Characterization of Absorption Bands in Ti:sapphire Crystals

Moulton, Peter F.; Cederberg, Jeffrey G.; Stevens, K. T.; Foundos, Greg; Košelja, M.; Preclíková, Jana

doi:10.1364/assl.2018.am4a.2

Cited by 6 publications

(16 citation statements)

References 9 publications

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“…This concentration is rather high. For instance, in samples investigated in [13] the concentration of Ti was in the range from 0.006 to 0.2 wt%. Samples used in Refs.…”

Section: Equilibrium Concentrations Of Defects In Ti:sapphirementioning

confidence: 99%

“…This conclusion is in agreement with experimental study [30] where it was shown that thermal carbon treatment of raw materials (Al It is instructive to evaluate the relation between the FOM and c Ti 3+ /c Ti 3+ −Ti 4+ . To do that we use the data of [13]. One of the samples investigated in [13] (labeled as SY1b) had FOM = 12.…”

Section: Influence Of Co-doping On Fommentioning

confidence: 99%

“…Based on this observation the authors of Ref. [13] arrived at the conclusion that the Ti 3+ -Ti 4+ pair model of NIR absorption needs a revision.…”

Section: Introductionmentioning

confidence: 99%

“…In Secs. V and VI we answer a number of questions that arose in [13] and clarify the role of several factors that may increase the FOM such as an appropriate choice of the temperature of annealing, adding of certain compounds into the atmosphere or into the melt under the growth or annealing, co-doping with nonisovalent atoms. This analysis is another principal result of the paper.…”

Section: Introductionmentioning

confidence: 99%

“…The problem of NIR absorption was revisited recently in [13] where the absorption data in the range of wavelengths from 190 nm to 2000 nm were analyzed with reference to many Ti:sapphire samples of different origin. A sample with a large fraction of Ti 4+ (that was confirmed by a very weak absorption by this sample at λ = 490 nm) was used as a reference.…”

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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“…This concentration is rather high. For instance, in samples investigated in [13] the concentration of Ti was in the range from 0.006 to 0.2 wt%. Samples used in Refs.…”

Section: Equilibrium Concentrations Of Defects In Ti:sapphirementioning

confidence: 99%

Section: Influence Of Co-doping On Fommentioning

confidence: 99%

“…Based on this observation the authors of Ref. [13] arrived at the conclusion that the Ti 3+ -Ti 4+ pair model of NIR absorption needs a revision.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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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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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Titanium Sapphire: A Decade of Diode-Laser Pumping

Coyle

Hopkins

Lagatsky

et al. 2019

2019 Conference on Lasers and Electro-Optics Europe &Amp; European Quantum Electronics Conference (CLEO/Europe-EQEC)

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For many years, Ti:sapphire was the prototypical example of a solid-state laser material that could not be diode pumped. The rationale for this assessment follows from the laser properties of Ti:sapphire, which combine to demand high brightness pumping in the blue-green region (see fig. 1 [1]). The development of efficient Gallium Nitride (GaN) based laser diodes eroded this logic [2], and improvements in the spatial brightness of GaN diode lasers subsequently enabled the first demonstration of a directly diode-laser pumped Ti:sapphire laser in 2009 [3]. This presentation will outline the physics that makes diode-pumping difficult, and the developments that mean, it is, nonetheless, possible. Interestingly, diodepumping of CW and modelocked Ti:sapphire lasers was achieved not by a radical redesign of the laser, but by careful optimisation of existing approaches that enabled the rapidly improving brightness of GaN diode lasers to be exploited [3][4][5].The performance of these early systems was modest. In part, this was because the performance of GaN diodes was still marginal for Ti:sapphire pumping. However, this early work hinted at a second issuethat of pump induced loss for blue, rather than green pumping [3]. Rigorous subsequent work by Sawada et al. [6] and Moulton et al. [7] has begun to unpick the physics behind this effect. However, probably the most significant factor in the subsequent improvements in the performance and functionality of diodepumped Ti:sapphire lasers has been the emergence of higher power and longer wavelength GaN diode lasers. These diodes have been harnessed by a number of groups world-wide to enable ground-breaking demonstrations. Particular highlights include the demonstration of Kerr-lens modelocking [8], of a frequency comb [9], of a regenerative amplifier [10], of broad tuneability [11], and the announcement of a first commercial system [12]. This progress indicates a bright future for diode-pumped Ti:sapphire lasers.

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Characterization of Absorption Bands in Ti:sapphire Crystals

Cited by 6 publications

References 9 publications

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

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

Review of laser‐diode pumped Ti:sapphire laser

Titanium Sapphire: A Decade of Diode-Laser Pumping

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