Μm Emission Of Er3 Research Articles

Enhancing 2.7 µm emission of Er3+ in bismuth glass by introducing ZnO

In recent years, 2.7 μm lasers have attracted the attention of many researchers due to their wide application in military, medical, aerospace and other fields. This study investigates the gain effect of ZnO on Er3+-doped bismuthate glasses by partially replacing GeO2 in the glass with ZnO. It is found that under 980 nm pump excitation, with the increase of ZnO, the emission of Er3+ at 1.5 μm and 2.7 μm was enhanced. This result is consistent with the changing trend of J-O parameter Ω2. All these results confirmed that the introduction of ZnO into bismuthate glasses is a reasonable and effective method to enhance the mid-infrared 2.7 μm emission in Er3+-doped bismuthate glasses. Therefore, the current research indicates that an appropriate amount of ZnO in Er3+-doped bismuthate glasses is a suitable materials for 2.7 um fiber lasers.

Exploring the optical properties of the 1.53 μm emission in Er3+-doped glass, anti-glass and ceramic in TeO2 - Ta2O5 – Bi2O3 system

A series of 80TeO2 - 10Ta2O5 – 10Bi2O3 glasses, anti-glasses and ceramics doped with different concentrations of Er₂O₃, ranging from 0.25 % to 2 % mol, were synthesized to explore their structural transformation and optical properties. The maximum solubility of Er₂O₃ was identified at 1.25 % mol, beyond which the glass transitioned from an amorphous to a crystalline structure. The anti-glasses and ceramics obtained from the heat treatment of the parent glasses were also studied to gain insights into their optical properties. This study reveals a direct relationship between Er3+ ions concentration and full width at half maximum (FWHM) of photoluminescence spectra. The increase in Er3+ ions concentration correlates with a rise in FWHM, indicative of spectral broadening. Anti-glass exhibits a higher emission intensity, followed by ceramic and then glass, reflecting their distinct structural properties. Anti-glass doped with 1 % mol Er2O3 shows an FWHM over 130 nm under 578 mW pumping. The lifetime of the excited state 4I13/2 increases with the Er2O3 content in the anti-glass and the ceramic, with a notable decrease at 1 % mol Er2O3 ions for both materials, while in glass, the decrease is observed at 0.5 %. Emission cross-sections decrease with increasing Er3+ ions concentration and power, influenced by factors like thermal effects and saturation. The Judd-Ofelt theory highlights structural differences, with glasses having a more disordered structure and with an increase in the Ω₆ parameter across all materials, implying enhanced electric dipole line strength and spontaneous emission probability with higher Er₂O₃ content. Overall, this comprehensive study provides valuable insights into the optical behavior of Er3+ ions in these materials, essential for applications in laser design and optical amplifiers.

In-band luminescence thermometry in the third biological window and multicolor emission of Er-doped fluoride and oxide nanoparticles

In this study we present a morphological and spectroscopical characterization of three different erbium doped nanocrystal samples, namely two oxides (Y2O3:3%Er, Sc2O3:3%Er) and one fluoride (YF3:5%Er). The spectroscopic study offers a comprehensive comparison of their multicolor emissions, ranging from the visible to the mid-infrared region. Emissions from the first five excited states are presented and the emission cross sections of the 4I11/2 → 4I15/2, 4I11/2 → 4I13/2, and 4I13/2 → 4I15/2 transitions have been calculated and compared with literature results for the oxide compounds providing a confirmation for the 1.5 μm emission of Er:Y2O3, a correction over published values for the 2.7 μm emission of Er:Y2O3, and also new results for the Er:Sc2O3 emission cross section values of all the infrared bands. Moreover, this study explores the application of the 4I13/2 emission for in-band luminescence thermometry within the third biological window. An optimized segmentation of the 1.5 μm emission permits to achieve high relative and absolute sensitivities using just one dopant ion.

Effective 3.5 μm emission of Er3+ ions in fluoroindate glass with improved thermal stability

The development of effective 3.5 μm laser derived from a gain medium doped with Er3+ ions is of great significance for research on mid-infrared (MIR) lasers. Existing 3.5 μm laser materials are unable to exhibit both stable thermal and excellent MIR optical properties simultaneously. In this study, a system of fluoroindate glasses was prepared and analyzed through differential scanning calorimetry (DSC) and Raman spectra. The thermal stability was improved by regulating the Al(PO3)3 content with the value of ΔT up to 110 °C. Notably, a maximum Er3+ concentration up to 11 mol% can be contained in this transparent high-optical-quality glass with an effective 3.5 μm emission. In addition, the energy transfer mechanisms and theoretical calculation results of the absorption and emission coefficients also verify the outstanding 3.5 μm fluorescence of Er3+ in the proposed fluoroindate glass, which can provide a new and attractive choice for 3.5 μm laser gain media.

