a distributed bragg reflector includes a base substrate and a gain medium formed on the base substrate . a waveguide positioned above the base substrate in optical communication with the gain medium and defines a gap extending between the base substrate and the waveguide along a substantial portion of the length thereof the waveguide having a grating formed therein . a heating element is in thermal contact with the waveguide and electrically coupled to a controller electrically configured to adjust optical properties of the waveguide by controlling power supplied to the heating element .