Pub Date : 2000-09-10DOI: 10.1109/IQEC.2000.907964
P. Jonsson, J. Rarity, S. Kitson, P. Tapster
Summary from only given. We are trying to develop high efficiency sources of single photons for quantum optics applications. We aim to do this by isolating single dye molecules thus limiting our maximum emission per pump pulse to a single photon. We show that a single dye molecule can be used for single-photon generation. However, dye molecules have problems with photostability. The molecules undergo irreversible bleaching after approximately 10/sup 5/ to 10/sup 6/ photon emissions.
{"title":"Investigation of dye molecules for single-photon generation","authors":"P. Jonsson, J. Rarity, S. Kitson, P. Tapster","doi":"10.1109/IQEC.2000.907964","DOIUrl":"https://doi.org/10.1109/IQEC.2000.907964","url":null,"abstract":"Summary from only given. We are trying to develop high efficiency sources of single photons for quantum optics applications. We aim to do this by isolating single dye molecules thus limiting our maximum emission per pump pulse to a single photon. We show that a single dye molecule can be used for single-photon generation. However, dye molecules have problems with photostability. The molecules undergo irreversible bleaching after approximately 10/sup 5/ to 10/sup 6/ photon emissions.","PeriodicalId":267372,"journal":{"name":"Conference Digest. 2000 International Quantum Electronics Conference (Cat. No.00TH8504)","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114166878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-09-10DOI: 10.1109/IQEC.2000.907799
T. Coudreau, K.S. Zhang, M. Martinelli, A. Maître, C. Fabre
Quasi-phase matched crystals are very promising materials for nonlinear optics because of their high nonlinear coefficient. We have built a CW triply resonant OPO using a periodically poled lithium niobate crystal. It is pumped at 1.06 /spl mu/m and produces signal and idler beams around degeneracy in the range 2-2.3 /spl mu/m. Tunability is achieved by mode hopping when the temperature is varied. This device has an ultra-low threshold of 300 /spl mu/W. It can be operated in a stable way over long period of time. Due to the so-called cascaded nonlinearities, OPO can efficiently reduce the fluctuations of the pump beam reflected by the cavity without reducing too much its intensity. We have been able to measure on the reflected pump beam a noise reduction of 30% (not corrected for detection efficiency), corresponding to 38% reduction of the quantum fluctuations below shot noise at 4 times above threshold. Our set-up constitutes an efficient and simple "quantum noise eater" for laser beam around 1 /spl mu/m in the mW range.
{"title":"Ultra-low threshold operation and pump squeezing with a triply-resonant CW OPO using periodically poled lithium niobate","authors":"T. Coudreau, K.S. Zhang, M. Martinelli, A. Maître, C. Fabre","doi":"10.1109/IQEC.2000.907799","DOIUrl":"https://doi.org/10.1109/IQEC.2000.907799","url":null,"abstract":"Quasi-phase matched crystals are very promising materials for nonlinear optics because of their high nonlinear coefficient. We have built a CW triply resonant OPO using a periodically poled lithium niobate crystal. It is pumped at 1.06 /spl mu/m and produces signal and idler beams around degeneracy in the range 2-2.3 /spl mu/m. Tunability is achieved by mode hopping when the temperature is varied. This device has an ultra-low threshold of 300 /spl mu/W. It can be operated in a stable way over long period of time. Due to the so-called cascaded nonlinearities, OPO can efficiently reduce the fluctuations of the pump beam reflected by the cavity without reducing too much its intensity. We have been able to measure on the reflected pump beam a noise reduction of 30% (not corrected for detection efficiency), corresponding to 38% reduction of the quantum fluctuations below shot noise at 4 times above threshold. Our set-up constitutes an efficient and simple \"quantum noise eater\" for laser beam around 1 /spl mu/m in the mW range.","PeriodicalId":267372,"journal":{"name":"Conference Digest. 2000 International Quantum Electronics Conference (Cat. No.00TH8504)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114282294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-09-10DOI: 10.1109/IQEC.2000.908088
H. Rigneault, J. Broudic, B. Gayral, J. Gerard
Due to a lower mode volume, 3D structures lead to higher radiative lifetime reduction and a measured Purcell factor of 5 has been reported recently for quantum boxes located in micropillar cavities. Since this type of structure is etched from a planar microcavity it is interesting to study the emission directivity for different pillar diameters. We observe a broadening of the angular emission (/spl lambda/=932 nm) when the pillar diameter decreases. Other investigations concerning the angular behaviour for the various discrete modes show that the angular radiation pattern is strongly wavelength dependent and results both from planar microcavity effects and mode diffraction.
