Optical Damage Resistance Ability Research Articles

Photorefractive Properties of Molybdenum and Hafnium Co-Doped LiNbO3 Crystals

A series of LiNbO3: Mo, Hf crystals with 0.5 mol % fixed MoO3 and various HfO2 concentrations (0.0, 2.0, and 3.5 mol %) were grown by the Czochralski technique. The photorefractive properties of the LiNbO3: Mo, Hf crystals were investigated by two-wave coupling measurements and the beam distortion method was employed to obtain the optical damage resistance ability. The UV-visible and OH− absorption spectra were also studied. The experimental results imply that the photorefractive properties of LiNbO3: Mo crystals at laser wavelengths of 532, 488, and 442 nm can be greatly enhanced by doping HfO2 over the threshold concentration. At 442 nm especially, the response time of LN: Mo, Hf3.5 can be shortened to 0.9 s with a diffraction efficiency of 46.07% and a photorefractive sensitivity reaching 6.28 cm/J. Besides this, the optical damage resistance at 532 nm is 3 orders of magnitude higher than that of the mono-doped LiNbO3: Mo crystal, which is beneficial for applying it in the field of high-intensity lasers.

Birefringence Gradient and Exposure Energy of Hf:Yb:Nd:LiNbO3 Crystals with Various [Li]/[Nb] Ratios

A series of Hf:Yb:Nd:LiNbO3 crystals with different [Li]/[Nb] ratios (0.946, 1.05, 1.20, and 1.38) were grown using the Czochralski method. X-ray diffraction phase results of the samples show that the LiNbO3 doped Hf4+, Yb3+, and Nd3+ only have a slight change in the lattice constant. The birefringence gradient of the HfYbNd4 sample measured using the birefringence gradient method was 3.3 × 10−5 ∆R/cm−1, which was the best optical uniformity. The optical damage resistance ability was measured using the light-induced scattering exposure energy flus threshold method. When the [Li]/[Nb] ratios in the melt achieve 1.38, the exposure energy achieves 120.74 J/cm2, which is approximately 87 times higher than HfYbNd1.

Dopant occupancy and exposure energy in Hf:Nd:LiNbO3 crystal as a function of [Li]/[Nb] ratios

A series of Hf: Nd: LiNbO3 crystals with various [Li]/[Nb] ratios ([Li]/[Nb] = 0.94, 1.05, 1.20, 1.38) in the melt were grown by conventional Czochralski technique. The distribution coefficients of Hf4+ and Nd3+ ions were recorded by an inductively coupled plasma-atomic emission spectrometer (ICP-AES). The effective distribution coefficient of Hf4+ is reduced and that of Nd3+ is increased with the increase of [Li]/[Nb] ratio in the melts. In all cases, the effective distribution coefficients is less than 1. The IR transmission spectroscopy of the Hf: Nd: LiNbO3 crystals were measured, getting the results that Hf: Yb: Ho: LiNbO3 crystals with 1.05 [Li]/[Nb] ratios was the stoichiometric. The optical damage resistance ability of Hf:Nd:LiNbO3 crystals were studied by light-induced scattering exposure energy flux threshold method and it increases with the increasing of [Li]/[Nb] ratios. When the [Li]/[Nb] ratio is 1.38 in the melt (the sample 4#), the exposure energy achieves 687.35 J/cm2, approximately 441 folds than that of the sample 1# ([Li]/[Nb] = 0.94) in magnitude.

Optical properties of Mg2+, Yb3+, and Ho3+ tri-doped LiNbO3 crystals**Project supported by the National Natural Science Foundation of China (Grant No. 51301055), the Youth Science Fund of Heilongjiang Province, China (Grant No. QC2015061), the Special Funds of Harbin Innovation Talents in Science and Technology Research, China (Grant No. 2015RQQXJ045 ), and the Science Funds for the Young Innovative Talents of

