters and fabry-perot interferometers for the far infrared, Appl. Optics 1, 642 (1962)



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