Femtosecond laser-written Tm:KLu(WO<sub>4</sub>)<sub>2</sub> waveguide lasers

Kifle, Esrom; Mateos, Xavier; Aldana, Javier Rodríguez Vázquez de; Ródenas, Airán; Loiko, Pavel; Choi, Sun Young; Rotermund, Fabıan; Griebner, Uwe; Petrov, Valentín; Aguiló, Magdalena; Dı́az, Francesc

doi:10.1109/cleoe-eqec.2017.8087068

Cited by 8 publications

(20 citation statements)

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“…A depressed-index channel WG with a circular cladding was fabricated by fs-DLW in a bulk monoclinic crystal of Tm:KLu(WO 4 ) 2 (shortly KLuW) [23]. The crystal itself was grown by the Top-Seeded Solution Growth (TSSG) Slow-Cooling method using potassium ditungstate (K 2 W 2 O 7 ) as a flux and a [010]-oriented seed [26].…”

Section: Femtosecond-laser-written Waveguidementioning

confidence: 99%

“…The WG propagation (passive) loss δ loss was estimated using the Caird analysis [33] (taking into account the laser performance at low output coupling [23]) as ~1.0 ± 0.3 dB/cm. The laser emission was linearly polarized, E || N m , the polarization was naturally-selected by the anisotropy of the gain.…”

Section: Continuous-wave Lasermentioning

confidence: 99%

“…As for channel WGs produced by fs-DLW, solely "fast" SAs have been used, incl. graphene, topological insulator (Bi 2 Te 3 ) and SWCNTs [20][21][22][23]. Typically, these lasers generated μs-long pulses with a low average output power.…”

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confidence: 99%

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Fs-laser-written thulium waveguide lasers Q-switched by graphene and MoS₂

et al. 2019

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We report the generation of mid-infrared (~2 µm) high repetition rate (MHz) sub-100 ns pulses in buried thulium-doped monoclinic double tungstate crystalline waveguide lasers using two-dimensional saturable absorber materials, graphene and MoS 2 . The waveguide (propagation losses of ~1 dB/cm) was micro-fabricated by means of ultrafast femtosecond laser writing. In the continuous-wave regime, the waveguide laser generated 247 mW at 1849.6 nm with a slope efficiency of 48.7%. The laser operated at the fundamental transverse mode with a linearly polarized output. With graphene as a saturable absorber, the pulse characteristics were 88 ns / 18 nJ (duration / energy) at a repetition rate of 1.39 MHz. Even shorter pulses of 66 ns were achieved with MoS 2 . Graphene and MoS 2 are therefore promising for high repetition rate nanosecond Q-switched infrared waveguide lasers. IntroductionWaveguide (WG) lasers emitting in the spectral range of ~2 μm are of interest for spectroscopy, telecom and environmental sensing applications [1]. This is because their emission is eye-safe and matches the absorption lines of various atmospheric and biomolecules. The laser operation at ~2 μm is achieved using such trivalent rare-earth ions as Thulium (Tm 3+ ) or Holmium (Ho 3+ ). In the former case, the transition of interest is 3 F 4 → 3 H 6 . Due to the large Stark splitting of the Tm 3+ ground-state, its emission is wavelength-tunable. The Tm 3+ ions feature strong absorption at ~0.8 μm ( 3 H 6 → 3 H 4 transition) allowing for their efficient pumping by AlGaAs laser diodes and Ti:Sapphire lasers. Moreover, the crossrelaxation for adjacent Tm 3+ ions, 3 H 4 + 3 H 6 → 3 F 4 + 3 F 4 , can potentially raise the pump quantum efficiency up to 2.Efficient continuous-wave (CW) thulium WG lasers are known [2,3]. Several methods have been used to fabricate WGs based on Tm 3+ -doped materials, e.g., liquid phase epitaxy (LPE) in combination with ion beam etching [2], optical bonding [4], ion diffusion [5], reactive co-sputtering [6] and femtosecond direct laser writing (fs-DLW) also referred as ultrafast laser inscription (ULI) [7]. In the latter approach, the output of an ultrafast (fs) An overview of PQS thulium WG lasers reported to date is presented in Table 1. Regarding planar WG lasers produced by LPE, a "slow" SA (Cr 2+ :ZnS) was employed in a Tm:KY(WO 4 ) 2 laser yielding 1.2 μs / 0.12 μJ (duration / energy) pulses at a low repetition rate of 10 kHz [24]. The use of a "fast" SWCNT-based SA in a similar laser lead to much shorter pulses of 83 ns / 33 nJ at 1.39 MHz [25]. However, both these lasers generated spatially multimode output.

