N-(4-nitrophenyl)-N-methylamino-aceto-nitrile: a new organic material for efficient second-harmonic generation in bulk and waveguide configurations I Growth, crystal structure, and characterization of organic crystal-cored fibers

Abstract

Second-harmonic generation (SHG) is theoretically investigated in weakly guiding organic crystal-cored fibers (OCCF’s), where the crystal axes are parallel to the corresponding waveguiding ones. The analysis made for all acentric point groups clearly singled out core orientations favorable for efficient SHG (under appropriate phase-matching conditions). The analysis of molecular orientations maximizing the relevant nonlinear (NL) coefficients shows that NL organic materials optimized for efficient SHG in the bulk are also optimized for efficient SHG in OCCF’s. We discuss the growth methods of OCCF’s and present the results obtained when two organic materials, N-(4-nitrophenyl)-(L)-prolinol (NPP) and N-(4-nitrophenyl)-N-methylamino-aceto-nitrile (NPAN), are used. The crystal structure of the new material NPAN as well as related NL properties are presented for the first time to the authors’ knowledge. The nonlinear properties of NPAN are comparable with those of the best phase-matchable organic material, NPP.