Borri, Paola

Hvam, Jørn Märcher

Langbein, Wolfgang Werner

Online Research Database In Technology

                       General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.  • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal   If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.     Downloaded from orbit.dtu.dk on: Dec 17, 2017Coherent Optical Spectroscopy of SemiconductorsHvam, Jørn Marcher; Langbein, Wolfgang Werner; Borri, PaolaPublished in:Proceedings of the European Quantum Electronics ConferencePublication date:1998Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Hvam, J. M., Langbein, W. W., & Borri, P. (1998). Coherent Optical Spectroscopy of Semiconductors. InProceedings of the European Quantum Electronics Conference (pp. 167-167). IEEE.09.00 Tu15 Femtosecond Photobiology Villy Sundsiram Depamnenl ofChemicai Physics. Lund University, Box 124, S-221 00 Lund, Sweden Fax +46 462224119. E-mail: Villy.Sundsuom~ehemphys.lu.sc lhia i ~ t ~ n r l  ' $ 1 1 .  Jrr;us tcchn.ques and apphcaoons offemtosecond photobiology k ~ t ,  uloa.siwn pulse genemum. dctecridn .u.d mcliurement techniques will be bnc!l) rev.ewed. '1 hen, sc \~c~nl  examples oiullratast dyoanucs in biological systems I\ AI he d t . \ ~ u > d  Illtrdhrt ,peclmxopy has pro\ idcd a wcalh  of new ir lfomtaon h u t  the J)nuniu* anJ l ' u n ~ u n  ofmany hlJlagicdl ) w m s  AsewJnplcs we will rliiicss d~ :I erg) old elecrron traisfer processss in photosynhetic and antficrnl light-enera convening s!itcms anJ isomerization reactions oirelinal c h m u p h o r c s  ,II p~rotetw L& by ttarure in energ) coobefling and signaling syswms l . ' l r r a r h o r r p J i ~ ~ J o r  43numrc~ in h ~ o l t i ~ .  Kcactions forming the functional hasis o i  hiologrcol Jystznu wc elementag. chemical rcamons like energ) old charge t ~ ~ ~ . ~ i ~ ,  hnr  h r c d m g  and i:mnmg, t u ~ m m l a l i m s .  pwrun r r h n s r i ~ ~  etc. 'lhe d m c t  FIUJ!. 01 these re3ciions in rcnl time frcqumtly requires suh-101) femtosecond t m c  r ~ . s o I u t m  W.JcIy tunable and lou-rr!terlslt) pdlsvr arc uitcn d ~ ~ t d g w u s  t i u ~ l ~ i ~ t c  the rud) ofsen>mie bi.,Iogi;ol b ) s e m r  absorbing light w e r  a broad mtge o i  wa\ekngths. How ultmshon-pulse Ti S a p p h n  technology can be uu*l w dL;mnpli,h thi, tu11 be d i x u s s l .  Plurosinr).mr mrsy . ,omrrs lm Energy m i l  elecuun u.maier reactwm s e  the bui r  dfthe phmi)n the tc  light-enerw convening processes. me avulahtltty of sirticturd nknilat.oli to alotiuc resoluuon of tnmy photorynmctic pgmeot.pmrrms h b  mdrlL. i t  possible I J  htud! in great drwil the dynamics nnd function o f t h a e  I) stems. Topix of current interest that will be discussed are Thc nature orlight cxitatianr in pliotos)nthetw antenna proteins: the mwhantsm ofenrrgy relaxation snd lrmst'er tn ant."a proteim and how rlrcLTUsc wd nuclew cohcrmcc contribute to the b c t i o n ,  the mcchnntsm ofprimar). charge separation in the photo,ynthrit< rrnction center. phuloqnthetw pigment systems as modcls tor artificial photos) ohcm a d  photonic sysrems. .4 l+$I .h i .cn  i i ~ . r r u m  Iwmmzuiion Iead1on is extensively used by nature to several pignie.it-protciie far Ii&wnerg) .dn\ mjioti (bwturrorhodop,in. photoaitlve y c . l ~ u  p r d m ,  and aipaiing (rhudopiin and phytochrome) The nature of the priman phx. r c d m  md how i t  is relatcd to the fuiicrio~i oithe protclns u r l l  hc e u " c d  and caiiipucd nith d mudrl d)c systcm d e r  1,) 08.00-10.00 [IThA - Time-Resolved Optical l n t e k i o n  with Semiconductors Presider: M. Aeschlimann, ETH, Zunch, SWITERUND GALA 