Physical Review A

Magnetically induced suppression and enhancement of optical excitation of ruby at anticrossing points

Roman L. Kolesov

Published Apr 19, 2006• 1 citation

Abstract

Sharp resonances in optical excitation of ruby by laser pulses are observed as Zeeman sublevels anticross in an external magnetic field. For the ${R}_{1}$ optical line of ruby $(694.3\phantom{\rule{0.3em}{0ex}}\mathrm{nm})$ excitation drops when the external magnetic field strength approaches $4.14\phantom{\rule{0.3em}{0ex}}\mathrm{kG}$ while for the ${R}_{2}$ line $(692.9\phantom{\rule{0.3em}{0ex}}\mathrm{nm})$ it increases in $4.14$ and $2.07\phantom{\rule{0.3em}{0ex}}\mathrm{kG}$ fields. A simple theoretical description of the observed effects on the basis of level mixing explains both situations.

DOI: 10.1103/physreva.73.043808

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Zeeman Effect of R-lines in Ruby under a High Magnetic Field

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Journal of the Physical Society of JapanMar 1, 197925 citations

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Physical Review A

Magnetically induced suppression and enhancement of optical excitation of ruby at anticrossing points

Roman L. Kolesov

Published Apr 19, 2006• 1 citation

Publisher

Abstract

Sharp resonances in optical excitation of ruby by laser pulses are observed as Zeeman sublevels anticross in an external magnetic field. For the

{R}_{1}

optical line of ruby

(694.3\phantom{\rule{0.3em}{0ex}}\mathrm{nm})

excitation drops when the external magnetic field strength approaches

4.14\phantom{\rule{0.3em}{0ex}}\mathrm{kG}

while for the

{R}_{2}

line

(692.9\phantom{\rule{0.3em}{0ex}}\mathrm{nm})

it increases in

4.14

and

2.07\phantom{\rule{0.3em}{0ex}}\mathrm{kG}

fields. A simple theoretical description of the observed effects on the basis of level mixing explains both situations.

DOI: 10.1103/physreva.73.043808

Related papers

Zeeman Effect of R-lines in Ruby under a High Magnetic Field

Hidenobu Hori, Hiroshi Mollymoto, Muneyuki Date

The Zeeman effect of R-absorption lines in ruby was observed in a high pulsed magnetic field up to 520 kOe using an optical multichannel analyzer. The experiment was done under a thermal equilibrium condition ( T =130 K) and the Zeeman line intensity is satisfactorily explained. When a magnetic field is applied perpendicular to the C 3 -axis, the excited \barE and 2\barA states show a level mixing and the observed pattern indicates a clear Paschen-Back effect The observed g // -values of the excited states are -2.49±0.05 and 1.49±0.05 for \barE and 2\barA, respectively. g ⊥ -values for these levels were estimated to be smaller than 0.1 at 500 kOe.The Zeeman effect of R-absorption lines in ruby was observed in a high pulsed magnetic field up to 520 kOe using an optical multichannel analyzer. The experiment was done under a thermal equilibrium condition ( T =130 K) and the Zeeman line intensity is satisfactorily explained. When a magnetic field is applied perpendicular to the C 3 -axis, the excited \barE and 2\barA states show a level mixing and the observed pattern indicates a clear Paschen-Back effect The observed g // -values of the excited states are -2.49±0.05 and 1.49±0.05 for \barE and 2\barA, respectively. g ⊥ -values for these levels were estimated to be smaller than 0.1 at 500 kOe.

