Novel Widely Tunable Monolithically Integrated Laser Source

We report a novel type of monolithically integrated tunable semiconductor laser. The tuning is achieved by three intracavity Mach-Zehnder interferometers, realized in passive waveguides and using voltage-controlled electro-optic phase modulators requiring only four control voltages. The potential of the design is demonstrated by a realized laser system that shows an optical linewidth of 363 kHz, output power of 3 mW, and a record tuning range of 74.3 nm. Such a continuous wavelength span is in excess of any monolithic semiconductor laser reported up to date. Precision of the tuning mechanism is demonstrated by a scan over a 0.89-GHz-wide absorption line of acetylene. The laser design is suitable for a number of applications, including gas spectroscopy, telecommunication, and optical coherence tomography. The laser has been fabricated in a multi-project wafer run on an indium phosphide-based generic photonic foundry platform and demonstrates the potential of these technology platforms.