Möhrle, MartinMartinMöhrleLee, Moon-HyeokMoon-HyeokLee2022-03-082022-03-082021https://publica.fraunhofer.de/handle/publica/312556The present invention concerns a tunable Dense Wavelength Division Multiplex (DWDM) intra cavity laser device (100) comprising a first optical wave guide (101) comprising a first optical grating section (111), a second optical wave guide (102) comprising a second optical grating section (112), an active gain section (103) spatially separated from the second optical grating section (112) and a phase section (104), and a DWDM-filter comprising an intra-cavity ring resonator (106) located between the first optical wave guide (101) and the second optical wave guide (102) for coupling optical waves between the first and second optical wave guides (101, 102). The tunable laser device (100) is tunable in a discrete manner depending on a length of the ring resonator (106) that is selected such that the free spectral range of the ring resonator (106) matches a predetermined fixed wavelength spacing grid.en621patent3840138