Stimulated Emission Cross-section Research Articles

Structural, optical behavior and Judd-Ofelt analysis of europium-doped silicophosphate glasses for red-emitting device applications

Silicophosphate glasses doped with europium are of great interest in fundamental fields such as photonics, luminous diodes, optoelectronics, and lasers. In the present study, we have focused on exploring the effect of the europium (Eu3+) dopant on the structural, physical, and optical properties of silicophosphate glasses. In this study, pure and europium-doped silicophosphate glasses were synthesized by using the sol-gel method. To evaluate the structural and optical properties of the prepared glasses, X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV–visible spectroscopy, photoluminescence spectra, and luminescence decay of trivalent europium ions in glasses were examined. XRD revealed that all of the synthesized glasses contained amorphous phases. FTIR transmittance spectra demonstrated that the addition of europium in the silicophosphate glass leads to a reduction in the dimensionality of the network as a result of the rupture of the Si–O–Si bonds into their structure. The band gap energy of the samples increases with the dopant of europium. The photoluminescence spectrum shows the line characteristics of the Eu (III) ion 5D0→7FJ (J = 0, 1, 2, 3 and 4). Large bands were observed, suggesting non-homogeneous sites that are characteristics of amorphous systems. The intensity parameters ΩJ (J = 2, 4) and the radiative properties of Eu3+ ions in the prepared glasses, such as the stimulated emission cross-section (σe), transition probability (A), radiative lifetime (τcal), and branching ratio (βR) were determined, and Eu3+ emission may be suggested for suitable laser applications due to its high value of βR=52.71%. Furthermore, the CIE 1931 color coordinates of the synthesized glass (x, y) are within the range of (0.63, 0.36) and are quite close to the standard red color (0.67, 0.33), indicating that pure bright red emission has been achieved. The obtained results show that the europium-doped silicophosphate glasses can be appropriate for use as a red laser material.

Stimulated emission cross sections and temperature‐dependent spectral shifts of neutral nitrogen‐vacancy centers in diamonds

AbstractThe neutral nitrogen‐vacancy (NV0) defects in diamond are photostable color centers, suitable for a wide range of applications in science and engineering. However, the photophysical properties of the centers have not yet been fully characterized. This work measured the stimulated emission cross sections of NV0 in a single‐crystal diamond by two‐photon excitation of its matrix at 344 nm. From the measured photoluminescence spectrum and the fluorescence lifetime of 20 ± 1 ns, we determined a peak stimulated emission cross section of 1.43 ± 0.07 × 10−17 cm2 at 650 nm for the NV0 centers. In addition, we have also examined the thermal shifts of the zero‐phonon line of NV0 centers in nanoscale diamonds (~100 nm in diameter) over the temperature range of 30–120°C. A temperature measurement sensitivity of 0.2 K·Hz−1/2 was achieved, which is about two‐fold better than that of NV−, despite that the fluorescence intensity of NV0 is about six‐fold lower than that of NV− in the same nanoparticles. The result is attributed to the smaller electron–phonon coupling strength of the neutral center, compared with its negatively charged counterpart.

Judd-Ofelt Analysis and Emission Properties of Dy3+ Ions in Borogermanate Glasses.

Borogermanate glasses singly doped with Dy3+ ions were synthesized and then studied using the absorption and luminescence spectra. Spectroscopic changes of Dy3+ ions have been examined for compositional-dependent glasses with various molar ratios GeO2:B2O3. In this work, several spectroscopic parameters of Dy3+ ions were obtained experimentally and compared to the calculated values from the Judd-Ofelt theory. Luminescence spectra measured for borogermanate glasses consist of blue, yellow and red bands, which correspond to 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2 transitions of Dy3+, respectively. Luminescence lifetimes for the 4F9/2 excited state are reduced, whereas the stimulated emission cross-sections for the most intense 4F9/2 → 6H13/2 yellow transition of Dy3+ increase with increasing GeO2 and decreasing B2O3 concentrations in glass-hosts. Quantum efficiency of the 4F9/2 (Dy3+) excited state is nearly independent on molar ratios GeO2:B2O3. Attractive spectroscopic properties related to the 4F9/2 → 6H13/2 transition of Dy3+ ions are found for borogermanate glasses implying their potential utility for yellow laser action and solid-state lighting technology.