{"title":"Far field radiation pattern from quantum boxes located in micropillars","authors":"H. Rigneault, J. Broudic, B. Gayral, J. Gerard","doi":"10.1109/IQEC.2000.908088","DOIUrl":"https://doi.org/10.1109/IQEC.2000.908088","url":null,"abstract":"Due to a lower mode volume, 3D structures lead to higher radiative lifetime reduction and a measured Purcell factor of 5 has been reported recently for quantum boxes located in micropillar cavities. Since this type of structure is etched from a planar microcavity it is interesting to study the emission directivity for different pillar diameters. We observe a broadening of the angular emission (/spl lambda/=932 nm) when the pillar diameter decreases. Other investigations concerning the angular behaviour for the various discrete modes show that the angular radiation pattern is strongly wavelength dependent and results both from planar microcavity effects and mode diffraction.","PeriodicalId":267372,"journal":{"name":"Conference Digest. 2000 International Quantum Electronics Conference (Cat. No.00TH8504)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114645404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-09-10DOI: 10.1109/IQEC.2000.908073
V. Shatokhin, S. Kilm
Spectral detection of resonance fluorescence allows to regard atomic spectra as a sequence of elementary scattering events accompanied by emissions of photons with different frequencies. What the reduced atomic state (RAS) is after such a photon detection represents fundamental interest and appears important in understanding some correlation experiments. We report about derivation of analytic expression for the RAS for the important particular case of the well separated spectral lines of the resonance fluorescence spectrum.
{"title":"Atomic inversion after a photon detection","authors":"V. Shatokhin, S. Kilm","doi":"10.1109/IQEC.2000.908073","DOIUrl":"https://doi.org/10.1109/IQEC.2000.908073","url":null,"abstract":"Spectral detection of resonance fluorescence allows to regard atomic spectra as a sequence of elementary scattering events accompanied by emissions of photons with different frequencies. What the reduced atomic state (RAS) is after such a photon detection represents fundamental interest and appears important in understanding some correlation experiments. We report about derivation of analytic expression for the RAS for the important particular case of the well separated spectral lines of the resonance fluorescence spectrum.","PeriodicalId":267372,"journal":{"name":"Conference Digest. 2000 International Quantum Electronics Conference (Cat. No.00TH8504)","volume":"121 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115781035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-09-10DOI: 10.1109/IQEC.2000.907879
I. Velchev, F. Brandi, W. Hogervorst, W. Ubachs
With the combined techniques of pulsed-dye-amplification (PDA) and harmonic generation we generate Fourier-transform limited pulses in the wavelength domain 58-115 nm that allow for high resolution laser spectroscopic studies. Since the PDA runs at the frequency of a narrowband CW laser there is easy access to measure the absolute frequency of the transition. A first example is that of a precision measurement of the 3p/sup 6/-3p/sup 5/4s'[1/2]/sub 1/ resonance in argon at 105 nm. Based on the on-line recording of saturation spectroscopy of I/sub 2/-hyperfine components in the B-X system, the absolute frequency can be determined. We derive a new value for the ionization potential. Also the transition isotope shift on this transition can be measured, even with higher precision, since only relative measurements are required. Work is in progress to investigate isotope shifts and hyperfine structures in various excited levels of krypton and xenon, again with VUV and XUV laser excitation, with the aim of determining accurate values for the ionization potentials.
