Excited-state Absorption In Er3 Research Articles

Broadband wavelength excitable Er3+, Ni2+ co-doped MgGa2O4 up-conversion phosphor

Ni2+, Er3+ co-doped MgGa2O4 phosphors have been synthesized via high temperature solid-state reaction method. The photons in wavelength range 900–1700 nm could be absorbed by the phosphor and then up-converted into 660 nm emission by energy-transfer process among the Er3+ and Ni2+ ions as well as excited state absorption of Er3+ ions. The Ni2+ and Er3+ concentration and excitation power dependent up-conversion performances have been investigated. The sensitization energy transfer efficiency is 11.2% in the MgGa2O4: 5% Ni2+, 0.4% Er3+ sample which gives the strongest up-conversion emission. The developed broadband up-conversion phosphor has a wide range of potential photonic applications including photovoltaic cell, infrared detection and night vision.

Enhanced mid-infrared emission by energy transfer in Er3+/Yb3+ co-doped zirconium fluoride-chloride transparent glass

Transparent Er3+/Yb3+ co-doped zirconium fluoride-chloride (ZFC) glass are firstly prepared for mid-infrared emission. The stronger 2750 nm emission from Er3+: ZFC glass is owing to a stronger covalence and local asymmetry of the crystal field around the Er3+ ions. The low phonon energy (600 cm−1) of ZFC glass are calculated from FTIR spectra and confirmed by Raman spectra. The low OH− concentration (9.75 × 10−17 cm−3) and high transmittance (1300-4000 cm−1) of ZFC glass are beneficial to mid-infrared emission. Co-doping rare earth ions Yb3+ enhances the 2750 nm emission. The energy transfer process between Yb3+ and Er3+ are identified based on luminescence spectra and decay curves. The role of Yb3+ plays the sensitizer on Er3+: 4I11/2 and enhances the excited state absorption of Er3+: 4I13/2 → 4F9/2, which is good for transition Er3+: 4I11/2 → 4F13/2. Thus, Er3+/Yb3+: ZFC glass with large emission cross section (1.06 × 10−20 cm2) is a potential laser application material.

White light generation via sequential stepwise absorption and energy-transfer frequency upconversion in Tm3+/Er3+-codoped glass

White light emission with CIE-1931 coordinates close to the standard equal-energy white light illuminant, and color temperature in the 4000–6500K range was produced in Tm3+/Er3+-codoped glasses through frequency upconversion. Multi-Stokes Raman emissions generated in an optical fiber pumped at 1.064µm were used, seeking out the 3H5 thulium absorption band around 1.2µm as the departure point. The new and efficient excitation approach allowed the generation of near infrared (800nm), red (650nm), and blue (480nm) emission due to frequency upconversion excited via ground-state absorption and excited-state absorption in Tm3+ ions. Energy-transfer followed by excited-state absorption in Er3+ ions, provided the generation of the green (530, 550nm) and red (660nm) components to compose white light. The excitation mechanism for the Tm3+ ions is assigned to stepwise multi-wavelength excitation using Stokes Raman emission in an optical fiber, followed by stepwise excited-state absorption of the pump photons. Energy-transfer Tm3+[3F4] + Er3+[4I15/2] →Tm3+[3H6] + Er3+[4I9/2] followed by excited-state absorption of multi-Stokes Raman emissions populate erbium visible emitting level. Excitation power color tuneability of the overall light emission was also achieved.

Visible upconversion in Er3+/Yb3+ co-doped LaAlO3 phosphors

The Er3+ doped and Er3+/Yb3+ co-doped LaAlO3 phosphors have been synthesized by the combustion method and characterized their structural, morphological, elemental, vibrational and optical properties. The optical absorption and upconversion properties of the synthesized phosphors have been studied. Upon co-doping Yb3+ ions into Er3+:LaAlO3, the blue, green and red upconversion emissions of Er3+ ions have been enhanced about ~20, ~54 and ~22 times, under 978nm laser excitation. The observed upconversion emissions could be due to excited state absorption in Er3+:LaAlO3, whereas energy transfer is dominant mechanism in Er3+/Yb3+:LaAlO3 phosphors. The tuning in the color emitted from the synthesized phosphors towards the green region has been found due to incorporation of the Yb3+ ions. With increase in the pump power, the color emitted from the co-doped phosphor is not tuned significantly, showing its applicability in making the green display devices.

