A Telluromolybdate Mid-Infrared Nonlinear Optical Crystal with Wide Transparency and Strong Second-Harmonic Generation Response

Abstract Nonlinear optical (NLO) crystals are fundamental to the development of all-solid-state laser technology, as they enable the extension of frequency ranges for coherent light generation. Herein, we report a novel mid-infrared (MIR) NLO telluromolybdate crystal, Cd13Mo4Te18O61 (CMTO), synthesized via a flux-assisted spontaneous crystallization process. CMTO adopts the Imm2 (No. 44) space group and features a variety of asymmetric building blocks. Notably, CMTO achieved a well-balanced combination of properties, including a large band gap of 3.04 eV, a wide transparency range of 0.29–6.0 μm and a strong second harmonic generation (SHG) response about 3 times as strong as that of KDP. Additionally, it possesses a suitable birefringence value of 0.135 at 1064 nm. First-principles calculations further elucidate that the optical activities of CMTO are predominantly influenced by Te–O and Mo–O polyhedral motifs. Collectively, these findings identify CMTO as a promising candidate for MIR NLO crystals.