Yb-doped KY(WO4)2 planar waveguide laser

Abstract

High-quality monoclinic KY͑WO 4 ͒ 2 optical waveguides were grown by liquid-phase epitaxy, and laser operation of an Yb-doped KY͑WO 4 ͒ 2 waveguide was demonstrated for the first time to our knowledge. Continuous-wave laser emission near 1 m was achieved with both surface and buried planar waveguides. An output power of 290 mW was obtained in the fundamental mode and the slope efficiency was above 80%. OCIS codes: 140.3070, 140.3380, 140.5680, 230.7390, 310.1860OCIS codes: 140.3070, 140.3380, 140.5680, 230.7390, 310. , 310.2790 Crystals of monoclinic KY͑WO 4 ͒ 2 (KYW) doped with different rare-earth ions are recognized as very promising materials for solid-state lasers operating at room temperature, both in pulsed and continuouswave (cw) mode. 1,2 Due to its high refractive indices, of the order of 2.0, KYW is highly suitable for the fabrication of integrated optical devices. Rare-earth ions incorporated into KYW exhibit very high absorption and emission cross sections. In particular, the Yb 3+ ion in KYW has an absorption maximum near 981 nm with a cross section, for polarization parallel to the N m principal optical axis, ϳ15 times larger than that of YAG:Yb. The short absorption length in highly doped KYW:Yb together with an extremely small laser quantum defect as low as 1.6% (Ref. 3) makes this material a favorable candidate for the thin-disk laser concept, 4 where the active medium is a thin crystal or deposited layer. Recently, cw laser operation normal to a thin layer of KYW doped with 20 at. % Yb (with respect to the Y site) on a KYW substrate was demonstrated and the maximum output power reached 40 mW at 1030 nm. © 2006 Optical Society of America 5In this Letter we report the epitaxial growth of high-quality optical waveguides and, for the first time to our knowledge, on waveguide laser operation based on a double tungstate crystal composite. The waveguide geometry provides potentially high pumppower densities and excellent overlap of pump and resonator modes. This approach requires fabrication of large-area, defect-free thin layers of KYW:Yb on appropriate substrates, having small lattice mismatch and close-to-perfect interfaces between the layer and the substrate to ensure low-loss propagation.Liquid-phase epitaxy (LPE) is a well-known technique for producing high-quality oxide films for laser applications, in which a single-crystal layer can be grown from a molten solution on an oriented singlecrystal substrate.6 During LPE of rare-earth-iondoped KYW layers employing a low-temperature chloride solvent, 7 3D island nucleation generated insertion defects, which limited the maximum layer thickness to approximately 10 m and led to nonoptimum interface quality.The tungstate solvent K 2 W 2 O 7 , which we employed successfully in the present work, can potentially offer larger thickness and good layer quality.5,8 Undoped 1 mm thick KYW crystals grown by a modified Czochralski method with laser-grade polished (010) faces served as substrates. Building on previous work, 5 we employed the vertical dipping tech...

Graphene Q-switched Yb:KYW planar waveguide laser

“…The waveguides can be fabricated inside dielectric gain media by various techniques, including diffusion bonding, ion implantation, liquid-phase epitaxy and ultrafast laser inscription. [20][21][22][23][24] provide high intra-cavity pump intensity even with low-power pumping, excellent overlap of the pump and cavity modes, and efficient heat dissipation. The operation of waveguide lasers Q-switched or mode-locked using SESAMs and other SAs based on Cr-doped crystals, carbon nanotubes and graphene has been demonstrated.…”

“…Figure 4 used in this work. The refractive indices of the PMMA layer, few-layer graphene, Yb:KYW guiding layer and KYW substrate are assumed as 1.4817, 3, 2.0006, and 2, respectively, 21,34 and their thicknesses are set to 0.5 µm, 1.02 nm, 26.4 µm, and 100 µm, respectively, as illustrated in Fig. 4(a).…”

Potassium double tungstate waveguides with high ytterbium concentration for optical amplification

“…%) epitaxial layer was demonstrated. The use of planar waveguide for lasing purpose using KY(WO4)2:Yb 3+ epitaxial layer * was reported in 2006 [62]. The results in [62] is reproduced in Figure 2.6, where a waveguiding effect in the layer was clearly shown.…”

“…These layers are grown on undoped potassium double tungstate substrate using cost-effective liquid phase epitaxy technique [60][61][62][63]. By co-doping the Yb 3+ -activated layer with optically inert trivalent gadolinium (Gd…”

Spectroscopic excitation and quenching processes in rare-earth-ion-doped AI203 and their impact on amplifier and laser performance

“…Possible applications include power amplifiers, small-signal amplifiers in sensing applications and free-space laser communications [56]. In recent years significant efforts have been undertaken to develop erbium-and ytterbium-doped waveguide amplifiers and lasers to enhance or generate light at the ions' specific emission wavelengths on a robust, low-cost, miniature chip [57][58][59][60][61][62][63].…”