Mirrorless laser action in micromachined buried waveguides made in Nd:YAG ceramic crystals

G.A. TORCHIA, A. RÓDENAS, E. CANTELAR, A: BENAYAS, L. ROSO AND D. JAQUE

Paris, Francia

Conferencia; 3rd EPS-QEOD EUROPHOTON; 2008

This Femtosecond (fs) Direct Laser Writing (DLW) of transparent materials is attracting much attention because of the unique possibility of three-dimensionally modifying, at the micrometric and sub-micrometric scale, the optical properties of the irradiated media [1]. This fact boosts the fabrication of 3D waveguiding structures in optical media for different applications such as photonic crystal, second harmonic generation, laser action, optical memories, optical parametric amplification etc. It is well known that when fs pulses are focused inside dielectric material permanent changes in the refractive index are induced by the nonlinear absorption process, in such way different types of optical waveguides could be obtained [2,3]. The further use of the DLW technique for the fabrication of low-loss channel waveguides in laser materials could be highly advantageous with respect to other fabrication approaches, and could also lead to technology breakthroughs in the development of three dimensionally integrated optical circuits. This work deals on the high efficiency laser gain obtained for buried waveguide made in Nd:YAG ceramic crystals by means of femtosecond laser writing. Two optical breakdown tracks, separated 20 mm, work as the boundary for the guiding structures. Mirroless laser action was achieved by using as output coupler the Fresnel´s reflection in the interface crystal-air (R=0.08) at the exit end face of the crystal.  Slope efficiency at about 60% has been determined for 1,064 mm laser wavelength. Up to 70 mW output power for the integrated laser was also reported in this paper [4].