29 research outputs found
Enabling novel features of heterogeneous III-V on Si lasers with resonant si embedded photonic molecules mirrors
Thermal Considerations In Electrically-pumped Metallo-dielectric Nanolasers
Metal nanocavity-based lasers show promise for dense integration in nanophotonic devices, thanks to their compact size and lack of crosstalk. Thermal considerations in these devices have been largely overlooked in design, despite the importance of self-heating and heat dissipation to device performance. We discuss the sources of self-heating in electrically-pumped wavelength-scale nanolasers, and the incorporation of these heat sources into a heat dissipation model to calculate laser operating temperature. We apply this thermal model to an example electrically-pumped nanolaser operating at room temperature. © 2014 SPIE.8980The Society of Photo-Optical Instrumentation Engineers (SPIE)Lee, J.H., Khajavikhan, M., Simic, A., Gu, Q., Bondarenko, O., Slutsky, B., Nezhad, M.P., Fainman, Y., Electrically pumped sub-wavelength metallo-dielectric pedestal pillar lasers (2011) Optics Express, 19, pp. 21524-21531. , OctDing, K., Ning, C.Z., Fabrication challenges of electrical injection metallic cavity semiconductor nanolasers (2013) Semiconductor Science and Technology, 28, p. 124002. , NovHill, M.T., Oei, Y.-S., Smalbrugge, B., Zhu, Y., De Vries, T., Van Veldhoven, P.J., Van Otten, F.W.M., Smit, M.K., Lasing in metallic-coated nanocavities (2007) Nature Photonics, 1, pp. 589-594. , SeptNezhad, M.P., Simic, A., Bondarenko, O., Slutsky, B., Mizrahi, A., Feng, L., Lomakin, V., Fainman, Y., Room-temperature subwavelength metallo-dielectric lasers (2010) Nature Photonics, 4, pp. 395-399. , AprKhajavikhan, M., Simic, A., Katz, M., Lee, J.H., Slutsky, B., Mizrahi, A., Lomakin, V., Fainman, Y., Thresholdless nanoscale coaxial lasers (2012) Nature, 482, pp. 204-207. , JanGu, Q., Slutsky, B., Vallini, F., Smalley, J.S.T., Nezhad, M.P., Frateschi, N.C., Fainman, Y., Purcell effect in sub-wavelength semiconductor lasers (2013) Optics Express, 21 (13), p. 15603Ning, C.Z., What is Laser Threshold (2013) IEEE Journal of Selected Topics in Quantum Electronics, 19, pp. 1503604-1503604. , MayHess, O., Pendry, J.B., Maier, S.A., Oulton, R.F., Hamm, J.M., Tsakmakidis, K.L., Active nanoplasmonic metamaterials (2012) Nature Materials, 11, pp. 573-584. , JulyDing, K., Hill, M.T., Liu, Z.C., Yin, L.J., Van Veldhoven, P.J., Ning, C.Z., Record performance of electrical injection sub-wavelength metallic-cavity semiconductor lasers at room temperature (2013) Optics Express, 21 (4), pp. 4728-4733Hobson, W.S., Mohideen, U., Pearton, S.J., Slusher, R.E., Ren, F., SiN x/sulphide passivated GaAs/AlGaAs microdisk lasers (1993) Electronics Letters, 29 (25), pp. 2199-2200Ding, K., Ning, C.Z., Metallic subwavelength-cavity semiconductor nanolasers (2012) Light: Science & Applications, 1, pp. e20. , JulyNing, C.Z., Indik, R.A., Moloney, J.V., Self-consistent approach to thermal effects in vertical-cavity surface-emitting lasers (1995) JOSA B, 12 (10), pp. 1993-2004Smalley, J.S.T., Gu, Q., Fainman, Y., Temperature dependence of the spontaneous emission factor in subwavelength semiconductor lasers (2014) IEEE Journal of Quantum Electronics, 50, pp. 175-185. , MarYu, S.F., (2003), Analysis and design of vertical cavity surface emitting lasers, Wiley - VCH, JanSchmidt, N.M., Goldberg, Y.A., (1996) Handbook Series on Semiconductor Parameters Volume 2: Ternary and Quaternary III-V Compounds, 2. , Handbook Series on Semiconductor Parameters, World Scientific, London, JanSchmidt, N.M., Goldberg, Y.A., (1996) Handbook Series on Semiconductor Parameters Volume 1: Si, Ge, C (Diamond), GaAs, GaP, GaSb, InAs, InP, InSb, 1. , Handbook Series on Semiconductor Parameters, World Scientific, London, JanZhang, P., Lau, Y.Y., Tang, W., Gomez, M.R., French, D.M., Zier, J.C., Gilgenbach, R.M., Contact resistance with dissimilar materials: Bulk contacts and thin film contacts (2011) Electrical Contacts (Holm) 2011 IEEE 57th Holm Conference, pp. 1-6. , IEEE, SeptAgrawal, G.P., Dutta, N.K., (1993) Semiconductor Lasers, , Van Nostrand Reinhold, New York, JanYoneoka, S., Lee, J., Liger, M., Yama, G., Kodama, T., Gunji, M., Provine, J., Kenny, T.W., Electrical and Thermal Conduction in Atomic Layer Deposition Nanobridges Down to 7 nm Thickness (2012) Nano Lett, 12, pp. 683-686. , FebWank, J.R., George, S.M., Weimer, A.W., Nanocoating individual cohesive boron nitride particles in a fluidized bed by ALD (2004) Powder Technology, 142, pp. 59-69. , AprDörre, E., Hübner, H., (1984) Alumina: Processing, Properties, and Applications, , Springer-Verlag, Berlin, JanKleiner, M.B., Kuhn, S.A., Weber, W., Thermal conductivity measurements of thin silicon dioxide films in integrated circuits (1996) Electron Devices, IEEE Transactions on, 43 (9), pp. 1602-1609Adachi, S., (1992) Physical Properties of III-V Semiconductor Compounds, , John Wiley & Sons, Inc., Mörlenbach, JanLange, N.A., (1999) Lange's Handbook of Chemistry, , McGraw-Hill Professional 15 ed., JanAndersson, S., Dzhavadov, L., Thermal conductivity and heat capacity of amorphous SiO2: Pressure and volume dependence (1992) Journal of Physics: Condensed Matter, 4 (29), p. 6209Lide, D.R., (2003) CRC Handbook of Chemistry and Physics, CRC Press 84 Ed., , JuneBassous, E., Fabrication of novel three-dimensional microstructures by the anisotropic etching of (100) and (110) silicon (1978) IEEE Transactions on Electron Devices, 25, pp. 1178-1185. , OctCahill, D.G., Thermal conductivity measurement from 30 to 750 K: The 3 method (1990) Review of Scientific Instruments, 6 (12), p. 802Cahill, D.G., Katiyar, M., Abelson, J.R., Thermal conductivity of alpha-Si:H thin films (1994) Physical Review B, 50 (9), p. 6077Borca-Tasciuc, T., Kumar, A.R., Chen, G., Data reduction in 3 method for thin-film thermal conductivity determination (2001) Review of Scientific Instruments, 72 (4), p. 2139Wang, R.Y., Segalman, R.A., Majumdar, A., Room temperature thermal conductance of alkanedithiol self-assembled monolayers (2006) Applied Physics Letters, 89 (17), p. 173113Majumdar, A., Scanning thermal microscopy (1999) Annual Review of Materials Science, 29 (1), pp. 505-585Kim, K., Jeong, W., Lee, W., Reddy, P., Ultra-high vacuum scanning thermalmicroscopy for nanometer resolution quantitative thermometry (2012) ACS Nano, 6, pp. 4248-4257. , MayShen, S., Henry, A., Tong, J., Zheng, R., Chen, G., Polyethylene nanofibres with very high thermal conductivities (2010) Nature Nanotechnology, pp. 1-5. , MarLiu, Z., Shainline, J.M., Fernandes, G.E., Xu, J., Chen, J., Gmachl, C.F., Continuous-wave subwavelength microdisk lasers at λ = 1.53?m (2010) Optics Express, 18, pp. 19242-19248. , AugLuo, T., Chen, G., Nanoscale heat transfer - From computation to experiment (2013) Physical Chemistry Chemical Physics, 15 (10), pp. 3389-341
