Recent progress of 40 GHz high-speed LiNbO3 optical modulator

This paper describes the recent progress and status of 40 GHz high-speed LiNbO3 optical modulators, and newly designed two types - a backslot type and a ridge type - LiNbO3 optical modulators with high-speed and low-switching voltage. The backslot is formed on the backside of LiNbO3 substrate by using micro-machining laser etching. The backslot type modulator is designed, fabricated and characterized. The ridge type modulator with an overhanged upper electrode is also calculated. The properties of the designed two types modulators, effective refractive index for the modulation wave nm, modulation bandwidth fm, overlap integral Gamma and switching voltage V pi are calculated. The optimum properties of the backslot type modulator, fm=73GHz and the switching voltage V pi =2.8V is calculated, and fm=130GHz and V pi = 1.9V is achieved for the ridge type modulator at a wavelength 1.5 mum. The fabricated backslot type modulator achieved the optical 3dB bandwidth fm greater than or equal to 28GHz and the driving voltage V pi =2.8V.