We performed high-resolution magneto-optical spectroscopy of the hyperfine transitions from
4I15/2 to the
4I13/2 and
4I9/2 multiplets of
167Er3+ and
166Er3+ in an isotopically purified
7LiYF4 crystal in various external magnetic fields up to 0.7 T. The obtained experimental results are interpreted in the framework of the generalized theoretical approach. The derived model successfully explains all the experimentally observed optical hyperfine transitions by using a single set of basic parameters found for the crystal-field interaction, magnetic dipole and electric quadrupole hyperfine interactions, together with Zeeman interactions at different orientations of the external magnetic field. A number of the studied quantum transitions appears to be promising for use in Raman quantum storage at optical telecommunication wavelengths.
Two-pulse, stimulated and accumulated photon echoes are investigated for the first time in a highly doped crystal Tm:YAG containing 10 at.% Tm3+. The decay curves of the two-pulse and stimulated photon echoes generated at 793,15 nm on the transition 3H6(1)-3H4(1) of the impurity ions are measured in the absence of an applied magnetic field. Parameters describing the energy and phase relaxation are determined. The dependence of the accumulated photon echo intensity on the number of excitation pulse pairs is investigated.
Temporal sequences of different spectral components of the 4/11/2 → 4/13/2 manifold in YAlO3:Er have been analyzed in a laser operated at 300 K. Several lines can oscillate in a spiking train. Their position in the pulse is discussed in terms of population inversion, laser linewidth, and resonant ion-ion interaction. Erbium crystals with dopant concentrations of 10, 20, and 50% have been used in the experiments. The wavelengths of the 3-µm transitions range from 2.71 to 2.92 µm. They are strongly dependent on the crystal orientation with respect to the polarization of the laser light. The polarization dependence of the most prominent emission lines has been determined for laser crystals oriented with their axes along the crystallographic a and b directions. The bandwidth of the laser lines has been measured with a resolution of 0.12 nm using a grating spectrometer in combination with an image converter. The bandwidth ranges from 0.3 nm at 2.73µm up to 2.6 nm at 2.92 µm.
When introduced as dopants into
Y2O3,
Er3+ ions replace
Y3+ ions at two crystallographic sites of
C2 and
C3i point symmetries. The
C3i site is particularly interesting, given that the inversion symmetry prohibits static electric-dipole moments and electric-dipole transitions, resulting in 1.5 \textmu{}m optical transitions characterized by purely magnetic-dipole properties. Employing $\mathrm{E}{\mathrm{r}}^{3+}\phantom{\rule{4pt}{0ex}}^{4}I_{15/2}\ensuremath{\leftrightarrow}^{4}I_{13/2}$ transitions, we examined the inherent
C3i site of
Er3+ in
Y2O3 for its potential in quantum information science and spectral hole burning applications. Our approach involved absorption and site-selective fluorescence spectroscopy to discern
Er3+ energy levels and revealed an excited-state lifetime of 14.6 ms. High-resolution laser spectroscopy at 3.7 K indicated an inhomogeneous linewidth of 1.3 GHz in our sample. Orientation-dependent Zeeman laser absorption spectroscopy facilitated the determination of the full
g tensors for both the ground and excited states, confirming the
C3i site assignment. Furthermore, it identified a suitable magnetic field direction for mitigating decoherence, a finding corroborated through two-pulse photon echo spectroscopy. Our study presents photon echo coherent transient measurements related to magnetic-dipole-allowed rare-earth ion transitions at the
C3i site. The observed decoherence, attributed to spectral diffusion arising from $\mathrm{E}{\mathrm{r}}^{3+}\text{\ensuremath{-}}\mathrm{E}{\mathrm{r}}^{3+}$ magnetic-dipole interactions, underscores the complex spin dynamics at play in systems with multiple inequivalent dopant sites. Coupled with the practicality of telecom laser wavelengths, our investigation highlights the promise of magnetic-dipole transitions in advancing quantum information science and spectral hole burning applications.
We report on a high-resolution optical and magneto-optical spectroscopy, luminescence, and electron paramagnetic resonance (EPR) studies of yttrium orthophosphate single crystals doped with erbium, which are promising telecom-wavelength materials for applications in quantum electronics and quantum information processing. An observation of the hyperfine structure in optical spectra of
167Er isotope in
Er:YPO4 is presented. Energies and symmetries of 40 crystal-field levels of
Er3+ in
Er:YPO4 and
g factors of some of them were determined and successfully modeled on the basis of crystal-field calculations. The obtained set of crystal-field parameters was used in modeling the hyperfine structure observed in the optical and EPR spectra of
Er:YPO4 single crystals.
We report the first observation and study of the photon echo in Er3+:LuLiF4. The energy transition is 4 I 15/2 → 4 F 9/2 (λ = 6536 Å). The density of ErF3 is 0.025 wt %. The operation temperature is 1.9 K. Measurements were made at low (up to 1200 Oe) and even zero external magnetic fields. We studied the behavior of the photon echo intensity vs. the magnetic field magnitude and direction about the crystal axis C and vs. the laser pulse separation t 12 and observed an exponential growth and then, after a certain plateau, an exponential decrease in the photon echo intensity as a function of magnetic field upon increasing the magnetic field from zero. The parameters describing the exponential growth and decrease are independent of the direction of magnetic field. The value of the magnetic field (∼20–200 Oe) at which the echo intensity is maximal and the value of the maximum itself decrease with increasing pulse separation t 12 and the angle Θ between the magnetic field and crystal axis. The echo intensity decreases exponentially with increasing Θ. The parameter describing the exponential decrease is independent of the magnitude of the field. The echo intensity as a function of pulse separation shows exponential decay. The phase relaxation time depends on the magnitude and direction of the magnetic field. T 2 is equal to 202 ± 16 ns at zero magnetic field. A phenomenological formula is suggested, which qualitatively presents the mentioned dependences, and the polarization properties of the backward photon echo in this crystal are studied. Because the ion of trivalent erbium is an optimum data carrier, the above results show that fine control of the multichannel transfer of processed optical information may be achieved by weak magnetic fields.