中国物理B ›› 2010, Vol. 19 ›› Issue (2): 24214-024214.doi: 10.1088/1674-1056/19/2/024214

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

潘裕斌1, 吴嫦2, 张德龙3   

  1. (1)Department of Electronic Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, China; (2)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, Tianjin 300072, China; (3)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, Tianjin 300072, China;Department of Electronic En
  • 收稿日期:2008-11-18 修回日期:2009-09-10 出版日期:2010-02-15 发布日期:2010-02-15
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos.~50872089 and 60577012) and the Research Grants Council of the Hong Kong Special Administrative Region, China (Grant No.~CityU 1194/07).

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

Zhang De-Long(张德龙)a)b)† , Wu Chang(吴嫦)a), and Pun Edwin Yue-Bun(潘裕斌)b)   

  1. a 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, Tianjin 300072, China; b Department of Electronic Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, China
  • Received:2008-11-18 Revised:2009-09-10 Online:2010-02-15 Published:2010-02-15
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 50872089 and 60577012) and the Research Grants Council of the Hong Kong Special Administrative Region, China (Grant No. CityU 1194/07).

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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.

Abstract: 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.

Key words: near-stoichiometric Ti:LiNbO3 strip waveguide, varied substrate refractive index, Li-composition profile, 2D refractive index profile

中图分类号:  (Optical waveguides and couplers)

  • 42.79.Gn
78.20.Ci (Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)) 78.30.Hv (Other nonmetallic inorganics) 42.82.Cr (Fabrication techniques; lithography, pattern transfer) 42.82.Et (Waveguides, couplers, and arrays)