Concentration dependent Dy3+- doped lithium fluoro borotellurophosphate glasses’ structural and optical investigations for white light emission under UV excitation for solid-state lighting applications

Concentration dependent Dy3+ - doped lithium fluoro borotellurophosphate glasses were prepared by conventional melt quenching technique by varying the dopant concentration (0.1, 0.25, 0.5, 1.0 & 1.5 wt %). The structural and compositional analyses have been carried out through XRD, FTIR, SEM and EDAX respectively. The optical studies were made to analysis the optical behavior of the Dy3+ ions in the synthesized glasses through absorption and emission spectra. The nephelauxetic ratio and bonding parameter were calculated from the absorption spectra. The oscillator strength fexp and fcal along with σrms were evaluated and reported. The JO intensity parameters (Ω2, Ω4 and Ω6) have been calculated and trends reported. The photoluminescence spectra were recorded under 384 nm excitation. The radiative properties like emission band position (λp), effective bandwidth (Δλeff), radiative transition probability (A), stimulated emission cross-section (σpE), calculated and experimental branching ratios (βR) for the Dy3+-doped lithium fluoro borotellurophosphate glasses were calculated using JO intensity parameters and emission data. The CIE color coordinates (x,y) and Y/B ratio values were calculated from the photoluminescence spectra. The color correlated temperature (CCT) were determined from the (x,y) values and possibility for white light emissions from the synthesized glasses were analyzed under UV excitation. The decay analysis shows the non-exponential behavior of the present glasses.

Photoluminescence and X‐Ray‐Induced Luminescence Behavior of Sm2O3‐Doped Oxyfluoroborate Scintillating Glass for Radiation Detecting Material

Various concentrations of samarium (Sm3+) ion‐activated oxyfluoroborate (ANCB:AlF3‐NaF‐CaF2‐B2O3) glasses are fabricated for its applications in red‐emitting lasers and scintillators. From the optical absorption spectrum, Ω2,4,6 intensity parameters and several radiative parameters along with the high value of absorption (2.96 × 10−21 cm2) and emission (14.13 × 10−22 cm2) cross sections are calculated. By stimulating at 403 nm, a transition corresponding to 4G5/2 → 6H7/2 (596 nm) is very intense and emits orange‐reddish luminescence of Sm3+ ion in ANCB glasses. The decay curves are fit to the Inokuti–Hirayama (I–H) model to determine the energy transfer in Sm3+: ANCB glasses. The X‐ray‐excited luminescence (XEL) spectra are determined with an X‐ray source by supplying the voltage of 50 kV and current 30 mA. The lasing parameters like stimulated emission cross section (14.13 × 10−22 cm2), optical gain (30.52 × 10−22 cm2 s), and quantum efficiency (80%) are found to be high for the 4G5/2 → 6H9/2 transition of Sm3+ ions. The quality of the emitted red light for the ANCBSm0.5 glass is calculated in terms of the (x, y) color coordinates and correlated color temperatures (CCT < 3000 K). The integral scintillation efficiency of glasses shows the maximum value of 23% in comparison with Bi4Ge3O12 scintillation crystal.

Photoluminescence and optical transition investigations of europium doped bismuth borate glasses for laser and LEDs applications

The current work present the fabrication and characterization of lithium based bismuth borate glasses doped with different europium contents. The grown samples were evaluated for its structural, physical, optical and luminescence investigations. The structural confirmation were conducted by XRD and FTIR spectra. The Absorption spectrum observed in UV-Vis-NIR region and demonstrate two sharp peaks at 2092 and 2200 nm. The bandgap and Judd-Ofelt parameters Ω2, Ω4, Ω6 were computed from absorption spectrum of LiBBiEu2.0 glass. Under 395-nm excitation five emission bands were discovered in the emission spectra. From photoluminescence emission spectra the radiative properties like branching ratio (83), stimulated emission cross section (590.595 × 10−22 cm2), and radiative transition probability (4087.90 s−1), were determined for 5D0→ 7F2 transition. The high optical gain 1.193 × 10−20 cm2 s of LiBBiEu2.0 glass make it possible to be used as best lasing material. From the 5D0 emission level of decay curve the experimental lifetime were calculated which decreased with rise in Eu3+ contents. The increased in orange-red (R/O) ratio with increase in Eu3+ contents confirm asymmetric environment around Eu3+ ions in the host glasses. Based on these results the developed glasses can be used as promising material in red LEDs and red laser in optical devices.

