Transmission Electron Microscope Study of Secondary Phases in Cr3+:LiCaAlF6 Single Crystals

Lacayo, G.; Hähnert, I.; Klimm, D.; Reiche, P.; Neumann, Wolfgang

doi:10.1002/(sici)1521-4079(199911)34:9<1221::aid-crat1221>3.0.co;2-u

Cited by 5 publications

(3 citation statements)

References 11 publications

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“…Especially, the Cr:LiCAF crystal that was used in this study was from a very early growth with relatively high losses (~> 1% per cm). This high level of passive loss in Cr:LiCAF was caused mostly by micron-sized or smaller precipitates arising during the growth process [45][46][47] and it is now possible to grow Cr:LiCAF crystals with passive losses below 0.2% per cm [48]. We also note that, despite the high loss Cr:LiCAF crystal that was available in this study, the slope efficiencies obtained with the tapered diode pumped system (41%), is much higher than what can be obtained (19%) while pumping with broad-stripe single-emitter diodes [31].…”

Section: Results Of Continuous-wave Lasing Experimentsmentioning

confidence: 56%

Femtosecond Cr:LiSAF and Cr:LiCAF lasers pumped by tapered diode lasers

Demırbas¹,

Schmalz²,

Sumpf³

et al. 2011

Opt. Express

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We report compact, low-cost and efficient Cr:Colquiriite lasers that are pumped by high brightness tapered laser diodes. The tapered laser diodes provided 1 to 1.2 W of output power around 675 nm, at an electrical-to-optical conversion efficiency of about 30%. Using a single tapered diode laser as the pump source, we have demonstrated output powers of 500 mW and 410 mW together with slope efficiencies of 47% and 41% from continuous wave (cw) Cr:LiSAF and Cr:LiCAF lasers, respectively. In cw mode-locked operation, sub-100-fs pulse trains with average power between 200 mW and 250 mW were obtained at repetition rates around 100 MHz. Upon pumping the Cr:Colquiriite lasers with two tapered laser diodes (one from each side of the crystal), we have observed scaling of cw powers to 850 mW in Cr:LiSAF and to 650 mW in Cr:LiCAF. From the double side pumped Cr:LiCAF laser, we have also obtained ~220 fs long pulses with 5.4 nJ of pulse energy at 77 MHz repetition rate. These are the highest energy levels reported from Cr:Colquiriite so far at these repetition rates. Our findings indicate that tapered diodes in the red spectral region are likely to become the standard pump source for Cr:Colquiriite lasers in the near future. Moreover, the simplified pumping scheme might facilitate efficient commercialization of Cr:Colquiriite systems, bearing the potential to significantly boost applications of cw and femtosecond lasers in this spectral region (750-1000 nm).

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Section: Results Of Continuous-wave Lasing Experimentsmentioning

confidence: 56%

Femtosecond Cr:LiSAF and Cr:LiCAF lasers pumped by tapered diode lasers

Demırbas¹,

Schmalz²,

Sumpf³

et al. 2011

Opt. Express

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Section: Introductionmentioning

confidence: 99%

“…However, initially, it did not draw much attention, mostly due to the high level of parasitic losses (∼2% per cm) observed in Cr:LiCAF during the early years of its production (for Cr:LiSAF passive losses have been around ∼0.2% per cm) [34][35][36][37][38]. This high level of passive losses in Cr:LiCAF rooted mostly from micrometer-sized or smaller precipitates arising during the growth process [35,36], which obstructed efficient laser operation in this low-gain medium. On the other hand, compared to Cr:LiSAF, Cr:LiCAF has several advantages, including a higher intrinsic slope efficiency [39], a higher thermal conductivity [39], a higher thermal quenching temperature [40], a lower thermal lensing [41], a lower quantum defect, a lower excited-state absorption [9,10], and a lower upconversion rate [42].…”

Section: Introductionmentioning

confidence: 99%

Low-cost, broadly tunable (375–433 nm & 746–887 nm) Cr:LiCAF laser pumped by one single-spatial-mode diode

et al. 2012

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We describe a low-cost, compact, and efficient Cr(3+):LiCaAlF(6) (Cr:LiCAF) laser that is broadly tunable in the near infrared (746-887 nm) and blue/ultraviolet (375-433 nm) regions of the optical spectrum. The pump source is a 660 nm single-mode-diode with 145 mW of output power. A melt-grown Cr:LiCAF crystal with an extremely high figure of merit above 2000 was used as the gain medium. This enabled the construction of a high-Q-cavity with continuous wave (cw) lasing thresholds as low as 3 mW, slope efficiencies as high as 54%, and output powers up to 63 mW. The stored intracavity power levels were above 30 W. By placing a beta-barium-borate crystal at a second intracavity focus, we could obtain tunable cw blue/ultraviolet radiation with output powers up to 3.5 mW around 400 nm. When mode-locked using a saturable Bragg reflector around 800 nm, the Cr:LiCAF laser produced 95 fs pulses with average powers of 33 mW and peak powers of 3.58 kW at a repetition rate of 85.5 MHz. Extracavity second harmonic generation enables generation of femtosecond pulses around 400 nm. These results demonstrate the possibility to grow Cr:LiCAF crystals with passive losses below 0.15% per cm, which enables construction of low-cost and complexity systems that are pumped only with one low-power single-mode-diode.

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