Product Code: ICA11_M1004

Waveguides and Markings Inside Transparent Materials by Fs-Laser Radiation
Authors:
Dagmar Schaefer, Chair for Laser Technology LLT, RWTH Aachen University; Aachen Germany
Dennis Beckmann, Chair for Laser Technology LLT, RWTH Aachen University; Aachen Germany
Maren Hoerstmann-Jungemann, Chair for Laser Technology LLT, RWTH Aachen University; Aachen Germany
Ingomar Kelbassa, Chair for Laser Technology LLT, RWTH Aachen University; Aachen Germany
Presented at ICALEO 2011

Femtosecond laser writing is an important technique for the realization of many devices. Waveguides, in-volume markings and micro structured devices are flexibly producible with the direct writing technique opening a huge market. Application fields for markings are markets like logistics, identification and advertisement in addition to waveguides for beam shaping of laser radiation and diagnostic in medical engineering.
Using focused ultrashort laser pulses localized refractive index changes in the volume of transparent materials are created. A FCPA fiber laser provides femtosecond laser pulses with a variable repetition rate (f=0.1-5MHz). The available laser system in combination with a high speed scanning system (v>100mm/s) enables precise modifications (<1µm) in the volume of the materials.
Laser-induced refractive index changes enable the direct writing of waveguides in glass materials. Using femtosecond double pulses instead of single pulses waveguides with a higher numerical aperture are generated because of changed non-linear absorption effects.
By writing parallel and orthogonal lines with distances in the micrometer range two- and three-dimensional colorful markings are producible in glass and sapphire without microcracks. The colors are a result of diffraction and interference effects and change with the viewing angle.
Results of the latest and actual research regarding precise micro structuring of transparent materials with femtosecond laser systems will be presented and discussed.