Applied Physics Letters

Visual observations of macroscopic inhomogeneous broadening of the R1 line in ruby

Paul E. Jessop, A. Szabó

Published Sep 15, 1980• 9 citations

Abstract

Observation of sharp spatial variations of the R1 fluorescence of ruby at 5 K resonantly excited by a 1-MHz-linewidth scanning cw dye laser indicates the presence of gross macroscopic strain broadening in Czochralski and Verneuil crystals. The implications of these results in several current studies are discussed.

DOI: 10.1063/1.91993

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Applied Physics Letters

Visual observations of macroscopic inhomogeneous broadening of the R1 line in ruby

Paul E. Jessop, A. Szabó

Published Sep 15, 1980• 9 citations

Publisher

Abstract

DOI: 10.1063/1.91993

Related papers

Fluorescence-line-narrowing and energy-transfer studies in ruby

Peter M. Selzer, David L. Huber, B. B. Barnett +1 more

Fluorescence-line-narrowing and time-resolved studies have been conducted in ruby crystals and powders, in concentrations varying from 0.025 to 0.9 at.%. The resonance fluorescence component of the ${R}_{1}$ line at low temperatures is observed to increase dramatically as the laser is tuned from line center toward the low-energy wing of the inhomogeneously broadened absorption. This is presumed to indicate the presence of weakly coupled pairs in the wings of the line. Intraline and interline (${R}_{1}\ensuremath{\rightarrow}{N}_{1,2}$) energy transfer have also been studied, and an elaboration of earlier work is given. Time-resolved selective-excitation scans have revealed numerous channels in the vicinity of the $R$ lines by which the different pairs can be directly excited. These are assumed to be Cr ions near enough to a pair to be in a highly perturbed environment. Various experimental results are shown to be consistent with a model of rapid transfer between resonant Cr ions which feeds the pairs via a weak, nonresonant coupling to these perturbed ions. Macroscopic strain broadening is also shown to be favored over microscopic broadening, and the implications for Anderson localization in ruby are discussed.Fluorescence-line-narrowing and time-resolved studies have been conducted in ruby crystals and powders, in concentrations varying from 0.025 to 0.9 at.%. The resonance fluorescence component of the ${R}_{1}$ line at low temperatures is observed to increase dramatically as the laser is tuned from line center toward the low-energy wing of the inhomogeneously broadened absorption. This is presumed to indicate the presence of weakly coupled pairs in the wings of the line. Intraline and interline (${R}_{1}\ensuremath{\rightarrow}{N}_{1,2}$) energy transfer have also been studied, and an elaboration of earlier work is given. Time-resolved selective-excitation scans have revealed numerous channels in the vicinity of the $R$ lines by which the different pairs can be directly excited. These are assumed to be Cr ions near enough to a pair to be in a highly perturbed environment. Various experimental results are shown to be consistent with a model of rapid transfer between resonant Cr ions which feeds the pairs via a weak, nonresonant coupling to these perturbed ions. Macroscopic strain broadening is also shown to be favored over microscopic broadening, and the implications for Anderson localization in ruby are discussed.

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Arthur G. Szabo

Using resonance ruby-laser excitation, narrowing of the ruby ${R}_{1}$ fluorescence line to width 0.002 ${\mathrm{cm}}^{\ensuremath{-}1}$ at 4.2\ifmmode^\circ\else\textdegree\fi{}K is observed. Absence of spectral diffusion indicates that a short-range interaction rather than earlier postulated multipolar interactions is responsible for energy transfer in concentrated ruby.Using resonance ruby-laser excitation, narrowing of the ruby ${R}_{1}$ fluorescence line to width 0.002 ${\mathrm{cm}}^{\ensuremath{-}1}$ at 4.2\ifmmode^\circ\else\textdegree\fi{}K is observed. Absence of spectral diffusion indicates that a short-range interaction rather than earlier postulated multipolar interactions is responsible for energy transfer in concentrated ruby.

Physical Review LettersOct 5, 1970241 citations

Optical hole burning in ruby

Paul E. Jessop, T. Muramoto, A. Szabó

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.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.

Physical review. B, Condensed matterFeb 1, 198043 citations

Fluorescence-line-narrowing and time-resolved studies have been conducted in ruby crystals and powders, in concentrations varying from 0.025 to 0.9 at.%. The resonance fluorescence component of the

{R}_{1}

line at low temperatures is observed to increase dramatically as the laser is tuned from line center toward the low-energy wing of the inhomogeneously broadened absorption. This is presumed to indicate the presence of weakly coupled pairs in the wings of the line. Intraline and interline (${R}_{1}\ensuremath{\rightarrow}{N}_{1,2}$) energy transfer have also been studied, and an elaboration of earlier work is given. Time-resolved selective-excitation scans have revealed numerous channels in the vicinity of the

R

lines by which the different pairs can be directly excited. These are assumed to be Cr ions near enough to a pair to be in a highly perturbed environment. Various experimental results are shown to be consistent with a model of rapid transfer between resonant Cr ions which feeds the pairs via a weak, nonresonant coupling to these perturbed ions. Macroscopic strain broadening is also shown to be favored over microscopic broadening, and the implications for Anderson localization in ruby are discussed.

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.

The first experimental evidence for distinct spectral and spatial energy transfer in ruby via nonradiative coupling is presented. Monochromatic laser excitation of the

{R}_{1}

line results in a rise of the inhomogeneous background on a millisecond time scale, consistent with a one-phonon---assisted process and contrary to recent theory. However, time-resolved studies of trap fluorescence suggest a rapid, coherent, spatial transfer within the

{R}_{1}

line which does not shift frequency.

Using resonance ruby-laser excitation, narrowing of the ruby

{R}_{1}

fluorescence line to width 0.002 ${\mathrm{cm}}^{\ensuremath{-}1}$ at 4.2\ifmmode^\circ\else\textdegree\fi{}K is observed. Absence of spectral diffusion indicates that a short-range interaction rather than earlier postulated multipolar interactions is responsible for energy transfer in concentrated ruby.

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.