Double optical grating

An optical grating comprising:

• a top cladding;
• a first grating including a plurality of discrete metallic bars spaced apart by a first pitch, the first pitch corresponding to a first idealized efficiency curve;
• a core having a top side and a bottom side, the bottom side including a plurality of discrete ridges spaced apart by a second pitch different from the first pitch and forming a second grating, the second pitch corresponding to a second idealized efficiency curve, top side being adjacent to the top cladding, the first grating residing between a portion of the top cladding and the top side of the core;
• a bottom cladding adjacent to the bottom side of the core, the core residing between the bottom cladding and the top cladding;
• and
• a mirror, the bottom cladding residing between the core and the mirror;
• wherein the optical grating has an idealized efficiency curve corresponding to the sum of the first idealized efficiency curve and the second idealized efficiency curve, the idealized efficiency curve being substantially symmetric and having a substantially flat central peak.

An optical grating comprising:

• a top cladding;
• a core having a top side and a bottom side, the top side including a plurality of discrete ridges spaced apart by a first pitch and forming a first grating, the first pitch corresponding to a first idealized efficiency curve, top side being adjacent to the top cladding;
• a second grating including a plurality of discrete metallic bars spaced apart by a second pitch different from the first pitch, the second pitch corresponding to a second idealized efficiency curve;
• a bottom cladding adjacent to the bottom side of the core, the second grating residing between a portion of the bottom cladding and the bottom side of the core;
• and
• a mirror, the bottom cladding residing between the core and the mirror;
• wherein the optical grating has an idealized efficiency curve corresponding to the sum of the first idealized efficiency curve and the second idealized efficiency curve, the idealized efficiency curve being substantially symmetric and having a substantially flat central peak.

A method for providing an optical grating configured for light of a wavelength, the method comprising:

• providing a bottom cladding;
• providing a core having a top side and a bottom side, the bottom side including first plurality of discrete ridges spaced apart by a first pitch and forming a bottom grating,
• the first pitch corresponding to a first idealized efficiency curve;
• providing a top grating including a second plurality of discrete ridges spaced apart by a second pitch on the top side of the core, the second grating having a second idealized efficiency curve corresponding to the second pitch, the first grating and the second grating being configured such that the optical grating has an idealized efficiency curve corresponding to the sum of the first idealized efficiency curve and the second idealized efficiency curve and such that the idealized efficiency curve has a substantially flat central peak;
• and
• providing a top cladding, the core residing between the bottom cladding and the top cladding, the top grating residing between a portion of the top cladding and the top side of the core.

A method for providing an optical grating configured for light of a wavelength, the method comprising:

• providing a bottom cladding;
• providing a bottom grating including a first plurality of discrete ridges spaced apart by a first pitch on the bottom cladding, the first pitch corresponding to a first idealized efficiency curve;
• providing a core having a top side and a bottom side, the top side including second plurality of discrete ridges spaced apart by a second pitch and forming a top grating,
• the to grating having a second idealized efficiency curve corresponding to the second pitch, the bottom grating and the top grating being configured such that the optical grating has an idealized efficiency curve corresponding to the sum of the first idealized efficiency curve and the second idealized efficiency curve and such that the idealized efficiency curve has a substantially flat central peak;
• providing a top cladding, the core residing between the bottom cladding and the top cladding.