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

Kifle, Esrom; Loiko, Pavel; Aldana, Javier R. Vázquez de; Romero, Carolina; Ródenas, Airán; Choi, Sun Yung; Bae, Jong Hoa; Rotermund, Fabıan; Zakharov, V. K.; Вениаминов, А. В.; Aguiló, Magdalena; Díaz, Francesc; Griebner, Uwe; Petrov, Valentín; Mateos, Xavier

doi:10.1364/prj.6.000971

Cited by 25 publications

(14 citation statements)

References 58 publications

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“…Finite element method simulations of the surface WG accounting for various processes contributing to the refractive index change (damage and stress-optic index changes) have been performed. The refractive index change at sub-μm tracks was estimated from this analysis to be Δn ¼ À0.01 þ 0.0017i at the wavelength of~1.85 μm [31]. Note that the estimated real part of the complex refractive index, Re(Δn), is higher than the value obtained from the measured numerical aperture of a similar waveguide [32].…”

Section: Fs-dlw Double Tungstate Waveguide Lasersmentioning

confidence: 81%

“…In Table 3, we summarized the results on passively Q-switched Tm WG lasers reported so far [17,18,31,60,112,[118][119][120][121][122]. Two classes of SAs were implemented, namely, "fast" and "slow" ones.…”

Section: Discussionmentioning

confidence: 99%

“…In Ref. [31], type III surface channel WG geometry (with a half-ring cladding) was implemented for Tm:KLuW. Finite element method simulations of the surface WG accounting for various processes contributing to the refractive index change (damage and stress-optic index changes) have been performed.…”

Section: Fs-dlw Double Tungstate Waveguide Lasersmentioning

confidence: 99%

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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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Section: Fs-dlw Double Tungstate Waveguide Lasersmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 99%

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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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“…Graphene and MoS 2 are interesting for PQS fs-DLW Tm surface waveguide lasers relying on evanescent field interaction [41]. In such a way, the limitation due to the heating of the SA by the residual pump will be diminished and the Q-switching conversion efficiency with respect to the CW regime will be enhanced.…”

Section: Passively Q-switched Lasermentioning

confidence: 99%

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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“…Efficient bulk [32] and waveguide [33] Tm:MDT lasers are known. Recently, fs-DLW channel WG lasers based on MDTs doped with Yb 3+ [34], Er 3+ [35] and Tm 3+ [36], [37] ions were reported. In the case of Tm 3+ doping, a surface channel WG laser generated 0.17 W at 1.85 μm with a slope efficiency of 37.8% and moderate propagation losses of 0.7 dB/cm [37].…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Laser Inscription and ∼2 μm Laser Operation of Y-Branch Splitters in Monoclinic Crystals

Kifle

Loiko

Romero

et al. 2020

J. Lightwave Technol.

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We report on the first active surface Y-branch waveguide in the ∼2 µm spectral range. Depressed-cladding rectangular-cross-section surface waveguides with a splitting ratio of 1 × 2 are fabricated by femtosecond direct laser writing in a thulium (Tm 3+ ) doped monoclinic double tungstate crystal. Confocal laser microscopy and µ-Raman spectroscopy reveal well preserved crystallinity of the waveguide core. Under high-brightness laser pumping at 0.8 µm, a simultaneous continuous-wave laser operation in both arms is achieved resulting in a total output power of 0.46 W at ∼1.84 µm with a slope efficiency of 40.6% and a laser threshold of 0.28 W. The laser output is linearly polarized and spatially multimode (TE 12 /TE 22 ) with a power splitting ratio between arms of 52.1/47.9%). The waveguide propagation losses at 1.84 µm are ∼1.6 dB/cm and the loss from the Y-junction is 0.1 dB. The fabricated waveguides represent a route towards advanced photonic micro-structures such as a Mach-Zehnder interferometer for bio-sensing at ∼2 µm.

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

Cited by 25 publications

References 58 publications

Watt-level ultrafast laser inscribed thulium waveguide lasers

Watt-level ultrafast laser inscribed thulium waveguide lasers

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

Ultrafast Laser Inscription and ∼2 μm Laser Operation of Y-Branch Splitters in Monoclinic Crystals

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

Cited by 25 publications

References 58 publications

Watt-level ultrafast laser inscribed thulium waveguide lasers

Watt-level ultrafast laser inscribed thulium waveguide lasers

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

Ultrafast Laser Inscription and ∼2 μm Laser Operation of Y-Branch Splitters in Monoclinic Crystals

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