Mode-controllable waveguide fabricated by laser-induced phase transition in KTN

Area of Science:

• Materials Science
• Optoelectronics
• Laser Physics

Background:

• Potassium tantalate niobate (KTN) crystals possess a significant electro-optical effect.
• Developing advanced optical waveguides is crucial for integrated photonics.
• Femtosecond laser direct writing (FLDW) offers precise material modification capabilities.

Purpose of the Study:

• To fabricate hexagonal cladding waveguides in KTN crystals using FLDW.
• To investigate the impact of laser-induced phase transitions on waveguide properties.
• To achieve excellent polarization-maintaining capabilities and active control of light propagation.

Main Methods:

• Femtosecond laser direct writing (FLDW) for waveguide fabrication.
• Confocal micro-Raman spectroscopy to analyze laser-induced modifications.
• Characterization of waveguide birefringence and polarization-maintaining features.

Main Results:

• Successful fabrication of hexagonal cladding waveguides in KTN.
• Observation of laser-induced phase transitions within filament areas.
• Enhanced waveguide birefringence due to confined polar nanoregions, enabling strong polarization maintenance.
• Demonstration of temperature-dependent control over waveguide polarization modes.

Conclusions:

• FLDW in KTN crystals enables the creation of high-performance polarization-maintaining waveguides.
• Laser-induced phase transitions are key to enhancing waveguide birefringence.
• Switchable polarization-maintaining functionality can be achieved through temperature control.