A series of LiNbO3 crystals tri-doped with Mg, Yb, and Ho are grown by the conventional Czochraski technique. The concentrations of Mg, Yb, and Ho ions in Mg:Yb:Ho:LiNbO3 crystals are measured by using an inductively coupled plasma atomic emission spectrometry. The x-ray diffraction is proposed to determine the lattice constant and analyze the internal structure of the crystal. The light-induced scattering of Mg:Yb:Ho:LiNbO3 crystal is quantitatively described via the threshold effect of incident exposure energy flux. The exposure energy () is calculated to discuss the optical damage resistance ability. The exposure energy of Mg(7 mol):Yb:Ho:LiNbO3 crystal is 709.17 J/cm2, approximately 425 times higher than that of the Mg(1 mol):Yb:Ho:LiNbO3 crystal in magnitude. The blue, red, and very intense green bands of Mg:Yb:Ho:LiNbO3 crystal are observed under the 980-nm laser excitation to evaluate the up-conversion emission properties. The dependence of the emission intensity on pumping power indicates that the up-conversion emission is a two-photon process. The up-conversion emission mechanism is discussed in detail. This study indicates that Mg:Yb:Ho:LiNbO3 crystal can be applied to the fabrication of new multifunctional photoluminescence devices.

Investigations on growth and property of mid-infrared lithium selenoindate single crystals

Lithium selenoindate (LiInSe2) crystals with high optical quality are successfully grown by small-angle inclined horizontal temperature gradient condensation. In order to evaluate the various characteristics, the powder X-ray diffraction (XRD) spectrum, optical damage resistance ability and Vickers hardness in lithium selenoindate crystals were studied. The growth crystals have orthorhombic nature, a = 6.184 Å, b = 7.092 Å and c = 8.207 Å. The damage thresholds of LiInSe2 crystal with the front face and back face were 224 mW/cm2 and 165 mW/cm2. Also the Vickers hardness number of LiInSe2 crystal was found to be 342.4 kg/mm2.

Influence of dopants on the optical damage and absorption edge in doped LiNbO3 crystals

The optical damage resistance ability of the co-doped M:Fe:LiNbO3 crystals with 0.03wt% Fe2O3 and various concentration of M (M=Mn, Mg, or Zn,) were measured experimentally. The shift of the fundamental absorption edge as well as the absorption coefficient was obtained in order to investigate their defect structures. A method of confirming the polarization ability dimension of doped ions is brought forward. The indirect transition properties of the fundamental absorption edge below 3.8eV were investigated experimentally. Possible models to explain the experiments results are discussed.

Comparisons and analyses of the properties of laser-induced damage to SiO2 and ZnS

To compare the optical damage resistance ability of SiO2 and ZnS, the processes of electrons reproduction of the two materials have been studied. The relationship of multiphoton ionization rate, avalanche ionization rate and the multiphoton parameter < x + 1 > with the intensity of the incident laser is calculated. The damage thresholds induced by the laser with different pulse widths are calculated too. In addition, the respectable role of the recombination and diffusion for an electron in the electronic proliferation processes is examined. Calculation results show that SiO2 has a higher damage threshold while τ < 1 ns, and ZnS has a higher damage threshold while τ > 1 ns.

Influence of In2O3 codoping on the upconversion emission properties of Er3+-doped near-stoichiometric LiNbO3 crystals

Two near-stoichiometric lithium niobate (NSLN) crystals codoped with Er3+(1mol%) and In3+ (0 and 0.3mol%) were grown from Li-rich melt ([Li]/[Nb]=1.38, molar ratio) by the conventional Czochralski method. The Er, In contents and [Li]/[Nb] ratios in the crystals were measured by an inductively coupled plasma atomic emission spectrometer (ICP-AES). The OH− absorption spectra were investigated to characterize the defect structure of the crystals. The optical damage resistance ability was characterized by the transmission facula distortion method. The results indicate that the optical damage resistance ability is enhanced by one order of magnitude for Er:NSLN codoped with 0.15mol% In2O3. The electronic transitions of Er3+ ions were analyzed based on ultraviolet–visible absorption spectra. The upconversion fluorescence spectra excited by an 800nm femtosecond laser were measured at room temperature. The results show that three emission peaks centered at 535, 551 and 673nm exist in both crystals and the intensities at these three peaks of In:Er:NSLN are larger than those of Er:NSLN, but an additional 400nm peak appears in In:Er:NSLN. The 400nm emission peak is verified experimentally to be the second harmonic generation of 800nm light.

