Near-stoichiometric Ti:LiNbO3 strip waveguide with varied substrate refractive index in waveguide layer  

作　　者：张德龙 吴嫦 潘裕斌 

机构地区：[1]School of Precision Instruments and Opto-electronics Engineering,Tianjin University,Tianjin 300072,China,and Key Laboratory of Optoelectronics Information Science and Technology,Ministry of Education [2]Department of Electronic Engineering,City University of Hong Kong,83 Tat Chee Avenue,Kowloon,Hong Kong SAR,China

出　　处：《Chinese Physics B》2010年第2期329-335,共7页中国物理B（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 50872089 and 60577012);the Research Grants Council of the Hong Kong Special Administrative Region, China (Grant No. CityU 1194/07)

摘　　要：We report the near-stoichiometric Ti：LiNbO3 strip waveguides fabricated by vapour transport equilibration （VTE） at 1060~^{／circ}C for 12 h and co-diffusion of 4--8~／mu m wide, 115-nm thick Ti-strips. Optical studies show that these waveguides are monomode at 1.5~／mu m and have losses of 1.3 and 1.1~dB/cm for the TM and TE modes, respectively. In the waveguide width/depth direction, the mode field follows a Gauss/Hermite--Gauss profile. A secondary ion mass spectrometry study reveals that the Ti profile follows a sum of two error functions along the width direction and a complementary error function in the depth direction. Micro-Raman analysis shows that the Li-composition in the depth direction also follows a complementary error function. The mean Li/Nb ratio in the waveguide layer is about 0.98. The inhomogeneous Li-composition profile results in a varied substrate index in the guiding layer, and the refractive index profile in the guiding layer is given.We report the near-stoichiometric Ti：LiNbO3 strip waveguides fabricated by vapour transport equilibration （VTE） at 1060~^{／circ}C for 12 h and co-diffusion of 4--8~／mu m wide, 115-nm thick Ti-strips. Optical studies show that these waveguides are monomode at 1.5~／mu m and have losses of 1.3 and 1.1~dB/cm for the TM and TE modes, respectively. In the waveguide width/depth direction, the mode field follows a Gauss/Hermite--Gauss profile. A secondary ion mass spectrometry study reveals that the Ti profile follows a sum of two error functions along the width direction and a complementary error function in the depth direction. Micro-Raman analysis shows that the Li-composition in the depth direction also follows a complementary error function. The mean Li/Nb ratio in the waveguide layer is about 0.98. The inhomogeneous Li-composition profile results in a varied substrate index in the guiding layer, and the refractive index profile in the guiding layer is given.

关 键 词：near-stoichiometric Ti：LiNbO3 strip waveguide varied substrate refractive index Li-composition profile 2D refractive index profile 

分 类 号：TN252[电子电信—物理电子学] TQ174.758[化学工程—陶瓷工业]