Low-loss waveguides of benzylidene-aniline derivatives by organic molecular beam heteroepitaxy

An organic nonlinear optical crystal waveguide consisting of 4'-nitrobenzylidene-3-acetamino-4-methoxyaniline (MNBA) and 4'-nitrobenzylidene-3-ethylcarbonylamino-4-methoxyaniline (MNBA-Et) has been fabricated by a two-step heteroepitaxial growth technique. An MNBA-Et homoepitaxial layer used as a buffer layer prevents the formation of a MNBA polycrystalline domain at the heteroepitaxial interface. The MNBA-Et homoepitaxial layer also improves the crystallinity of a single-domain MNBA heteroepitaxial layer. The transmission loss of the MNBA-MNBA-Et slab waveguide is reduced to less than 3 dB/cm by the insertion of the MNBA-Et homoepitaxial layer. (C) 2003 Optical Society of America.