Design of a High-Performance Infrared Nonlinear Optical Crystal via a Multiple Flexible-Group Synergistic...

Area of Science:

• Materials Science
• Optics
• Solid State Physics

Background:

• Developing high-performance infrared (IR) nonlinear optical (NLO) crystals faces challenges balancing NLO coefficient, laser damage threshold (LDT), and IR transparency.
• Existing NLO materials often compromise on one or more critical properties.

Purpose of the Study:

• To establish a structure-property relationship for NLO response in diamond-like compounds.
• To develop a predictive strategy for discovering novel IR NLO crystals.
• To identify and characterize a new exceptional IR NLO material.

Main Methods:

• Established a sixth-power scaling relation (d_ijk ∝ F^6) between NLO coefficient and average flexibility index (F).
• Employed a multiple flexible-group synergistic polarization strategy for material design.
• Synthesized and characterized the proposed crystal, Cd2In3Si2P7 (CISP).

Main Results:

• Discovered CISP, an exceptional IR NLO crystal with the largest recorded second-harmonic generation (SHG) effect among pnictides.
• CISP exhibits high NLO coefficients (d22 = 137.6 pm/V, d23 = 89.3 pm/V @ 1500 nm) and a high LDT (10.3 × AgGaS2).
• CISP demonstrates a broad IR transmission range (0.62–18.0 μm) and moderate birefringence (0.098 @ 2050 nm).

Conclusions:

• The established structure-property relationship and design strategy are effective for discovering high-performance IR NLO materials.
• CISP shows significant potential as a promising material for IR NLO applications.
• The study introduces a valuable descriptor for understanding structure-property correlations in polarizable materials.