1000 K optical ratiometric thermometer based on Er3+ luminescence in yttrium gallium garnet

Abstract

The temperature dependence of the Er3+ green luminescence in Y3Ga5O12 crystal were analysed under ultraviolet and near-infrared laser excitations for optical sensing purposes. Changes in the relative green emission intensities from the 2H11/2 and 4S3/2 thermally-coupled multiplets to the 4I15/2 ground state were measured from room temperature up to 1000 K. The calibrated temperature scale shows a maximum in the absolute thermal sensitivity of ~23.9 × 10−4K−1 at 580 K and a relative thermal sensitivity of ~1.36%K−1 at RT, combining results for both blue and near-infrared laser excitations. The excellent results obtained, compared with other Er3+-based optical temperature sensors, are a consequence of the advantages of garnet crystals as optically efficient hosts that, apart from an impressive capability to be synthesized both as bulk and fiber forms, allow extending the long working temperature range up to 1000 K, and beyond, to the melting point limit close to 2000 K. In addition, the use of green emissions for the temperature calibration, with negligible black-body radiation disturbance, only needs a low-cost, basic setup that uses commercially available lenses, lasers and detectors. All these facts support the Er3+-doped Y3Ga5O12 garnet crystal as a potential candidate as temperature sensor, showing large sensitivity and good temperature resolution for ultra-high temperature industrial applications.