Error-free external modulation of a single-frequency injection laser at 1.5 Gbit/s using a Ti:LiNbO3 waveguide switch

We have used a packaged high-speed Ti:LiNbO3 directional coupler switch to externally modulate a CW-operated cleaved-coupled-cavity laser oscillating at 1.3 ¿m wavelength. The performance of the modulator was evaluated by measuring bit error rates for the dominant mode of the laser using a monochromator as a selective bandpass filter. Error-free encoding was achieved for a non-return-to-zero rate of 1.5 Gbit/s. This result and observation of the optical spectrum demonstrate that the external modulation did not degrade the CW characteristics of the laser.