Diffusion characteristics study of locally Er-doped noncongruent, Li-deficient Ti:Er:LiNbO_3 strip waveguide

摘要

Locally Er~(3+)-doped noncongruent, Li-deficient Ti:Er:LiNbO_3 strip waveguide was fabricated with a technological process in sequence of preparation of Li-deficient LiNbO_3 substrate using Li-poor vapor transport equilibration (VTE), Er~(3+), and Ti~(4+) diffusion in wet O_2. The Li_2O content change was evaluated from the measured birefringence. The Ti~(4+) and Er~(3+) profile characteristics in the waveguide were studied by secondary ion mass spectrometry. The results show that the VTE and subsequent Er~(3+) diffusion procedures resulted in totally ～0.8 mol% Li_2O content reduction. The Ti~(4+) profile follows a sum of two error functions in the width direction and a Gaussian function in the depth direction of waveguide. The Er~(3+) profile follows also a Gaussian function. At 1130 ℃, the Ti~(4+) surface/depth diffusivity and surface concentration are 8.5 ± 1.3/1.98 ± 0.06 μm~2/h and ~7 mol%, respectively, and the Er~(3+) diffusivity and surface concentration are (12.8 ± 0.3) × 10~(-2) μm~2/h and ~0.6 mol%, respectively.