Gravity‐Field Self‐Regulatory Engineering Enables PbIn ₆ Te ₁₀ Nonlinear Optical Crystals Boosting Laser‐Induced Damage Threshold

ABSTRACT

Mid‐ to far‐infrared (MFIR) laser sources are essential for spectroscopy, remote sensing, communication, and environmental monitoring. However, scalable growth of high‐quality lead indium telluride (PbIn ₆ Te ₁₀ , PIT), as a promising nonlinear optical (NLO) material for MFIR frequency conversion, has long been hindered by lead segregation. Gravity‐induced accumulation of these intrinsic segregants destabilizes the growth interface, leading to heterogeneous nucleation and cracking. Herein, we develop a gravity‐field self‐regulatory strategy to grow crack‐free PIT single crystals reaching Ø27 × 145 mm. MFIR frequency conversion devices fabricated from these crystals achieve a high nanosecond‐regime laser‐induced damage threshold of 24.2 MW/cm ² under 7.2 µm, 17 ns pulsed irradiation, with validated second harmonic generation featuring synchronous pulse compression for generating narrower mid‐infrared pulses. The enhanced performance arises from the gravity‐mitigated horizontal Bridgman method, which alleviates gravity‐induced interface disturbance and enables low‐gradient growth to suppress lead segregation, the primary drivers of growth defects. This work provides a robust growth strategy for segregation‐prone multi‐component NLO crystals, paving the way for next‐generation compact, high‐sensitivity MFIR spectroscopic systems.