Dependence of femtosecond writing parameters in waveguide formation process within significantly broad depths range

摘要: Direct femtosecond laser inscription has become an advanced and widespread maskless technology for waveguides writing inside optical materials. One of the advantages consists in combination both high efficiency integral optics perfect thermal spectral characteristics bulk elements. In paper we proposed, what is believed to be first time, induced structures with modified refractive index (reduced down −6 × 10−3) within significantly broad depth range (more than 550 μm) waveguide mode field diameter 200 μm, 30 mm length numerical aperture 0.04. Proposed result broadens application into large formation hybrid integral-bulk schemes that create opportunity develop novel Laser tracks controlled were written aspherical lens at all depths between 1100 μm under surface sample. Continuous process different was based on dynamic adjustment pulses energy compensate negative effect spherical aberration. investigation examined dependences geometry depth. Experiments carried out Nd:phosphate glass cumulative regime (repetition rate 2 MHz) compared simulation. It shown, dependence working focusing nonlinear, nonmonotonic differs positive shift from optimal correction lens.