A tunable laser operating from 2011 – 2042 nm realized as a monolithic InP photonic integrated circuit and fabricated within a multi project wafer run is presented. The laser is tuned using an intracavity filter based on nested asymmetric Mach-Zehnder interferometers with electrorefractive modulators. The device is intended for a single line gas spectroscopy and was designed and realized using a generic integration technology