Enhancing 2.7 µm emission of Er3+ in bismuth germanium glasses by introducing BaF2 in the composition

Recently, 2.7 µm lasers have attracted much attention because of their wide applications in remote sensing, and medical laser surgery. The effect of Bi2O3 ↔ BaF2 substitution in the Er3+ doped Bi2O3-GeO2-BaF2 glasses on physical and 2.7 µm emission properties have been studied. Under the excitation of 976 nm LD, an intense and broad 2.7 µm emission originating from the 4I11/2 → 4I13/2 transition of Er3+ was observed. BaF2 was found to enter the glass network as Ba2+ and F−, which may contribute to a reduction in the bridge oxygen content. The 1.55 µm emission was attenuated and the 2.7 µm emission was enhanced due to the combined effect of F− reducing the OH− content of the glass and Ba2+ expanding the distance between Er3+ ions. Furthermore, the peak emission cross-section is calculated to be 12.9 × 10−21 cm2. The Er3+ doped Bi2O3-GeO2-BaF2 glasses show potential as broadband mid-infrared emission gain material.

Benefit of Pr3+ ions to the spectral properties of Er3+/Pr3+:SrLaAlO4 crystal for use in 2.7 μm mid-infrared laser

High optical quality Er3+ single doped and Er3+/Pr3+ co-doped SrLaAlO4 crystals were grown by the Czochralski method. Detailed spectroscopic analyses of Er3+:SrLaAlO4 and Er3+/Pr3+:SrLaAlO4 crystals were carried out. With the presence of Pr3+, the intensities of the red up-conversion and near-infrared emissions reduce to 1/4 and 1/10, while the intensity of mid-infrared emission increases to 1.6 times of those for Er3+:SrLaAlO4. Furthermore, the lifetimes of 4I11/2 upper and 4I13/2 lower laser levels for 2.7 μm emission fall from 1.06 ms to 4.42 ms–0.73 ms and 0.93 ms. It means that the self-termination bottleneck in Er3+ 2.7 μm laser was inhibited in a great degree. Deactivation effect of Pr3+ ions as well as the energy transfer mechanism in Er3+/Pr3+:SrLaAlO4 crystal are discussed in detail. The results indicate that the introduce of deactivation ion Pr3+ can be beneficial for achieving an enhanced 2.7 μm emission in Er3+/Pr3+:SrLaAlO4.

An investigation of 3.5 μm emission in Er3+-doped fluorozirconate glasses under 638 nm laser excitation

An investigation of 3.5 μm emission in Er3+-doped fluorozirconate glasses under 638 nm laser excitation

Intense broadband 3.1 μm emission in Er3+-doped fluoroaluminate-tellurite glass for mid-infrared laser application

Er3+ single doped fluoroaluminate-tellurite glasses were made by employing a conventional melt-quenching technique. A strong fluorescence around 3.1 μm was achieved from Er3+-doped fluoride glasses, under a 980 nm laser diode pump, which was assigned to the Er3+: 4S3/2 → 4F9/2 radiation transition process. The up-conversion and mid-infrared spectra of emission for fluoroaluminate-tellurite glasses with various concentrations of Er3+ ions dopant was researched. In addition, the calculated fluorescence lifetime value about 3.1 μm reaches 0.48 ms. The findings indicate that fluoroaluminate-tellurite glasses doped with Er3+ have prospects of being developed into 3.1 μm mid-infrared fiber and laser materials.

Tm3+ heavily doped NIR-III bioprobe with 1 µm Stokes shift towards deep-tissue applications

Recently developed rare earth ions doped NIR-NIR bioprobes, with excitation and emission both falling in the NIR region, have attracted wide attention due to their deep-tissue penetration, high signal-to-noise ratio, and high imaging resolution. The current NIR-NIR bioprobes focused mainly on the 1.5 µm emission of Er3+. Here, we developed a novel bioprobe utilizing the 1.8 µm emission of Tm3+ upon 0.8 µm excitation. After an inert shell effectively suppressing the surface quenching effect, the strong cross relaxation 3H4 + 3H6 → 3F4 + 3F4 between heavily doped Tm3+ greatly improves the luminescence intensity at 1.8 µm. As a result, the formed Tm3+ based NIR-III bioprobe exhibits better penetration ability of the state-of-the-art Er3+ based NIR-III bioprobe, and holding an even larger Stokes shift beneficial for the multiplexed bioimaging and labeling applications.

