Apparatus for efficiently transforming a single frequency, linearly polarized laser beam into principally two orthogonally polarized beams having different frequencies

Apparatus for generating at least a pair of parallel, linearly-orthogonally polarized beams of different frequency, said apparatus comprising:

• a multifaceted, anisotropic optical crystal having an optic axis, z, said crystal having a first facet that is nominally parallel to said optic axis;
• transducer means affixed to said first facet for generating an acoustic beam and directing it into said anisotropic optical crystal so that it propagates generally perpendicular to said optic axis to provide an interactive region within said anisotropic optical crystal where the width of said interactive region is generally coextensive with the width of said acoustic beam;
• means for driving said transducer to generate said acoustic beam at a predetermined frequency, f.sub.0 ;
• means for providing at least two linearly-orthogonally polarized input beams of illumination each with a predetermined frequency, f.sub.L ;
• and
• means for introducing said linearly polarized input beams into said anisotropic optical crystal so that each propagates through said interaction region at least once with a predetermined portion of each being converted by small-angle Bragg diffraction to a second beam, orthogonally polarized with respect to its associated input beam and altered in frequency by said acoustic beam frequency, f.sub.0, the remainder of said input beams and said second beams continuing to propagate through said anisotropic optical crystal along a path of travel as orthogonally polarized emergent beams, said anisotropic optical crystal having at least one other facet structured to fold the optical path for beams traveling through said anisotropic optical crystal while controlling their angular divergence outside of said interaction region so that said emergent beams are available outside of said anisotropic crystal as two external beams each comprising two linearly-orthogonally polarized components for subsequent downstream use, two of said linearly-orthogonally polarized components being selected as principal beams.

Apparatus for generating at least a pair of parallel, linearly-orthogonally polarized beams of different frequency, said apparatus comprising:

• a multifaceted, anisotropic optical crystal having an optic axis, z, said crystal having a first facet that is nominally parallel to said optic axis;
• transducer means affixed to said first facet for generating an acoustic beam and directing it into said anisotropic optical crystal so that it propagates generally perpendicular to said optic axis to provide an interactive region within said anisotropic optical crystal where the width of said interactive region is generally coextensive with the width of said acoustic beam;
• means for driving said transducer to generate said acoustic beam at a predetermined frequency, f.sub.0 ;
• means for providing at least two linearly-orthogonally polarized input beams of illumination each with a predetermined frequency, f.sub.L ;
• means for introducing said linearly polarized input beams into said anisotropic optical crystal so that each propagates through said interaction region at least once with a predetermined portion of each being converted by small-angle Bragg diffraction to a second beam, orthogonally polarized with respect to a corresponding one of aid input beams and altered in frequency by said acoustic beam frequency, f.sub.0, the remainder of said input beams and said second beams continuing to propagate through said anisotropic optical crystal along a path of travel as emergent beams, said emergent beams exiting from said anisotropic optical crystal through an exit facet thereof;
• and
• external means for intercepting at least one of said input beams or said diverging emergent beams and controlling them to provide a pair of parallel, principal linear-orthogonally polarized beams available outside of said anisotropic optical crystal for subsequent downstream use.

Apparatus for generating a pair of parallel, linearly-orthogonally polarized beams of different frequency, said apparatus comprising:

• a multifaceted, anisotropic optical crystal having an optic axis, z, said crystal having a first facet that is nominally parallel to said optic axis;
• transducer means affixed to said first facet for generating an acoustic beam and directing it into said anisotropic optical crystal so that it propagates generally perpendicular to said optic axis to provide an interactive region within said anisotropic optical crystal;
• means for driving said transducer to generate said acoustic beam at a predetermined frequency, f.sub.0 ;
• means for providing at least two linearly-orthogonally polarized input beams of illumination each with a predetermined frequency, f.sub.L ;
• and
• means for introducing said linearly-orthogonally polarized input beams into said anisotropic optical crystal at predetermined angles of incidence so that each propagates through said interaction region at least twice with a predetermined portion of each converted by small-angle Bragg diffraction to a second beam, orthogonally polarized with respect to a corresponding input beam and altered in frequency by said acoustic beam frequency, f.sub.0, the remainder of said input beams and said second beams continuing to propagate through said anisotropic optical crystal along a path of travel as orthogonally polarized emergent beams, said input beams passing through said interactive region at least twice to make relatively more efficient use of acoustic power and experiencing phase shifts with respect to said acoustic beam upon passing through said interactive region, said anisotropic optical crystal having at least one other facet structured and arranged to at least partially control said emergent beams, so that they are available outside of said anisotropic optical crystal as two external beams available for subsequent downstream use, each of said external beams comprising two linearly-orthogonally polarized components and selected ones of said linearly-orthogonally polarized components being parallel, having predetermined relative intensities and spatial separation between their respective energy flux profiles;
• and
• means for controlling the phase of beams with respect to the phase of said acoustic beam as the beams propagate through said anisotropic optical crystal.