08.00 OThAl (Invited) Coherent Optical Spectroscopy of Semiconductors J. M. Hvm. W. Lanebein and P. Borri Mikroelektranik Centret. The Technical University ofllenmark. D I U  building 345 east DK-2800 Lyngby. Denmark. Tel. +45 -4525 5758, Fax +45 - 4588 7762. e-mail: hvmi2mic.dtu.dk Coherent optical spectroscopy in the form of transient fuur-wave mixing (TFWM) has been used extensively to investigate the exciton and hiexciton dynamics in  semiconductor materials, alloys. and lawdimensional heterostrucwea. The dephasing times of excitons and biexcitons is determined from the decay of the spectrally resolved non-linear signal as a function of the delay (positive and negative) beween the incident pulses in a t w o - h i  TFWM experiment. From the temperature dependence of the dephasing limes the exciton-phonon is determined. and the exciton-exciton interactions (collisions) are revealed by the exciton density dependence thc depltasing times. lhe polarization selection mlrs or thr TFWM signal me used to identify the hicxciton contribution to the signal, as well as to identify thc other origins ofthe non-linear signal, such as phase-space filling. local-field effects and excitation-induced dephasing. Randomly fluctuating potentials. due to either alloy disorder or interface ruughneis in  IOW- dimensional structures. tend to localize excitons and bicxcitons and gwr risr IO an inhomogeneous broadening of the excitonic resananceb. .41 the samc time the TFWM signal changer from a free-polarization-decay in the homogeneously broadened system In a photon echo in the inhomogcncously broadened system.' The localizatian alters the cxcjton-exciton and the exciton-phonon inleractions and thereby changes the dephasing rates of the excitations. Punher. the localization changrs the exciton and biexciton binding energies, and in parlicular their ratio. Blcaciton binding energics are determined from spectral resolution of thr  nonlinear signal. as n,ell as by nonlinear quanlum- beat speclmscopy. The laner is useful. OT necessaly, when the broadcning is comparable to the biexciton binding energy. The ratio between the binding energies of the biexciton and the exciton depends strongly on the dimensionality of the cmfined SVUCIUK and'nr lhe degree of localization by random fluctuations. It changes from about 0.1 in homogeneous bulk semiconductnrs (Ilaynes. rule) over about 0.2 u1 quasi lwo-dimensional quantum wrllr' to ahout 0.4 in strongly localizedlconfined zero-dimensional smctures (quanNm dots). Again, the crucial parameter is the localization energy (broadening) compared to the biexciton binding energy. In strongly inhomogenwusly broadened systems, the random fluctuations cause an inhomogeneous distribution of biexciton binding energies, which apain results in the observation of a fast decay of l h e  biexciton signal as a function of the delay between the incident pulses. This has falsely been intcrpreted as a fast (homogeneous) dephasing of the biexcitons, but it only reflects destructive interference due to the distribution of biexciton binding energies? I I. Erland, K.-H. Pantke. V. Mizeikis, V.G. Lyssenko, and 1.M. Hvnm, Phys. Rev, B 50, 15047 (1994). $1996). R7383 (1997). D. Birkedal, I. Singh,V.G. Lyssenko, J. Erland. and J.M. Hvam, Phys. Rev. Lett 76,672 W. Langbein J.M. Hvam, M. Umlauff, H. Kalt, U. Jobst, and D. Ilommel, Phys. Rev. R 55, Thursday / 167 

Coherent Optical Spectroscopy of Semiconductors

http://orbit.dtu.dk/ws/files/4633678/Lang.PDF

Coherent Optical Spectroscopy of Semiconductors

Abstract

Similar works

Full text

Available Versions

Online Research Database In Technology