Optical damage resistance of Hf:Fe:LiNbO3 crystals with various [Li]/[Nb] ratios

AbstractHf:Fe:LiNbO3 crystals were grown in air by the Czochralski technique with various [Li]/[Nb] ratios ([Li]/[Nb]=0.94, 1.05, 1.20) in melt. The defect structure and location of doped ions were analyzed by the UV‐visible absorption spectra. The optical damage resistance of Hf:Fe:LiNbO3 crystals was investigated by the photoinduced birefringence change and the transmitted light spot distortion method. The results show that the optical damage resistance ability of Hf:Fe:LiNbO3 crystals decreases with the increase of the [Li]/[Nb] ratio. The dependence of the optical damage resistance of Hf:Fe:LiNbO3 crystals on the defect structure is discussed in detail. (© 2011 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Growth and property of Zn-doped near-stoichiometric LiTaO 3 crystal

Near-stoichiometric LiTaO 3 (SLT) and Zn-doped near-stoichiometric LiTaO 3 (Zn:SLT) crystals with 10–15 mm in diameter and 10 mm in length were grown by using TSSG technique with K 2O as the flux. The effect of adding amount of K 2O was discussed in the growing process. The crystals were characterized by inductively coupled plasma-optical emission (ICP-OES), X-ray diffraction (XRD) and differential thermal analysis (DTA). The lattice constants of Zn:SLT were smaller than those of SLT and Curie temperature was higher than that of SLT. It was found that Zn doping is an efficient way to improve the optical damage resistance ability of SLT crystal. Compared with SLT crystal, Zn:SLT exhibited a much higher optical damage threshold, more than 500 MW/cm 2, which was attributed to Zn self-compensated effect that formed the charge compensated complexes, (Zn Ta) 3−–3(Zn Li) + in SLT crystal.

Defect structure and optical damage resistance of Hf:Fe:LiNbO 3 crystals

A series of Hf:Fe:LiNbO 3 crystals were grown by the Czochralski technique with various doping concentrations of HfO 2. Their defect structures were analyzed by the UV–visible absorption spectra and infrared absorption spectra. The optical damage resistance of Hf:Fe:LiNbO 3 crystals was measured by the photo-induced birefringence change and the transmitted light spot distortion method. The results show that the optical damage resistance ability of Hf:Fe:LiNbO 3 crystals enhances remarkably with the HfO 2 concentration increasing when the HfO 2 concentration is lower than its threshold concentration (4 mol%). However, when the HfO 2 concentration exceeds its threshold concentration, the optical damage resistance ability of the crystals returns to decrease. This unusual behavior is explained by using the photovoltaic field produced in the crystals.

Defect structure and optical damage resistance of Hf:Fe:LiNbO3 crystals with various [Li]/[Nb] ratios

AbstractHf:Fe:LiNbO3 crystals were grown in air by the Czochralski technique with various ratios of [Li]/[Nb]=0.94, 1.05, 1.20 in melt. The defect structure and location of doped ions were analyzed by the UV‐visible and infrared spectroscopy. The optical damage resistance ability of Hf:Fe:LiNbO3 crystals was measured by the photo‐induced birefringence change and the transmitted light spot distortion method. The results show that the optical damage resistance ability of Hf:Fe:LiNbO3 crystals is enhanced with the increase of the [Li]/[Nb] ratio. The dependence of the optical damage resistance of Hf:Fe:LiNbO3 crystals on the defect structure is discussed in detail. (© 2010 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Optical properties of Ce:Mn:LiNbO 3 crystals with various [Li]/[Nb] ratios

Ce(0.1 mass%):Mn(0.015 mass%):LiNbO 3 Crystals were grown by the Czochralski method from melts with various Li/Nb ratios (0.94, 1.05, 1.20, 1.38). Several spectra were used to investigate the influence of the Li/Nb ratio in the melt on the intrinsic defect and location of doped ions. As it can be seen, the lattice constants decrease, the Curie temperature increases, the absorption edge of Ce:Mn:LiNO 3 crystals has a violet shift, and the position of the infrared transmission peak has an Einstein shift with the increase of the Li/Nb ratio. The holographic storage properties were also measured by a two-beam coupling equipment, while the optical damage resistance ability of samples was scaled by the light spot distortion method. The maximal inflection of refractive index and the dynamic range of crystals were calculated. The results show that the holographic storage properties of the crystals are affected by the Li/Nb ratio. Among all samples, the Ce:Mn:LiNbO 3 crystal grown from the melt with the Li/Nb ratio 1.38 has the best holographic storage properties.

