Conversion Of Nd Research Articles

Designing Nd-doped bismuth selenide nanosheets with boosted photothermal conversion for imaging guided cancer therapy

Rational design and preparation of multifunctional low dimensional nanomaterials are of great importance for in vivo imaging and safety therapy. Meanwhile, nanomaterials with good bio-compatible and effectively photothermal conversion are still demanded to be fabricated in biomedicine. In this work, we have developed two-dimensional bismuth selenide nanosheets as the imaging and photothermal nanoagents. Through doping engineering, the near infrared photothermal conversion of Nd doped nanosheets was boosted by 52 %, which is higher than many previous works. Besides, the prepared nanomaterials can realize infrared and in vivo computed X-ray tomography bioimaging, due to the rich optical-magnetic properties of Nd atoms. The in vitro and vivo experiments with mice display that the Nd doped nanosheets have low toxicity and high biocompatibility. More importantly, the nanomaterials can efficiently achieve photothermal tumor ablation. It is suggested that designed and developed nanosheets have promising applications for biomedicine.

Insight into photon conversion of Nd3+ doped low temperature grown p and n type tin oxide thin films

p and n type SnOx thin films are successfully functionalized with optically active Nd3+ ions for efficient UV photon conversion.

Three-wavelength green laser using intracavity frequency conversion of Nd:Mg:LiTaO3 with a MgO:PPLN crystal

A green laser with multi-wavelength emission was demonstrated using intracavity frequency conversion (frequency doubling and frequency summing) in a Nd:Mg:LiTaO3 laser. MgO-doped periodically poled lithium niobate (MgO:PPLN) was used as a nonlinear crystal in this work. A 62 mW that could emit light at 546, 542 and 538 nm was obtained by end pumping with a 808-nm laser diode. The speckle contrast ratio for the three-wavelength laser was only 3.36 %, a quarter of the value of the conventional 532-nm laser.

Nonlinear optical conversion of Nd:glass laser multimode radiation into the second harmonic in KDP crystal

The second-harmonic generation (SHG) of Nd:glass multimode laser radiation in a 3 cm long KDP crystal has been studied both experimentally and theoretically for type I doubling at power densities of up to 2.5 GW cm−2, radiation divergence of 0.5–3.5 mrad and between 100–1000 transverse modes. The theoretical calculations of SHG were performed in the fixed-field approximation, fixed-intensity approximation and in the nonlinear regime. The maximum experimental conversion efficiency of 52% was obtained for the case of partially polarized radiation with divergence of 0.5 mrad and 100 transverse modes.

Efficient conversion of Nd:YAG laser radiationto the eye-safe spectral region by stimulated Raman scatteringin BaWO4 crystal

The possibility of increasing the efficiency of one-cascade 1.5-μm SRS lasing in a BaWO4 crystal placed into an external SRS cavity and pumped by a nanosecond Nd:YAG laser at a wavelength of 1.34 μm is studied. Conditions that prevent energy outflow to the second Stokes SRS component with a wavelength of 1.78 μm are found, which allowed us to increase the efficiency of one-cascade intracavity SRS lasing at 1.53 μm up to 60% and the slope efficiency up to the quantum limit (∼80% at the SRS pulse energy up to 20 mJ). The use of pumping by laser pulse trains provided the possibility of increasing the 1.53-μm SRS radiation energy to 40 mJ in a three-pulse train.

Optimization of single-layer sol-gel antireflection coatings on potassium dihydrogen phosphate crystals in quadrature geometry for second-harmonic conversion of high-power Nd:glass lasers

Quadrature geometry of two potassium dihydrogen phosphate crystals is a standard configuration to achieve efficient second-harmonic conversion of Nd:glass high-power lasers. Antireflection coatings on the entrance face of the first crystal and on the exit face of the second one are easily designed using quarterwave optical thicknesses adjusted separately for minimum reflectivity at the fundamental wavelength and at its second harmonic. It is however not possible to simultaneously obtain the lowest reflectivity for both the wavelengths on the inner faces. We describe a theoretical optimization of a single-layer sol-gel silica coating that allows maximum transmission of energy in the fundamental and second harmonic, taken together, across the inner faces of the two crystals. The optimum thickness is a function of the conversion efficiency to the second harmonic, and hence of the incident intensity of the fundamental wave. We have deposited sol-gel silica single-layer coatings of this optimum thickness, and the total reflectivity at fundamental and second-harmonic wavelengths taken together was measured and compared with the theoretically calculated values.

Structural evolution and Raman study of nanocarbons from diamond nanoparticles

Nanocarbons with a variety of morphologies were found after diamond nanoparticles (ND) were annealed at a low temperature. The conversion of ND to nanocarbons is a process of structural evolution that causes increase of sp 2 bonding structure and decrease of sp 3 bonding structure in nanostructure. While being annealed, ND are converted to carbon onions and undergo phase transition in a series of ND → bucky diamond → carbon onions → graphitic ribbons. The structural evolution of nanocarbons reflects the higher stability of planar graphitic ribbons over carbon onions.