Effects Of Non-uniform Size Distribution On The Spectral Optical Gain Properties Of Ingaas/ingaasp Quantum Bots
We present the theoretical study of optical gain in quantum dots based on the InGaAs/InGaAsP system. A complete computational tool was developed to allow the analysis of the effects of the size distribution of the dots. Spectral gain curves are generated for InGaAs/InGaAsP dots where high optical gain and high independence of spectral characteristics are obtained for a uniform distribution of dots. With typical non-uniform distribution, we show a reduction in gain by a factor of 3. Also, we predict the onset of new transition peaks and a red shift in the most probable operating lasing wavelength. © 2006 The Electrochemical Society.41385390Peter J. A. Thijs, Luuk F. Tiemeijer, J. J. M. Binsma, and Teus van Dongen, IEEE J. Quantum Electron. 30, 477 (1994)Allen C. Ni., P. J. Poole, P. Marshall, J. Fraser, S. Raymond and S. Fafard, Appl. Phys. Lett. 80, 3629 (2002)Xua, B., Wang, Z.G., Chen, Y.H., Jin, P., Ye, X.L., Liu, H.Y., Zhang, Z.Y., Liu, F.Q., (2004) IEEE 13th International Conference on Semiconducting and Insulating Materials, 113Kovsh, A.R., Zhukov, A.E., Egorov, A.Y., Ustinov, V.M., Ledentsov, N.N., Maksimov, M.V., Tsatsul'nikov, A.F., Kop'ev, P.S., (1999) Semiconductors, 33 (2), p. 184Frateschi, N.C., Levi, A.F.J., (1996) J. Appl. Phys, 80, p. 644Agraval, G.P., Dutta, N.K., (1993) Semiconductor Lasers, , Second Edition, Van Nostrand ReinholdLeonard, D., Fafard, S., Pond, K., Zhang, Y.H., Merz, J.L., Petroff, P.M., (1994) J. Vac. Sci. Technol. B, 12 (4), p. 2516Yamada, M., Ishiguro, H., Nagato, H., (1980) Jap. J. Appl. Phys, 19, p. 135Mendoza-Alvarez, J.G., Pires, M.P., Landi, S.M., Lopes, A.S., Souza, P.L., Villas-Boas, J.M., Studart, N., (2006) Physica E, 32 (1-2), p. 85Sormunen, J., Riikonen, J., Mattila, M., Sopanen, M., Lipsanen, H., (2005) Nanotechnology, 16, p. 163
Evidences Of The Simultaneous Presence Of Bow-tie And Diamond Scars In Rare-earth Doped Amorphous Silicon Microstadium Resonators
Microdisks and microstadium resonators were fabricated on erbium doped amorphous hydrogenated silicon (a-Si:H 〈Er〉) layers sandwiched in air and native Si O2 on Si substrates. Annealing condition is optimized to allow large emission at 1550 nm for samples with erbium concentrations as high as 1.02× 1020 atoms cm3. Near field scanning optical microscopy shows evidence of the simultaneous presence of bow-tie and diamond scars. These modes indicate the high quality of the resonators and the potentiality for achieving amorphous silicon microcavity lasers. © 2008 American Institute of Physics.1036Frateschi, N.C., Levi, A.F.J., (1996) J. Appl. Phys., 80, p. 644. , JAPIAU 0021-8979 10.1063/1.362873McCall, S.L., Levi, A.F.J., Slusher, R.E., Pearton, S.J., Logan, R.A., (1992) Appl. Phys. Lett., 60, p. 289. , APPLAB 0003-6951 10.1063/1.106688Gmachl, C., Capasso, F., Narimanov, E.E., Nockel, J.U., Stone, A.D., Faist, J., Sivco, D.L., Cho, A., (1998) Science, 280, p. 1556. , SCIEAS 0036-8075 10.1126/science.280.5369.1556Judd, B.R., (1962) Phys. Rev., 127, p. 750. , PHRVAO 0031-899X 10.1103/PhysRev.127.750Desurvire, E., (1994) Erbium-Doped Fiber Amplifiers, , (Wiley, New