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

Physical review. B, Condensed matter

Optical hole burning in ruby

Paul E. Jessop, T. Muramoto, A. Szabó

Published Feb 1, 1980• 43 citations
Publisher

Abstract

We report experimental and theoretical studies of optical hole burning in the inhomogeneous ${R}_{1}$ line of ruby at low temperatures. Both Stark-shifting and pump-probe techniques using narrow-band single-frequency lasers were employed. In addition to the observation of narrow holes, we have found that a large (up to 70%) decrease in absorption occurs outside the hole and that the relative size of this decrease is constant over the entire inhomogeneous line. This effect is ascribed to fast resonant cross-spin relaxation in the ground-state levels which drives all spins within the optically pumped volume to a common spin temperature. A theoretical model is formulated which describes the power-broadened hole shapes as well as the off-resonance decrease in the absorption coefficient. Fair agreement with experiment is obtained for the case of a magnetic field applied along the $c$ axis; however, sizable deviations from the theory are seen for zero field. We conclude that further studies are needed to elucidate the nature of the Al superhyperfine-broadening mechanism. An upper limit of 1200 nm is deduced for the size of macroscopically broadened regions in ruby.

DOI
10.1103/physrevb.21.926

Related papers

Observation of hole burning and cross relaxation effects in ruby

A. Szabó

In this paper we report, for the first time, the observation of optical hole burning in a solid, ruby. In addition, we describe experimental results which show that optical saturation of the inhomogeneously broadened ${R}_{1}$ line in ruby at 4.2\ifmmode^\circ\else\textdegree\fi{}K occurs not only for ions in resonance with the saturating radiation but also for ions at frequencies up to about 50 MHz away from the radiation frequency. This result and others are consistent with a model in which cross relaxation occurs in the ground-state levels between ions in resonance with the laser beam and nonresonant ions.

Physical review. B, Solid state•Jun 1, 1975•131 citations

Optical hole burning and spectral diffusion in ruby

A. Szabó, Rein K. Kaarli

Frequency-domain optical hole burning of the ${\mathit{R}}_{1}$ line ${[}^{4}$${\mathit{A}}_{2}$(-1/2)\ensuremath{\leftrightarrows}E\ifmmode\bar\else\textasciimacron\fi{}(-1/2) transition] in dilute ruby is studied at 2 K and with a field of 3.6 kG applied along the c axis. A pump-probe (PP) technique is used with precise probe-frequency shifting obtained by an acousto-optic modulator. For sufficiently short PP pulses (50 \ensuremath{\mu}s), two holes (narrow and wide) are observed. The narrow (\ensuremath{\sim}20 kHz half width at half maximum at low power) hole-width dependence on Rabi frequency approximately agrees with that inferred from free-induction-decay measurements. For the present concentration (0.0034 wt. % ${\mathrm{Cr}}_{2}$${\mathrm{O}}_{3}$) and field, the narrow hole width is determined by fluctuating fields produced by Cr-Cr spin flips [A. Szabo, T. Muramoto, and R. Kaarli, Phys. Rev. B 42, 7769 (1990)]. When the PP delay time is varied, the amplitude of the narrow hole decays with a 1/e time constant of \ensuremath{\sim}300 \ensuremath{\mu}s compared to the E\ifmmode\bar\else\textasciimacron\fi{} fluorescence lifetime of 4 ms. The wide hole (\ensuremath{\sim}500 kHz half width at half maximum) is due to Al-Cr superhyperfine interactions and is created by a spectral diffusion mechanism driven by Al-spin flipping in the host lattice.

Physical review. B, Condensed matter•Dec 1, 1991•48 citations

Optical spin polarization in ruby enhances slow light by high-contrast transient spectral hole-burning

Hans Riesen, Aleksander K. Rebane, W. D. Hutchison +1 more

The spin-lattice relaxation time in the 4 A 2 ground state of C r 3 + in ruby can be on the order of magnitude of seconds at liquid helium temperatures in low magnetic fields B | | c . This allows for highly efficient optical pumping of the spin levels in this system. Such pumping can then in turn be employed to drastically increase the optical density of the inhomogeneously broadened R 1 ( ± 3 / 2 ) or R 1 ( ± 1 / 2 ) lines and also to narrow the spectral hole width because Cr–Cr electron-spin flips (cross relaxation) are suppressed in the ground state, leading to longer dephasing times T 2 ∗ . Both effects can be employed to further reduce the group velocity of light pulses propagating through a transient spectral hole.

