Growth and THz generation in organic nonlinear optical crystal: N,N′ bis(4-nitrophenyl)-(1R,2R)-diaminocyclohexane (BNDC)

Abstract

We report on the growth of large size organic single crystal of a C2-symmetric bis amide molecule, N,N′ bis(4-nitrophenyl)-(1R,2R)-diaminocyclohexane (BNDC) for the first time. Optical quality BNDC single crystals of sizes 1.7 × 1.9 × 0.5 cm3 and 1.5 × 0.5 × 0.2 cm3 are successfully grown from mixed solvents by varying the molar ratios. The physical properties of the as-grown BNDC crystals are studied and discussed in detail. From the powder X-ray diffraction study, the lattice parameters of the as-grown BNDC crystal are determined to be a = 10.237 Å, b = 12.827 Å and c = 13.622 Å (α = β = γ = 90°) which matches with the reported CCDC file (155122). BNDC crystal melts at 212 °C and no phase change behavior is observed. BNDC crystal shows good optical transmittance between 519 and 2000 nm. The slim P–E hysteresis loop reveals soft magnetism in BNDC crystal. The presence of ferroelectric domains is visualized using AFM. We demonstrate the THz generation in BNDC crystal for the first time using Ti:Sapphire Laser with a wavelength of 800 nm of 140 femtosecond pulses with 80 MHz repetition rate. We employed optical rectification technique for THz generation, and efficiency of generated power of the electric field for BNDC crystal was of the order of 10–4 V at 700 mW incident laser power.