A semiconductor laser device comprising: a substrate; a layer formed on the substrate, the layer having first and second regions, the first region of the layer including one or more voids; a gain section (1416, 1708) provided on the layer; a phase section (1414, 1704) provided on the layer; a first mirror section (1412, 1702) provided on the layer, the first mirror section comprising: a waveguide core, at least part of the waveguide core is provided over at least a portion of the void; a first grating provided on the waveguide core; a first cladding provided between the layer and the waveguide core and supported by the second region of the layer; a second cladding provided on the waveguide core; and a heat source configured to change a temperature of at least one of the waveguide core and the grating, a second mirror section (1418, 1712) provided on the layer, wherein the gain section (1416, 1708) and the phase section (1414, 1704) are provided between the first mirror section (1412, 1702) and the second mirror section (1418, 1712), wherein an optical mode propagating in the waveguide core of the mirror section does not incur substantial loss due to interaction with portions of the mirror section above and below the waveguide core, characterized in that one of the gain section (1416, 1708) and the phase section (1414, 1704) includes a flared portion (1706, 1710). a substrate; a layer formed on the substrate, the layer having first and second regions, the first region of the layer including one or more voids; a gain section (1416, 1708) provided on the layer; a phase section (1414, 1704) provided on the layer; a first mirror section (1412, 1702) provided on the layer, the first mirror section comprising: a waveguide core, at least part of the waveguide core is provided over at least a portion of the void; a first grating provided on the waveguide core; a first cladding provided between the layer and the waveguide core and supported by the second region of the layer; a second cladding provided on the waveguide core; and a heat source configured to change a temperature of at least one of the waveguide core and the grating, a second mirror section (1418, 1712) provided on the layer, wherein the gain section (1416, 1708) and the phase section (1414, 1704) are provided between the first mirror section (1412, 1702) and the second mirror section (1418, 1712), wherein an optical mode propagating in the waveguide core of the mirror section does not incur substantial loss due to interaction with portions of the mirror section above and below the waveguide core, characterized in that one of the gain section (1416, 1708) and the phase section (1414, 1704) includes a flared portion (1706, 1710). a waveguide core, at least part of the waveguide core is provided over at least a portion of the void; a first grating provided on the waveguide core; a first cladding provided between the layer and the waveguide core and supported by the second region of the layer; a second cladding provided on the waveguide core; and a heat source configured to change a temperature of at least one of the waveguide core and the grating, a second mirror section (1418, 1712) provided on the layer, wherein the gain section (1416, 1708) and the phase section (1414, 1704) are provided between the first mirror section (1412, 1702) and the second mirror section (1418, 1712), wherein an optical mode propagating in the waveguide core of the mirror section does not incur substantial loss due to interaction with portions of the mirror section above and below the waveguide core, characterized in that one of the gain section (1416, 1708) and the phase section (1414, 1704) includes a flared portion (1706, 1710).