Abstract: A tunable laser device comprises a multi-section distributed feedback (DFB) laser having a first Bragg section including a waveguide and a Bragg grating, a second Bragg section comprising a waveguide and a Bragg grating, and a phase section being longitudinally located between the first Bragg section and the second Bragg section. The phase section is made of a passive material, and each Bragg section has a first longitudinal end joining the phase section and a second longitudinal end opposed to the phase section. The Bragg grating of at least one Bragg section has a grating coupling coefficient which decreases from the first longitudinal end to the second longitudinal end of the at least one Bragg section.