70% slope efficiency from an ultrafast laser-written Nd:GdVO_4 channel waveguide laser

Abstract

We report high efficiency continuous wave laser oscillations at 1063.6 nm from an ultrafast laser written Nd(3+):GdVO4 channel waveguide under the 808 nm optical excitation. A record 17 mm·s(-1) writing speed was used while the low propagation loss of the waveguide (~0.5 dB·cm(-1)) enabled laser performance with a threshold pump power as low as 52 mW and a near to quantum defect limited laser slope efficiency of 70%.

Crystalline Waveguide Lasers in the Visible and Near-Infrared Spectral Range

“…The slope efficiency of this waveguide laser is comparable with Nd:YAG ceramic waveguide lasers [37]. However, the highest efficiency of Neodymium doped fs-laser written waveguide lasers could be achieved with Nd:GdVO 4 waveguides [68].…”

Efficient lasing in Nd:GdVO4depressed cladding waveguides produced by femtosecond laser writing

“…For the core waveguide in the structure of WG1 and the single cladding waveguide WG2, the waveguide laser at 1064 nm were demonstrated to only support zero-order mode, which makes the 30-μm diameter cladding waveguide laser a single-mode system. Compared with the dual-line Type II Nd:GdVO 4 waveguide lasers, the cladding waveguide mode is more symmetric [16]. The isotropic induced stress field makes an important contribution to the symmetric single modal profile compared to the anisotropic stress field in the double-line waveguide report in the previous work [33].…”

“…The circular depressed double cladding waveguides were produced by using the laser facility of the Universidad de Salamanca, Spain, in which system a Ti:Sapphire regenerative amplifier (Spitfire, Spectra Physics, USA) was used as laser source. It delivered linearly-polarized pulses of 120 fs and 795 nm central wavelength at 1 kHz repetition rate as in previous works [16,[20][21][22][23]. The maximum available pulse energy was 1 mJ but it was reduced with a calibrated neutral density filter placed after a half-wave plate and a linear polarizer, in order to get a fine control of the incident energy.…”

“…The guiding structures include Type I waveguides (also called directly written structures, typically with single line writing with positive refractive index change in the written tracks), Type II waveguides (also called stress-induced waveguides, typically with double-line geometry, locating in the region between two filaments with negative refractive index changes) and depressed cladding waveguides (also called Type III configuration, typically locating in a core surrounded by a number of low-index fs-laser written filaments) [6]. Type I and Type II structures have been realized in many materials, such as glass and LiNbO 3 [7] crystal for Type I waveguides and rare-earth doped YAG [8][9][10][11][12][13], Nd:GGG [14], LiNbO 3 [7]and Nd doped vanadates [15,16] for Type II waveguides. Compared with Type I structures, the depressed cladding waveguides possess a few unique features, such as good thermal stabilities and the well preserved bulk features in the waveguide area.…”

“…Owing to its high thermal conductivity, high damage threshold and excellent spectroscopic properties, specially to the higher laser slope efficiencies compared to the Nd:YAG or Nd:YVO 4 gain media, Nd:GdVO 4 crystal is of great relevance for the development of solid state lasers [26][27][28]. Channel waveguides have been fabricated in Nd:GdVO 4 crystals by swift heavy ion irradiation [29], pulse laser deposition [30] and double-line fs-laser inscription [16]. In this work, we report on the fabrication of Nd:GdVO 4 circular cladding waveguides constructed with multiple fs-laser damage tracks and the efficient continuous wave (cw) output laser oscillation at 1064.5 nm in the cladding waveguides.…”