Optimum design of coplanar waveguide for LiNbO/sub 3/ optical modulator

In this paper, we first present a novel finite element method combined with the conformal mapping (FEM-CM) for a quasi-static analysis of coplanar waveguides (CPW). Using this approach, the optimum CPW structures for the use in the Ti:LiNbO/sub 3/ optical modulator are discussed in detail to realize optical-microwave phase velocity match and electrode-source characteristic impedance match. Our numerical results reveal that both conditions can be satisfied simultaneously by introducing a SiO/sub 2/ buffer layer and thicker electrodes. The modulator efficiency with respect to the voltage-length product is also evaluated for the optimized structures. Finally, the design guidelines to the optimum CPW structure are presented. >

[1]  M. Kondo,et al.  A wide-band Ti:LiNbO/sub 3/ optical modulator with a conventional coplanar waveguide type electrode , 1992, IEEE Photonics Technology Letters.

[2]  Moshe Nazarathy,et al.  40 GHz electro-optic modulator with 7.5 V drive voltage , 1988 .

[3]  T. Miyoshi,et al.  Finite element analysis of leakage magnetic flux from an induction heating system , 1982 .

[4]  Tsutomu Kitoh,et al.  New travelling-wave electrode Mach-Zehnder optical modulator with 20 GHz bandwidth and 4.7 V driving voltage at 1.52 mu m wavelength , 1989 .

[5]  D. Dolfi,et al.  50 GHz velocity-matched broad wavelength LiNbO/sub 3/ modulator with multimode active section , 1992 .

[6]  Tsutomu Kitoh,et al.  Spectral-domain analysis of coplanar waveguide traveling-wave electrodes and their applications to Ti:LiNbO/sub 3/ Mach-Zehnder optical modulators , 1991 .

[7]  R. A. Becker,et al.  Traveling‐wave electro‐optic modulator with maximum bandwidth‐length product , 1984 .

[8]  Ramu V. Ramaswamy,et al.  Overlap integral factors in integrated optic modulators and switches , 1989 .

[9]  A Broad-Band Traveling-Wave Ti:LiNbO3 Optical Phase Modulator , 1991 .

[10]  Xiang Zhang,et al.  Influence of Cross-Sectional Deformation on Coplanar Waveguide Characteristics for the Use of Optical Modulator (Special Issue on Electromagnetic Theory) , 1994 .

[11]  H. Ogawa,et al.  Analysis of CPW for LiNbO/sub 3/ optical modulator by extended spectral-domain approach , 1992, IEEE Microwave and Guided Wave Letters.

[12]  H. Omori,et al.  Analysis of an induction heating system by the finite element method combined with a boundary integral equation , 1987 .

[13]  R. Alferness.  Waveguide Electrooptic Modulators , 1982 .

[14]  M. Yanagibashi,et al.  Highly efficient 40-GHz bandwidth Ti:LiNbO/sub 3/ optical modulator employing ridge structure , 1993, IEEE Photonics Technology Letters.

[15]  R. W. McElhanon,et al.  40 GHz, low half-wave voltage Ti:LiNbO/sub 3/ intensity modulator , 1992 .