Growth, spectroscopy and CW laser operation of Ho3+ doped CaY0.9Gd0.1AlO4 single crystal

Ho3+-doped CaY0.9Gd0.1AlO4 single crystal was successfully grown by the Czochralski technique for the first time. The polarized absorption spectra, polarized luminescence spectra and fluorescence decay curve of the crystal were investigated at room temperature. The spectroscopic parameters are calculated based on Judd–Ofelt theory, the values of Ω2,4,6 were calculated to be 3.16 × 10−20 cm2, 3.93 × 10−20 cm2, 0.91 × 10−20 cm2, respectively. The Ho:CaY0.9Gd0.1AlO4 crystal exhibits strong emission at 2013 nm for π- and 2032 nm for σ-polarizations with stimulated emission cross section of 6.64 × 10−20 cm2 and 1.90 × 10−20 cm2, respectively. The fluorescence lifetime of the 5I7 level was measured to be 6.60 ms. The continuous-wave (CW) laser operation of Ho:CaY0.9Gd0.1AlO4 crystal around 2 μm was demonstrated.

Structural analysis of Eu3+ in Li2O-MO-B2O3-Eu2O3(M=Mg, Ca, Sr, Ba) glass using XANES and EXAFS

The research focuses on the structural changes, coordination and interatomic distance of Europium doped Li2O-MO-B2O3 (M = Mg, Sr) glasses. The detailed analysis was subjected to understand Eu3+ ions in lithium magnesium borate and lithium strontium borate glasses as determined by the extended X-ray absorption fine structure analysis. XANES spectra of Eu2O3 content doped in the present glasses showed Eu3+ state upon the x-ray as incident source. The metal LIII edges, and K edges are investigated concerning alkaline earth ion glasses and their interactions with local environment. In this work, europium and barium ions in lithium borate glasses are studied by LIII-edges, strontium and calcium ions in lithium borate glasses are studied by K-edges using X-ray absorption spectroscopy to reveal the relationship between alkali earth metal ions with Eu3+, Ba2+, Ca2+, and Sr2+ ion local structure. The nearest neighbors of Eu for the first shell were analyzed for Eu–O distance in Eu3+-doped glasses by EXAFS analysis and found to be in the range of 2.35–2.36 Å. Judd-Ofelt analyses were performed, and JO parameters showed Ω4> Ω2> Ω6 trend for Mg, Ca, Sr in lithium borate glasses while a Ω2> Ω4> Ω6 trend for Ba in lithium borate glasses. Radiative properties were analyzed using JO parameters to calculate stimulated emission cross-section, branching ratio, and radiative lifetime. The calculation was also taken care of with thermal correction and found that the data obtained after thermal correction shows higher values.

Low threshold amplified spontaneous emission and lasing from single crystals and polymer microspheres based on a blue aggregation-enhanced emission molecule

Organic semiconductors as a gain medium have attracted much attention in organic lasers due to their unique properties, i.e., large stimulated emission cross section, widely tunable spectrum region, and mechanical flexibility. Aggregation-caused quenching broadly exists in amorphous solid films and single crystals, which result in high threshold. Here, we studied amplified spontaneous emission (ASE) and lasing properties of an aggregation-enhanced emission (AEE) molecule, namely, 2PB-AC, who owns high photoluminescence quantum efficiency in a solid film and a single crystal. The grown long rod-like single crystals exhibited very good ASE characteristics with a threshold of 48 μJ cm−2 and a full width at half-maximum (FWHM) of 8.4 nm. Furthermore, when forming polymer microspheres by a surface tension-induced self-assembly method, a low lasing threshold of 0.32 mJ cm−2 and a FWHM of 0.41 nm were also obtained well, and their lasing modes could be modulated by changing the diameter of the microspheres. The investigations on transient photoluminescence dynamics and femtosecond transient absorption analysis demonstrated that the high radiative decay rate and the well separation between a stimulated emission band and an excited state absorption band are the main reasons of good lasing performance, indicating that AEE molecules are promising lasing materials.