York)Kühne, H., Weiser, G., Terukov, E.I., Kusnetsov, A.N., Kudoyarova, V.Kh., (1999) J. Appl. Phys., 86, p. 896. , JAPIAU 0021-8979 10.1063/1.370820Fuhs, W., Ulber, I., Weiser, G., (1997) Phys. Rev. B, 56, p. 9545. , PRBMDO 0163-1829 10.1103/PhysRevB.56.9545Tessler, L.R., (1999) Braz. J. Phys., 29, p. 616. , BJPHE6 0103-9733Bresler, M.S., Gusev, O.B., Kudoyarova, V.Kh., Kuznetsov, A.N., Pak, P.E., Terukov, E.I., Yassievich, I.N., Sturm, A., (1995) Appl. Phys. Lett., 67, p. 3599. , APPLAB 0003-6951 10.1063/1.115330Shin, J.H., Serna, R., Hoven, G.N., Polman, A., Sark, W.G.J.H.M., Vrendenberg, A.M., (1996) Appl. Phys. Lett., 68, p. 997. , APPLAB 0003-6951 10.1063/1.116124Fredrickson, J.E., Waddell, C.N., Spitzer, W.G., Hubler, G.K., (1982) Appl. Phys. Lett., 40, p. 172. , APPLAB 0003-6951 10.1063/1.93032Hoyland, J.D., Sands, D., (2006) J. Appl. Phys., 99, p. 063516. , JAPIAU 0021-8979 10.1063/1.2186378Kalkman, J., Tchebotareva, A., Polman, A., Kippengerb, T.J., Min, B., Vahala, K.J., (2006) J. Appl. Phys., 99, p. 83103. , JAPIAU 0021-8979Polman, A., Min, B., Kalkman, J., Kippenberg, T.J., Vahala, K.J., (2004) Appl. Phys. Lett., 84, p. 1037. , APPLAB 0003-6951 10.1063/1.1646748Wintres, H.F., Kay, E., (1967) J. Appl. Phys., 38, p. 3928. , JAPIAU 0021-8979 10.1063/1.1709043Polman, A., (1997) J. Appl. Phys., 82, p. 1. , JAPIAU 0021-8979 10.1063/1.366265Heller, E.J., (1984) Phys. Rev. Lett., 53, p. 1515. , PRLTAO 0031-9007 10.1103/PhysRevLett.53.1515Bogomolny, E., (1988) Physica D, 31, p. 169. , PDNPDT 0167-2789 10.1016/0167-2789(88)90075-9Bunimovich, L.A., (1974) Funct. Anal. Appl., 8, p. 254. , FAAPBZ 0016-2663Lebental, M., Lauret, J.S., Hierle, R., Zyss, J., (2006) Appl. Phys. Lett., 88, p. 31108. , APPLAB 0003-6951Nockel, J.U., Stone, A.D., Chen, G., Grossman, H.L., Chang, R.K., (1996) Opt. Lett., 21, p. 1609. , OPLEDP 0146-9592Mestanza, S.N.M., Von Zuben, A.A., Frateschi, N.C., (2002) Future Trends in Microelectronics-The Nano Millennium, pp. 364-371. , in, edited by S. Luryi, J. Xu, and A. Zaslavsky (Wiley, New York
Analysis Of A High Sensitivity Optical Micro Sensor Based On Stadium Optical Resonators
We present an analysis of the spectral behavior of a stadium optical cavity under small perturbation of its effective index of refraction for the development of a resonant optical sensor. A dimensional reduction up to 1000 time with respect to conventional Mach-Zehnder interferometers without the need for an external light source is shown. Also, discontinuous behavior in the spectrum is shown to be very suitable for a trigger function application.PV 2005-085459Prieto, F., Sepúlveda, B., Calle, A., Liobera, A., Dominguez, C., Abad, A., Montoya, A., Lechuga, M.L., (2003) Nanotechnology, 14Rosen, N.A., Charash, W.E., Hirsh, E.F., (2002) J. Surgical Res., 106Schipper, E.F., Brugman, A.M., Dominguez, C., Lechuga, L.M., Kooyman, R.P.H., (1997) J. Greve, Sensor and Actuators B, 40Boyd, R.W., Heebner, J.E., (2001) Appl. Optics, 40, p. 31Heller, E.J., (1984) Phys. Ver. Lett., 53, p. 1515Mestanza, S.N.M., Von Zuben, A.A., Frateschi, N.C., Proceedings of Future Trends in Microeletronic Workshop/2001, , Ile de Bendor, France (June 25-29)Hakki, B.W., Paoli, T.L., (1975) J. Appl. Phys., 46 (3), p. 1299Hong, S.-C., Kothiyal, G.P., Debbar, N., Bhattacharya, P., Singh, J., (1988) Phys. Rev. B, 37, p. 87
Laser Reflectometry Applied To The In-situ Etching Control In An Electron Cyclotron Resonance Plasma System
