All-angle phase matching condition and backward second-harmonic localization in nonlinear photonic crystals

Area of Science:

• Nonlinear optics
• Photonics
• Condensed matter physics

Background:

• Two-dimensional photonic crystals offer unique light manipulation properties.
• Nonlinear optical phenomena, such as second-harmonic generation (SHG), are crucial for frequency conversion.
• Achieving efficient and controlled SHG in photonic crystals remains a challenge.

Purpose of the Study:

• To demonstrate isotropic phase matching in nonlinear two-dimensional photonic crystals.
• To achieve backward second-harmonic generation by combining left- and right-handed properties.
• To investigate the resulting second-harmonic localization effects.

Main Methods:

• Designing and fabricating nonlinear two-dimensional photonic crystals.
• Utilizing left- and right-handed properties at fundamental and second-harmonic frequencies.
• Analyzing the phase matching conditions and SHG directionality.

Main Results:

• Isotropic phase matching was successfully demonstrated.
• Backward second-harmonic generation was achieved by combining specific handedness properties.
• An unusual second-harmonic localization effect was observed in perfect lattice photonic crystals.

Conclusions:

• The designed nonlinear photonic crystals enable efficient and controlled second-harmonic generation.
• The combination of isotropic phase matching and tailored handedness properties leads to novel optical phenomena.
• This work opens possibilities for advanced photonic devices with unique light localization capabilities.