Takashi Yamane

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.

Rectangularly configured 4*4 Ti:LiNbO/sub 3/ matrix switch with low drive voltage

A matrix switch with a novel architecture has been demonstrated. A rectangularly configured 4*4 switch has been designed and fabricated on a 65-mm-long z-cut Ti:LiNbO/sub 3/ chip. The average drive voltage of 16 Delta beta -reversal directional couplers is 9 V for a cross state and 20 V for a bar state. The drive voltage difference of 11 V is about half that of the conventional matrix switch. Drive voltage deviations are within +or-0.5 V. The average insertion loss is 4.7 dB, and deviations for different paths are within +or-0.3 dB, and deviations for different paths are within +or-0.3 dB. The crosstalk of all crosspoint switches is also estimated based on crosstalk output measurements. >

Low-drive-voltage Ti:LiNbO 3 Mach-Zehnder modulator using a coupled line

A Ti:LiNbO3 Mach-Zehnder modulator with an asymmetric traveling-wave electrode has been studied for use as a high speed external modulator because of its low chirp and wide bandwidth.1 The overly high drive voltage prohibits practical use, however. Our attempts to reduce the drive voltage by, for example, using two traveling-wave electrodes,2 have met with problems, such as the interaction of microwaves.