{"title":"Precision VUV laser spectroscopy on Ar, Kr and Xe","authors":"I. Velchev, F. Brandi, W. Hogervorst, W. Ubachs","doi":"10.1109/IQEC.2000.907879","DOIUrl":"https://doi.org/10.1109/IQEC.2000.907879","url":null,"abstract":"With the combined techniques of pulsed-dye-amplification (PDA) and harmonic generation we generate Fourier-transform limited pulses in the wavelength domain 58-115 nm that allow for high resolution laser spectroscopic studies. Since the PDA runs at the frequency of a narrowband CW laser there is easy access to measure the absolute frequency of the transition. A first example is that of a precision measurement of the 3p/sup 6/-3p/sup 5/4s'[1/2]/sub 1/ resonance in argon at 105 nm. Based on the on-line recording of saturation spectroscopy of I/sub 2/-hyperfine components in the B-X system, the absolute frequency can be determined. We derive a new value for the ionization potential. Also the transition isotope shift on this transition can be measured, even with higher precision, since only relative measurements are required. Work is in progress to investigate isotope shifts and hyperfine structures in various excited levels of krypton and xenon, again with VUV and XUV laser excitation, with the aim of determining accurate values for the ionization potentials.","PeriodicalId":267372,"journal":{"name":"Conference Digest. 2000 International Quantum Electronics Conference (Cat. No.00TH8504)","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115490996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-09-10DOI: 10.1109/IQEC.2000.908160
M. Giudici, G. Giacomelli, S. Ballé, J. Tredicce
Summary form only given. Recently, Pikovsky and Kurts studied the effect of noise in fluctuations of the time between successive excitable pulses are minimized for a well-defined amount of the input noise. They named such a behavior coherence resonance. We present an experimental investigation of the effects of noise in an excitable optical system, namely, a semiconductor laser with optical feedback. Changing the amount of noise, and choosing the adequate indicators, we report experimental evidence of coherence resonance.
{"title":"Coherence resonance in an optical system","authors":"M. Giudici, G. Giacomelli, S. Ballé, J. Tredicce","doi":"10.1109/IQEC.2000.908160","DOIUrl":"https://doi.org/10.1109/IQEC.2000.908160","url":null,"abstract":"Summary form only given. Recently, Pikovsky and Kurts studied the effect of noise in fluctuations of the time between successive excitable pulses are minimized for a well-defined amount of the input noise. They named such a behavior coherence resonance. We present an experimental investigation of the effects of noise in an excitable optical system, namely, a semiconductor laser with optical feedback. Changing the amount of noise, and choosing the adequate indicators, we report experimental evidence of coherence resonance.","PeriodicalId":267372,"journal":{"name":"Conference Digest. 2000 International Quantum Electronics Conference (Cat. No.00TH8504)","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123234065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-09-10DOI: 10.1109/IQEC.2000.907938
H. Perrin, B. Mercier, M. Gorlicki, M. Ducloy, J. Keller, V. Lorent
Summary form only given. We present a new mechanism for reaching quantum degeneracy of a 2D bosonic atomic gas. We use the dipole force created by two evanescent waves of different colors to confine /sup 87/Rb atoms in a quasi 2D geometry. The Morse like resulting potential has a depth on the order of 100 /spl mu/K. We also present a loading mechanism for this trap, taking advantage of the potential profiles of different Zeeman sublevels.
{"title":"Towards a 2D degenerate quantum gas","authors":"H. Perrin, B. Mercier, M. Gorlicki, M. Ducloy, J. Keller, V. Lorent","doi":"10.1109/IQEC.2000.907938","DOIUrl":"https://doi.org/10.1109/IQEC.2000.907938","url":null,"abstract":"Summary form only given. We present a new mechanism for reaching quantum degeneracy of a 2D bosonic atomic gas. We use the dipole force created by two evanescent waves of different colors to confine /sup 87/Rb atoms in a quasi 2D geometry. The Morse like resulting potential has a depth on the order of 100 /spl mu/K. We also present a loading mechanism for this trap, taking advantage of the potential profiles of different Zeeman sublevels.","PeriodicalId":267372,"journal":{"name":"Conference Digest. 2000 International Quantum Electronics Conference (Cat. No.00TH8504)","volume":"573 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124698294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-09-10DOI: 10.1109/IQEC.2000.907794
I. Maurin, J. Hermier, A. Bramati, E. Giacobino
Semiconductor lasers are particularly well suited for the implementation of pump-noise suppression since it is possible to drive them with a current the noise of which is well below shot noise. Indeed, if the quantum efficiency of the carrier-to-photon conversion is high enough, the electron statistics of the pumping can be transferred to the light emission, yielding a reduction of the intensity noise in the laser. In this simple picture, the maximal amount of squeezing is equal to the quantum efficiency. However, experimental results on intensity noise reduction by pump-noise suppression are usually above this limit. This discrepancy suggests that additional noise sources must be involved. We have investigated the recently proposed "pump-blocking" effect. If the carrier number rises above its stationary value, more of the injected carriers find occupied quantum states, and therefore less of them are allowed into the active layer. These excess carriers are a source of noise and hinder the pump-noise suppression. They also give rise to a voltage noise across the laser diode that we have experimentally measured.