OH-absorption properties of the optical damage region in codoped In/Mg:LiNbO 3 crystals with various Li/Nb ratios

OH-absorption properties of the optical damage region in a series of codoped In/Mg:LiNbO 3 crystals with various Li/Nb ratios have been investigated. The OH −-associated vibrational peak at 3507 cm −1 is confirmed to occur in crystals with Li/Nb ratio of 0.94. For codoped In/Mg:LiNbO 3 crystals with Li/Nb ratio of 1.05 and 1.20, the OH −-associated vibrational peaks are detected at 3536 and 3507 cm −1 as well. A new peak at 3518 cm −1 attributed to a (In Nb) 2−–OH −–(Mg Nb) 3− defect center is revealed in crystals with Li/Nb ratio 1.38. When the “In–Mg threshold” concentration is reached, the optical damage resistance ability of codoped In/Mg:LiNbO 3 crystals is greatly improved.

Growth and Holographic Storage Properties of Sc, Fe Co-Doped Lithium Niobate Crystals

The holographic storage properties of Fe (0.03% (mass fraction) Fe 2O 3):LiNbO 3 doped with Sc at different levels (0, 1%, 2%, 3%) were investigated. The Sc threshold concentration in Fe:LiNbO 3 was implied to be about 3% (mole fraction) because O-H vibration absorption peak of Sc (3%):Fe:LiNbO 3 was at 3508 cm −1, compared with 3484 cm −1 of crystals with lower Sc doping level. Sc(3%):Fe:LiNbO 3 exhibited higher optical damage resistance ability. The threshold intensity (wavelength 488 nm) of Sc (3%):Fe:LiNbO 3 was 2.2 × 10 2 W · cm −2, two orders of magnitude higher than that of Fe:LiNbO 3. Holographic storage properties of the crystals were determined in an extraordinary polarized laser of wavelength 632.8 nm by a two-wave coupling method. It was found that in terms of holographic storage properties, the optimal doping concentration of Sc was 2% (mole fraction) among this crystal series.

Increased optical damage resistance of Zr:LiNbO3 crystals

AbstractZr: LiNbO3 crystals has been grown. The crystal composition and phase are analyzed by X‐ray diffration. The optical damage resistance ability of Zr: LiNbO3 crystals is studied by the Sénarmont compensation method and the transmitted beam pattern distortion method. The saturated value of the birefringence change of 6 mol% Zr: LiNbO3 crystal is 1.01×10‐4, which is seven times smaller than that of congruent pure LiNbO3 crystal. The results of UV‐Visible and IR absorption spectra of Zr: LiNbO3 crystals powerfully confirm that the optical damage resistance threshold concentration of the Zr4+ ions doped in LiNbO3 crystals is about 6 mol% in the melt. (© 2007 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Increased optical damage resistance in Ce:Cu:LiNbO3 by doping with Sc2O3 for quasi‐nonvolatile holographic storage

AbstractA series of Sc:Ce:Cu:LiNbO3 crystals were prepared using the Czochralski method and the occupation mechanism of the dopants is discussed in terms of the results of infrared and UV–visible spectra. The optical damage resistance ability and quasi‐nonvolatile holographic properties of the samples were also obtained. The defect structure is discussed, accounting for the optical damage resistance and two‐photon holographic response speed. (© 2007 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Holographic associative memory by phase conjugate of four-wave-mixing in Sc:Fe:LiNbO3 crystal

Sc:Fe:LiNbO3 crystal series doped with Sc2O3 in different levels have been grown by Czochralski technology. The optical damage resistance ability of crystals improves significantly with the increase of Sc doping amount. The intensity threshold of Sc(3 mol%):Fe:LiNbO3 is two orders of magnitude higher than that of Fe:LiNbO3. By four-wave-mixing method, the phase conjugate refractivity and response time are determined. The holographic associative memory system has been demonstrated by using Sc(3 mol%):Fe:LiNbO3 as recording material and Sc(2 mol%):Fe:LiNbO3 as phase conjugate mirror. The reconstructed image is complete and clear.