Simultaneous realization of FIR-based multimode optical thermometry and photonic molecular logic gates in Er3+ and Yb3+ co-doped SrTiO3 phosphor

Abstract

Er3+ and Yb3+ co-doped SrTiO3 phosphors were synthesized and characterized by using the x-ray powder diffraction method, field emission scanning electron microscopy, and photoluminescence spectroscopy. The samples were subjected to thorough luminescence analysis. Under 980 nm infrared (IR) excitation, the (2H11/2,4S3/2) → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3+ gave green and red emissions, respectively. The up-conversion mechanism of the synthesized phosphor was studied using the power-dependent emission spectra of the SrTiO3:Yb3+, Er3+ phosphor. A rate equation model for the up-conversion mechanism of SrTiO3:Yb3+, Er3+ has been proposed. The temperature-dependent responses of various thermal and non-thermally coupled emission lines of Er3+ ions were used to elaborate the thermal sensing capabilities of the synthesized phosphor. The fluorescence intensity ratio technique was used for the temperature sensing measurements. Sensing measurements were performed in the temperature range of 303 to 618 K. Relative sensitivities of 1.28% K−1, 0.15% K−1, 0.98% K−1, and 0.15% K−1 were observed using various thermally and non-thermally coupled energy levels. Furthermore, using heat and incident IR excitation as physical inputs, we have shown that the synthesized phosphor can also be used to design various elementary logic gates such as AND, INHIBIT, and DEMULTIPLEX photonic molecular logic gates. A high switching ratio of ∼143% for the AND gate and ∼44.8% for the INHIBIT gate was observed using the scheme presented in this manuscript. The synthesized phosphor has the potential to be used as a bifunctional material for optical thermometry and molecular logic devices.