Structured all-optical domain inversion in iron-doped lithium niobate

Area of Science:

• Materials Science
• Photonics
• Nonlinear Optics

Background:

• All-optical domain inversion in lithium niobate (LiNbO3) is a key technique for fabricating nonlinear optical devices.
• Previous methods were limited to using Gaussian beams, restricting pattern complexity and control.

Purpose of the Study:

• To explore the use of structured light for fabricating 2D domain patterns in lithium niobate.
• To investigate the relationship between domain growth dynamics and light exposure parameters.
• To demonstrate precise control over domain shape and size using amplitude-modulated visible laser light.

Main Methods:

• Utilized amplitude-modulated continuous-wave visible laser light controlled by a spatial light modulator.
• Employed 3D second-harmonic generation (SHG) laser scanning microscopy, SHG k-spectroscopy, and scanning electron microscopy for domain evaluation.
• Analyzed domain growth dynamics in relation to light field amplitude and exposure duration.

Main Results:

• Demonstrated the fabrication of various 2D domain patterns using structured light.
• Observed initial nanodomain growth aligned with crystallographic directions, followed by shape determination based on light field amplitude and exposure time.
• Successfully created uniform single and multiple spatially shaped domains with lateral extensions from 300 nm to over 400 μm.

Conclusions:

• Structured light offers a versatile and effective method for controlling domain inversion in lithium niobate.
• The findings highlight the potential for shaping quasi-phase-matched optical processes by precisely controlling domain formation.
• This technique advances the fabrication of complex optical devices with tailored nonlinear properties.