Influence of TiO2 concentration on near-infrared luminescence of Er3+ ions in barium gallo-germanate glasses

Erbium (Er)-doped barium gallo-germanate (BGG) glasses modified by TiO2 have been investigated for near-infrared luminescence applications. Luminescence at 1.5 μm associated to 4I13/2 → 4I15/2 transition of Er3+ ions has been examined in function of TiO2 concentration. Several spectroscopic and near-infrared (NIR) laser parameters for Er3+ such as stimulated emission cross-section, luminescence bandwidth and lifetime, quantum efficiency, gain bandwidth and figure of merit were determined based on experiments and theoretical calculations using the Judd-Ofelt framework. Our systematic investigations indicate that Er-doped glass with molar ratio GeO2:TiO2 = 1:2 shows excellent luminescence properties and could be successfully applied to near-infrared broadband optical amplifiers.

Judd-Ofelt analysis and luminescence characteristics of Eu3+ doped Nepheline (NaAlSiO4)-based glass ceramics for solid-state lighting applications

The present work addresses on the optical and spectroscopic properties of glass ceramics containing a hexagonal NaAlSiO4 crystalline phase (Nepheline) and Eu3+ dopant, prepared by melt-quenching technique followed by subsequent heat treatment. The precipitation of NaAlSiO4 crystals in the glass system with increasing heating temperature was determined by XRD analysis. The existing vibrational bands such as BO3, BO4, SiO2 and O-H groups in the glass network and the increase in the amount of non-bridging oxygens with increasing heating temperature of the precursor glasses were evaluated through FTIR spectroscopy. Morphological changes in the glass surface induced with the growth of NaAlSiO4 crystals is recorded by field emission scanning electron microscopy at resolutions of 1 µm and 200 nm. The impact of heating temperature and Eu3+ ions embedded in the NaAlSiO4 crystalline phase on the optical properties was studied using absorption spectra, excitation, emission spectra, and decay curves. The glass ceramics exhibited a decrease in their bandgap energy values and an increase in their Urbach energy values with heat treatment at higher temperatures. The Judd-Ofelt (J-O) intensity parameters evaluated from the emission spectra showed the trend Ω2>Ω4. The emission bands with intense electric dipole transition 5D0→7F2, long decay lifetimes, and improved quantum efficiency of Eu3+ ions evidenced the partitioning of Eu3+ ions into the NaAlSiO4 crystalline phase. Radiative calculations from the emission spectra showed a higher stimulated emission cross-section for glass ceramics. The CIE-1931 color coordinates, correlated color temperature (CCT, K), and color purity measurements favoured red emission from Eu3+ ions with better quality. Therefore, the prepared glass ceramics can favour the need for LED applications and laser devices.

Study of Eu3+–Gd3+ co-doped Ba–Bi–B glasses for red-laser applications: Physical, structural, photoluminescence and time-resolved spectral characteristics

A series of Eu3+ and Eu3+/Gd3+ co-doped barium-bismuth-borate (Ba–Bi–B) glasses were prepared by melt-quench technique. And deliberated the physical, structural, and spectroscopic properties of all glasses and explored the energy transfer process from Gd3+ to Eu3+ ions. The density of glasses increased with increasing of Gd3+ concentration in co-doped glasses. Characteristics of steady-state and time-resolved photoluminescence (PL) of Eu-doped and Eu3+-Gd3+ co-doped glasses under different excitation wavelengths suggested the prospects of the investigated glass system for display device applications. PL spectrum displays a strong red emission peak centered at 612 nm due to the Eu3+: 5D0→ 7F2 transition. Less intense emissions centered at 577 nm (7F0), 590 nm (7F1), 651 nm (7F3) and 700 nm (7F4) are also observed from the radiative transitions of the excited state 5D0 of Eu3+ions. The values of radiative parameters such as transition probability, branching ratios, and stimulated emission cross-sections were obtained from Judd–Ofelt theory analysis and indicated the aptness of the Ba–Bi–B glasses for optical devices. A 5-fold enhancement in the PL intensity was observed in 1.0 mol% Eu3+ and 3.0 mol% Gd3+ co-doped glass under λExci. = 394 nm excitation. The calculated commission Internationale de l'eclairage color coordinates and correlated color temperature values show that the Ba–Bi–B glasses are useful for red-laser and display device applications.