ECR BCl3 etching of InGaP/GaAs/InGaAs quantum well laser structures was performed to produce vertical walls with good morphology. Laser reflectometry shows a reduced etching rate for p+-InGaP material. Etching thickness control within 200 angstrom is achieved for InGaP layers.261661
Optimized Electrolyte For Electrochemical Capacitance-voltage Profiling Of Carrier Concentration In In0.49ga0.51p
Electrolyte characterization and optimization for the electrochemical capacitance-voltage profiling of carrier concentration in In0.49Ga0.51P is presented. The conditions for operation under minimum electrolyte interference are found based on the complex impedance analysis of an electrolyte-semiconductor junction. Carrier concentration results obtained with the optimized electrolyte are shown to both provide good etch depth control and to agree with Hall measurements. The same optimization scheme may be used for the characterization of other semiconductor material.281214281432Jones, K.A., Laureau, R.T., Monahan, T., Flemish, J.R., Pfeffer, R.L., Sherriff, R.E., Litton, C.W., Look, D.C., (1995) J. Electron. Mater., 24, p. 1641Kapre, R.M., Tsang, W.T., Chen, Y.K., Wu, M.C., Chin, M.A., Choa, F.S., (1992) J. Cryst. Growth, 124, p. 177Olson, M., Ahrenkiel, R.K., Dunlavy, D.J., Keyes, B., Kibbler, A.E., (1989) Appl. Phys. Lett., 55, p. 1208Ambridge, T., Faktor, M.M., (1975) Inst. Phys. Conf. Ser., 24, p. 320Blood, P., (1986) Semicond. Sci. Technol., 1, p. 7Green, R.T., Walker, D.K., Wolfe, C.M., (1986) J. Electrochem. Soc., 133, p. 2278Ambridge, T., Stevenson, J., Redstall, M., (1980) J. Electrochem. Soc., 127, p. 228Skriniarova, J., Kovac, J., Breza, J., Gregusova, D., (1998) Sensors and Materials, 4, p. 213Sluyters-Reserch, M., Sluyters, J.H., (1970) Electroctroanalytical Chemistry, 4. , ed. A.J. Bard New York: Marcel Dekker, Chap. 1Smits, F.M., (1962) Bell Syst. Tech. J., 41, p. 387Das Neves, S., Paoli, M.A., (1993) J. Electrochem. Soc., 140, p. 2599Kemp, T.J., (1990) Ellis Horwood Series in Physical Chemistry, , London: Ellis Horwood Limited, Chap. 1 and Chap. 8.
Photonic Molecules For Optical Signal Processing
We demonstrate how CMOS compatible photonic molecules (PM) can break the fundamental interdependence among quality factor (Q), channel spacing and size of microring resonators. Different PM architectures are presented for efficient and compact optical signal processing.5455Barea, L.A.M., Vallini, F., De Rezende, G.F.M., Frateschi, N.C., Spectral engineering with cmos compatible soi photonic molecules (2013) IEEE Photonics J., 5 (6), pp. 2202717-2202717Barea, L.A.M., Val Lini, F., Jarschel, P.F., Frateschi, N.C., Silicon technology compatible photonic molecules for compact optical signal processing (2013) Appl. Phys. Lett, 103 (20), p. 201102. , NovSouza, M.C.M.M., Barea, L.A.M., Vallini, F., Rezende, G.F.M., Wiederhecker, G.S., Frateschi, N.C., Embedded coupled microrings with high-finesse and close-spaced resonances for optical signal processing (2014) Opt. Express, 22 (9), pp. 10430-10438. , MayTzuang, L.D., Soltani, M., Lee, Y.H.D., Lipson, M., High rf carrier frequency modulation in silicon resonators by coupling adjacent free-spectral-range modes (2014) Opt. Lett, 39 (7), pp. 1799-1802. , AprXu, Q., Almeida, V.R., Lipson, M., Micrometer-scale all-optical wavelength converter on silicon (2005) Opt. Lett, 30 (20), pp. 2733-2735. , OctLi, Q., Zhang, Z., Liu, F., Qiu, M., Su, Y., Dense wavelength conversion and multicasting in a resonance-split silicon microring (2008) Appl. Phys. Lett, 93 (8), p. 081113. , Au