Journal of the Physical Society of JapanMar 1, 197925 citations

Level mixing and anisotropy effect in resonant Raman electron paramagnetic transitions in ruby for B perpendicular to c

Xingye Lu, S. Venugopalan, Hyunjung Kim +3 more

Doubly resonant Raman electron paramagnetic transitions in ruby (Al ${}_{2}$ O ${}_{3}$ :Cr ${}^{3+}$ ) have been investigated using dye laser excitation tuned across the range of the Zeeman components of its well-known ${R}_{1}$ emission line. With magnetic field B normal to c, the optic axis of ruby, it is seen that the Raman electron paramagnetic resonance (EPR) lines exhibit significant intensity enhancements due to the simultaneous occurrence of ``in resonance'' and ``out resonance,'' as visualized in the Kramers-Heisenberg formalism of inelastic light scattering. The specific Raman EPR features observed in the present study, together with their resonances, however, differ markedly from those observed in our previous investigation with $\mathbf{B}\ensuremath{\parallel}\mathbf{c}$. These differences can be traced to level mixing effects within the Zeeman multiplet of the ${}^{4}{A}_{2}$ (ground) state on the one hand, and the negligible value of ${g}_{\ensuremath{\perp}}$ for the $\mathrm{E\ifmmode \bar{}\else \={}\fi{}}$ (excited) state of the ${R}_{1}$ emission line on the other. Furthermore, we note that with B\ensuremath{\perp}c and under resonant conditions, the experimentally observed \ensuremath{\Delta} $m$ $=$ \ifmmode\pm\else\textpm\fi{}1 pair of Stokes and anti-Stokes Raman lines are not connected by time-reversal symmetry.Doubly resonant Raman electron paramagnetic transitions in ruby (Al${}_{2}$O${}_{3}$:Cr${}^{3+}$) have been investigated using dye laser excitation tuned across the range of the Zeeman components of its well-known ${R}_{1}$ emission line. With magnetic field B normal to c, the optic axis of ruby, it is seen that the Raman electron paramagnetic resonance (EPR) lines exhibit significant intensity enhancements due to the simultaneous occurrence of ``in resonance'' and ``out resonance,'' as visualized in the Kramers-Heisenberg formalism of inelastic light scattering. The specific Raman EPR features observed in the present study, together with their resonances, however, differ markedly from those observed in our previous investigation with $\mathbf{B}\ensuremath{\parallel}\mathbf{c}$. These differences can be traced to level mixing effects within the Zeeman multiplet of the ${}^{4}{A}_{2}$ (ground) state on the one hand, and the negligible value of ${g}_{\ensuremath{\perp}}$ for the $\mathrm{E\ifmmode \bar{}\else \={}\fi{}}$ (excited) state of the ${R}_{1}$ emission line on the other. Furthermore, we note that with B\ensuremath{\perp}c and under resonant conditions, the experimentally observed \ensuremath{\Delta}$m$ $=$ \ifmmode\pm\else\textpm\fi{}1 pair of Stokes and anti-Stokes Raman lines are not connected by time-reversal symmetry.

Physical Review BMay 17, 20113 citations

Optically Induced Magnetization in Ruby

Jan P. van der Ziel, N. Bloembergen

The magnetization of ruby in a magnetic field at 300\ifmmode^\circ\else\textdegree\fi{}K is changed when the ruby is optically pumped with linearly polarized radiation from a $Q$ -switched ruby laser. With a magnetic field parallel to the trigonal axis, laser light polarized parallel to this axis induces transitions from the spin \ifmmode\pm\else\textpm\fi{}\textonehalf{} levels of the $^{4}A_{2}$ ground state to the levels of the $\overline{E}(^{2}E)$ excited state. The change in ${M}_{z}$ is linearly proportional to $H$ except near the anticrossing points of the $^{4}A_{2}$ spin levels at 2.07 and 4.14 kG. At these field strengths, there is an enhancement of the magnetization caused by state mixing of the $^{4}A_{2}$ wave functions. When $H$ has a small component perpendicular to the $z$ axis, a magnetization is detected parallel to this component in the vicinity of 4.14 kG. The effect requires a long ground-state relaxation time. In a separate experiment, the relaxation of ${M}_{z}$ was found to vary from 0.13 \ensuremath{\mu}sec in zero magnetic field to a constant value of 0.57 \ensuremath{\mu}sec for fields above 60 G.The magnetization of ruby in a magnetic field at 300\ifmmode^\circ\else\textdegree\fi{}K is changed when the ruby is optically pumped with linearly polarized radiation from a $Q$-switched ruby laser. With a magnetic field parallel to the trigonal axis, laser light polarized parallel to this axis induces transitions from the spin \ifmmode\pm\else\textpm\fi{}\textonehalf{} levels of the $^{4}A_{2}$ ground state to the levels of the $\overline{E}(^{2}E)$ excited state. The change in ${M}_{z}$ is linearly proportional to $H$ except near the anticrossing points of the $^{4}A_{2}$ spin levels at 2.07 and 4.14 kG. At these field strengths, there is an enhancement of the magnetization caused by state mixing of the $^{4}A_{2}$ wave functions. When $H$ has a small component perpendicular to the $z$ axis, a magnetization is detected parallel to this component in the vicinity of 4.14 kG. The effect requires a long ground-state relaxation time. In a separate experiment, the relaxation of ${M}_{z}$ was found to vary from 0.13 \ensuremath{\mu}sec in zero magnetic field to a constant value of 0.57 \ensuremath{\mu}sec for fields above 60 G.