{"title":"Pump-blocking and intensity noise in semiconductor lasers","authors":"I. Maurin, J. Hermier, A. Bramati, E. Giacobino","doi":"10.1109/IQEC.2000.907794","DOIUrl":"https://doi.org/10.1109/IQEC.2000.907794","url":null,"abstract":"Semiconductor lasers are particularly well suited for the implementation of pump-noise suppression since it is possible to drive them with a current the noise of which is well below shot noise. Indeed, if the quantum efficiency of the carrier-to-photon conversion is high enough, the electron statistics of the pumping can be transferred to the light emission, yielding a reduction of the intensity noise in the laser. In this simple picture, the maximal amount of squeezing is equal to the quantum efficiency. However, experimental results on intensity noise reduction by pump-noise suppression are usually above this limit. This discrepancy suggests that additional noise sources must be involved. We have investigated the recently proposed \"pump-blocking\" effect. If the carrier number rises above its stationary value, more of the injected carriers find occupied quantum states, and therefore less of them are allowed into the active layer. These excess carriers are a source of noise and hinder the pump-noise suppression. They also give rise to a voltage noise across the laser diode that we have experimentally measured.","PeriodicalId":267372,"journal":{"name":"Conference Digest. 2000 International Quantum Electronics Conference (Cat. No.00TH8504)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124758984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-09-10DOI: 10.1109/IQEC.2000.908018
D. Hutchings, J. Arnold
Nonlinear polarisation dynamics in semiconductor waveguides is a topic of current interest with applications in vectorial spatial solitons and all-optical switching schemes. It is generally found that as the change in refractive index induced by the Kerr nonlinearity becomes comparable to the birefringence of the waveguide, the single-polarised (TE and TM) stable stationary eigenmode becomes unstable and there is an emergence of a pair of mixed-polarised stable stationary eigenmodes (i.e. bifurcation). The bifurcation in the mode with the lower propagation constant is attributable to the anisotropy in the nonlinear refraction between the TE and TM polarisations. These phenomena have been scrutinised both in the plane-wave and spatial soliton cases obtaining analytic results for the bifurcation threshold. Of interest is the additional degree of control obtained with a longitudinal magnetic field through the magneto-optic effect which may, for example, allow the polarisation state to be switched from one stationary state to another. The polarisation dynamics are analysed in terms of the Stokes parameters allowing the evolution trajectories to be mapped on a Poincare sphere for the non-dissipative case. We derive the Hamiltonian for the system consisting of terms for the anisotropic Kerr nonlinearity, waveguide birefringence and longitudinal magneto-optic effect. From the Hamiltonian the evolution equations in terms of the Stokes parameters can be subsequently obtained.
