PHASE MATCHING METHOD FOR WAVEGUIDE TYPE NONLINEAR OPTICAL ELEMENT

摘要

PURPOSE:To obtain a waveguide type nonlinear optical element having high second harmonic wave generating efficiency by controlling the light of a waveguide layer by the external force or temp. in the thickness direction, thereby executing phase matching. CONSTITUTION:The phase matching of the optical waveguide having the waveguide layer consisting of the org. nonlinear optical element having a high refractive index and a clad layer having a low refractive index is executed by changing the thickness of the waveguide layer by exerting compressing force to said waveguide in the thickness direction of the waveguide layer from the outside or changing the temp. of the waveguide. The thickness of the waveguide layer decreases and the refractive index of the waveguide layer is decreased by an optoelastic effect if external force is exerted to the waveguide layer in the thickness direction thereof. The critical waveguide layer thickness to impart phase matching is then shifted in the thick direction. The actual waveguide layer thickness is, therefore, equal to the critical waveguide layer thickness by the adequate load and the phase matching is attained. The control of the waveguide layer thickness is also possible by changing the temp. of the waveguide. The phase matching method for the waveguide type nonlinear optical element exhibiting the high second harmonic wave generating efficiency is thereby obtd.