Abstract

High speed communication and signal processing are driving increasing interest in the creation of optical carriers with specially tailored intensity modulation. Applications include mmWave over fiber, THz generation by photomixing, optical sampling, time division multiplexing and coherent communications. Mode-locked laser diodes are promising candidates for these applications but their intensity profile and mode spacing or pulse repetition rate is usually determined by the material dispersion and the cavity length. We have applied a spectral filtering technique that enables the selection of a finite number of lasing modes in a Fabry-Perot (FP) cavity to the problem of passive mode-locking. This enabled us to fabricate mode-locked devices that generate both sinusoidal and pulsed intensity output [1, 2]. Here we will illustrate this technique by describing a device designed to support a discrete comb of six modes. This device incorporates 48 slotted regions etched into the ridge waveguide of the laser. The cavity schematic and mode-locked spectrum of the fabricated device are shown in Fig. 1 (a) and (b). Near-transform limited pulsed output at 100 GHz with 2 ps pulse duration was obtained [2].

© 2011 Optical Society of America