Discrete diffraction and spatial gap solitons in photovoltaic LiNbO3 waveguide arrays

Area of Science:

• Nonlinear optics
• Condensed matter physics
• Photonic crystals

Background:

• Waveguide arrays are crucial for controlling light propagation.
• Nonlinear optical effects enable advanced photonic functionalities.
• Photorefractive materials offer unique optical properties.

Purpose of the Study:

• To investigate light propagation in 1D waveguide arrays with saturable self-defocusing nonlinearity.
• To demonstrate discrete diffraction and spatial gap soliton formation.
• To explore the role of the transmission spectrum in soliton dynamics.

Main Methods:

• Experimental fabrication of waveguide arrays using titanium in-diffusion in lithium niobate.
• Theoretical modeling of light propagation dynamics.
• Optical experiments utilizing a photorefractive copper-doped lithium niobate crystal.

Main Results:

• Demonstration of low-intensity discrete diffraction.
• Observation of high-intensity spatial gap soliton formation.
• Solitons arise from the first band of the transmission spectrum.

Conclusions:

• Saturable nonlinearity enables distinct light propagation regimes.
• Spatial gap solitons are formed in engineered photonic lattices.
• The bulk photovoltaic effect in photorefractive materials drives the observed nonlinear optical phenomena.