Near-infrared Laser Applications Research Articles

Synthesis and spectroscopic analysis of NaCaYF6:Nd3+, Yb3+NIR emitting phosphor

Near Infra–red (NIR) emitting NaCaYF6:Nd3+and co–doped with Yb3+phosphor has been prepared by hydrothermal synthesis. The formation of Gagarinite structure of the host matrix with space group P63/m was confirmed by XRD and Rietveld analysis. FESEM analysis confirms the spherical morphology along with the homogeneity, and mapping of elemental composition by EDS analysis. NIR emission at 1065 nm due to 4F3/2→4I11/2 electronic transition of Nd3+ ion upon the exposure to 577 nm light. The prominent PL emission at 994 nm from NaCaYF6:Nd3+,Yb3+ phosphor was obtained due to 2F5/2→2F7/2 electronic transition of Yb3+ion. Yb3+ emission was sensitized by Nd3+ activator. The intensity of Yb3+emission increases at the cost of the Nd3+ luminescence. The results are ascribed to the energy transfer from Nd3+to Yb3+. The theoretical Judd-Ofelt (J-O) analysis was also reported to confirm the obtained luminescence behaviour and energy transfer (ET) mechanism of the phosphor. The obtained results specify that the phosphor has a potential application such as in–vivo, in−vitro imaging and NIR laser applications.

Optical spectroscopy of Nd3+-doped cadmium-rich borate glasses for near-infrared laser applications

The structural and spectroscopic properties of Nd3+-activated cadmium-rich borate (inverted) glasses are analyzed for near-infrared laser applications. The evaluation of the optimal glass-emitting sample by the Judd–Ofelt (JO) theory revealed JO parameter values of 4.56 × 10–20 cm2 (Ω2), 2.56 × 10–20 cm2 (Ω4), and 3.84 × 10–20 cm2 (Ω6). The Ω2 value, along with the experimental oscillator strength, suggested that the cadmium-rich borate glass could provide a more asymmetrical Nd3+ environment than other borate glasses like lithium-strontium-zinc, sodium-calcium, and lithium-lead-aluminum. In addition, the quality spectroscopy factor (χ = Ω4/Ω6) of 0.67 suggested that the 4F3/2 → 4I11/2 emission could be more suitable for laser applications. The stimulated emission cross-section (σp), theoretical quantum yield (ηQ), gain bandwidth (σp × Δλem), and optical gain (σp × τrad) laser parameters were close to those reported in sodium-calcium-borate, zinc-aluminum-barium-borate, and bismuth-borate glasses, while the non-radiative rate (WNR) and emission intensity saturation (IS) resulted to be lower. The emission spectra, under 808 nm laser excitation, displayed the featured neodymium 4F3/2 → 4I9/2,11/2,13/2 transitions, being the 4F3/2 → 4I11/2 (1058 nm) transition the more dominant one, in agreement with the χ parameter value. Nd3+ contents higher than 1.4 mol% led to emission quenching due to the increment of the cross-relaxation and/or energy migration rate. Such processes, according to the Inokuti–Hirayama model, were mainly mediated by electric dipole–dipole interactions within Nd–Nd clusters.

Selective near-infrared laser programming for shape-memory polymer–carbon nanotube composite material 4D printing

Abstract Light stimulation can realise the remote control of the deformation of the specific position of 4D printing structure. Shape-memory polymer–carbon nanotube (CNT) composite materials, with outstanding near-infrared photothermal conversion rate and shape-memory ability, is one type of the most popular light responsive smart materials. However, current studies focused on the photothermal effect and shape-memory applications of light-responsive shape-memory polymer composite (SMPC) sheet structures, and there is no research on the photothermal effect in the depth direction of light-responsive SMPC three-dimensional structures. Here, we prepared a UV curable, mechanically robust, and highly deformable shape-memory polymer (IBBA) as the matrix of light responsive SMPC. CNTs were added as photothermal conversion materials. We explore the photothermal effect of near-infrared laser on the surface and depth of IBBA–CNT composites cube. Shape-memory experiments show that different folded shapes can be obtained by selective near-infrared laser programming. Selective near-infrared laser programming three-dimensional movable type plate shows a programming application in depth direction of three-dimensional light-responsive intelligent structure. This research extends the application of near-infrared laser in 4D printing to the depth direction of intelligent structures, which will bring more complex and interesting 4D printing structures in the future.

LD-pumped all-solid-state single-longitudinal-mode Pr3+:LiYF4 laser at 915 nm

We report an InGaN laser diode (LD) pumped 915 nm single-longitudinal-mode (SLM) Pr3+:LiYF4 (Pr:YLF) laser for the first time. The all-solid-state 915 nm SLM laser is achieved by inserting two pieces of Fabry–Perot (F-P) etalons with different thicknesses in the resonant cavity. The maximum power of the SLM laser is ∼ 115 mW with the narrowest spectral linewidth of ∼ 110 MHz and the beam quality Mx2 and My2 factors are measured to be 1.16 (x) and 1.10 (y), respectively. In addition, we perform a theoretical simulation of combined F-P etalons transmittance. The experimental result is well-matched with the theoretical simulation. The first achievement of the 915 nm SLM Pr:YLF laser further expands the near-infrared laser applications.