Comparison of asymmetric and symmetric cavity configurations of erbium-doped fiber laser in active Q-switched regime

We present a comparative analysis of the dynamics of an actively Q-switched erbium-doped fiber laser assembled in two configurations of Fabry–Perot cavity, asymmetric and symmetric, specified by the location of an acousto-optic Q-switch modulator relative to the output couplers. In both configurations, the length of an active (Er3+-doped) fiber is chosen such that the laser does not spuriously emit at the moments when the modulator is blocked, which is important for the pulse-on-demand operation. We show experimentally that the symmetric cavity configuration permits enlarging of the active fiber length twice as compared to the asymmetric one, thereby increasing the energy and decreasing the duration of output pulses. We also demonstrate that in the symmetric cavity configuration the laser emits a train of short (≈18 ns width on a 3 dB level) and stable Q-switch pulses with a couple of much smaller in magnitude adjacent subpulses. We apply the traveling waves’ method for making an accurate modeling of the laser dynamics in both implementations. The modeling takes into account all the point intracavity losses as well as the distributed ones, including the loss stemming from the excited-state absorption of Er3+ ions. The results of numerical simulations of the laser dynamics in both implementations are shown to be in excellent agreement with experiments.

Effect of Ce3+‐codoping on the spectroscopic properties of Er‐doped YAG particles

AbstractThe Er3+‐single‐doped and Er3+/Ce3+‐codoped YAG particles were synthesized by solid‐phase synthesis method. The luminescence spectra of infrared and visible regions were measured at room temperature. Compared with the Er3+‐single‐doped YAG, the sample with 1%Er3+ and 10%Ce3+ has the highest luminescence intensity at ∼1.5 µm band, and the samples with Ce3+ have the weaker upconversion visible emission and the shorter lifetime of 4I11/2 level. That codoping with Ce3+ was confirmed to be an effective method to improve the quantum efficiency of Er3+ ∼1.5 µm radiation and to decrease the energy loss from the excited state absorption of Er3+.

Red to Green Upconversion in Er3+-Doped BaTiO3 Nanorods

We investigated the frequency upconversion (UC) process in BaTiO3:Er3+ nanocrystals for excitation wavelengths in the range 638 to 660 nm. Green upconversion emissions at 526 and 547 nm corresponding to 2H11/2 --> 4I15/2 and 4S3/2 --> 4I15/2 to transitions of the Er3+ were observed. The excitation spectrum for UC emissions presented three bands, due to ground state and excited state absorption of Er3+ ions. The UC intensity as a function of the laser power was investigated and it was found this a two-photon absorption process.

Synthesis of Ordered Macroporous Pt/Ru Nanocomposites for the Electrooxidation of Methanol

We investigated the frequency upconversion (UC) process in BaTiO3:Er3+ nanocrystals for excitation wavelengths in the range 638 to 660 nm. Green upconversion emissions at 526 and 547 nm corresponding to 2H11/2 --> 4I15/2 and 4S3/2 --> 4I15/2 to transitions of the Er3+ were observed. The excitation spectrum for UC emissions presented three bands, due to ground state and excited state absorption of Er3+ ions. The UC intensity as a function of the laser power was investigated and it was found this a two-photon absorption process.

Excited-state absorption of Er3+-doped LiNbO3

The excited state absorption spectra of an Er:LiNbO3 single crystal are reported and analyzed versus polarization in both visible and near infrared spectral regions between 500 and 1800 nm. These spectra are completed with excited state excitation (ESE) spectra of the bright green anti-Stokes fluorescence observed in this material. These ESE spectra are recorded more particularly around 800 and 980 nm, and the results are analyzed in view of up-conversion laser operation after diode laser pumping around these two wavelengths.

The excited state absorption of Er3+:LiYF4 and Er3+:Na5Y9F32

The excited state absorption cross-sections in π and σ polarisations are obtained for the transition 4I13/2→4I11/2 and 4I13/2→4I9/2 in Er3+:LiYF4. The population ratio between the two excited states 4I11/2 and 4I13/2 in Er3+:LiYF4 and Er3+:Na5Y9F32 have been performed using the measured gain cross-sections in the range 2.6–3 μm. The experiments have been done for two pump wavelengths—488 nm and 1.534 μm.

Time-resolved spectra of excited-state absorption in Er3+ doped YAlO3

A pump- and probe-beam technique is used for measuring time-resolved excited-state absorption (ESA) and stimulated-emission (SE) spectra of Er3+ doped YAlO3. The Er3+ 4I15/2 -> 4F7/2 transition of the sample is excited at 488 nm by an excimer laser pumped dye laser. The ESA and SE of broadband xenon flashlamp light is monitored between 300 and 860 nm by an optical multichannel analyzer (OMA). The analysis of the experimental results provides information on the effective cross sections ESA and SE originating from several levels and on the populations of these levels. To our knowledge this represents the first detailed investigation of time-resolved ESA and SE over a broad spectral range in rare-earth doped materials.