Diffractive grating coupler and method

A volume grating for use in an optical coupler, comprising:

• first means for variably altering the propagation of a guided wave according to a preferential order;
• second means for focusing light in a first dimension;
• third means for focusing light in a second dimension;
• and
• fourth means for causing a predetermined light intensity profile at an output plane of the volume grating.

A method for coupling light from a waveguide to a focused point, comprising the steps of:

• directing a laser light beam into a waveguide having a volume grating;
• coupling the laser light with a plurality of slanted grating fringes having a variable slant angle along a waveguide light propagation direction;
• and
• focusing the laser light with a predetermined surface grating pattern having a decreasing surface grating period along the waveguide light propagation direction in the volume grating.

A surface relief grating for use in an optical coupler, comprising:

• a waveguide;
• a predetermined number of separated grating ridges disposed in the waveguide, the separated grating ridges forming a predetermined surface grating pattern having a decreasing surface grating period along a waveguide light propagation direction;
• and
• the separated grating ridges having a variable slant angle along the waveguide light propagation direction.

An optical communication system, comprising:

• an optical fiber;
• an optical circuit;
• a transmitter;
• a receiver;
• and
• an optical coupler;
• said optical coupler further comprising a volume grating having a plurality of variably slanted grating fringes along a waveguide light propagation direction.

A volume grating for use in an optical coupler, comprising:

• a predetermined surface grating pattern having a surface grating period decreasing along a waveguide light propagation direction in the volume grating;
• a plurality of slanted grating fringes having a variable slant angle along the waveguide light propagation direction;
• and
• wherein the predetermined surface grating pattern further includes an increasing radius of curvature along the waveguide light propagation direction.

A volume grating for use in an optical coupler, comprising:

• a predetermined surface grating pattern having a surface grating period decreasing along a waveguide light propagation direction in the volume grating;
• a plurality of slanted grating fringes having a variable slant angle along the waveguide light propagation direction;
• wherein the variable slant angle is configured to provide a predetermined light intensity profile at an output plane of the volume;
• and
• wherein the predetermined light intensity profile propagates into a preferential order.

A method for coupling light from a waveguide to a focused point, comprising the steps of:

• directing a laser light beam into a waveguide having a volume grating;
• coupling the laser light with a plurality of slanted grating fringes having a variable slant angle along a waveguide light propagation direction;
• focusing the laser light with a predetermined surface grating pattern having a decreasing surface grating period along the waveguide light propagation direction;
• and
• focusing the laser light with fringes having an increasing radius of curvature along the waveguide light propagation direction in the predetermined surface grating pattern.

An optical coupler for use in optical communications systems which comprises:

• a volume grating having a predetermined surface grating pattern;
• a plurality of variably slanted grating fringes along said volume grating;
• and
• wherein the predetermined surface grating pattern of the volume grating has an increasing radius of curvature along a waveguide light propagation direction.

An optical communication system, comprising:

• an optical fiber;
• an optical circuit;
• a transmitter;
• a receiver;
• an optical coupler, said optical coupler further comprising a volume grating having a plurality of variably slanted grating fringes along a waveguide light propagation direction;
• wherein the volume grating has a predetermined surface grating pattern;
• and
• wherein the predetermined surface grating pattern of the volume grating has an increasing radius of curvature along the waveguide light propagation direction.