Tunable optical reflector chip for external cavity laser

An optical reflector chip (10) comprising a waveguide arrangement (11) configured to guide optical radiation and a modulation device (3). The waveguide arrangement (11) comprises a Bragg grating section (111), the Bragg grating section (111) comprising a periodic structure exhibiting a periodically varying refractive index to reflect the optical radiation within a wavelength reflection band defined by the periodic structure. The modulation device (3) comprises a modulation element (30, 30'), at least a first electrode (31) and a second electrode (31), wherein the first electrode (31) and the second electrode (32) are configured to actuate the modulation element (30, 30') upon the application of a voltage between the first electrode (31) and second electrode (32). The modulation element (30, 30') is arranged such that actuating the modulation element (30, 30') by applying the voltage between the first electrode (31) and the second electrode (32) tunes the periodic structure of the Bragg grating section (111), whereby a shift of the wavelength reflection band is induced.