Intrinsic optical bistability and temperature sensing in the Laser–Induced Anti-Stokes broadband white light emission

Abstract

In this work, we provide a detailed investigation into the underlying mechanisms of laser-induced white light emission (LIWE) and examine the effects of particle size and bulk properties on the optical features of lanthanide sesquioxides. The upconversion emission colour is tunable by changes in sample packing density, laser diode intensity and continuous excitation wavelength at 808 or 980 nm up to 11 kW cm⁻². The results demonstrate that the slope for the linear fit for Log I_LIWE vs Log P_D should not be interpreted as the number of photons in the LIWE process. The temporal dynamics and photoconductivity analysis indicate that multiphoton ionisation and avalanche processes are not involved in LIWE generation. The minor resistance oscillations (within one order of magnitude) over a timescale of seconds, along with photocurrent intensities in the nA, can be attributed to a light-to-heat mechanism induced by laser excitation. The single emitters reported here present intrinsic optical bistability coupled to temperature sensing in a wide range, 972−2542 K, with a high resolution of 0.2 K. The photophysical analysis indicates that there are two optical bistable emissions at low/high laser power densities.