Widely Tunable Laser on an InP Photonic Integrated Circuit

We present a widely tunable laser design based on three intra-cavity Mach-Zehnder interferometers. The laser has been fabricated in a multi-project wafer run and does not require high precision lithography, as needed for SGDBR lasers. We demonstrate 20 nm of tuning range with output powers of approximately 1 mW in fiber. With an excess of 30 dB in side-mode suppression ratio, the laser can find applications in gas spectroscopy, which is also supported by an absorption measurement in an HCN-filled gas cell. Tuning has been demonstrated solely relying on electro-optical phase modulators, providing a potentially faster tuning scheme than temperature or current based tuning mechanisms.