Comprehensive study of spectroscopic and holographic properties of the chlorine-containing photo-thermo-refractive glass doped with neodymium ions

A study of the optical, spectral-luminescent and holographic properties of the chlorine-containing photo-thermo-refractive (PTR) glass doped with neodymium ions was carried out. The chlorine-containing PTR glass has been recently produced by replacing the bromine in the standard PTR glass with chlorine. The glass was doped with different concentrations of neodymium ions. The spectroscopic analysis of neodymium in the glass has been performed using the Judd-Ofelt theory based on experimental absorption and emission measurements. Spectroscopic parameters, such as the Judd-Ofelt intensity parameters, radiative and non-radiative transition probabilities, fluorescence lifetimes, stimulated emission cross-sections, and branching ratios, were obtained and found to be comparable with the parameters of the standard PTR glass doped with neodymium. The mechanism of non-radiative energy transfer was analyzed based on the lifetime kinetics measurements. It was found that cross-relaxation among neodymium ions is the dominant non-radiative energy transfer mechanism.Holographic characteristics of the chlorine-containing PTR glasses doped with neodymium have been also studied. The volume Bragg grating was recorded in the doped and undoped glasses. It was found that the UV exposure and heat treatment do not change the spectroscopic characteristics of neodymium ions in the glasses, while the neodymium ions reduce the sensitivity of the glass. The energy transfer from cerium to neodymium when irradiating using the 325-nm laser makes the hologram recording possible on the samples of low neodymium concentrations only. Studying the spectroscopic and holographic properties of the chlorine-containing PTR glass doped with neodymium ions demonstrates the potential of using such a material in the applications of photonics integration and monolithic optical devices like distributed-feedback lasers.

Highly efficient hexagonal-phase Nd3+ doped KLaF4 nanoparticles colloidal suspension for liquid lasers

Innovative approach in the exploration of high-power liquid laser media, utilizing hexagonal KLaF4: x% Nd3+ (x = 1–30 mol%) nanoparticle colloidal solutions synthesized from one-step chemical route is hereby presented. The phase purity and nano size distributions of the nanoparticles are confirmed from X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The concentration dependent absorption and steady-state and dynamic infrared emission (at 1058 nm, 4F3/2 → 4I11/2) features of Nd3+ ion of KLaF4: x% Nd3+ liquid media are closely examined. The estimated stimulated emission cross-sections, branching ratios and quantum efficiencies establishes the potentiality of these hexagonal nanoparticle colloidal solutions for high power liquid laser applications. Inokuti-Hirayama (I–H) and diffusion dominated Yokota-Tanimoto (Y-T) models are employed to examine the dynamic emission evolution of KLaF4: x% Nd3+ (x ≥ 5–30 mol%). The proposed study substantiate that the colloidal solution can serve as a new laser media for low-cost and high-energy liquid lasers and amplifiers.

Photophysical, optical and lasing analysis of fluorinated β-keto carboxylate europium(III) complexes

Six luminescent, bright red Eu(III) complexes with a β-keto-carboxylic acid as prime ligand and N-donor aromatic systems as auxillary ligand were synthesised via ecologically efficient grinding method. The distinctive red peak (5D0 → 7F2) of Eu(III) ion is exhibited in emission spectra of all complexes. The luminescent properties of complexes were analysed through decay time, color coordinates, luminescence efficiency and Judd Ofelt parameters. The value of Ω2 is found to be higher than Ω4 which indicated hypersensitive nature of 5D0 → 7F2 transition. The results established the complexes as a strong contender for red light emitting display devices. The fluorescence branching ratios, stimulated emission cross section, gain band width and optical gain showed the good lasing strength of 5D0 → 7F2 transition of complexes. The complexes exhibited decent thermal stability and have optical energy band gap value in semiconductor range, thus can have relevance in optoelectronic devices. Energy transfer mechanism was investigated for complexes which affirmed the efficacious transfer of energy from ligands to Eu(III) ion. The synthesised complexes were also assayed for antimicrobial and antioxidant properties. All complexes are reported to show better antioxidant behaviour than the prime ligand and also exhibited upstanding antibacterial activities.

