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Li C, Krauß N, Schäfer G, Ebner L, Kliebisch O, Schmidt J, Winnerl S, Hettich M, Dekorsy T. High-speed asynchronous optical sampling based on GHz Yb:KYW oscillators. OPTICS EXPRESS 2017; 25:9204-9212. [PMID: 28437994 DOI: 10.1364/oe.25.009204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A low-cost scheme of high-speed asynchronous optical sampling based on Yb:KYW oscillators is reported. Two GHz diode-pumped oscillators with a slight pulse repetition rate offset serve as pump and probe source, respectively. The temporal resolution of this system is limited to 500 fs mainly by the pulse duration of the oscillators and also by relative timing jitter between the oscillators. A near-shot-noise noise floor around 10-6 (∆R/R) is obtained within a data acquisition time of a few seconds. The performance of the system is demonstrated by measurements of coherent acoustic phonons in a semiconductor sample that resembles a semiconductor saturable absorber mirror or an optically pumped semiconductor chip.
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Photon number statistics uncover the fluctuations in non-equilibrium lattice dynamics. Nat Commun 2015; 6:10249. [PMID: 26690958 PMCID: PMC4703887 DOI: 10.1038/ncomms10249] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 11/19/2015] [Indexed: 11/08/2022] Open
Abstract
Fluctuations of the atomic positions are at the core of a large class of unusual material properties ranging from quantum para-electricity to high temperature superconductivity. Their measurement in solids is the subject of an intense scientific debate focused on seeking a methodology capable of establishing a direct link between the variance of the atomic displacements and experimentally measurable observables. Here we address this issue by means of non-equilibrium optical experiments performed in shot-noise-limited regime. The variance of the time-dependent atomic positions and momenta is directly mapped into the quantum fluctuations of the photon number of the scattered probing light. A fully quantum description of the non-linear interaction between photonic and phononic fields is benchmarked by unveiling the squeezing of thermal phonons in α-quartz.
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Squeezed Phonon Wave Packet Generation by Optical Manipulation of a Quantum Dot. PHOTONICS 2015. [DOI: 10.3390/photonics2010214] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Hase M, Katsuragawa M, Monia Constantinescu A, Petek H. Coherent phonon frequency comb generated by few-cycle femtosecond pulses in Si. EPJ WEB OF CONFERENCES 2013. [DOI: 10.1051/epjconf/20133104020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Mizoguchi K, Morishita R, Oohata G. Generation of coherent phonons in a CdTe single crystal using an ultrafast two-phonon laser-excitation process. PHYSICAL REVIEW LETTERS 2013; 110:077402. [PMID: 25166406 DOI: 10.1103/physrevlett.110.077402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Revised: 11/07/2012] [Indexed: 06/03/2023]
Abstract
The detection-energy dependence of a coherent phonon in a (001) CdTe crystal, generated by ultrashort laser pulses with the center energy transparent or opaque to the sample, is investigated using a spectrally resolved pump-probe method. At the excitation in the transparent region, the detection-energy dependence of the phonon amplitude has two peaks at the energy shifted by one times the phonon energy of CdTe from the center energy of the probe pulses. On the other hand, the amplitude in the opaque region shows two peaks at the energy shifted by about two times the phonon energy. This difference occurs even though the observed energies of the coherent phonons in both regions are the same as that of the longitudinal optical phonon of CdTe. The energy shifts in the detection-energy dependence imply that the emission and absorption of one phonon and two phonons in the transparent and opaque regions, respectively, are implicated in coherent phonon generation. In this study, the detection-energy dependence is examined from the viewpoint of the third-order nonlinear susceptibility based on the impulsive stimulated Raman scattering process under nonresonant and resonant conditions.