Journal of the Optical Society of America B•Aug 21, 2020•3 citations

Optical-Microwave Double-Resonance Studies of Ruby

A. Szabó

Studies of the resonant interaction of radiation from a liquid-nitrogen-cooled ruby laser with a ruby crystal in the temperature range 4.2°–100°K are described. The interaction was measured by observation of the change which occurs in the Cr3+ ground state EPR absorption on laser irradiation. At low radiation intensities, the temperature dependence of this change is shown to be determined by the well-known thermal tuning behavior of the R lines. Precise measurement of the relative laser and ruby-sample absorption frequencies by this technique of double-resonance spectroscopy is described. Under optical saturation conditions, additional temperature-dependent pumping effects occur at low temperatures. In particular, as the ruby temperature is increased from 4.2° to 40°K, the laser-induced change in EPR absorption is observed to undergo a large increase. This increase cannot be explained by a relative thermal shift of the laser and absorption frequencies which is known to be very small in this temperature range. The phenomena are attributed in part to the temperature-dependent homogeneous linewidth which determines the widths of the holes burnt into the inhomogeneous strain-broadened R lines. Calculations indicate that the related temperature-dependent thermalization process which redistributes excited Cr3+ among the 2E levels quantitatively accounts for most of the increase.

Journal of Applied Physics•Nov 1, 1968•3 citations

Experimental Tests of the Optical Bloch Equations for Solids

Alex Szabo

Following a brief review of laser frequency and time domain techniques for overcoming inhomogeneous broadening of optical transitions in solids, recent studies on the failure of the optical Bloch equations (OBE) in describing saturation and coherent transient phenomena in ruby will be discussed. Experiments using free induction decay (FID), as in the original work on the system Pr3+:LaF3 by DeVoe and Brewer1, as well as extensions to rotary echos2 and hole-burning3 will be described. At low fields (~ 0.4 T), the time and frequency domain linewidth variation with Rabi frequency agree provided care is taken to avoid line broadening caused by spectral diffusion4. Recent work at high fields (~ 5 T), where Cr-Cr electron spin flipping is suppressed5, shows that spectral diffusion decreases and the dephasing time increases. Observed frequency domain hole widths as narrow as 18 kHz (FWHM) have been obtained for the 4 A2(−1/2)→E¯(−1/2) optical transition in dilute ruby using a pump-probe technique4. Work with such narrow holes emphasizes the fundamental limits imposed by the uncertainty principle and as an aside, a thought experiment where single photons are transmitted through "frequency slits" will be discussed.

Spectral Hole-Burning and Related Spectroscopies: Science and Applications•Jan 1, 1992•0 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.

