Organic crystals growth for optical channel waveguides

Optical channel waveguides of meta-nitroaniline (m-NA) crystal, which has potential applications to nonlinear optical devices, have been fabricated on glass substrates having fine grooves. The crystal growth was performed by zone-melting, scanning a CO₂ laser beam along the grooves filled with the polycrystal m-NA. Optical and X-ray observations showed that zone-melting changed the polycrystalline state to a single crystalline state with the 〈001〉 direction along the groove. The scattering loss for a 5 mm-long m-NA crystal waveguide (100 μm both in width and in depth) was found to decrease from 50 dB to 2.5 dB with this process.