Enhancing of 4F3/2 → 4I9/2 transition of Nd3+ doped BaO-Ga2O3– Al2O3–B2O3 glasses for near-infrared laser applications

Neodymium, Barium Gallium Aluminium Borate glasses having the composition of [35% B2O3 + 35% BaO + 15% Ga2O3 + (15-x)% Al2O3 + x% Nd2O3, (x = 0, 0.5, 1 and 2%)] were prepared using traditional melt quenching method. Physical properties such as refractive index (n), molar volume (VM), density (ρ), band-gap (Eg), and Urbach energy (ΔE) were measured and calculated. The results revealed that our glass has allowed indirect band-gap transitions and the addition of Nd3+ reduced the Eg energies from 3.24 to 3.01 eV. The Judd-Ofelt parameters were obtained using the least-square technique and they were used to compute the total radiative probability (At), radiative lifetime (τr), fluorescence branching ratio (Br), and quantum efficiency (η) for the meta-stable level 4F3/2. The glass system showed a high Spectroscopic factor (χ) ranging from 1.61 to 1.98. The Br showed that the 4F3/2 → 4I9/2 transition (883 nm) was enhanced at the expense of the 4F3/2 → 4I11/2 transition (1064 nm) and (4F3/2 → 4I13/2) transition (1342 nm). A relatively high quantum efficiency (η = 0.78) was noticed for our glass. Generally the spectroscopic properties and gain factor (γ) showed that the present glass system is a promising candidate for near-infrared laser applications (883 nm).

Fe3O4 Composite Superparticles with RGD/Magnetic Dual-Targeting Capabilities for the Imaging and Treatment of Non-Small Cell Lung Cancer.

In clinical practice, the incidence and mortality of non-small cell lung cancer are increasing year by year, which is a serious threat to the health of patients. Once the optimal surgical window is missed, the toxic side effects of chemotherapy have to be confronted. With the rapid development of nanotechnology in recent years, medical science and health have been greatly impacted. Therefore, in this manuscript, we design and prepare chemotherapeutic drug vinorelbine (VRL)-loaded polydopamine (PDA) shell-coated Fe3O4 superparticles, and further graft the targeted ligand RGD onto their surface. Because of the introduction of the PDA shell, the toxicity of the prepared Fe3O4@PDA/VRL-RGD SPs is greatly reduced. At the same time, due to the existence of Fe3O4, the Fe3O4@PDA/VRL-RGD SPs also have MRI contrast capability. Under the dual-targeting effect of RGD peptide and external magnetic field, Fe3O4@PDA/VRL-RGD SPs can accumulate into tumors effectively. The accumulated superparticles in the tumor sites can not only effectively identify and mark the location and boundary of the tumor under MRI, guideing the application of near-infrared laser, but also release the loaded VRL under the stimulation of the acidic microenvironment of the tumor to play the role of chemotherapy. On further combination with photothermal therapy under laser irradiation, A549 tumors are completely eliminated without recurrence. Our proposed RGD/magnetic field dual-targeting strategy can effectively improve the bioavailability of nanomaterials and contribute to better imaging and therapeutic effects, which has a promising application prospect in the future.

Yb3+, Er3+: CeF3 crystals: Growth, first-principles simulation, and near-infrared optical properties

Yb3+, Er3+: CeF3 crystals were successfully grown via Bridgman-Stockbarger technique, and their structure and physicochemical properties were characterized and analyzed. The results have shown that the maximum phonon vibrational frequency of the crystals is 391 cm−1. Under 980 nm excitation, Yb3+ ions doping can effectively improve the luminescence intensity at 1550 nm. The maximum luminescence intensity was achieved at the Yb3+ ion concentration of 3 at.%. The energy transfers, concentration quenching mechanisms and the factors affecting the fluorescence decay time were investigated in detail. The band gap structure, density of states and charge distribution of Yb3+, Er3+: CeF3 crystals were studied in depth by first principles simulation. This work proves that Yb3+, Er3+: CeF3 crystals have great potential for the near-infrared laser applications.

Spectroscopic analysis of Nd3+-doped cadmium-vanadate invert glasses for near-infrared laser applications

