Abstract: A tunable laser device (1) comprises integrally formed first and second ridge waveguides (5, 6). A longitudinally extending ridge (12) defines first and second light guiding regions (19, 20) of the first and second waveguides (5, 6) which communicate with each other. A plurality of first slots (27) extending laterally in the ridge (12) adjacent the first waveguide (5), and a plurality of second slots (28) extending laterally in the ridge (12) adjacent the second waveguide (6) produce first and second mirror loss spectra of the respective first and second waveguides (5, 6) with minimum peak values at respective first and second wavelength values.