Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Annual Meeting Optical Society of America

Transient gain measurements of nonradiative dynamics in chromium doped forsterite (Cr4+:Mg2SiO4)

Antonio S. Seas, Vladimir Petricevic, Robert R. Alfano

Published Jan 1, 1990• 0 citations
Publisher

Abstract

The gain dynamics of photoexcited chromium-doped forsterite (Cr4+:Mg2SiO4) were measured by means of a pulsed excite-and-probe technique. The nonradiative relaxation time within the 3T2 vibronic state was determined by measuring the change in the induced gain of the probe pulse as a function of the pumpprobe delay. A 30 ps, 1.064 m pulse from a mode-locked Nd:YAG laser was split into two beams. The first beam provided the pump pulse to populate the 3T2 manifold. The other beam was focused in a calcite crystal to generate a 1.2 m probe pulse by means of stimulated Raman scattering. The transient gain was determined from the measured ratio of the transmitted probe intensity for unpumped and pumped cases as a function of the pumpprobe delay. The rise time (time for growth of the gain from 10% to 90%) was calculated to be 50 ps. A rate-equation analysis of population in the various states was used to extract a value for the vibrational relaxation time from the experimental data under the assumption of Gaussian pump and probe pulses. The best fit to the experimental data of gain as a function of time yields a value of 10 5 ps for the intra-3T2-state vibrational relaxation time.

DOI
10.1364/oam.1990.tuyy1

Related papers

Transient excited-state absorption measurements in chromium-doped forsterite

Nickolay Zhavoronkov, Valentin P. Petrov, FRANK NOACK

The nonradiative transition dynamics between the excited ${}^{3}{A}^{\ensuremath{''}}{[}^{3}{E(}^{3}{T}_{1a})]$ state and the metastable ${}^{3}{A}^{\ensuremath{''}}{[}^{3}{E(}^{3}{T}_{2})]$ storage state of the tetravalent chromium ion $({\mathrm{Cr}}^{4+})$ in forsterite is investigated using femtosecond excite-and-probe technique. Following excitation to ${}^{3}{T}_{1a}$ with pump pulses at 750 or 773 nm the induced excited state absorption was probed with femtosecond pulses in the ultraviolet (306 nm), visible (650 nm), and infrared (1500 nm). The nonradiative decay time from ${}^{3}{T}_{1a}$ to ${}^{3}{T}_{2}$ was estimated from the rise time of the excited state absorption at 1500 nm using a rate equations model and its value at room temperature is only 3\ifmmode\pm\else\textpm\fi{}1 ps.

Physical review. B, Condensed matter•Jan 15, 2000•3 citations

Accurate determination of saturation parameters for Cr^4+-doped solid-state saturable absorbers

Alphan Sennaroğlu, Umıt Demırbas, Sarper Özharar +1 more

We describe a systematic, rigorous procedure for the determination of the optical absorption saturation parameters for Cr4+:YAG and Cr4+:forsterite crystals at 1064 nm. A rate-equation approach was used to analyze the cw and pulsed transmission data of several crystals by accounting for the transverse as well as longitudinal variation of the beam intensity, saturation effects, and excited-state absorption. Use of an iterative procedure whereby the cw and pulsed data were simultaneously analyzed led to a considerable reduction in the error for the determination of cross sections. The average value of the absorption cross section sigmaa and the normalized excited-state absorption cross section fp=sigmaesa/sigmaa were determined to be 6.13×10−19 cm2 and 0.45, respectively, for Cr4+:forsterite and 19.6×10−19 cm2 and 0.06, respectively, for Cr4+:YAG. Detailed comparison was also made with previous saturation measurements in the literature. Our results further show that lumped models based on the thin-length approximation should be used with caution in the determination of cross sections, especially when the pump beam is tightly focused inside the absorber.

Journal of the Optical Society of America B•Feb 1, 2006•43 citations

Picosecond excite-and-probe absorption measurement of the 4T2 state nonradiative lifetime in ruby

Swapan Kumar Gayen, W. -B. Wang, Vladimir Petricevic +2 more

In a picosecond excite-and-probe absorption measurement, a 527-nm picosecond pulse excites the 4T2 state of the Cr3+ ion in ruby and a 3.4-μm picosecond probe pulse monitors the growth and decay of population in the 2E state as a function of pump-probe delay. From the growth of population in the metastable 2E state, an upper limit of 7 ps for the nonradiative lifetime of the 4T2 state is determined.

Applied Physics Letters•Sep 1, 1985•24 citations

The Study Of Ultra-Fast Relaxation Phenomena Within Nd:Yag And Hopg Crystals.

