Grating reflector

A wavelength tunable or wavelength sweepable vertical cavity surface emitting laser, comprising:

• a movable grating reflector comprising a mesh structure of a mesh material, the mesh structure defining a mesh plane and having a thickness normal to the mesh plane and comprising a plurality of parallel bars and a plurality of parallel crossbars, the crossbars extending along a direction orthogonal to the bars, the bars and crossbars defining a two-dimensional grid of elongated holes, each hole extending through the mesh structure in a direction normal to the mesh plane, each hole being defined between two adjacent bars and two adjacent crossbars, the holes being elongated along a direction parallel to the bars, the holes having a substantially rectangular shape with rounded corners, the two dimensional grid being defined by a plurality of cross-shaped unit cells of the grid, each of the unit cells comprising a bar section and a crossbar section intersecting the bar section to form the cross shape that includes four interior corners, each of the four interior corners being rounded and having a radius of curvature, the bar section having a bar width and a bar section length, the crossbar section having a crossbar width and a crossbar section length;
• wherein each of the unit cells having a unit cell volume defined by the thickness of the mesh structure, the bar section length, the bar section width, the crossbar section length, the crossbar width and by the radii of curvature of the four interior corners;
• wherein the grating reflector has a reflectivity in a bandwidth around a center wavelength higher than 0.99, and wherein a ratio between the unit cell volume and the center wavelength in the mesh material cubed is between 1.35 and 1.55.

A method for manufacturing a grating reflector, the grating reflector comprising a mesh structure of a mesh material, the mesh structure defining a mesh plane and having a thickness normal to the mesh plane and comprising a plurality of parallel bars and a plurality of parallel crossbars, the crossbars extending along a direction orthogonal to the bars, the bars and crossbars defining a two-dimensional grid of elongated holes, each hole extending through the mesh structure in a direction normal to the mesh plane, each hole being defined between two adjacent bars and two adjacent crossbars, the holes being elongated along a direction parallel to the bars, the holes having a substantially rectangular shape with rounded corners, the two dimensional grid being defined by a plurality of cross-shaped unit cells of the grid, each of the unit cells comprising a bar section and a crossbar section intersecting the bar section to form the cross shape that includes four interior corners, each of the four interior corners being rounded and having a radius of curvature, the bar section having a bar width and a bar section length, the crossbar section having a crossbar width and a crossbar section length, each of the unit cells having a unit cell volume defined by the thickness of the mesh structure, the bar section length, the bar width, the crossbar section length, the crossbar width and by the radii of curvature of the four interior corners;

• wherein the method comprises:
• selecting the thickness of the mesh structure, the bar section length, the bar width, the crossbar section length, the crossbar width and the radii of curvature of the four interior corners such that a reflectivity of the reflector in a bandwidth around a predetermined center wavelength is higher than a predetermined threshold reflectivity;
• and
• manufacturing the grating reflector having the selected thickness of the mesh structure, the selected bar section length, the selected bar width, the selected crossbar section length, the selected crossbar width and the selected radii of curvature.