Fs laser writing in Nd3+ doped GeO2-PbO glasses for the production of a new double line waveguide architecture for photonic applications

Abstract

A new double line waveguide architecture produced in Nd3+ doped GeO2-PbO glasses is presented for photonic applications. These glasses produced with the melt quenching technique have interesting characteristics that make them attractive for photonic applications: large transmission window (400–5000 nm), large polarizability, low melting temperature (1200° C) with respect to silicates, low cut-off phonon energy (~800 cm-1), large mechanical resistance, high chemical durability and high refractive index (~2.0). The double line waveguides are written directly into Nd3+ doped GeO2-PbO glasses using a Ti:Sapphire femtosecond (fs) laser, operating at 800 nm, delivering 30 fs pulses at 10 kHz repetition rate. The two written lines that form the double waveguide are formed by several collinearly overlapping lines. Results of the output mode profile, the M2 beam quality factor at 632 and 1064 nm and refractive index change are presented, as well as the parameters used for laser writing. Double waveguides written with 4 and 8 overlapping lines, writing speed of 0.5 mm/s and pulse energy of 30 μJ demonstrated to be adequate parameters for writing; refractive index changes of ~10-3 were found at 632 nm for all the cases. The present results demonstrated that Nd3+ doped GeO2-PbO glasses with the new double line waveguide architecture are promising materials for the fabrication of passive and active components for photonic applications. Further investigation will focus on the influence of the writing parameters on the optical performance of the different waveguides, and evaluate the potential of the materials as optical amplifiers at 1064 nm.