Bryant T. Wysocki

A monolithic two-section quantum dot semiconductor laser is differentially pumped to form non-uniform current injection in the gain region. It is shown that the nature of the pulse spectral content can be manipulated through differential gain. This provided a simple and inexpensive method of optimizing the semiconductor laser performance and also demonstrated that mode locked operation can be achieved with a much larger set of injection current/absorber bias voltage pairs than was previously possible with single-pad current injection. Significantly greater absorber bias voltages were available during differential pumping; thereby reducing absorber recovery time as well as the inferred pulse length. The enhanced spectral bandwidth provided by differential pumping provided an electronic method of pulse length reduction. The capacity for wavelength tuning was also demonstrated by differential pumping with a center wavelength shift of approximately 12nm. Additionally, the design and configuration of a femtosecond IR optical parametric oscillator demonstrating continuous pulsed tunability from 1040 to 1150 nm is presented along with the examination of relaxation rates for optically excited electrons from the pump3 ing level (4 F 5 ) to the metastable upper lasing level (4 F 2 ) in neodymium doped 2 Yttrium aluminum garnet (Nd:YAG) laser crystals. The 4 F 5 lifetime was the2 oretically predicted to be approximately 12 picoseconds using the Energy Gap Law. Finally, the ultrafast relaxations of photoexcited carriers in thin films of exfoliated highly ordered pyrolytic graphite (HOPG) were examined using the equal-pulse correlation technique which provides the means to efficiently extract a relatively fast relaxation process obscured by a significantly slower one. In addition, it allows for measurements on the order of one tenth the laser pulse width, extending the temporal range of existing pump probe systems without the need for customized femtosecond lasers or complicated pulse compression systems. The HOPG samples exhibited an extremely fast relaxation due to intraband carrier-carrier thermalization observed at 15 ± 10 fs followed by intraband carrier-phonon interaction on the order of 175 ± 30 fs. A modulation in the absorption depth of 1.4 percent was observed in the samples from partial saturation due to Pauli blocking.

•May 29, 2011•0 citations

Vibrational dephasing measurements with cw mode-locked dye lasers

J.P. Heritage

Recent advances in the development of synchronously mode-locked dye-laser systems have permitted the first low-power measurement of the time-resolved dephasing dynamics of a Raman active molecular vibration. Excitation and delayed probing of the coherent ensemble of vibrators is accomplished with the help of synchronized picosecond pulse trains from two independently tunable mode-locked dye lasers. A new probe technique, based on a gain measurement, is employed that provides a signal that scales linearly with the coherent vibrational amplitude. We demonstrate this technique with the first measurement of the dephasing dynamics of the normal mode (656.5 cm−1) of CS2 in the liquid state. An exponential decay with time constant 20±1 psec is obtained for the isotropic component of the coherent scattering.

Applied Physics Letters•Apr 1, 1979•71 citations

Analysis of dephasing signal in picosecond stimulated-Raman-gain experiments

Martine M. De Maziere, Chris Sierens, D. Schoemaker

A detailed theoretical analysis is presented of the dephasing signal measured in four-beam picosecond time-resolved stimulated-Raman-gain experiments. The analytical expressions derived are successful in simulating observations on the CS2 model system under various experimental conditions. It is established that the tail of the curve for sufficiently long delay times is uniquely determined by the vibrational Raman term that yields the vibrational dephasing time T2. It is also found that the rotational dephasing time cannot be fundamentally determined from the rotational Raman peak centered around zero delay. Furthermore, it is shown that the coherence properties of the stimulating laser fields, as distinguished from their pure pulse-envelope properties, are crucially important in determining the time resolution of the experiments and for explaining several experimental phenomena observed under mismatched excitation-pulse conditions. In this respect, the domain model for mode-locked pulses has proved to be useful. It is found that the time resolution of the dephasing measurements is determined by the combined pulse-coherence time of the driving fields and not by the cross-correlation width of the pulse envelopes.

