Femtosecond pulse and terahertz two-tone generation from facet-free multi-segment laser diode in InP-based generic foundry platform.

In this paper, a monolithically integrated ∼1.55 µm semiconductor laser in the fourth harmonic colliding pulse mode locking configuration is reported. This device was developed within a multi-project wafer run at an InP-based active-passive generic foundry. The 1.66-mm Fabry-Pérot cavity is formed with two on-chip reflector building blocks rather than cleaved facets. In the cavity, three absorber sections symmetrically divide the cavity in four gain segments. This laser diode is able to emit 100-GHz pulse trains with 500-fs pulse duration as well as two-tone emissions with a frequency separation of 2.7 THz. The dependence of the spectral behavior on the forward bias current for gain sections and the reverse bias voltage for absorber sections are experimentally demonstrated.