Energy Transfer and Cross-Relaxation Induced Efficient 2.78 μm Emission in Er3+/Tm3+: PbF2 mid-Infrared Laser Crystal

An efficient enhancement of 2.78 μm emission from the transition of Er3+: 4I11/2 → 4I13/2 by Tm3+ introduction in the Er/Tm: PbF2 crystal was grown by the Bridgman technique for the first time. The spectroscopic properties, energy transfer mechanism, and first-principles calculations of as-grown crystals were investigated in detail. The co-doped Tm3+ ion can offer an appropriate sensitization and deactivation effect for Er3+ ion at the same time in PbF2 crystal under the pump of conventional 800 nm laser diodes (LDs). With the introduction of Tm3+ ion into the Er3+: PbF2 crystal, the Er/Tm: PbF2 crystal exhibited an enhancing 2.78 μm mid-infrared (MIR) emission. Furthermore, the cyclic energy transfer mechanism that contains several energy transfer processes and cross-relaxation processes was proposed, which would well achieve the population inversion between the Er3+: 4I11/2 and Er3+: 4I13/2 levels. First-principles calculations were performed to find that good performance originates from the uniform distribution of Er3+ and Tm3+ ions in PbF2 crystal. This work will provide an avenue to design MIR laser materials with good performance.

High efficient and broadband ∼3.5 μm emission of Er3+:YAG crystal

The YAG single crystals doped with 10 at.%, 20 at.% and 50 at.% Er3+ were successfully grown by the micro-pulling down method and spectroscopic properties of the crystals were investigated. The main interest was focus on the relation between the Er3+ concentration and ∼3.5 μm emission of Er3+:YAG crystals. Room temperature absorption spectra were analyzed by the Judd-Ofelt theory. The stimulated emission cross-sections were calculated by the Füchtbauer-Ladenburg equation. The fluorescence intensities and peak emission cross-sections of the crystals at ∼3.5 μm are slightly decreasing with the increase of Er3+ concentration. The trend of the emission properties in NIR and visible region with the Er3+ concentration was also discussed and compared. The results indicate that the highly doped Er3+ concentration is beneficial to realize the ∼3.5 µm laser output.

Enhanced 1.53 µm emission of Er3+ in nano-Ag embedded sodium-boro-lanthanate glasses

The manuscript reports the influence of Ag NPs on the luminescence performance of Er3+ ions activated in borate glass host. The formation and dispersion of Ag NPs in the glass matrices revealed by absorption and HR-TEM measurements. The average size of Ag NPs was found to be 2.80, 7.36, and 16.02 nm, for ELB-1, ELB-2, and ELB-3 glasses, respectively. Utilizing the UV-Visible-NIR absorption spectra, the Judd-Ofelt parameters (Ωλ= 2, 4, 6) were calculated. It was found that the Ω2 values of glasses increased with increase in Ag NPs concentration, suggested that the enhanced covalency and reduced symmetry around the Er3+ ions. The visible luminescence emission under 378 nm excitation shows the emission bands positioned at 535 (2H11/2→4I15/2, green), 547 (4S3/2→4I15/2, green), and 624 (4F9/2→4I15/2, red) nm. NIR emission of all the glasses exhibits an intense peak at 1.53 µm due to 4I13/2 → 4I15/2 transition of Er3+ ions. The visible and NIR emission enhancement was noticed up to 0.1 mol% of AgCl and subsequent quenching at higher concentrations. The mechanisms responsible for luminescence enhancement and quenching has been underlined. The glass host doped with 0.1 mol% of AgCl (i.e., ELB-1) possesses high stimulated emission cross section along with optical gain width which suggests the glass containing 0.1 mol% AgCl is beneficial for solid state IR lasers and fiber-optic communication applications.

Highly efficient ~3.4 μm emission of Er3+-doped TeO2 based glasses via resonant energy transfer and multi-phonon relaxation processes

To clarify the relation between the concentration and ~3.4 μm emission of Er3+, a series of TeO2 based glasses with Er3+ concentration from 2.0 to 10.0 mol% were prepared by conventional melting-quenching method. The physical and spectroscopic characteristics of Er3+-doped tellurite glasses were systematically investigated. The Judd-Ofelt theory was used to analyze the absorption spectra. The emission intensity of ~2.7 μm and upconversion at 550 and 670 nm were discussed. The intensity increased when the Er3+ concentration increased to 6 mol%, and then drastically decreased with further increasing Er3+ concentration. The trend of the emission properties in NIR with the Er3+ concentration was also discussed. With increasing Er3+ concentration, the emission cross section at ~3.4 μm increased from 1.37 × 10−21 cm2 to 2.53 × 10−21 cm2. The results indicate that the highly doped Er3+ concentration may be an effective route to achieve efficient ~3.4 μm emission in Er3+ doped tellurite glasses.

