Masaharu Doi

Advanced LiNbO/sub 3/ optical modulators for broadband optical communications

This paper describes advanced lithium niobate (LiNbO3) optical modulators for broadband optical communications. It includes 40-Gb/s ultralow voltage modulators, compact modulators and modulators for frequency comb generator and short pulse generation

Driver-less 40 Gb/s LiNbO/sub 3/ modulator with sub-1 V drive voltage

We have succeeded in reducing the drive voltage of a 40Gb/s LiNbO/sub 3/ modulator to 0.9 V, which is the lowest-drive-voltage 40Gb/s LiNbO/sub 3/ modulator in the world. The modulator can be driven within the break down voltage of a SiGe transistor. This result was achieved using a new design concept that featured a wide-gap, long CPW (coplanar waveguide) electrode.

A low DC-drift Ti:LiNbO3 modulator assured over 15 years

The use of the Ti:LiNbO3 modulator has begun in advanced optical transmission experiments (1) and it is planned for commercial optical transmission systems. There has, however, been no report to guarantee the long-term reliability of Ti:LiNbO3 devices against DC drift. DC drift is complicated by temperature and humidity. We prevented the temperature and humidity drift by employing a Si coating technique (1). We evaluated the long-term DC drifts of our modulator and confirmed that it is stable enough for use in commercial optical transmission systems.

40 Gb/s Low-drive-voltage LiNbO 3 Optical Modulator for DQPSK Modulation Format

Low-drive-voltage (3.5 V) and uniform modulation characteristics of MZIs were achieved with Z-cut dual-drive nested-MZIs structure and the wide-gap design between signal and ground electrodes, resulting in precise constellation mappings in 43 Gb/s DQPSK modulation.

Suppression of thermal drift in an ultra-high-speed LiNbO 3 optical modulator

We have succeeded in suppressing the thermal drift of an ultra-high-speed LiNb03 optical modulator by using domain inversion. This low thermal drift modulator can be used by a low-voltage, low-cost bias source.

Lambda utility project

This paper describes summary and recent achievements of Lambda Utility Project, which is one of the major Photonic Network R&D Projects supported by the Ministry of Internal Affairs and Communications (MIC) and National Institute of Information and Communications Technology (NICT) Japan.