Organic crystal isopropyl-4-acetylphenylurea and waveguide second-harmonic generation

Abstract

A new organic crystal isopropyl-4-acetylphenylurea (IAPU) was identified as a promising candidate for blue second-harmonic generation (SHG). The nonlinear optical d coefficient obtained is d22=30.5 pm/V at the fundamental wavelength 1064 nm, and the crystal's transmitting range is 380–1400 nm. Thin, single crystalline films fabricated on the glass substrate are useful for waveguide-device applications. For the improvement of SHG efficiency and the relaxation of phase-matching conditions, the concept of thickness-noncritical phase matching (TNCPM) in a four-layer waveguide is proposed. Modal dispersion calculations for the various four-layer structures suggested the possibility of TNCPM from the TE0ω mode to TE12ω mode and from the TE0ω mode to the TE22ω mode by adjustment of the refractive indices of the two guiding layers.