High slope efficiency and high refractive index change in direct-written Yb-doped waveguide lasers with depressed claddings

Femtosecond laser induced phenomena in transparent solid materials: Fundamentals and applications

“…As suggested above, local refractive index changes originating from electronic and structural modification of matter are the building "blocks" of laser-induced optical functions in bulk transparent materials, which provides a well established method for the fabrication of integrated photonic devices [46,[291][292][293][294][295][315][316][317][318][319][320][321][322][323][324][325][326][327]. Recently, great efforts have been devoted, which are of scientific and industrial importance as they offer complex circuitry and hybrid functionality on a small footprint.…”

“…Compared to other fabrication methods, the direct femtosecond laser writing technique offers the advantage of a rapid and one step route with the potential for fabrication of 3D photonic architectures [229]. For example, waveguides and Bragg-gratings can be directly incorporated during the same processing setup to create a monolithic laser with narrow linewidth output [229,316]. As shown in Figs.…”

Ultrafast-laser-inscribed 3D integrated photonics: challenges and emerging applications

“…The typical femtosecond-laser-induced refractive index changes are in the range of 10 −4 to 10 −2 depending on the material and exposure conditions [60][61][62][63][64]. This index contrast is comparable to standard optical fibres, enabling efficient coupling between optical fibres and laserinscribed waveguides.…”

Ultrafast laser inscribed 3D integrated photonics

“…63 We have successfully applied the depressed cladding waveguide architecture to create fingernail-sized waveguide laser emitting at 1, 1.9, 2.1 and 2.9 µm. [64][65][66][67][68] In particular, lasers emitting at 1.9 µm based on thulium doped ZBLAN can be very efficient, reaching slope efficiencies of 67% in continuous wave operation at > 200 mW average output power ( Fig. 6(a)).…”