Shanghai Institute of Optics and Mechanics Reveals Thermo-Optical Dynamics of Laser-Driven Phase Transition in VO2

Ultra-Intense Laser Science Excellence Innovation Brief

(Issue 822)

September 15, 2026

Shanghai Institute of Optics and Fine Mechanics Reports Major Progress in VO₂ Phase-Change Thermo-Optical Dynamics

Recently, a team led by Researcher Wang Jun at the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, made progress in mid-infrared thermo-optical modulation of VO₂. Focusing on the phase transition of VO₂/SiO₂ heterostructures driven by continuous mid-infrared lasers, the team systematically revealed the multi-stage thermo-optical response, from thermal accumulation and phase-transition acceleration to thermal saturation, and established a quantitative analytical framework linking incident power, switching speed and response stability. The findings were published in Photonics Research under the title “Stage-resolved thermo-optical switching dynamics in VO₂/SiO₂ heterostructures under continuous mid-infrared excitation”.

VO₂ exhibits a reversible insulator–metal phase transition and holds strong potential for mid-infrared optical switches, optical limiting and adaptive photonic devices. However, most studies to date have focused on ultrafast pump-probe measurements or steady-state thermal modulation, leaving a lack of systematic understanding of the dynamic relationship among thermal accumulation, phase-transition evolution and optical response under continuous-wave laser irradiation.

Figure 1. Thermo-optic response process of the VO₂/SiO₂ heterostructure under continuous mid-infrared excitation.

The team used a 3.8 μm continuous mid-infrared laser to drive the VO₂/SiO₂ heterostructure, combining dual-band transmittance measurements, transfer matrix analysis and multiphysics thermal simulations to resolve the phase transition process stage by stage. The results show that the forward transition proceeds through a heat-diffusion-dominated stage, a rapid transition involving latent heat, and a thermal saturation stage; as the incident power increases, the transition is triggered significantly faster. The recovery process also exhibits a transient intermediate state, thermal memory and hysteresis caused by heat dissipation. Further analysis shows that thermal accumulation in the VO₂/SiO₂ system and the enhanced absorption of VO₂ during the transition are the key factors determining switching speed and stability.

The study establishes a complete dynamical picture of VO₂ thermo-optic switching under continuous mid-infrared excitation, providing experimental and theoretical grounds for understanding the optical–thermal–phase-transition coupling in phase-change materials, and offering new ideas for the design of mid-infrared optical switches, optical limiters and adaptive photonic devices.

Figure 2. VO₂ phase transition dynamics and multistage thermo-optic response characteristics at different laser powers.

Original paper