Strong green and middle infrared (MIR) photoluminescence (PL) has been observed in Er3+: GdVO4 crystal excited by a 488 nm argon laser. Nearly 25 times of magnitude increase of PL intensity has been obtained for both green and MIR emissions under moderate low magnetic field of 4 T. The temperature- and magnetic field- dependent PL demonstrated that both excitation and emission energy transitions have made contributions to the PL enhancement, and stronger PL enhancement usually happens at the transitions with energy levels possessing larger population of electrons. The results are important and encouraging since it not only reveals the originations of the magnetic induced PL enhancement, but also drag people closer to the utilization of magnetic induced PL modulations under moderate low magnetic field.
An optical method for the sensitive detection of excited energy levels in rare-earth luminescent materials is developed based on the magnetic field induced photoluminescence (PL) enhancement phenomenon observed in Er3+:YVO4 crystals. Since the PL intensity of rare-earth luminescent materials is sensitive to the excitation efficiency, continuous tuning of the excitation laser wavelength under a magnetic field could result in a mapping of PL enhancement peaks vs excitation wavelength. This enables us to figure out the fine energy levels and the corresponding Lander g factors of materials, such as Er3+:YVO4 crystal as an example. Comparison between this method and the Zeeman splitting technique demonstrates that the proposed technique is a powerful solution to detect the fine energy structures and Lander g factors of rare-earth luminescent materials.
Magnetic field-modulated luminescence in lanthanide-doped nanomaterials offers crucial insights for advancing magneto-optical technologies, yet the fundamental mechanisms governing luminescence are still not fully understood. Here, we report Zeeman-effect-induced luminescence suppression in Er3+-doped GdF3 nanoparticles under dual-wavelength excitation (808 nm broadband and 527 nm narrowband) at moderate magnetic fields (up to 1.3 T). Under 808 nm excitation, upconversion emissions (528, 546, and 656 nm) dominated by two-photon absorption exhibit >79% intensity suppression (0.89 T), attributed to energy mismatch caused by Zeeman splitting of sublevels. In contrast, under 527 nm excitation, downconversion emissions (656, 842, and 983 nm) show uniform suppression (∼66% at 1.3 T) due to magnetic field-induced splitting of the 2H11/2 energy level. A simplified model elucidates how Zeeman splitting alters absorption resonance, with theoretical calculations aligning closely with experimental trends. This study reveals the physical mechanisms of magnetic field modulation using dual-wavelength excitation, providing a foundation for expanding magneto-optical technologies in imaging and sensing applications.
Using a laser diode modulated at 250 and 500 MHz, dependence of enhanced absorption on both sample length and temperature was investigated in an erbium doped yttrium aluminum garnet crystal. The transmitted laser intensity decreased with a decay time of 300 ps for sample lengths greater than 3.0 mm and temperatures higher than 50 K when the incident laser intensity increased. In addition, an emission peak was observed near 835 nm corresponding to the transition from the S3/24 level to the I13/24 in Er3+. It was suggested that the enhanced absorption was caused by stimulated emission in three excited states.
This article presents the results of experiments in which the 19 429.67-${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ emission of an
Ar+ laser is used to pump the
Z1,
4I9/2, \ensuremath{\mu}=(5/2\ensuremath{\rightarrow}
F1,
2G9/2, \ensuremath{\mu}=(1/2 transition of
Nd3+ ions dilutely substituted at
La3+ sites in
LaCl3 crystals in an \ensuremath{\sim}1.6-K bath of liquid He. In some of the work
Er3+ ions are also present. When an external magnetic field is applied electron paramagnetic resonance (EPR) absorption of microwave energy by either
Nd3+ or
Er3+ results in marked intensity changes of
Nd3+ fluorescence emissions. The essential new feature of this work is the observation of the importance of the effects of the heating of the crystal above the bath temperature by both optical and microwave absorption. The heating by phonons generated in the radiationless transitions associated with the optical pumping cycle results in the emission of 17 E and D
Nd3+ fluorescences not observed in previous work with the crystal at \ensuremath{\sim}1.6 K. Because of the encapsulation of the crystals in silica envelopes in these experiments, the heating effects are especially marked at higher laser powers.These new fluorescences result from the state population redistributions effected by the rise in temperature of the crystal. EPR microwave absorption by either
Nd3+ or
Er3+ accompanied by spin-lattice relaxation results in a further increase in crystal temperature and further
Nd3+ state population redistributions with concommitant changes in the intensities of the fluorescence emissions from these states of
Nd3+. This affords a new mechanism for optically detected magnetic resonance (ODMR) of these rare-earth ions. This new mechanism for ODMR produces optical signals strikingly different from those previously studied which result from the changes in the populations of the two components of the ground
Z1 doublet of
Nd3+ produced by
Z1 microwave absorption or by microwave absorption by the
Er3+ ground doublet with subsequent transfer of Zeeman quanta between
Er3+ and
Nd3+ and resultant changes in optical pumping rates and fluorescence emissions. The factors contributing to the new mechanism for ODMR also account for the observed changes with temperature in the characters of the decays of the ODMR signals when microwave irradiation is terminated. With constant intensity laser irradiation in the absence of external magnetic fields the 28 observed fluorescence emissions oscillate in synchrony at frequencies (1/2 to (1/3 Hz, when the laser irradiation intensity lies in a certain narrow range. Several mechanisms considered as explanations of this phenomenon have failed to account for its observed features. It is clear, however, that these oscillations of emission intensity are accompanied by oscillations in the temperature of the crystal and of the populations of the emitting states.
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.