Excitation-dependent enhancement and quenching of the 1.54 μm emission from Er3+ ions in dichroic Cu nanocomposite glass

The 1.54 μm emission of Er3+ ions embedded in a dichroic Cu nanocomposite glass is shown to be either quenched or enhanced depending on the excitation wavelength. The synthesized material consisted of an aluminphosphate matrix co-doped with Cu and Er as prepared by thermal processing, and characterized by optical absorption and photoluminescence (PL) spectroscopy including an assessment of decay dynamics. The extinction spectrum presented a broad surface plasmon resonance (SPR) band for Cu nanoparticles (NPs) around 588 nm, while the glass appeared to scatter red light but transmit blue, i.e. exhibiting dichroism. Interestingly, the PL obtained for the 4I13/2 → 4I15/2 emission around 1.54 μm was enhanced under the excitation of the 4I15/2 → 4F9/2 transition at 650 nm, which turned out to be located toward the low energy wing of the SPR of Cu NPs. About a 12% PL boost was estimated relative to a merely Er3+-doped reference. Conversely, a PL quenching effect was manifested for resonant Er3+ excitations (e.g. 4I15/2 → 2H11/2 transition at 520 nm) overlaid with the 3d → 4sp interband transitions absorption in copper. It is suggested that favorable conditions for the PL enhancement are achieved for when the excitation of Er3+ ions can benefit from light scattering by plasmonic Cu particles, while an excitation energy transfer from Er3+ to Cu NPs via interband transitions leads to the quenching.

Broadened effect of Dy around 3 μm of Yb/Er/Dy: PbF2 crystal for broadband tunable lasers

AbstractIt is well known that the laser crystal with mid‐infrared (MIR) broadened and enhanced luminescence is of great significance for various applications, such as atmospheric monitoring, medical surgery and compact, and efficient coherent sources. Herein, we exploit the sensitization and deactivation effects of Yb3+/Dy3+ ions to achieve broadening and enhancement ~3 μm emission of Er3+: 4I11/2→4I13/2 transition in Yb3+/Er3+/Dy3+: PbF2 crystal. The energy transfer (ET) mechanism between Yb3+, Er3+, and Dy3+ was studied. A broadened and enhanced emission with a full width at half maximum of 265 nm was obtained at ~3 μm due to the fact that Er3+ and Dy3+ ions were used as the emission center at the same time. On the one hand, the incorporation of Dy3+ ion can solve the self‐termination bottleneck effect of Er3+ ion, reducing the lifetime of Er3+: 4I13/2 level. On the other hand, Dy3+ ion can simultaneously serve as the emission center of 3 μm, broadening and enhancing the emission of 3 μm. The experiments show that the corresponding ET efficiency Er3+: 4I13/2→Dy3+: 6H11/2 level is as high as 98.0%, indicating that Dy3+ ion can be used as an effective deactivating ion, benefitting to achieve broadening and enhancing MIR emission around 3 μm. Hence, the Yb3+/Er3+/Dy3+: PbF2 crystal is an attractive laser medium for MIR broadband tunable laser applications.

Validity of Judd-Ofelt spectroscopy based on diffuse reflectance spectrum and fluorescence lifetime of phosphor

Validity of Judd-Ofelt spectroscopy based on measured diffuse reflectance spectrum and fluorescence lifetime of a purely radiative electronic transition of rare-earth-ion in a powder material has been demonstrated. Two representative powder samples of Er3+-doped LiNbO3 and Er3+/Yb3+-codoped NaYF4, which have considerably different phonon energies, 880 and 380 cm−1, respectively, have been exemplified to demonstrate the validity. First, diffuse reflectance spectrum was measured for each powder sample and relative absorption spectrum was calibrated from it using Kubelka-Munk relation. Second, fluorescence lifetime of purely radiative 1.5 μm emission of Er3+ was measured and absolute absorption cross-section spectrum was calibrated on the basis of the assumption that the measured 1.5 μm fluorescence lifetime equals the radiative lifetime. Finally, the Judd-Ofelt parameters Ωt (t = 2, 4, 6) are calculated on the basis of the absolute absorption cross-section spectrum. For comparison, Judd-Ofelt analysis was also performed on the Er3+-doped LiNbO3 single-crystal on the basis of the absorption spectrum obtained from Beer-Lambert law. The Ωt result of Er3+-doped LiNbO3 powder sample is compared with that of single-crystal state. The comparison shows that the Ωt result of the powder sample can be considered as the same as that of the single-crystal state within the error, confirming the validity of the method. The study on the Er3+/Yb3+-codoped NaYF4 microcrystal powder allows us to reach the same conclusion.