Physical ReviewMay 17, 196557 citations

Observation of the Optical Analog of the Mössbauer Effect in Ruby

A. Szabó

Laser-induced fluorescence line narrowing of the ruby ${R}_{1}$ Zeeman spectra at 693.4 nm is reported using a continuous, stable, single-frequency ruby laser for resonant excitation. A resolution in excess of ${10}^{7}$ corresponding to a linewidth of \ensuremath{\sim} 30 MHz has been achieved. The linewidths are anisotropic with respect to the relative magnetic-field-crystal-axis orientation and, at low Cr concentrations, are expected to be determined by Cr-Al superhyperfine interactions.Laser-induced fluorescence line narrowing of the ruby ${R}_{1}$ Zeeman spectra at 693.4 nm is reported using a continuous, stable, single-frequency ruby laser for resonant excitation. A resolution in excess of ${10}^{7}$ corresponding to a linewidth of \ensuremath{\sim} 30 MHz has been achieved. The linewidths are anisotropic with respect to the relative magnetic-field-crystal-axis orientation and, at low Cr concentrations, are expected to be determined by Cr-Al superhyperfine interactions.

Physical Review LettersAug 9, 1971130 citations

Optically Induced Precessing Magnetization in Ruby near the Level Anticrossing Points in 4A2

Yukio Fukuda, Y. Takagi, Koichi Yamada +1 more

Using excitation by ultrashort light pulses from a mode-locked ruby laser, we have observed optically induced magnetization precessing at a frequency corresponding to the energy separation near the level anticrossing points of the ground state 4 A 2 in ruby at room temperature. The motion of the magnetization is detected by a pick-up coil. The decay time of the signal is 5∼6 ns. The analysis is made by using the model of fictitious spin 1/2 and the agreement with the experiment is satisfactory.Using excitation by ultrashort light pulses from a mode-locked ruby laser, we have observed optically induced magnetization precessing at a frequency corresponding to the energy separation near the level anticrossing points of the ground state 4 A 2 in ruby at room temperature. The motion of the magnetization is detected by a pick-up coil. The decay time of the signal is 5∼6 ns. The analysis is made by using the model of fictitious spin 1/2 and the agreement with the experiment is satisfactory.

Journal of the Physical Society of JapanMar 1, 197712 citations

Optical Excitation of Zeeman Coherence in Ruby

Y. Takagi, Yukio Fukuda, Koichi Yamada +1 more

Optically induced Zeeman coherences between various pairs of sublevels in the ground state 4 A 2 of a sample ruby (0.05 wt.%) were observed at room temperature by using impact excitation with circularly polarized resonant light pulses from a mode-locked ruby laser. The precessing magnetization associated with Zeeman coherence was detected magnetically in UHF, VHF and X-band microwave regions. The observed signals can be regarded as various types of ESR free induction decay signals and the decay times were of the order of nanosecond. Sustained precession signals were also observed. Characteristics of the signals were explained by numerical solutions of the Liouville equation.Optically induced Zeeman coherences between various pairs of sublevels in the ground state 4 A 2 of a sample ruby (0.05 wt.%) were observed at room temperature by using impact excitation with circularly polarized resonant light pulses from a mode-locked ruby laser. The precessing magnetization associated with Zeeman coherence was detected magnetically in UHF, VHF and X-band microwave regions. The observed signals can be regarded as various types of ESR free induction decay signals and the decay times were of the order of nanosecond. Sustained precession signals were also observed. Characteristics of the signals were explained by numerical solutions of the Liouville equation.

