Preparation of x-cut $LiNbO_3$ Optical Waveguide and the Change in Near-field Properties according to Ti thickness

x-cut $LiNbO_3$ 광도파로 제작 및 Ti 두께에 따른 Near-field 특성 변 화

The optical near-field patterns, propagation loss and mode sizes of x-cut $Ti:LiNbO_3$ optical waveguide which was fabricated by Ti-diffusion varying with Ti strip thickness in wet oxygen atmosphere were discussed at optical wavelength 1550nm. As Ti thickness increased from $760{\AA}$, the insertion loss of waveguide was decreased. But at Ti thickness $1500{\AA}$, mode sizes are widely broadened. The Ti thickness of below $1100{\AA}$ and above $1500{\AA}$ showed negative effects to propagation loss and fiber coupling. The best Ti thickness for fabricating low propagation loss and good fiber coupling was inferred to be between $1100{\AA}-1500{\AA}$ in our conditions. And for Ti thickness $1150{\AA}$, its propagation loss, horizontal/vertical mode sizes were showed 1.61 dB/cm, $11.9/8.9{\mu}m$ for TM, 0.22 dB/cm, $12.0/9.1{\mu}m$ for TE respectively.