Journal of the Optical Society of America B•Dec 1, 1989•4 citations
The gain dynamics of photoexcited chromium-doped forsterite (Cr4+:Mg2SiO4) were measured by means of a pulsed excite-and-probe technique. The nonradiative relaxation time within the 3T2 vibronic state was determined by measuring the change in the induced gain of the probe pulse as a function of the pumpprobe delay. A 30 ps, 1.064 m pulse from a mode-locked Nd:YAG laser was split into two beams. The first beam provided the pump pulse to populate the 3T2 manifold. The other beam was focused in a calcite crystal to generate a 1.2 m probe pulse by means of stimulated Raman scattering. The transient gain was determined from the measured ratio of the transmitted probe intensity for unpumped and pumped cases as a function of the pumpprobe delay. The rise time (time for growth of the gain from 10% to 90%) was calculated to be 50 ps. A rate-equation analysis of population in the various states was used to extract a value for the vibrational relaxation time from the experimental data under the assumption of Gaussian pump and probe pulses. The best fit to the experimental data of gain as a function of time yields a value of 10 5 ps for the intra-3T2-state vibrational relaxation time.
The nonradiative transition dynamics between the excited ${}^{3}{A}^{\ensuremath{''}}{[}^{3}{E(}^{3}{T}_{1a})]$ state and the metastable ${}^{3}{A}^{\ensuremath{''}}{[}^{3}{E(}^{3}{T}_{2})]$ storage state of the tetravalent chromium ion (Cr4+)({\mathrm{Cr}}^{4+})(Cr4+) in forsterite is investigated using femtosecond excite-and-probe technique. Following excitation to 3T1a{}^{3}{T}_{1a}3T1a​ with pump pulses at 750 or 773 nm the induced excited state absorption was probed with femtosecond pulses in the ultraviolet (306 nm), visible (650 nm), and infrared (1500 nm). The nonradiative decay time from 3T1a{}^{3}{T}_{1a}3T1a​ to 3T2{}^{3}{T}_{2}3T2​ was estimated from the rise time of the excited state absorption at 1500 nm using a rate equations model and its value at room temperature is only 3\ifmmode\pm\else\textpm\fi{}1 ps.
We describe a systematic, rigorous procedure for the determination of the optical absorption saturation parameters for Cr4+:YAG and Cr4+:forsterite crystals at 1064 nm. A rate-equation approach was used to analyze the cw and pulsed transmission data of several crystals by accounting for the transverse as well as longitudinal variation of the beam intensity, saturation effects, and excited-state absorption. Use of an iterative procedure whereby the cw and pulsed data were simultaneously analyzed led to a considerable reduction in the error for the determination of cross sections. The average value of the absorption cross section sigmaa and the normalized excited-state absorption cross section fp=sigmaesa/sigmaa were determined to be 6.13×10−19 cm2 and 0.45, respectively, for Cr4+:forsterite and 19.6×10−19 cm2 and 0.06, respectively, for Cr4+:YAG. Detailed comparison was also made with previous saturation measurements in the literature. Our results further show that lumped models based on the thin-length approximation should be used with caution in the determination of cross sections, especially when the pump beam is tightly focused inside the absorber.
A monolithic two-section quantum dot semiconductor laser is differentially pumped to form non-uniform current injection in the gain region. It is shown that the nature of the pulse spectral content can be manipulated through differential gain. This provided a simple and inexpensive method of optimizing the semiconductor laser performance and also demonstrated that mode locked operation can be achieved with a much larger set of injection current/absorber bias voltage pairs than was previously possible with single-pad current injection. Significantly greater absorber bias voltages were available during differential pumping; thereby reducing absorber recovery time as well as the inferred pulse length. The enhanced spectral bandwidth provided by differential pumping provided an electronic method of pulse length reduction. The capacity for wavelength tuning was also demonstrated by differential pumping with a center wavelength shift of approximately 12nm. Additionally, the design and configuration of a femtosecond IR optical parametric oscillator demonstrating continuous pulsed tunability from 1040 to 1150 nm is presented along with the examination of relaxation rates for optically excited electrons from the pump3 ing level (4 F 5 ) to the metastable upper lasing level (4 F 2 ) in neodymium doped 2 Yttrium aluminum garnet (Nd:YAG) laser crystals. The 4 F 5 lifetime was the2 oretically predicted to be approximately 12 picoseconds using the Energy Gap Law. Finally, the ultrafast relaxations of photoexcited carriers in thin films of exfoliated highly ordered pyrolytic graphite (HOPG) were examined using the equal-pulse correlation technique which provides the means to efficiently extract a relatively fast relaxation process obscured by a significantly slower one. In addition, it allows for measurements on the order of one tenth the laser pulse width, extending the temporal range of existing pump probe systems without the need for customized femtosecond lasers or complicated pulse compression systems. The HOPG samples exhibited an extremely fast relaxation due to intraband carrier-carrier thermalization observed at 15 ± 10 fs followed by intraband carrier-phonon interaction on the order of 175 ± 30 fs. A modulation in the absorption depth of 1.4 percent was observed in the samples from partial saturation due to Pauli blocking.
Recent advances in the development of synchronously mode-locked dye-laser systems have permitted the first low-power measurement of the time-resolved dephasing dynamics of a Raman active molecular vibration. Excitation and delayed probing of the coherent ensemble of vibrators is accomplished with the help of synchronized picosecond pulse trains from two independently tunable mode-locked dye lasers. A new probe technique, based on a gain measurement, is employed that provides a signal that scales linearly with the coherent vibrational amplitude. We demonstrate this technique with the first measurement of the dephasing dynamics of the normal mode (656.5 cm−1) of CS2 in the liquid state. An exponential decay with time constant 20±1 psec is obtained for the isotropic component of the coherent scattering.
A detailed theoretical analysis is presented of the dephasing signal measured in four-beam picosecond time-resolved stimulated-Raman-gain experiments. The analytical expressions derived are successful in simulating observations on the CS2 model system under various experimental conditions. It is established that the tail of the curve for sufficiently long delay times is uniquely determined by the vibrational Raman term that yields the vibrational dephasing time T2. It is also found that the rotational dephasing time cannot be fundamentally determined from the rotational Raman peak centered around zero delay. Furthermore, it is shown that the coherence properties of the stimulating laser fields, as distinguished from their pure pulse-envelope properties, are crucially important in determining the time resolution of the experiments and for explaining several experimental phenomena observed under mismatched excitation-pulse conditions. In this respect, the domain model for mode-locked pulses has proved to be useful. It is found that the time resolution of the dephasing measurements is determined by the combined pulse-coherence time of the driving fields and not by the cross-correlation width of the pulse envelopes.