Optical switching and photoluminescence in erbium implanted vanadium dioxide thin films

Vanadium dioxide (VO₂) undergoes an insulator-metal transition (IMT) that involves drastic changes in its electrical and optical properties at relatively low critical temperature T_c ≈ 67°C [1]. The switching speed when triggered by an optical impulse is incredibly fast, within a femtosecond timescale [2]. Erbium (Er³⁺) with a stimulated emission at the standard telecommunication wave-length of 1535nm has been used extensively in fiber-optic communication systems [3]. The combination of VO₂ and Er³⁺ could make an ultrafast optical switch that is capable of simultaneous signal amplification. In this work, we investigated the possibilities of making such a device, both theoretically and experimentally. Our experimental methods involve temperature-driven optical switching tests and photoluminescence (PL) spectroscopy on Er³⁺ implanted VO₂ thin films. The observations of the IMT of VO₂ and the PL of Er³⁺ in the thin films would be vital in determining whether the VO₂:Er system would work as an optical switch and amplifier. A range of implantation and post-annealing schemes were explored in an attempt to find the optimal processing conditions that would maximize the qualities of the optical switching and PL.