Phase transformation under direct laser writing in a YAG single crystal

A. G. Okhrimchuk,V. Mezentsev,A. S. Lipatiev,G. Orlova,E. V. Zharikov,P. G. Kazansky

doi:10.1364/ome.7.003408

Abstract

The transformation from Y3Al5O12 to perovskite YAlO3 crystal phase was observed during ultrafast laser writing in the bulk of a Y3Al5O12 single crystal. The control of the phase transformation was demonstrated by tuning parameters of laser writing. The phenomenon is interpreted in terms of structural changes in the overheated garnet melt under laser heating followed by rapid solidification, and at least 1-ms dwell time of overheated melt is required to start spontaneous crystallization. The appearance of the perovskite phase was confirmed by Raman spectroscopy, quantitative phase and polarization microscopies.

Highlights

Femtosecond laser inscription has rapidly progressed into an enabling technology for microand nano- scale phase transformation between the amorphous and the crystalline phases in glass matrixes for applications ranging from nonlinear frequency conversion to lasing in micro volumes [1,2,3,4,5,6]
We suggest that once perovskite phase has appeared at low velocity due to metastable crystallization, it further serves as a seed and prolongs crystallization path to YAP phase even when the dwell time τ becomes below 1 ms
Summary Controlled transformation of yttrium aluminium garnet (YAG) single crystal to polycrystalline perovskite YAlO3 and amorphous Al2O3 phases were obtained under direct femtosecond laser writing with 1 MHz repetition rate in the form of a millimeter long track with a few microns size cross-section

Summary

Introduction

Femtosecond laser inscription has rapidly progressed into an enabling technology for microand nano- scale phase transformation between the amorphous and the crystalline phases in glass matrixes for applications ranging from nonlinear frequency conversion to lasing in micro volumes [1,2,3,4,5,6]. In this paper we report on the phase transformation in Y3Al5O12 (YAG) single crystals into YAlO3 (YAP) crystals at microscopic scale. This phenomenon enables developing a range of photonic structures such as crystalline waveguides with high refractive index contrast for high peak and average power applications. Since YAG and YAP crystals have high segregation coefficients for rare-earth ions, the discovered effect of transformation paves the way for developing high power waveguide lasers with cavity length less than 1 cm

Laser writing of tracks

Discussions

Heat transfer analysis