Tunable semiconductor laser device and method for operating a tunable semiconductor laser device

Tunable semiconductor laser device comprising

• a semiconductor structure (10), said structure having end surfaces (1a, 1b) on opposing sides along a longitudinal axis (2) through the structure, the semiconductor structure (10) being formed to have an active region in an active region layer (12) between a top surface (4) and a bottom surface (5) of the structure, the top surface being in a plane defined by the longitudinal axis (2) and a lateral axis (3) perpendicular to the longitudinal axis (2);
• a longitudinal structure (20) provided on the top surface (4) of the semiconductor structure (10) and longitudinally extending over at least a part of the distance between the two opposing end surfaces (1a, 1b) in a direction parallel to the longitudinal axis (2), said longitudinal structure (20) being arranged to receive an electrical current through a contact surface (22);
• a first longitudinal interdigitated transducer, IDT, (35) provided either on the top surface (4) or beneath the top surface having a projection on the top surface, said first IDT (35) extending longitudinally in a direction parallel to the longitudinal axis (2) and being arranged to, in response to a signal from a signal generator, generate a surface acoustic wave, SAW, in a direction parallel to the longitudinal axis (2),
• wherein the first IDT (35) is arranged on one lateral side of the longitudinal structure (20) and at a distance along the lateral axis (3) from said structure and parallel to the longitudinal structure (20) with the IDT (35) or projection thereof and the longitudinal structure (20) longitudinally extending side by side with each other, and wherein the distance in the lateral direction between the longitudinal structure (20) and the IDT (35) is between 50 nm and 100 micron (μm).