Pressure-assisted sintering and characterization of Nd:YAG ceramic lasers

Spark plasma sintering (SPS) is an advanced one-stage, rapid, near-net shape densification technique combining uniaxial pressure with resistive heating. Various transparent ceramics have been successfully fabricated by SPS, despite the existence of inherent carbon contamination and residual pores. Due to the disk-shape of SPS-processed samples, the technique may be suited for producing thin-disk ceramic laser materials. Nevertheless, an in-depth study of these materials has never been reported. With that goal in mind, the major focus of this study was to characterize the laser performance of Nd:YAG ceramics fabricated by one-stage SPS under conventional (60 MPa) and high (300 MPa) applied pressures. In addition to measuring the lasing slope efficiency and threshold, the passive losses associated with each sample were also evaluated. Surprisingly, it was found that in-line transmittance spectra do not provide accurate predictions of laser performance due to the nature of residual porosity. Moreover, homogeneity and beam quality were assessed, and comparisons were drawn between conventional and high-pressure SPS ceramics. This study lays the groundwork for the future of laser materials fabricated by SPS or similar pressure-assisted techniques.

Automated summary

Spark plasma sintering (SPS) is an advanced densification technique used to fabricate various transparent ceramics, offering potential for producing thin-disk ceramic laser materials. This study focused on characterizing the laser performance of Nd:YAG ceramics fabricated using one-stage SPS under different pressures, revealing that residual porosity affects the accuracy of predicting laser performance based on in-line transmittance spectra. Additionally, comparisons between conventional and high-pressure SPS ceramics were made, setting the stage for future advancements in laser materials fabricated by SPS or similar techniques.