Thulium-doped channel waveguide laser with 1.6 W of output power and exceeding 80% slope efficiency

Dalfsen, K. van; Aravazhi, S.; Grivas, C.; García-Blanco, Sonia M.; Pollnau, Markus

doi:10.1109/cleoe-iqec.2013.6801991

Cited by 22 publications

(39 citation statements)

References 5 publications

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“…However, measurements of the residual transmitted pump power indicated that a maximum of ~90% of the incident pump power is actually coupled to the channel. The Tm 3+ absorption cross-section of σ a ≈ 8 × 10 -20 cm 2 in the composition [15] is calculated as a weighted average [19] of the cross-sections in the pure compounds. The waveguide is long compared to the absorption length of pump light, 1/(σ a N d ) = 0.25 mm in the absence of ground-state bleaching.…”

Section: Methodsmentioning

confidence: 99%

“…The refractive indices n of the KY 1-x-y-z Gd x Lu y Tm z (WO 4 ) 2 layer were measured [15] and adjusted by varying the x, y, and z fractions of Gd 3+ , Lu 3+ , and Tm 3+ ions on the Y 3+ site, respectively, to obtain a fundamental-mode channel waveguide. The layer was lapped and polished to a thickness of 14.3 μm, covered with a photoresist mask, and channels with different widths of 10−25 μm were patterned 1.9 μm deep by Ar + -beam milling [17].…”

Section: Methodsmentioning

confidence: 99%

“…On the other hand, since the Tm 3+ laser transition at 2 µm terminates in the ground-state multiplet, at higher Tm 3+ concentrations this laser exhibits residual reabsorption losses in the wings of the pump mode that can be overcome only at higher pump intensities. Optimizing these parameters, we have demonstrated a channel waveguide laser in a Tm 3+ -doped potassium double tungstate operating at 1840 nm, with 1.6 W of output power and a slope efficiency of ~80% [15].…”

Section: Introductionmentioning

confidence: 99%

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On the efficiency of Tm-doped 2μm lasers

et al. 2015

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A potassium double tungstate layer with the composition KY 0.40 Gd 0.29 Lu 0.23 Tm 0.08 (WO 4 ) 2 was grown onto a pure KY(WO 4 ) 2 substrate by liquid-phase epitaxy, microstructured by standard lithography and Ar-ion etching, and overgrown by a pure KY(WO 4 ) 2 layer. The end-facets were polished. Laser experiments were performed on these buried, ridge-type channel waveguides in a resonator with one butt-coupled mirror and Fresnel reflection from the other endfacet, resulting in a high output-coupling degree of 89%, compared to intrinsic round-trip losses of only 2%. By pumping with a Ti:Sapphire laser at 794 nm, 1.6 W of output power at 1.84 μm with a maximum slope efficiency of ~80% was obtained. To the best of our knowledge, this result represents the most efficient 2-μm channel waveguide laser to date. We determined the optimum Tm 3+ concentration in double tungstate channel waveguides to be at least 8at.% for efficient lasing. The theoretical limit of the slope efficiency depends on the Stokes efficiency which here is 43.2%, the outcoupling efficiency which here is 99%, and the pump quantum efficiency. The pump quantum efficiency of a 2-µm Tm 3+ laser pumped around 800 nm hinges on the efficiency of its cross-relaxation process. By fitting the macroscopic cross-relaxation parameter which linearly depends on the Tm 3+ concentration to concentration-dependent luminescencedecay data, calculating the overall decay rate of the pump level, and deriving the concentration-dependent pump quantum efficiency, we obtain a theoretical limit for the slope efficiency of 83% for the chosen Tm 3+ concentration. The experimental slope efficiency of ~80% closely approaches this limit.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the efficiency of Tm-doped 2μm lasers

et al. 2015

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“…Nevertheless, due to the strong pump confinement over the entire length of a channel waveguide, leading to extremely high pump intensities at rather low pump powers, the pump threshold of a rare-earth-ion-doped channel waveguide laser remains rather small, typically in the range of a few to a few tens of milliwatt of absorbed pump power. Moreover, due to the high gain compared to their bulk counterparts, channel waveguide lasers can operate at very high outcoupling degrees [31], by which their outcoupling efficiency, defined as the useful divided by the total resonator losses, approaches unity [32]. It allows for very high laser slope efficiencies at the typical laser transitions in rare-earth ions.…”

Section: Gain In Rare-earth-ion-doped Dielectric Waveguidesmentioning

confidence: 98%

“…Near 2 µm wavelength, a YAG:Tm 3+ planar waveguide produced a slope efficiency of 68% [39]. In Tm 3+ -doped potassium double tungstates, optimization of dopant level has enabled channel waveguide lasers with slope efficiencies exceeding 70% [40] and recently ~80% [32]. A planar-waveguide YLF:Tm 3+ laser was demonstrated with 76% slope efficiency [41], and recently planar waveguide lasers in the visible spectral range have been achieved in the same host material by exploiting transitions in Pr 3+ [42].…”

Section: Gain In Rare-earth-ion-doped Dielectric Waveguidesmentioning

confidence: 99%

Rare-Earth-Ion-Doped Channel Waveguide Lasers on Silicon

Pollnau

2015

IEEE J. Select. Topics Quantum Electron.

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This paper reviews the recent developments in rareearth-ion-doped planar and channel waveguide lasers. Optical gain in rare-earth-ion-doped waveguides has been increased by two orders of magnitude to ~1000 dB/cm and waveguide lasers with extremely high slope efficiencies and output powers exceeding the Watt level have been demonstrated. Of particular interest in integrated optics is the recent integration of rareearth-ion-doped channel waveguide lasers in amorphous materials directly deposited on a silicon substrate. Remarkable performance with respect to slope efficiency, output power, and laser linewidth has been achieved.

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Spectroscopy of Tm3+-doped CaF2 waveguiding thin films grown by Liquid Phase Epitaxy

Loiko

Brasse

Basyrova

et al. 2021

Journal of Luminescence

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Thulium-doped calcium fluoride (Tm:CaF2) single-crystalline films are grown on (100)-oriented undoped bulk CaF2 substrates by Liquid Phase Epitaxy (LPE) using LiF as a solvent. Their spectroscopic properties are studied in details. For ~2 at.% Tm-doped films, the active ions are predominantly isolated and are located in oxygen-assisted trigonal sites, C3v(T2). With increasing the Tm doping level, ion clustering is promoted but it is slowed down as compared to bulk crystals. For ~6 at.% Tm-doped films, the majority of active ions form clusters resulting in a "glassy-like" spectroscopic behavior (smooth and broad spectral bands). For such layers, the maximum stimulated-emission cross-section for the 3 F4 → 3 H6 transition is 0.14×10 -20 cm 2 at 1856 nm, the luminescence lifetime of the 3 F4 state is 21.70 ms and the emission bandwidth exceeds 180 nm. The transition probabilities of Tm 3+ ions are determined using the Judd-Ofelt theory. The waveguiding properties of the Tm:CaF2 films are confirmed. Highly-doped Tm:CaF2 epitaxial films are promising for waveguide lasers at ~2 μm.

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Thulium-doped channel waveguide laser with 1.6 W of output power and exceeding 80% slope efficiency

Cited by 22 publications

References 5 publications

On the efficiency of Tm-doped 2μm lasers

On the efficiency of Tm-doped 2μm lasers

Rare-Earth-Ion-Doped Channel Waveguide Lasers on Silicon

Spectroscopy of Tm3+-doped CaF2 waveguiding thin films grown by Liquid Phase Epitaxy

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