Giant Second Harmonic Generation by Photoinduced Phase Engineering

Area of Science:

• Materials Science
• Optics
• Condensed Matter Physics

Background:

• Miniaturizing nonlinear optical devices is crucial for technological advancement.
• Two-dimensional (2D) materials offer a potential solution to phase-matching limitations in bulk crystals.
• Laser-driven effects for enhancing nonlinear properties in 2D materials are underexplored.

Purpose of the Study:

• To demonstrate an optical method for achieving a significant second-order parametric response in 2D materials.
• To investigate the role of laser pulse duration in controlling nonlinear optical properties.
• To explore metastable noncentrosymmetric 1M-WS₂ as a candidate for advanced optical applications.

Main Methods:

• Utilizing selective laser pulse durations to control nonlinear optical effects.
• Fabricating and characterizing metastable noncentrosymmetric 1M-WS₂.
• Measuring the effective second harmonic generation (SHG) coefficient.

Main Results:

• Achieved a giant second-order parametric response in 1M-WS₂.
• Reported a record effective second harmonic generation coefficient of approximately 2000 pm/V.
• Identified unique structural distortions in the 1M phase as key to the enhanced nonlinear response.

Conclusions:

• Laser-driven effects offer a controllable and accessible method to enhance nonlinear optical properties in 2D materials.
• Metastable noncentrosymmetric 1M-WS₂ exhibits exceptional nonlinear optical performance.
• 1M-WS₂ is a promising material for next-generation compact optical modulators and nanolasers.