Nd3+ activated CdO-V2O5 invert glasses were synthesized by the well-stablished melt quenching technique, using starting proportions of 95.0 and 5.0 mol% of CdO and V2O5, respectively. The XRD patterns revealed that the glass system remains amorphous up to 4.0 mol% of Nd3+. Such fact was mainly attributed to the low V2O5 content, which avoided the segregation of additional phases. The minimal addition of 0.1 mol% of Nd3+ reduced the direct and indirect glass bandgap energies from 2.79 to 2.66 eV, and from 2.48 to 2.13 eV, respectively. For higher Nd3+ contents, the bandgap energy was recovered, reaching values of 2.78 and 2.40 eV for direct and indirect allowed transitions, respectively. This fact was associated with a Burstein-Moss like effect, observed in semiconductors highly doped. The tail of the absorption edge revealed that the Urbach energy systematically grows with the addition of Nd3+, because of the creation of localized states into the bandgap. The Judd-Ofelt (JO) parameters obtained by least-square method from the experimental and theoretical oscillator strengths, were found in the Ω2 = 5.24-11.04 × 10−20 cm2, Ω4 = 2.26-4.47 × 10−20 cm2, and Ω6 = 2.85-6.28 × 10−20 cm2 range. Such values are close to those reported in other popular glass systems. The stimulated emission cross-section peak (σp) values calculated for the glass sample doped with 2.0 mol% resulted to be 0.26 × 10−20 cm2 (Nd3+: 4F3/2 → 4I9/2) and 0.81 × 10−20 cm2 (Nd3+: 4F3/2 → 4I11/2). The Nd3+ emission spectra, recorded upon 585 nm excitation (Nd3+: 4I9/2 → 4G5/2 + 2G7/2), showed the near-infrared Nd3+ emission bands at 881 nm (Nd3+: 4F3/2 → 4I9/2), 1063 nm (Nd3+: 4F3/2 → 4I11/2) and 1341 nm (Nd3+: 4F3/2 → 4I13/2), being dominated for that coming from the Nd3+: 4F3/2 → 4I11/2 transition. The overall emission reached the optimum intensity at 2.0 mol% of Nd3+, with a maximum quantum efficiency (ηQE) of 0.23. From the emission spectra important laser parameters such as gain bandwidth (σEMI(λp) × Δλem) and optical gain (σEMI(λp) × τR), were determined for the sample with the highest ηQE value. The σEMI(λp) × Δλem values resulted to be 11.3 and 32.0 × 10−27 cm3 for the Nd3+: 4F3/2 → 4I9/2, 11/2 transitions, respectively. The σEMI(λp) × τR parameter values were 11.1 and 35.3 × 10−25 cm2s for Nd3+: 4F3/2 → 4I9/2,11/2 transitions, respectively. The Inokuti-Hirayama model suggested that the Nd3+ cross-relaxation process might be dominated by an electric dipole-dipole interaction, inside Nd3+-Nd3+ clusters.

Homotypic biomimetic coating synergizes chemo-photothermal combination therapy to treat breast cancer overcoming drug resistance

Breast cancer (BC) is a leading cause of death in women worldwide and multidrug resistance (MDR) severely limits its treatment since chemotherapy is the standard approach for treating BCs. In this work, high biocompatibility resulted from biomimetic coating, magnetic and homotypic targeting plus triggered release properties were integrated in one smart drug delivery system (DDS) to overcome drug resistance and to achieve combination cancer therapy. MCF-7 cancer cell membrane coating was applied to chitosan-PLGA based DDS entrapping photothermal iron oxide nanoparticles (PIO NPs), Doxorubicin (Dox) and Mcl-1-siRNA. Such coating facilitated homotypic targeting of MCF-7/ADR cells, whereas PIO NPs facilitated magnetic targeting by the external magnetic field, thereby resulting in high in vitro cellular uptake and in vivo accumulation at the tumor site. Upon NIR (near-infrared) laser irradiation and at acidic pH, the DDS exhibited triggered release. The cytotoxicity of Dox on MCF-7 and MCF-7/ADR cells significantly improved by the developed DDS due to increased intracellular Dox accumulation. Application of NIR laser and external magnetic field resulted in maximum therapeutic outcome utilizing chemo-photothermal combination and the DDS was able to inhibit almost 80% tumor growth in MCF-7/ADR tumor model. This new nanoplatform holds strong promise in BC therapy and can be exploited to treat other cancers.

Magneto-optic pyrochlore ceramics of Tb2Hf2O7 for Faraday rotator.

In the first demonstration of the Faraday effect in an optical-grade Tb2Hf2O7 (THO) ceramic, its optical properties and the Verdet constant's wavelength dependence were evaluated at room temperature. The transmittance loss of this material was equally low as for the terbium gallium garnet, a well-known magneto-optic material. The Verdet constant at 1064 nm was 50.4 rad/Tm, which was 1.4 times greater than that of the terbium gallium garnet. THO ceramics show great potential for use in Faraday devices in near-infrared laser applications.

Band Structure and Optical Gain of InGaAs/GaAsBi Type-II Quantum Wells Modeled by the k · p Model**Supported by the National Basic Research Program of China under Grant No 2014CB643902, the Key Program of Natural Science Foundation of China under Grant No 61334004, the National Natural Science Foundation of China under Grant No 61404152, and the Strategic Priority Research Program of

Optical gains of type-II InGaAs/GaAsBi quantum wells (QWs) with W, N, and M shapes are analyzed theoretically for near-infrared laser applications. The bandgap and wave functions are calculated using the self-consistent k · p Hamiltonian, taking into account valence band mixing and the strain effect. Our calculations show that the M-shaped type-II QWs are a promising structure for making 1.3 μm lasers at room temperature because they can easily be used to obtain 1.3 μm for photoluminescence with a proper thickness and have large wave-function overlap for high optical gain.