High-precision FoM measurement setup for Ti:sapphire crystals

0573332 - ÚFP 2024 RIV US eng J - Journal Article
Miller, V. - Žídek, Karel
High-precision FoM measurement setup for Ti:sapphire crystals.
Applied Optics. Roč. 62, č. 5 (2023), s. 1345-1350. ISSN 1559-128X. E-ISSN 2155-3165
R&D Projects: GA MŠMT(CZ) EF16_026/0008390
Institutional support: RVO:61389021
Keywords : Ti:sapphire * crystals * FoM measurement
OECD category: Thermodynamics
Impact factor: 1.9, year: 2022
Method of publishing: Limited access
https://opg.optica.org/ao/abstract.cfm?uri=ao-62-5-1345

The figure of merit (FoM) of Ti:sapphire (Ti:Sa) crystals is a generally used means to evaluate the quality of the crystals. Despite the importance of Ti:Sa, the question of FoM measurement precision stayed out of focus, while the commercially available spectrometers provide unsatisfactory 3σ precision reaching ±60%. In this paper, we present a setup for a single-pass high-precision transmission measurement for three different wavelengths (532, 780, and 1560 nm) based on Nd:YAG and Er:YAG lasers. A synchronous detection via a double integrated sphere enabled us to achieve the transmission uncertainty of 0,01–0,03%. With the presented setup, we show that it is possible to determine the FoM values with 3σ precision of ±7, 5 %. Owing to the high FoM precision, we were able to trace spatial inhomogeneities of an unannealed Ti:Sa crystal produced by a commercial manufacturer Crytur. Our measurements demonstrate that the FoM values can be significantly affected by the crystal inhomogeneities and angular mismatch between the c axis of the Ti:Sa and polarization orientation.
Permanent Link: https://hdl.handle.net/11104/0343795