Optical absorption and color centers in large Ti: Sapphire crystals grown by horizontally directed crystallization under reducing conditions

Nizhankovskii, S. V.; Sidelnikova, N. S.; Baranov, V. V.

doi:10.1134/s1063783415040216

Cited by 13 publications

(12 citation statements)

References 23 publications

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“…29 According to the principle of isomorphism, in order to replace Al 3+ in sapphires, Ti 4+ must replace two Al 3+ ions at the same amount of Fe 2+ to maintain charge balance. 30,31 The proportion of Ti 4+ and Fe 2+ should be close to 1 : 1; thus, the most dominant element in total iron should be Fe 3+ .…”

Section: Xrfmentioning

confidence: 99%

Cause analysis of chatoyancy of sapphires from Shandong, China

2019

RSC Adv.

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Section: Xrfmentioning

confidence: 99%

Cause analysis of chatoyancy of sapphires from Shandong, China

2019

RSC Adv.

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“…The main growth methods for Ti:sapphire laser crystals include vertical-gradient-freeze (VGF) technique, 37,38 heatexchanger method (HEM), 39,40 Czochraksi method (CZM), 41,42 flame-fusion method (FFM), 43 horizontally directed crystallization method (HDCM), 44 and Kyropoulos (Ks) technique. 45 The largest Ti:sapphire crystal of 235 mm diameter was currently produced by HEM and was successfully used in the 10 PW system.…”

Section: Ti:sapphire Laser Materialsmentioning

confidence: 99%

Review of laser‐diode pumped Ti:sapphire laser

Liu

Sun

Zheng

et al. 2021

Micro & Optical Tech Letters

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Ti:sapphire laser has an important position in ultrashort pulse generation and wavelength tuning. The use of expensive frequency-doubled diode-pumped solid-state laser as the pump source limits the promotion of its application to a certain extent. With the maturity of high-power bluegreen laser diodes (LDs), low-cost LD directly pumped Ti: sapphire laser becomes possible. After more than 10 years of development, the output parameters of LD pumped Ti: sapphire lasers have been greatly improved. Moreover, the lasers have been applied to optical frequency combs, multiphoton microscopy imaging, and so forth, both of which have achieved impressive results.

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“…[3-5, 8, 11] had the concentration of Ti less than 0.1 wt%. The concentration of Ti in samples grown in [6] was in the range from 0.1 to 0.25 wt%.…”

Section: Equilibrium Concentrations Of Defects In Ti:sapphirementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…A charge-transfer transition between O 2− and Ti 4+ causes ultraviolet (UV) absorption in Ti:sapphire [5]. Measurement of UV spectral characteristics gives the information on the concentration of Ti 4+ ions in Ti-sapphire samples [5,6]. Ti:sapphire exhibits weak near-infrared (NIR) absorption [3,4,[7][8][9][10] that results in losses at the wavelength of the laser emission.…”

Section: Introductionmentioning

confidence: 99%

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Control of charge state of dopants in insulating crystals: Case study of Ti-doped sapphire

Kravchenko

Fil

2020

Phys. Rev. Research

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We study mechanisms of control of charge state and concentration of different point defects in doped insulating crystals. The approach is based on the density functional theory calculations. We apply it to the problem of obtaining of Ti-doped sapphire crystals with high figure-of-merit (FOM). The FOM of a given sample is defined as the ratio of the coefficient of absorption at the pump frequency to the coefficient of absorption at the working frequency of Ti:sapphire laser. It is one of standard specifications of commercial Ti:sapphire laser crystals. It is believed that FOM is proportional to the ratio of the concentration of isolated Ti 3+ ions to the concentration of Ti 3+-Ti 4+ pairs. We find that generally this ratio is in inverse proportion to the concentration of Ti 4+ isolated substitutional defects with the coefficient of proportionality that depends on the temperature at which the thermodynamically equilibrium concentration of defects is reached. We argue that in certain cases the inverse proportion between concentrations of Ti 3+-Ti 4+ and Ti 4+ may be violated. The role of codoping in the control of the charge state of dopants is analyzed. We show that codopants that form positively (negatively) charged defects may decrease (increase) the concentration of positively charged defects formed by the main dopants. To evaluate the effect of codoping it is important to take into account not only isolated defects but defect complexes formed by codopants, as well. In particular, we show that codoping of Ti:sapphire with nitrogen results in an essential increase of the concentration of Ti 4+ and in a decrease of the FOM, and, consequently, growth or annealing in the presence of nitrogen or its compounds is unfavorable for producing Ti:sapphire laser crystals. The approach developed can be used for determining appropriate growth and annealing conditions for obtaining doped crystals with the required characteristics.

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Optical absorption and color centers in large Ti: Sapphire crystals grown by horizontally directed crystallization under reducing conditions

Cited by 13 publications

References 23 publications

Cause analysis of chatoyancy of sapphires from Shandong, China

Cause analysis of chatoyancy of sapphires from Shandong, China

Review of laser‐diode pumped Ti:sapphire laser

Control of charge state of dopants in insulating crystals: Case study of Ti-doped sapphire

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