{"title":"Control of the nonlinear polarisation dynamics in a semiconductor waveguide with a periodic magnetic field","authors":"D. Hutchings, J. Arnold","doi":"10.1109/IQEC.2000.908018","DOIUrl":"https://doi.org/10.1109/IQEC.2000.908018","url":null,"abstract":"Nonlinear polarisation dynamics in semiconductor waveguides is a topic of current interest with applications in vectorial spatial solitons and all-optical switching schemes. It is generally found that as the change in refractive index induced by the Kerr nonlinearity becomes comparable to the birefringence of the waveguide, the single-polarised (TE and TM) stable stationary eigenmode becomes unstable and there is an emergence of a pair of mixed-polarised stable stationary eigenmodes (i.e. bifurcation). The bifurcation in the mode with the lower propagation constant is attributable to the anisotropy in the nonlinear refraction between the TE and TM polarisations. These phenomena have been scrutinised both in the plane-wave and spatial soliton cases obtaining analytic results for the bifurcation threshold. Of interest is the additional degree of control obtained with a longitudinal magnetic field through the magneto-optic effect which may, for example, allow the polarisation state to be switched from one stationary state to another. The polarisation dynamics are analysed in terms of the Stokes parameters allowing the evolution trajectories to be mapped on a Poincare sphere for the non-dissipative case. We derive the Hamiltonian for the system consisting of terms for the anisotropic Kerr nonlinearity, waveguide birefringence and longitudinal magneto-optic effect. From the Hamiltonian the evolution equations in terms of the Stokes parameters can be subsequently obtained.","PeriodicalId":267372,"journal":{"name":"Conference Digest. 2000 International Quantum Electronics Conference (Cat. No.00TH8504)","volume":"428 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123145481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-09-10DOI: 10.1109/IQEC.2000.908028
L. Davila-Romero, D. Andrews
In several studies of second harmonic emission from isotropic suspensions it has been shown that the unusually strong signal detected from some particles, notably purple membrane material, is attributable to optical coherence within the separate particles of the suspension. As such, the emission displays an amalgam of the characteristics associated with full coherence (second harmonic generation) and incoherence (hyper-Rayleigh scattering). The principle of local additivity for the hyperpolarisabilities associated with different optical centres or chromophores within such systems leads to intriguing possibilities for materials strongly pumped by an ultrafast source. The key feature is the relationship between the hyperpolarisabilities of optical centres in their ground and electronic excited states under conditions of resonance with the applied radiation, a result which is derived from a full quantum electrodynamical treatment of the interaction. As a consequence of this relationship, the effective second order susceptibility of each domain or particle proves to be very strongly influenced by the instantaneous degree of optical excitation, and the harmonic signal acquires a temporal signature which faithfully registers the dynamics of optical excitation and decay. Thus, where a significant degree of optical excitation is established in such a system by a primary laser source, studying the characteristics of the second harmonic generated by a probe beam offers the means for direct measurement of the excited state population dynamics. It is shown that the effect is strongly dependent on the nature of the excited state damping, whose correct representation in the expressions for hyperpolarisability is crucial for analysis of the results.
{"title":"Second harmonic generation and the dynamics of optical excitation in small particles","authors":"L. Davila-Romero, D. Andrews","doi":"10.1109/IQEC.2000.908028","DOIUrl":"https://doi.org/10.1109/IQEC.2000.908028","url":null,"abstract":"In several studies of second harmonic emission from isotropic suspensions it has been shown that the unusually strong signal detected from some particles, notably purple membrane material, is attributable to optical coherence within the separate particles of the suspension. As such, the emission displays an amalgam of the characteristics associated with full coherence (second harmonic generation) and incoherence (hyper-Rayleigh scattering). The principle of local additivity for the hyperpolarisabilities associated with different optical centres or chromophores within such systems leads to intriguing possibilities for materials strongly pumped by an ultrafast source. The key feature is the relationship between the hyperpolarisabilities of optical centres in their ground and electronic excited states under conditions of resonance with the applied radiation, a result which is derived from a full quantum electrodynamical treatment of the interaction. As a consequence of this relationship, the effective second order susceptibility of each domain or particle proves to be very strongly influenced by the instantaneous degree of optical excitation, and the harmonic signal acquires a temporal signature which faithfully registers the dynamics of optical excitation and decay. Thus, where a significant degree of optical excitation is established in such a system by a primary laser source, studying the characteristics of the second harmonic generated by a probe beam offers the means for direct measurement of the excited state population dynamics. It is shown that the effect is strongly dependent on the nature of the excited state damping, whose correct representation in the expressions for hyperpolarisability is crucial for analysis of the results.","PeriodicalId":267372,"journal":{"name":"Conference Digest. 2000 International Quantum Electronics Conference (Cat. No.00TH8504)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121562868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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