Journal of the Physical Society of JapanAug 1, 198116 citations

Sharp resonances in optical excitation of ruby by laser pulses are observed as Zeeman sublevels anticross in an external magnetic field. For the

{R}_{1}

optical line of ruby

(694.3\phantom{\rule{0.3em}{0ex}}\mathrm{nm})

excitation drops when the external magnetic field strength approaches

4.14\phantom{\rule{0.3em}{0ex}}\mathrm{kG}

while for the

{R}_{2}

line

(692.9\phantom{\rule{0.3em}{0ex}}\mathrm{nm})

it increases in

4.14

and

2.07\phantom{\rule{0.3em}{0ex}}\mathrm{kG}

fields. A simple theoretical description of the observed effects on the basis of level mixing explains both situations.

Doubly resonant Raman electron paramagnetic transitions in ruby (Al

{}_{2}

{}_{3}

:Cr

{}^{3+}

) have been investigated using dye laser excitation tuned across the range of the Zeeman components of its well-known

{R}_{1}

emission line. With magnetic field B normal to c, the optic axis of ruby, it is seen that the Raman electron paramagnetic resonance (EPR) lines exhibit significant intensity enhancements due to the simultaneous occurrence of ``in resonance'' and ``out resonance,'' as visualized in the Kramers-Heisenberg formalism of inelastic light scattering. The specific Raman EPR features observed in the present study, together with their resonances, however, differ markedly from those observed in our previous investigation with $\mathbf{B}\ensuremath{\parallel}\mathbf{c}$. These differences can be traced to level mixing effects within the Zeeman multiplet of the

{}^{4}{A}_{2}

(ground) state on the one hand, and the negligible value of ${g}_{\ensuremath{\perp}}$ for the $\mathrm{E\ifmmode \bar{}\else \={}\fi{}}$ (excited) state of the

{R}_{1}

emission line on the other. Furthermore, we note that with B\ensuremath{\perp}c and under resonant conditions, the experimentally observed \ensuremath{\Delta}

m

=

\ifmmode\pm\else\textpm\fi{}1 pair of Stokes and anti-Stokes Raman lines are not connected by time-reversal symmetry.

The magnetization of ruby in a magnetic field at 300\ifmmode^\circ\else\textdegree\fi{}K is changed when the ruby is optically pumped with linearly polarized radiation from a

Q

-switched ruby laser. With a magnetic field parallel to the trigonal axis, laser light polarized parallel to this axis induces transitions from the spin \ifmmode\pm\else\textpm\fi{}\textonehalf{} levels of the

^{4}A_{2}

ground state to the levels of the

\overline{E}(^{2}E)

excited state. The change in

{M}_{z}

is linearly proportional to

H

except near the anticrossing points of the

^{4}A_{2}

spin levels at 2.07 and 4.14 kG. At these field strengths, there is an enhancement of the magnetization caused by state mixing of the

^{4}A_{2}

wave functions. When

H

has a small component perpendicular to the

z

axis, a magnetization is detected parallel to this component in the vicinity of 4.14 kG. The effect requires a long ground-state relaxation time. In a separate experiment, the relaxation of

{M}_{z}

was found to vary from 0.13 \ensuremath{\mu}sec in zero magnetic field to a constant value of 0.57 \ensuremath{\mu}sec for fields above 60 G.

Laser-induced fluorescence line narrowing of the ruby

{R}_{1}

Zeeman spectra at 693.4 nm is reported using a continuous, stable, single-frequency ruby laser for resonant excitation. A resolution in excess of

{10}^{7}

corresponding to a linewidth of \ensuremath{\sim} 30 MHz has been achieved. The linewidths are anisotropic with respect to the relative magnetic-field-crystal-axis orientation and, at low Cr concentrations, are expected to be determined by Cr-Al superhyperfine interactions.