Visible optical nonlinearity of vanadium dioxide dispersions

Area of Science:

• Solid State Physics
• Correlated Oxide Materials
• Nonlinear Optics

Background:

• Vanadium dioxide (VO2) is a functional material with significant physical properties.
• The nonlinear optical response and all-optical applications of VO2 have been underexplored.
• Understanding VO2's nonlinear optical characteristics is crucial for developing novel optical devices.

Purpose of the Study:

• To investigate the nonlinear optical properties of VO2 dispersions.
• To quantify the nonlinear refractive index (n2) and third-order nonlinear susceptibility (χ(3)) of VO2.
• To demonstrate proof-of-principle all-optical functions using VO2 dispersions.

Main Methods:

• Spatial Self-Phase Modulation (SSPM) and Spatial Cross-Phase Modulation (SXPM) techniques were employed.
• Measurements were conducted in the visible wavelength regime (671 nm and 532 nm).
• The response time of VO2 to light was analyzed to understand the underlying nonlinear process.

Main Results:

• VO2 dispersions exhibited significant nonlinear optical properties, with measured n2 and χ(3) values.
• At 671 nm, n2 = 3.06 × 10^-6 cm^2 W^-1 and χ(3) = 1.68 × 10^-4 esu.
• At 532 nm, n2 = 5.17 × 10^-6 cm^2 W^-1 and χ(3) = 2.83 × 10^-4 esu.
• The formation of diffraction rings was identified as an electronically coherent third-order nonlinear optical process.

Conclusions:

• VO2 dispersions possess excellent nonlinear optical responses suitable for all-optical applications.
• Proof-of-principle optical logic or-gates, all-optical switches, and inter-channel information transfer were successfully implemented.
• These findings establish a foundation for the development of VO2-based all-optical devices.