Photocatalysis of neodymium ion modified TiO 2 sol under visible light irradiation

Nd 3+ ion modified TiO 2 sol was prepared by chemical coprecipitation–peptization method. The sol particles were well distributed in colloid system and mean size was 10 nm by AFM analysis. Direct conversion of Nd 3+–TiO 2 sol particles from amorphous to semicrystalline phase was achieved at 62 °C and pH 1.0 with 12 h peptizing process. Photocatalytic reactivity of Nd 3+–TiO 2 sol was evaluated by photodegradation of phenol in solution under visible light irradiation. It was found that concentration decreased from initial 100 mg l −1 phenol to final 5.29 mg l −1 phenol and 75.2 mg l −1 phenol derivatives after 2 h photocatalysis This result indicates that Nd 3+–TiO 2 nanocolloids exhibited photocatalytic activity in the visible range. Meanwhile, total organic carbon (TOC) value declined from initial 37.1 mg l −1 to final 29.3 mg l −1, which indicates the weak capability of photomineralization, but the power of selective photocatalysis. The reaction mechanism of Nd 3+–TiO 2 sol photocatalysis was proposed as the process of self-sensitization and sub-bandgap overlapping.

Determination of the optimum phase-matching directions for the self-frequency conversion of Nd:GdCOB and Nd:YCOB crystals

We report on the nonlinear optical properties of Nd:Ca 4GdO(BO 3) 3 (Nd:GdCOB) and Nd:Ca 4YO(BO 3) 3 (Nd:YCOB) biaxial crystals by theoretical calculation. The phase-matching curves for the self-frequency conversion generation of both crystals are presented. The dependence of the effective nonlinear coefficients and walk-off angles on different phase-matching directions are discussed. The results show that the optimum type-I phase-matching directions for the self-frequency doubling and self-sum-frequency mixing lasers are not in the principal planes but are located respectively in the directions ( θ=67.1°, ϕ=132.35°) and ( θ=68.75°, ϕ=118.1°) for Nd:GdCOB, and ( θ=66.5°, ϕ=143.4°) and ( θ=65.9°, ϕ=134.1°) for Nd:YCOB.

Ultrafast picket fence pulse trains to enhance frequency conversion of shaped inertial confinement fusion laser pulses

A high-frequency train of 5-100-ps pulses (picket fence) is proposed to improve significantly the third-harmonic frequency conversion of Nd:glass lasers that are used to generate high-contrast-shaped pulses for inertial confinement fusion (ICF) targets. High conversion efficiency of the low-power foot of a shaped ICF pulse is obtained by use of a low duty cycle, multi-gigahertz train of approximately 20-ps pulses with high peak power. Even with less than 10% duty cycle, continuous illumination is maintained on the target by a combination of temporal broadening schemes. The picket fence approach is analyzed, and the practical limits are identified as applied to the National Ignition Facility laser. It is found that the higher conversion efficiency allows approximately 40% more third-harmonic energy to be delivered to the target, potentially enabling the larger drive needed for high-yield ICF target designs. In addition, the frequency conversion efficiency of these short pulses saturates much more readily, which reduces the transfer of fluctuations at the fundamental and thus greatly improves the power stability of the third harmonic.

Harmonic generation in organic dye vapors

Investigations of nonlinear optical frequency conversion of Nd:YAG laser radiation in naphthalene vapors are presented. The third harmonic generation (THG) caused by difference frequency generation in six-photon process has been studied. Phase-matching temperature for naphthalene vapor was found to be 170°C, at which synchronous conversion of pump radiation to the third harmonic was carried out. The THG conversion efficiency varied within 10 −10–10 −8 depending on pump intensity and cell temperature. Third- and fifth-order nonlinear optical susceptibilities were calculated and compared with the experimentally measured fifth-order susceptibility of naphthalene vapors.

Increased frequency conversion of Nd:YAG laser radiation with a variable-reflectivity mirror: erratum

The frequency-doubling efficiency of a Nd:YAG laser was increased by using a variable-reflectivity-mirror unstable resonator. At 5 Hz as much as 385 mJ of green light was obtained with an efficiency of 61%. The divergence of the converted light, which was 0.26 mrad at 0.5 Hz, close to the diffraction limit, increased to 0.69 mrad at 5 Hz.

Increased frequency conversion of Nd:YAG laser radiation with a variable-reflectivity mirror

The frequency-doubling efficiency of a Nd:YAG laser was increased by using a variable-reflectivity-mirror unstable resonator. At 5 Hz as much as 385 mJ of green light was obtained with an efficiency of 61%. The divergence of the converted light, which was 0.26 mrad at 0.5 Hz, close to the diffraction limit, increased to 0.69 mrad at 5 Hz.

High-Efficiency Frequency Conversion of Nd: YAG Laser Radiation

High-Efficiency Frequency Conversion of Nd: YAG Laser Radiation

Frequency conversion of Nd:YAG laser radiation in RDA

Frequency doubling and tripling of a Nd:YAG laser has been studied in a rubidium dihydrogen arsenate (RDA) crystal. An overall power conversion efficiency of 34% and 12% has been obtained for doubling and tripling, respectively. Some comparison with rubidium dihydrogen phosphate (RDP) crystal is reported for the generation of the third-harmonic radiation at 3547 Å.