Spectral broadening in femtosecond laser written waveguides in chalcogenide glass

Abstract

Nonlinear spectral broadening to 200 nm, from an initial width of 50 nm, has been demonstrated in gallium lanthanum sulphide glass waveguides from 1540 nm, 200 fs pulses at 30 nJ/pulse. A formation mechanism is presented for these femtosecond laser written waveguides, based on optical characterization and comparisons to previous work. Two different types of waveguide are identified. One has a characteristic long narrow structure and is formed through filamentation caused by self-focusing. The other has a characteristic "teardrop" structure, which is formed by a type IIA photosensitivity mechanism and cumulative heating of glass around a central laser-exposed region.

Mid-infrared spectral broadening in an ultrafast laser inscribed gallium lanthanum sulphide waveguide

“…After fabrication the input and output facets of the substrate were polished giving a sample length of 14.3 mm. The waveguide facets exhibit a distinct 'teardrop' shape similar to those observed in other chalcogenide glass substrates [19,20].…”

Femtosecond laser inscription of nonlinear photonic circuits in Gallium Lanthanum Sulphide glass

“…From the EDX measurements, presented in figure 8(d) (La in red, S in green and Ga in blue) no significant migration of the elements is observed inside the waveguide. These observations are in agreement with previously reported EDX studies performed in GLS waveguides, where no compositional changes were detected [29]. Then, from EDX and Raman measurements, the laser is inducing changes of the Ga-S and La-S bondings in the focal volume, producing a rearrangement of the glass network that leads to an increase in the refractive index.…”

Erbium‐Ion‐Doped Tellurite Glass Fibers and Waveguides—Devices and Future Prospective: Part II

“…Fabrication of buried waveguide structures in a silica matrix using a fs‐pulsed laser was demonstrated for the first time in 1996 by Davis et al . which set the precedence for using such ultra‐fast pulsed sources for inscribing waveguides in a wide range of glasses . The amplifier performance of fs‐inscribed waveguides is summarized in Table .…”

“…11,12 Femtosecond Laser Inscribed Waveguides for Amplification Fabrication of buried waveguide structures in a silica matrix using a fs-pulsed laser was demonstrated for the first time in 1996 by Davis et al 10 which set the precedence for using such ultra-fast pulsed sources for inscribing waveguides in a wide range of glasses. [13][14][15][16] The amplifier performance of fs-inscribed waveguides is summarized in Table I. In high refractive index glasses such as tellurites, the energy per pulse and the repetition rate of the inscribing fs-pulsed laser are two important parameters.…”