Exploration of modifier based structural and spectroscopic traits of Eu3+ doped boro-tellurite glasses for solar UV photons converting applications

A new series of stable host glass with different modifier cations have been formed with the molar composition15XO + 39B2O3 + 25TeO2 + 10Na2O + 10K2O + 1Eu2O3 (X = Li2, Ca, Sr, Ba, Zn) through traditional glass preparation technique of melt quenching. The effect caused by the incorporation of modifier cations on the radiative assets of Eu3+ ions in the present host glass were inspected through X-ray Diffraction (XRD), Fourier Transformed Infra-Red (FTIR), UV–vis-NIR, photoluminescence and luminescence decay spectral studies at room temperature. The broad diffraction band in the XRD pattern confirms glassy or amorphous nature of the synthesized samples. The functional modes of vibration and structural modules in the prepared glass samples were inspected through FTIR spectra. The 4f − 4f electronic transitions pertaining to the trivalent europium (Eu3+) ions in the new host glasses were scrutinized by UV–vis-NIR absorption studies where in the dominant covalent bonding nature of the Eu3+ ions with its nearby ligands have been confirmed via average nephelauxetic ratio (β) and bonding parameter(δ) values. Optical bandgap (indirect and direct) values were testified to identify the photon energy transparent window and to explore the tendency of the formation of non-bridging oxygens. Luminescence ability of the prepared samples was inspected by exciting at a wavelength of 465 nm. Among the prepared samples, Eu3+ ions emissions were observed and the highest intensity of emission occurred at 612 nm (5D0→7F2) for BTLi:Eu glass. The Judd-Ofelt parameters were estimated and used to evaluate the radiative parameters such as radiative lifetime (τrad), transition probability (A), branching ratio (βR), stimulated emission cross-section (σPE) of all the emissions observed in the produced glasses and the outcomes were equated with the related literature. The colour chromaticity coordinates and colour correlated temperature (CCT) were explored from the emission spectra using CIE 1931 diagram and the CCT values found to lie in the range of 2000–4000 K. The luminescence decay comfortably fitted to the single exponential decay profile which further confirms the non-appearance of energy transfer via mutual interaction amongst Eu3+ ions in all the present glasses. All the observed results indicate the fact that the incorporation of Li+ cations induces more attractive radiative features with 77 % of UV to visible quantum converting efficiency than all other cations used in this contemporary study and among the prepared glasses, BTLi:Eu glass exhibits a better capability in red light emitting electro-optical applications.

Spectral and FTIR Analysis of Dy3+ ions doped Zinc Lithium Cadmium Magnesium Borophosphate Glasses

Abstract: Glass of the system: (40-x) P2O5:10ZnO:10Li2O:10CdO:10MgO:20B2O3: xDy2O3. (where x=1, 1.5,2 mol %) have been prepared by melt-quenching method. (where x=1,1.5 and 2 mol%) have been prepared by melt-quenching technique. The amorphous nature of the prepared glass samples was confirmed by X-ray diffraction. Optical absorption, Excitation, fluorescence and FTIR spectra have been recorded at room temperature for all glass samples. Judd-Ofelt intensity parameters Ωλ (λ=2, 4 and 6) are evaluated from the intensities of various absorption bands of optical absorption spectra. Using these intensity parameters various radiative properties like spontaneous emission probability, branching ratio, radiative life time and stimulated emission cross–section of various emission lines have been evaluated

Tunable continuous-wave laser operation of Tm3+ ion doped tellurite glass near 2 μm