Physical Review Letters•Aug 9, 1971•130 citations
We report experimental and theoretical studies of optical hole burning in the inhomogeneous R1{R}_{1}R1​ line of ruby at low temperatures. Both Stark-shifting and pump-probe techniques using narrow-band single-frequency lasers were employed. In addition to the observation of narrow holes, we have found that a large (up to 70%) decrease in absorption occurs outside the hole and that the relative size of this decrease is constant over the entire inhomogeneous line. This effect is ascribed to fast resonant cross-spin relaxation in the ground-state levels which drives all spins within the optically pumped volume to a common spin temperature. A theoretical model is formulated which describes the power-broadened hole shapes as well as the off-resonance decrease in the absorption coefficient. Fair agreement with experiment is obtained for the case of a magnetic field applied along the ccc axis; however, sizable deviations from the theory are seen for zero field. We conclude that further studies are needed to elucidate the nature of the Al superhyperfine-broadening mechanism. An upper limit of 1200 nm is deduced for the size of macroscopically broadened regions in ruby.
In this paper we report, for the first time, the observation of optical hole burning in a solid, ruby. In addition, we describe experimental results which show that optical saturation of the inhomogeneously broadened R1{R}_{1}R1​ line in ruby at 4.2\ifmmode^\circ\else\textdegree\fi{}K occurs not only for ions in resonance with the saturating radiation but also for ions at frequencies up to about 50 MHz away from the radiation frequency. This result and others are consistent with a model in which cross relaxation occurs in the ground-state levels between ions in resonance with the laser beam and nonresonant ions.
Frequency-domain optical hole burning of the R1{\mathit{R}}_{1}R1​ line [4{[}^{4}[4A2{\mathit{A}}_{2}A2​(-1/2)\ensuremath{\leftrightarrows}E\ifmmode\bar\else\textasciimacron\fi{}(-1/2) transition] in dilute ruby is studied at 2 K and with a field of 3.6 kG applied along the c axis. A pump-probe (PP) technique is used with precise probe-frequency shifting obtained by an acousto-optic modulator. For sufficiently short PP pulses (50 \ensuremath{\mu}s), two holes (narrow and wide) are observed. The narrow (\ensuremath{\sim}20 kHz half width at half maximum at low power) hole-width dependence on Rabi frequency approximately agrees with that inferred from free-induction-decay measurements. For the present concentration (0.0034 wt. % Cr2{\mathrm{Cr}}_{2}Cr2​O3{\mathrm{O}}_{3}O3​) and field, the narrow hole width is determined by fluctuating fields produced by Cr-Cr spin flips [A. Szabo, T. Muramoto, and R. Kaarli, Phys. Rev. B 42, 7769 (1990)]. When the PP delay time is varied, the amplitude of the narrow hole decays with a 1/e time constant of \ensuremath{\sim}300 \ensuremath{\mu}s compared to the E\ifmmode\bar\else\textasciimacron\fi{} fluorescence lifetime of 4 ms. The wide hole (\ensuremath{\sim}500 kHz half width at half maximum) is due to Al-Cr superhyperfine interactions and is created by a spectral diffusion mechanism driven by Al-spin flipping in the host lattice.
The spin-lattice relaxation time in the 4 A 2 ground state of C r 3 + in ruby can be on the order of magnitude of seconds at liquid helium temperatures in low magnetic fields B | | c . This allows for highly efficient optical pumping of the spin levels in this system. Such pumping can then in turn be employed to drastically increase the optical density of the inhomogeneously broadened R 1 ( ± 3 / 2 ) or R 1 ( ± 1 / 2 ) lines and also to narrow the spectral hole width because Cr–Cr electron-spin flips (cross relaxation) are suppressed in the ground state, leading to longer dephasing times T 2 ∗ . Both effects can be employed to further reduce the group velocity of light pulses propagating through a transient spectral hole.
Studies of the resonant interaction of radiation from a liquid-nitrogen-cooled ruby laser with a ruby crystal in the temperature range 4.2°–100°K are described. The interaction was measured by observation of the change which occurs in the Cr3+ ground state EPR absorption on laser irradiation. At low radiation intensities, the temperature dependence of this change is shown to be determined by the well-known thermal tuning behavior of the R lines. Precise measurement of the relative laser and ruby-sample absorption frequencies by this technique of double-resonance spectroscopy is described. Under optical saturation conditions, additional temperature-dependent pumping effects occur at low temperatures. In particular, as the ruby temperature is increased from 4.2° to 40°K, the laser-induced change in EPR absorption is observed to undergo a large increase. This increase cannot be explained by a relative thermal shift of the laser and absorption frequencies which is known to be very small in this temperature range. The phenomena are attributed in part to the temperature-dependent homogeneous linewidth which determines the widths of the holes burnt into the inhomogeneous strain-broadened R lines. Calculations indicate that the related temperature-dependent thermalization process which redistributes excited Cr3+ among the 2E levels quantitatively accounts for most of the increase.
Following a brief review of laser frequency and time domain techniques for overcoming inhomogeneous broadening of optical transitions in solids, recent studies on the failure of the optical Bloch equations (OBE) in describing saturation and coherent transient phenomena in ruby will be discussed. Experiments using free induction decay (FID), as in the original work on the system Pr3+:LaF3 by DeVoe and Brewer1, as well as extensions to rotary echos2 and hole-burning3 will be described. At low fields (~ 0.4 T), the time and frequency domain linewidth variation with Rabi frequency agree provided care is taken to avoid line broadening caused by spectral diffusion4. Recent work at high fields (~ 5 T), where Cr-Cr electron spin flipping is suppressed5, shows that spectral diffusion decreases and the dephasing time increases. Observed frequency domain hole widths as narrow as 18 kHz (FWHM) have been obtained for the 4 A2(−1/2)→E¯(−1/2) optical transition in dilute ruby using a pump-probe technique4. Work with such narrow holes emphasizes the fundamental limits imposed by the uncertainty principle and as an aside, a thought experiment where single photons are transmitted through "frequency slits" will be discussed.
Laser-induced fluorescence line narrowing of the ruby R1{R}_{1}R1​ Zeeman spectra at 693.4 nm is reported using a continuous, stable, single-frequency ruby laser for resonant excitation. A resolution in excess of 107{10}^{7}107 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.