Enhancement of 1.8 μm emission in Er3+/Tm3+ co-doped tellurite glasses: Role of energy transfer and dual wavelength pumping schemes

Thulium (Tm3+) and erbium (Er3+)-doped tellurite glasses were synthesized and explored their spectroscopic properties for optical amplification and medical appliances. The emission at 1.8 μm of Tm3+ ions has been enhanced significantly in Er3+/Tm3+ co-doped tellurite glasses under dual pumping lasers at 808 and 980 nm. Emission cross-section of the Tm3+ ions is found to be 3.46 × 10−20 cm2 which was evaluated by utilizing the Mc-Cumber theory. The possible energy transfer mechanisms between Er3+ and Tm3+ ions under 808 and 980 nm excitations were investigated by utilizing the excitation, emission and decay curve analyses. Effect of dual wavelength pumping on the 1.5 and 1.8 μm spectral profiles is also enlightened. Decay curves of Tm3+:3H4 → 3F4 (1440 nm) transition and Er3+: 4I13/2 → 4I15/2 (1531 nm) transition in the Tm3+ singly and Er3+/Tm3+ co-doped tellurite glasses have been analyzed under 808 nm laser excitation. Energy transfer efficiency is evaluated between Er3+: 4I13/2 and Tm3+:3F4 states from the decay curves and it is found to be 83%. The results are significant and indicating that the Er3+/Tm3+ co-doped tellurite glasses could be a potential candidate for optical fiber amplification at around 1.8 μm region under dual wavelength pumping scheme.

The glass-forming region and 2.7 μm emission of Er3+-doped TeO2−Ta2O5−ZnO tellurite glass

An Er3+-doped TeO2 − Ta2O5 − ZnO (TTZ) tellurite glass has been investigated to explore its possible application in mid-infrared laser glass and fiber lasers. Glass-forming region of the ternary TTZ glass system was determined based on the thermodynamic calculation and experiments. Physical and optical properties of the TTZ glass were characterized in detail by using Raman, different scanning calorimetry, luminescence spectra, and fluorescence decay curves. An intense 2.7 μm emission was observed in Er3+-doped TTZ glasses upon the excitation of 980 nm laser diode (LD). The excellent thermal stability (△Tmax = 203 °C), low maximum phonon energy (~770 cm−1), high emission cross-section (0.82 × 10−20 cm2) and spectroscopic figure of merit (3.22 × 10−24 cm2s) indicate that the Er3+-doped TTZ glass could be a promising candidate for efficient ~ 3 μm fiber lasers and amplifiers.

Enhanced mid-infrared emission in Er3+/Tm3+ co-doped tungsten-tellurite glasses

Transparent Er3+/Tm3+ co-doped tungsten-tellurite (TWL) glasses with variable Er3+ concentration were prepared by the conventional melt-quenching method. The samples prepared were investigated by differential scanning calorimetry (DSC), absorption spectra, up-conversion, near and mid-infrared emission and lifetime decays. DSC analyses indicates a high transition temperature (Tg) and a large value of △T. Enhanced 2.7 μm emission in Er3+/Tm3+ co-doped TWL glasses presents its superiority in mid-infrared application. Based on above emission spectra and lifetime decays, the energy transfer mechanism between Er3+ and Tm3+ ions was discussed. Tm3+ ions are an effective sensitization for 2.7 μm emission of Er3+ ions in this glass for its high energy transfer efficiency (83.6%). A comparative study on emission performance suggests that this Er3+/Tm3+ codoped TWL glass is a competent candidates for mid-infrared laser materials.

Spectroscopic and laser properties of Er:LuGG crystal at ∼2.8 μm

We report ∼2.8 μm emission of Er3+-doped Lu3Ga5O12 crystal, as well as its laser performance. The continuous-wave (CW) and passively Q-switched lasers were both obtained for the first time at room temperature under 967 nm laser diode end pumping. A 384 mW of CW output power was obtained under the absorbed pump power of 3.28 W, corresponding to an optical-to-optical efficiency of 11.7%; the slope efficiency was 14.1%. A passively Q-switched laser with a maximum average output power of 274 mW was also achieved by utilizing a Bi2Te3/graphene heterostructure saturable absorber (SA). The shortest Q-switched pulse duration and the repetition rate were 340 ns and 135 kHz, respectively.