Error-free external modulation of a single-frequency injection laser at 1.5Gb/s using a Ti:LiNbO(3) waveguide switch.

We have used a packaged high-speed Ti:LiNbO(3) directional coupler switch to externally modulate a cw-operated coupled- cleaved-cavity laser oscillating at 1.3micron wavelength. The performance of the modulator was evaluated by measuring bit- error rates for the dominant mode of the laser using a monochromater as a selective bandpass filter. Error-free encoding was achieved for a non-return-to-zero rate of 1.5Gb/s. This result and observation of the optical spectrum demonstrate that the external modulation did not degrade the cw characteristics of the laser.