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Affiliation(s)
- K Mizoguchi
- Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531, Japan
| | - R Morishita
- Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531, Japan
| | - G Oohata
- Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531, Japan
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Hu J, Misochko OV, Nakamura KG. Manipulation of Squeezed Two-Phonon Bound States using Femtosecond Laser Pulses. EPJ WEB OF CONFERENCES 2013. [DOI: 10.1051/epjconf/20134104019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Sauer S, Daniels JM, Reiter DE, Kuhn T, Vagov A, Axt VM. Lattice fluctuations at a double phonon frequency with and without squeezing: an exactly solvable model of an optically excited quantum dot. PHYSICAL REVIEW LETTERS 2010; 105:157401. [PMID: 21230936 DOI: 10.1103/physrevlett.105.157401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Indexed: 05/30/2023]
Abstract
Time-dependent lattice fluctuations of an optically excited strongly confined quantum dot are investigated with the aim to analyze the characteristics commonly used for identifying the presence of squeezed phonon states. It is demonstrated that the appearance of fluctuations oscillating with twice the phonon frequency, commonly regarded as a clear indication of squeezed states, cannot be considered as such. The source of the discrepancy with earlier investigations is discussed. Conditions for generating a squeezed state by using a two-pulse excitation are analyzed.
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Affiliation(s)
- S Sauer
- Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, 48149 Münster, Germany
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Gebs R, Klatt G, Janke C, Dekorsy T, Bartels A. High-speed asynchronous optical sampling with sub-50fs time resolution. OPTICS EXPRESS 2010; 18:5974-5983. [PMID: 20389617 DOI: 10.1364/oe.18.005974] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report an ultrafast time-domain spectroscopy system based on high-speed asynchronous optical sampling operating without mechanical scanner. The system uses two 1 GHz femtosecond oscillators that are offset-stabilized using high-bandwidth feedback electronics operating at the tenth repetition rate harmonics. Definition of the offset frequency, i.e. the time-delay scan rate, in the range of a few kilohertz is accomplished using direct-digital-synthesis electronics for the first time. The time-resolution of the system over the full available 1 ns time-delay window is determined by the laser pulse duration and is 45 fs. This represents a three-fold improvement compared to previous approaches where timing jitter was the limiting factor. Two showcase experiments are presented to verify the high time-resolution and sensitivity of the system.
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Affiliation(s)
- R Gebs
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457, Germany.
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Johnson SL, Beaud P, Vorobeva E, Milne CJ, Murray ÉD, Fahy S, Ingold G. Non-equilibrium phonon dynamics studied by grazing-incidence femtosecond X-ray crystallography. Acta Crystallogr A 2010; 66:157-67. [DOI: 10.1107/s0108767309053859] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 12/14/2009] [Indexed: 11/10/2022] Open
Abstract
The timescales for structural changes in a single crystal of bismuth after excitation with an intense near-infrared laser pulse are studied with femtosecond pump-probe X-ray diffraction. Changes in the intensity and reciprocal-lattice vector of several reflections give quantitative information on the structure factor and lattice strain as a function of time, with a resolution of 200 fs. The results indicate that the majority of excess carrier energy that remains near the surface is transferred to vibrational modes on a timescale of about 10 ps, and that the resultant increase in the variance of the atomic positions at these times is consistent with the overall magnitude of lattice strain that develops.
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Johnson SL, Beaud P, Vorobeva E, Milne CJ, Murray ED, Fahy S, Ingold G. Directly observing squeezed phonon states with femtosecond x-ray diffraction. PHYSICAL REVIEW LETTERS 2009; 102:175503. [PMID: 19518793 DOI: 10.1103/physrevlett.102.175503] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2008] [Indexed: 05/19/2023]
Abstract
Squeezed states are quantum states of a harmonic oscillator in which the variance of two conjugate variables each oscillate out of phase. Ultrafast optical excitation of crystals can create squeezed phonon states, where the variance of the atomic displacements oscillates due to a sudden change in the interatomic bonding strength. With femtosecond x-ray diffraction we measure squeezing oscillations in bismuth and conclude that they are consistent with a model in which electronic excitation softens all phonon modes by a constant scaling factor.