Observation Of Resonance Modes In Inas/ingaasp/inp Quantum Dot Microdisk Resonators
We present the development of quantum dot microdisk resonators grown by Chemical Beam Epitaxy (CBE). Two stacked layers of InAs Quantum Dots (QDs) embedded in a lattice-matched InGaAsP (λ g=1.4 μm) are grown on (100) InP substrate. Evidence of the presence of resonant modes are observed both by eletroluminescense and absorption spectra at room temperature. © The Electrochemical Society.141505509McCall, S.L., Levi, A.F.J., Slusher, R.E., Pearton, S.J., Logan, R.A., (1992) Appl. Phys. Lett, 60, p. 289Nishi, K., Saito, H., Sugou, S., Lee, J., (1999) Appl. Phys. Lett, 74, p. 1111Kiravittaya, S., Rastelli, A., Schmidt, O.G., (2005) Appl. Phys. Lett, 87Ustinov, V.M., Meleev, N.A., Zhukov, A.E., Kovsh, A.R., Egorov, A.Y., Lunev, A.V., Volovik, B.V., Bimberg, D., (1999) Appl. Phys. Lett, 74, p. 2815Barik, S., Tan, H.H., Jagadish, C., (2006) Nanotechnology, 17, p. 1867Saito, H., Nishi, K., Sugou, S., (2001) Appl. Phys. Lett, 78, p. 267Jeong, W.G., Dapkus, P.D., Lee, U.H., Lim, J.S., Lee, D., Lee, B.T., (2001) Appl. Phys. Lett, 78, p. 1171Wang, R.H., Stintz, A., Varangis, P.M., Newell, T.C., Li, H., Malloy, K.J., Lester, L.F., (2001) IEEE Photonics Technol. Lett, 13, p. 767Schwertberger, R., Gold, D., Reithmaier, J.P., Forchel, A., (2002) IEEE Photonics Technol. Lett, 14, p. 735Ni, C., Allen, Poole, P.J., Marshall, P., Fraser, J., Raymond, S., Fafard, S., (2002) Appl. Phys. Lett, 80, p. 3629Fafard, S., Wasilewski, Z., McCaffrey, J., Raymond, S., Charbonneau, S., (1996) Appl. Phys. Lett, 68, p. 991Li, H., Daniels-Race, T., Wang, Z., (1999) J. Cryst. Growth, 200, p. 321Poole, P.J., McCaffrey, J., Williams, R.L., Lefebvre, J., Chithrani, D., (2001) J. Vac. Sci. Technol. B, 19, p. 1467Xua, B., Wang, Z.G., Chen, Y.H., Jin, P., Ye, X.L., Liu, H.Y., Zhang, Z.Y., Liu, F.Q., (2004) IEEE 13th International Conference on Semiconducting and Insulating Materials, 113Nieto, L., Bortoleto, J.R.R., Cotta, M.A., Magalhães-Paniago, R., Gutiérrez, H.R., (2007) Appl. Phys. Lett, 91, p. 063122Allen, C.N., Finnie, P., Raymond, S., Wasilewski, Z.R., Fafard, S., (2001) Appl. Phys. Lett, 79, p. 2701Sztucki, M., Schülli, T.U., Metzger, T.H., Beham, E., Schuh, D., Chamard, V., (2004) Superlattices Microstruct, 36, p. 1
Compact Photonic Molecules Based On Internally Coupled Microring Resonators
We demonstrate compact planar photonic molecules based on multiple ring resonators internally coupled to a larger ring. Spectral engineering is demonstrated where doublets and quadruplets resonances with high Q are obtained due to degeneracy anti-bunching. © OSA 2013.Bertolotti, M., Driessen, A., Michelotti, F., Microresonators as building block for VLSI photonics (2004) American Institute of Physics, , NYBogaerts, W., Silicon microring resonators (2012) Laser Photonics Rev., 6, pp. 47-73Vlasov, Y., McNab, S., Losses in single-mode silicon-on-insulator strip waveguides and bends (2004) Opt. Exp., 12, pp. 1622-1631Boriskina, S.V., Photonic molecules and spectral engineering. (2010) Photonic microresonator research and applications, pp. 393-421. , Springer U