Abstract
We report on the fabrication of depressed cladding waveguide lasers in Nd:YAG (neodymium doped yttrium aluminum garnet, Nd:Y3Al5O12) ceramics microstructured by femtosecond laser pulses. Full control over the confined light spatial distribution is demonstrated by the fabrication of high contrast waveguides with hexagonal, circular and trapezoidal configurations. The confocal fluorescence measurements of the waveguides reveal that the original luminescence features of Nd3+ ions are well-preserved in the waveguide regions. Under optical pump at 808 nm, cladding waveguides showed continuous wave efficient laser oscillation. The maximum output power obtained at 1064.5 nm is ~181 mW with a slope efficiency as high as 44%, which suggests that the fabricated Nd:YAG ceramic waveguides are promising candidates for efficient integrated laser sources.
Highlights
As the basic elements in integrated photonics, optical waveguide structures can confine the light propagation in small volumes, achieving high optical intensities with respect to bulk materials, in which high-performance photonic devices could be constructed in small circuitsReceived 8 Jun 2012; revised 25 Jul 2012; accepted 27 Jul 2012; published 31 Jul 2012 13 August 2012 / Vol 20, No 17 / OPTICS EXPRESS 18621[1]
Depending on the diverse parameters of the fs laser pulses and the material properties, the fs-laser micromachined waveguides can be with directly written structures, stress-induced waveguides (Type II with double line filaments), and depressed cladding waveguides
Compared with the wide application of Type I waveguides in numerous glasses and LiNbO3 crystal [10], and Type II waveguides in some laser crystals (e.g., Nd:YVO4 [11], Nd:GdVO4 [12], Nd:LuVO4 [13], rare-earth doped YAG crystals [14,15,16,17], Nd:GGG [18]) and LiNbO3 [10], the cladding structures receive less attention from the scientific community
Summary
As the basic elements in integrated photonics, optical waveguide structures can confine the light propagation in small volumes, achieving high optical intensities with respect to bulk materials, in which high-performance photonic devices could be constructed in small circuits. The scales of the cladding waveguide cross section could be designed to match the diameters of the multimode fibers; the fiber-waveguide-fiber integrated photonic chips may be constructed by using the depressed cladding structures As of yet, such depressed cladding structures have been fabricated in laser materials, such as Nd:YAG single crystal [19, 20] and Tm:ZBLAN glass [21]. Owing to the advantages of the fabrication technique, larger neodymium ion concentration could be achieved without degradation in the optical properties, at variance with their crystalline partners With combination of such advantages of the Nd:YAG ceramics and waveguide platform, it is very intriguing to construct a compact, cost-effective laser source for various photonic applications. We report on the continuous wave (cw) laser performance of the inscribed waveguides at 1.06 μm by using an end-pumping geometry
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