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Affiliation(s)
- S L Johnson
- Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
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Polli D, Rini M, Wall S, Schoenlein RW, Tomioka Y, Tokura Y, Cerullo G, Cavalleri A. Coherent orbital waves in the photo-induced insulator-metal dynamics of a magnetoresistive manganite. NATURE MATERIALS 2007; 6:643-7. [PMID: 17694062 DOI: 10.1038/nmat1979] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Accepted: 07/06/2007] [Indexed: 05/15/2023]
Abstract
Photo-excitation can drive strongly correlated electron insulators into competing conducting phases, resulting in giant and ultrafast changes of their electronic and magnetic properties. The underlying non-equilibrium dynamics involve many degrees of freedom at once, whereby sufficiently short optical pulses can trigger the corresponding collective modes of the solid along temporally coherent pathways. The characteristic frequencies of these modes range between the few GHz of acoustic vibrations to the tens or even hundreds of THz for purely electronic excitations. Virtually all experiments so far have used 100 fs or longer pulses, detecting only comparatively slow lattice dynamics. Here, we use sub-10-fs optical pulses to study the photo-induced insulator-metal transition in the magnetoresistive manganite Pr(0.7)Ca(0.3)MnO(3). At room temperature, we find that the time-dependent pathway towards the metallic phase is accompanied by coherent 31 THz oscillations of the optical reflectivity, significantly faster than all lattice vibrations. These high-frequency oscillations are suggestive of coherent orbital waves, crystal-field excitations triggered here by impulsive stimulated Raman scattering. Orbital waves are likely to be initially localized to the small polarons of this room-temperature manganite, coupling to other degrees of freedom at longer times, as photo-domains coalesce into a metallic phase.
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Affiliation(s)
- D Polli
- ULTRAS-INFM-CNR Dipartimento di Fisica, Politecnico di Milano, Milano 20133, Italy
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Jun-ichi T, Keisuke M, Toshirou Y. Raman lasing and cascaded coherent anti-Stokes Raman scattering of a two-phonon Raman band. OPTICS LETTERS 2006; 31:1501-3. [PMID: 16642152 DOI: 10.1364/ol.31.001501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Raman lasing of a two-phonon Raman band in the anti-Stokes side is demonstrated. Two femtosecond light pulses with identical wavelengths are irradiated onto a SrTiO3 crystal in a cross-beam configuration. Under low excitation power, several wave-mixing signals with identical wavelengths are emitted. When the power exceeds a critical value, cascaded coherent anti-Stokes Raman scattering (CARS) signals are emitted, the frequency step of which is coincident with that of the strongest two-phonon Raman band of 2TO2.
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Zhao J, Bragas AV, Lockwood DJ, Merlin R. Magnon squeezing in an antiferromagnet: reducing the spin noise below the standard quantum limit. PHYSICAL REVIEW LETTERS 2004; 93:107203. [PMID: 15447444 DOI: 10.1103/physrevlett.93.107203] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2003] [Indexed: 05/24/2023]
Abstract
We report the first experimental demonstration of quantum squeezing of a collective spin-wave excitation (magnon) using femtosecond optical pulses to generate correlations involving pairs of spins in an antiferromagnetic insulator MnF2. In the squeezed state, the fluctuations of the magnetization of a crystallographic unit cell vary periodically in time and are reduced below that of the ground-state quantum noise.
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Affiliation(s)
- Jimin Zhao
- Focus Center and Department of Physics, The University of Michigan, Ann Arbor, Michigan 48109-1120, USA
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Ohta K, Larsen DS, Yang M, Fleming GR. Influence of intramolecular vibrations in third-order, time-domain resonant spectroscopies. II. Numerical calculations. J Chem Phys 2001. [DOI: 10.1063/1.1359241] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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