Zero loss waveguide coupler

A coupler for coupling a radiation beam emitted from an exit of a first waveguide to an entrance of a second waveguide, comprising:

• a first phase compensating lens disposed adjacent to the exit of the first waveguide, said first phase compensating lens further being disposed within the emitted beam from the first waveguide;
• a second phase compensating lens disposed within the beam, said second phase compensating lens further being disposed adjacent to the entrance of the second waveguide;
• and
• a first imaging lens disposed within said beam, said imaging lens being interposed between said first and said second phase compensating lenses for imaging the exit of the first waveguide onto the entrance of the second waveguide, said first imaging lens adding a phase curvature to the image.

A coupler for coupling a radiation beam emitted from the exit of a first waveguide to an entrance of a second waveguide whereby the irradiance distribution of the beam reentering the waveguide is a substantial reproduction of the irradiance distribution of the beam exiting the waveguide, the first waveguide having an opening size that is different than the opening size of the second waveguide, said coupler comprising:

• an imaging lens disposed within the beam for imaging the exit of the first waveguide onto the entrance of the second waveguide, said imaging lens having a focal length of f and a magnification factor of M associated therewith, said imaging lens further adding a spherical phase curvature to the image of the exit;
• a phase compensating lens disposed adjacent to the entrance of the second waveguide, said phase compensating lens having a focal length of Mf, said phase compensating lens compensating for the spherical phase curvature added to the image of said exit by said imaging lens;
• and
• said imaging lens being disposed at a distance of (1+1/M)f away from the exit of the first waveguide and said compensating lens being disposed at a distance of (M+1)f away from said imaging lens and adjacent to the entrance of saidsecond waveguide.