Concentric Cylindrical Circumferential Laser

A semiconductor laser apparatus comprising:

• at least one cylindrical ring optical waveguide structure of selected radial width and diameter providing optical confinement in both the radial and axial dimensions, said optical waveguide including a multi-layered epitaxy grown on a suitable substrate consisting of an active layer stacked in the axial dimension between first and second layers, said first layer including a dopant one of n-type and p-type and said second layer doped the other n-type or p-type including gain confining region, whereby said gain confining region has a radial width that is less than said selected width, said optical waveguide capable of supporting a plurality of radial modes, one of a plurality of axial modes and a plurality of degenerate azimuthal modes, electrical contacts for providing current for the active layer, wherein said gain confining region has a geometry which is substantially matched to intensity profiles of a subset of modes of said plurality, thereby providing a modal gain difference between the selected mode subset and remainder of said mode plurality, wherein said gain confining region has a radial width that is less than the width in the radial direction to which said radial modes supported by the cylindrical ring waveguide extend, a circular output coupler enabling the circumferential radiative emission to exit the device said output coupler comprising of a circular axial surface exposing the active layer edge at a radius equal to or greater than the outer radius of said cylindrical ring waveguide with said surface containing an optical coating.

A method of forming a laser apparatus supporting circumferential radiation, comprising the steps of:

• providing an active material;
• optically confining the laser in the radial and axial dimension such that the laser can support a plurality of traveling wave modes comprising of at least one of a plurality of axial modes, a plurality of radial modes and a plurality of degenerate azimuthal modes;
• producing optical gain in the active material;
• and confining the optical gain to a region that substantially matches for each plurality of modes supported, a selected subset of modes of the plurality of modes more than at least one other mode of the plurality for providing a modal gain difference between selected modes and the remainder of the plurality of modes for favoring excitation of the selected modes which support efficient radial emission;
• providing a output pathway for the circumferential laser light to exit the laser apparatus;
• providing an external reflective mirror for reflecting the radially emitted radiation normal to the surface of the laser apparatus.