We provide an experimental investigation of the absorption saturation and 1.9-μm lasing characteristics of a bulk Tm3+:TZLN glass with the host composition of 74TeO2–12ZnO–4La2O3–10Na2O. By using a z-scan saturation measurement, the absorption cross section at 794 nm was determined to be 5×10−21cm2, in reasonable agreement with the value of 6×10−21cm2 obtained from small-signal transmission measurement. In lasing experiments, double pumping was employed at 794 nm and the bulk Tm3+:TZLN glass laser operated at the free running wavelength of 1926 nm. As high as 15.4 mW of continuous-wave output power was obtained with a 2.15% transmitting output coupler at the absorbed pump power of 284 mW. The slope efficiency with respect to the absorbed pump power was 7.1%. By using the threshold and power efficiency data, the stimulated emission cross section was further determined to be 6.8×10−21cm2at 1926 nm. Finally, continuous tuning of the laser output was demonstrated between 1845 and 1973 nm by using a quartz birefringent plate.

Nd3+ doped [formula omitted] glass systems: Structural and optical properties

The structural and optical characteristic features of B2O3 + Li2O + CaO + CaF2 (BLCofNd) glasses incorporated with Nd3+ as a dopant of different concentrations (mol%) are reported. The X-ray diffraction technique was used to study structural characteristics such as the amorphous nature of BLCOFNd glass samples, Infrared spectroscopy was used to investigate the presence of functional groups and their impact on optical characteristics (FTIR), It reveals the creation of a network by borate and other components with the characteristics of glasses demonstrating different stretching and oscillating behavior of borate functional groups. The recorded UV Vis-NIR spectra of BLCofNd glasses reveal the prepared glasses have strong absorption at 584 nm in the visible region and 805 nm in the NIR region for the transitions 4I9/2→4G5/2 and 4I9/2→4F5/2, these transitions are due to the excitation of electrons by induced absorption. The density (gm/cc) measurements seem to be a rise in the values with a proportionality increase in CaO concentration (mol%), which directly relates to the decrease in the interionic distance (ri) making the glasses optically dense. Judd–Ofelt intensity parameters (Ω2, Ω4 and Ω6) highlights a covalency symmetry with a higher degree and surrounding lattice distribution of Nd3+ ions with other glass elements present in the network. The radiative properties of BLCOFNd glass samples mainly relate to parameters of radiative transition probability (AR), and corresponding branching ratios (βcal and βrad), which are derived from oscillator strength (fexp) measurements, FWHM or peak bandwidth (Δλp), stimulated emission cross-section and gain bandwidth (σse. Δλp) foresees that BLCofNd glasses are best candidates for laser host materials. The neodymium-doped borate glass exhibits a high peak power due to its emission at 1.049 μm wavelength and has its applications as lasing material and is prominently used as a source to produce the secondary waves in the measurement of pollutants in the atmosphere, optical amplifiers, and in the industry for their high intensity in emitted radiation.

Mid-IR spectroscopy of Er3+doped low-phonon CsCdCl3and CsPbCl3crystals

The mid-IR spectroscopic properties ofEr3+doped low-phononCsCdCl3andCsPbCl3crystals grown by the Bridgman technique have been investigated. Using optical excitations at∼800nmand∼660nm, both crystals exhibited IR emissions at∼1.55,∼2.75,∼3.5, and∼4.5µmat room temperature. The mid-IR emission at 4.5 µm, originating from the4I9/2→4I11/2transition, showed a long emission lifetime of∼11.6msforEr3+dopedCsCdCl3, whereasEr3+dopedCsPbCl3exhibited a shorter lifetime of∼1.8ms. The measured emission lifetimes of the4I9/2state were nearly independent of the temperature, indicating a negligibly small nonradiative decay rate through multiphonon relaxation, as predicted by the energy-gap law for low-maximum-phonon energy hosts. The room temperature stimulated emission cross sections for the4I9/2→4I11/2transition inEr3+dopedCsCdCl3andCsPbCl3were determined to be∼0.14×10−20cm2and∼0.41×10−20cm2, respectively. The results of Judd–Ofelt analysis are presented and discussed.