A POLYMERIC FIVE-LAYER NONLINEAR OPTICAL WAVEGUIDE WITH A LARGE DIMENSION TOLERANCE AND LARGE OVERLAP INTEGRAL FOR MODE CONVERSION PHASE-MATCHING

摘要

In order to produce a highly efficient second harmonic generation (SHG) device, phase-matching must be fulfilled. In this paper, we propose a novel polymeric five-layer nonlinear optical waveguide to improve both the fabrication tolerance and the overlap for mode conversion phase-matching, In the case of poled polymers, the introduction of the inversion of the nonlinear susceptibility structure which induces the high overlap integral value is very difficult. We propose a relatively simple technique to fabricate the inversion of the nonlinear susceptibility structure across the poled polymer waveguides based on a five-layer structure. The five-layer waveguide can be prepared by just pasting two poled polymer films deposited onto a substrate onto each other with a small gap consisting of silicon oil or air. The calculation results show that the phase-matching thickness can be satisfied in the range of 0.44 up to 0.57 mu m, if the propagation length is 1 mm, This large dimension tolerance for phase-matching is at least 150 times larger than the fabrication tolerance of three-layer waveguides. The conversion efficiency can be improved also more than 6 orders of magnitude above that of three-layer waveguides due to their high overlap integral. [References: 30]