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Section: Femtosecond-laser-written Waveguidementioning

confidence: 99%

Section: Continuous-wave Lasermentioning

confidence: 99%

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Fs-laser-written thulium waveguide lasers Q-switched by graphene and MoS₂

et al. 2019

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“…In Ref. [18], proof of the concept was demonstrated using a bulk Tm:KLuWO 4 2 (shortly Tm:KLuW) crystal, and circular-cladding channel WGs were prepared. Power scaling of such lasers was shown in Ref.…”

Section: Introductionmentioning

confidence: 99%

“…[36], an fs-DLW Tm:ZBLAN glass WG laser PQS by graphene generated 2.8 μs/240 nJ pulses at an output power of only 6 mW. Very recently, we employed SWCNTs in an fs-DLW Tm:KLuW WG laser providing much shorter pulses (50 ns/7 nJ) while the output power was still low, 10.3 mW [18].…”

Section: Introductionmentioning

confidence: 99%

Passively Q-switched femtosecond-laser-written thulium waveguide laser based on evanescent field interaction with carbon nanotubes

et al. 2018

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Surface channel waveguides (WGs) were fabricated in a monoclinic Tm 3 :KLuWO 4 2 crystal by femtosecond direct laser writing (fs-DLW). The WGs consisted of a half-ring cladding with diameters of 50 and 60 μm located just beneath the crystal surface. They were characterized by confocal laser microscopy and μ-Raman spectroscopy, indicating a reduced crystallinity and stress-induced birefringence of the WG cladding. In continuous-wave (CW) mode, under Ti:sapphire laser pumping at 802 nm, the maximum output power reached 171.1 mW at 1847.4 nm, corresponding to a slope efficiency η of 37.8% for the 60 μm diameter WG. The WG propagation loss was 0.7 0.3 dB∕cm. The top surface of the WGs was spin-coated by a polymethyl methacrylate film containing randomly oriented (spaghetti-like) arc-discharge single-walled carbon nanotubes serving as a saturable absorber based on evanescent field coupling. Stable passively Q-switched (PQS) operation was achieved. The PQS 60 μm diameter WG laser generated a record output power of 150 mW at 1846.8 nm with η 34.6%. The conversion efficiency with respect to the CW mode was 87.6%. The best pulse characteristics (energy/duration) were 105.6 nJ/98 ns at a repetition rate of 1.42 MHz.

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Watt-level ultrafast laser inscribed thulium waveguide lasers

Kifle

Loiko

Romero

et al. 2020

Progress in Quantum Electronics

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We report on the first watt-level ultrafast laser inscribed Thulium waveguide (WG) lasers. Depressed-index buried channel WGs with a circular cladding (type III) are produced in monoclinic Tm 3þ :KLu(WO 4 ) 2 crystals. Laser operation is achieved under conventional ( 3 H 6 → 3 H 4 ) and in-band ( 3 H 6 → 3 F 4 ) pumping. In the former case, employing a Raman fiber laser emitting at 1679 nm as pump, the continuous-wave Tm channel WG laser generated 1.37 W at 1915-1923 nm with a record-high slope efficiency of 82.7% (with respect to the absorbed pump power), a threshold of only 17 mW and a spatially single-mode output with linear polarization. The WG propagation losses were 0.2 AE 0.3 dB/cm. Passive Q-switching of Tm channel WG lasers is achieved using Cr 2þ :ZnS and Cr 2þ :ZnSe saturable absorbers. With Cr 2þ :ZnS, record-short pulses of 2.6 ns/6.9 μJ at a repetition rate of 8.0 kHz were generated. The developed WGs are promising for compact GHz mode-locked lasers at~2 μm.

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Femtosecond laser-written Tm:KLu(WO₄)₂ waveguide lasers

Cited by 8 publications

References 4 publications

Fs-laser-written thulium waveguide lasers Q-switched by graphene and MoS₂

Fs-laser-written thulium waveguide lasers Q-switched by graphene and MoS₂

Passively Q-switched femtosecond-laser-written thulium waveguide laser based on evanescent field interaction with carbon nanotubes

Watt-level ultrafast laser inscribed thulium waveguide lasers

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Femtosecond laser-written Tm:KLu(WO4)2 waveguide lasers

Cited by 8 publications

References 4 publications

Fs-laser-written thulium waveguide lasers Q-switched by graphene and MoS2

Fs-laser-written thulium waveguide lasers Q-switched by graphene and MoS2

Passively Q-switched femtosecond-laser-written thulium waveguide laser based on evanescent field interaction with carbon nanotubes

Watt-level ultrafast laser inscribed thulium waveguide lasers

Contact Info

Product

Resources

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Femtosecond laser-written Tm:KLu(WO₄)₂ waveguide lasers

Fs-laser-written thulium waveguide lasers Q-switched by graphene and MoS₂

Fs-laser-written thulium waveguide lasers Q-switched by graphene and MoS₂