Thulium channel waveguide laser with 16  W of output power and ∼80% slope efficiency

Abstract

Laser experiments were performed on buried, ridge-type channel waveguides in 8 at.% thulium-doped, yttrium-gadolinium-lutetium co-doped potassium double tungstate. 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 in a laser resonator with a high output-coupling degree of 89%. To the best of our knowledge, this result represents the most efficient 2-μm channel waveguide laser to date.

Graphene Q-switched Tm:KY(WO4)2waveguide laser

“…Tm:KLuW. In addition, an increase of the Tm doping level to >5 at.% is desirable to reach a laser quantum efficiency of >1.95 owing to an efficient CR [6]. This will increase the laser slope efficiency and allow for further power scaling, as well as provide much better conditions for the bleaching of the graphene-SA due to a much smaller size of the laser mode.…”

“…The development of ~2 µm lasers with waveguide geometry [1][2][3][4] 4 , which leads to the excitation of two adjacent ions to the upper laser level by the absorption of a single pump photon [5]. The CR process enables a rather high slope efficiency of Tm lasers [6]. In addition, Tm lasers provide broad tuning of the laser emission at ~2 µm.…”

“…Particularly for the waveguide geometry, the concept of 'mixed' active layer host, KGd x Y y Lu z W (x + y + z = 1), has been to provide (i) optimum refractive index contrast and (ii) optimum lattice-matching with respect to the undoped substrate, usually KYW, as well as (iii) to ensure high doping levels of active ions [9][10][11]. High optical quality and low propagation loss (<0.2 dB cm −1 ) few µm-thick films of Tm:KGd x Y y Lu z W have been grown on bulk KYW substrates and continuouswave (CW) [4,6,12] and passively Q-switched (PQS) [13] laser operation has been reported to date. 2+ :ZnSe has been used as a saturable absorber (SA).…”

In-depth structural analysis of swift heavy ion irradiation in KY(WO4)2 for the fabrication of planar optical waveguides

“…Integrated on-chip amplifiers and lasers [1,2] find many applications in various fields, including telecommunications [3], datacom [4], biosensing [5,6] and LIDAR [7] amongst others. Potassium double tungstates (i.e., KY(WO 4 ) 2 , KGd(WO 4 ) 2 , in short KRE(WO 4 ) 2 ) -used for decades as active materials for high-power ultra-short pulsed lasers [8][9][10], thin-disk lasers [11,12] and Raman lasers [13][14][15] -have been recently demonstrated to deliver high gain per unit length in low-contrast waveguide amplifiers [16] and lasers [17][18][19], thanks to their high rare-earth ion solubility (together with a large interionic distance), high absorption and emission cross-sections when doped with rare-earth ions, and high achievable pump intensity in waveguide configuration. Even higher efficiency could be obtained by the fabrication of high-refractive index contrast waveguides in KY(WO 4 ) 2 .…”

Energy-transfer upconversion and excited-state absorption in KGdxLuyEr1-x-y(WO4)2 waveguide amplifiers

“…The thermomechanical [2] and spectroscopic properties [3] of these materials are superior to those found in many glass and crystalline hosts, mainly due to their strong anisotropy and high refractive index [3,4]. Channel waveguides in these materials have shown excellent performance in optical amplification [5] and lasing [6,7]. For Er 3+ -activated waveguide amplifiers and lasers operating in the telecom C-band at wavelengths near 1.5 µm [8], see Fig.…”