Monolithic twin-ridge laterally coupled diode lasers emitting at 1.3µm are presented that have a small-signal modulation bandwidth beyond the relaxation oscillation frequency of a single ridge. Spectra and spectrally resolved far fields are presented for three bias conditions: only one ridge lasing, both ridges lasing just above threshold, and both ridges lasing at biases well above threshold. In the first two cases the spectrum has single-peaked longitudinal modes, whereas the third cases shows splitting to in-phase and out-of-phase modes. The splitting frequency of the optical spectrum is measured to be 7.7 GHz. Small-signal modulation measurements reveal a strong resonance at 7.7 GHz, demonstrating an effect of lateral mode locking. As a result of this effect, the twin-ridge laser can be made to have a -3-dB bandwidth beyond that associated with its relaxation oscillation frequency.
© 2002 Optical Society of America
(140.2020) Lasers and laser optics : Diode lasers
(140.3290) Lasers and laser optics : Laser arrays
(140.4050) Lasers and laser optics : Mode-locked lasers
(140.7090) Lasers and laser optics : Ultrafast lasers
H. Lamela, B. Roycroft, P. Acedo, R. Santos, and G. Carpintero, "Experimental modulation bandwidth beyond the relaxation oscillation frequency in a monolithic twin-ridge laterally coupled diode laser based on lateral mode locking," Opt. Lett. 27, 303-305 (2002)