Stress-induced optical waveguides written by an ultrafast laser in Nd3+, Y3+ co-doped SrF2 crystals

B Hari Babu; Chengkun Lyu; Thomas Billotte; D Pallares-Aldeiturriaga; Bertrand Poumellec; J M Lopez-Higuera; Xiao-Tao Hao; Matthieu Lancry

doi:10.1364/AO.58.000984

Stress-induced optical waveguides written by an ultrafast laser in Nd³⁺, Y³⁺ co-doped SrF₂ crystals

Appl Opt. 2019 Feb 1;58(4):984-990. doi: 10.1364/AO.58.000984.

Authors

B Hari Babu, Chengkun Lyu, Thomas Billotte, D Pallares-Aldeiturriaga, Bertrand Poumellec, J M Lopez-Higuera, Xiao-Tao Hao, Matthieu Lancry

PMID: 30874146
DOI: 10.1364/AO.58.000984

Abstract

In this paper, we report on the ultrafast laser-induced birefringence, refractive index changes, and enhanced photoluminescence properties in the volume of neodymium (Nd), yttrium (Y) co-doped strontium fluoride (SrF₂) and Nd, Y co-doped calcium fluoride (CaF₂) crystals. The optical waveguides written with 500 kHz repetition rate provided lowest propagation loss of 1.63±0.21 dB cm^-1 for transverse magnetic (TM) polarization at 632.8 nm in Nd,Y:SrF₂ crystal. The measured retardance can be interpreted by stress-induced birefringence related to the permanent volume expansion, photo induced by a non-spherical irradiated zone. The absorption, steady-state, and time-resolved photoluminescence properties are also carried out in and out of the laser irradiated zone, enabling the local changes of the Nd and Y network in Nd,Y:SrF₂, as well as well-preserved Nd fluorescence in the written optical waveguides.