John M. Ballato

Aug 15, 2024 | opg.optica.org | John M. Ballato |Arash Mafi |Alexander Neumann |Thomas Hawkins

For the first time, to our knowledge, an all-solid transverse Andersonlocalizing optical fiber laser is demonstrated. A combination of themolten core and stack-and-draw fiber fabrication techniques is used toproduce a 112 µm core diameter fiber that is a random array ofYb-doped high index and passive low index regions.

Aug 2, 2024 | opg.optica.org | John M. Ballato |Martin Bernier |Thomas Hawkins |Tommy Boilard

Recent progress in the fabrication of Yb-doped silicate fibers with low concentration quenching and low background absorption loss has led to the demonstration of anti-Stokes-fluorescence cooling in several aluminosilicate compositions. This breakthrough is critical to combat deleterious thermal effects due to the quantum defect in fiber lasers and amplifiers. Since cooling efficiencies remain low (1–2.7%), it is paramount to engineer compositions that improve this metric.

May 21, 2024 | opg.optica.org | Maxime Cavillon |John M. Ballato |Thomas Hawkins |Miranda P. Stone

An all-glass optical fiber capable of two distinct methods of opticalthermometry is described. Specifically, a silica-clad, bariumfluorosilicate glass core fiber, when pumped in the infrared, exhibitsvisibly intense green defect luminescence whose intensity andupper-state lifetime are strong functions of temperature. Intensity-based optical thermometry over the range from 25°C to 130°Cis demonstrated, while a lifetime-based temperature sensitivity isshown from 25°C to 100°C.

Apr 9, 2024 | opg.optica.org | Mary Cahoon |John M. Ballato |Martin Bernier |Thomas Hawkins

The focus of this study was the development of a second generation offiber lasers internally cooled by anti-Stokes fluorescence. The laserconsisted of a length of a single-mode fiber spliced to fiber Bragggratings to form the optical resonator. The fiber was single-moded atthe pump (1040 nm) and signal (1064 nm) wavelengths. Its core washeavily doped with Yb, in the initial form of CaF2nanoparticles, and co-doped with Al to reduce quenching and improvethe cooling efficiency.

Aug 30, 2023 | nature.com | Meng Huang |Shiyu Sun |Li Shen |John M. Ballato

AbstractRaman scattering provides a convenient mechanism to generate or amplify light at wavelengths where gain is not otherwise available. When combined with recent advancements in high-power fiber lasers that operate at wavelengths ~2 μm, great opportunities exist for Raman systems that extend operation further into the mid-infrared regime for applications such as gas sensing, spectroscopy, and biomedical analyses.