50 GHz electro-optic modulators with BaTiO 3 epitaxial thin film platform for short distance optical communications

Future datacom and telecom applications as well as optical interconnects require high bandwidth, low-power, small area optical modulator devices [1], [2], [3], [4], [5]. No device technology to date has been shown with the concomitant properties of high electro-optic (EO) bandwidth, wide optical range, low power consumption, and compact size. We have taken an alternative approach of developing thin film BaTiO 3 as an optoelectronic material platform for high frequency, low operation voltage, and compact modulators. The BaTiO 3 thin film platform has competitive advantages over other legacy platforms for optical modulator applications. In brief, ferroelectric oxide thin film BaTiO 3 modulators have advantages of: (1) large EO coefficient, more than ten times higher compared to those of LiNbO 3 devices currently dominating optical modulator markets; (2) low driving voltage of 50 GHz demonstrated with potential reaching 100 + GHz regime; (4) potential for medium scale integration; and (5) integration with Si electronics leading to ultrahigh compact electrooptical components at low cost [6]. Using BaTiO 3 thin films with 1 mm long interaction length, we have demonstrated optical modulators with voltage-length products nearly an order of magnitude smaller than that of silicon [7]. We have also shown the potential for high frequency operation by demonstrating modulation out to 50 GHz [7], [8], [9].