Electrooptic light modulator with birefringent beamsplitter-recombiner

Claim 2

In combination: an optical beamsplitter-recombiner comprising an anisotropic medium for splitting an input light beam into two parallel displaced components having orthogonal polarization; optical means in the path of said beam components for operating upon said beam components to effect a variation of a characteristic of one of said components relative to the other of said components, said optical means including reflective means for returning said beam components to said splitterrecombiner, said anisotropy of said medium effecting a recombination of said beam components to form a single output beam.

Claim 3

The combination of claim 1 wherein said optical means is an electro-optic modulator for phase modulating at least a component of at least one of said beam component.

Claim 4

The combination of claim 2 wherein said splitter-recombiner medium exhibits a field-dependent anisotropy and wherein said combination includes means for applying an adjustable but substantially unvarying electric field across said medium.

Claim 5

An electro-optic modulator for modulating a polarized laser beam, comprising: aN optical beamsplitter comprising an anisotropic medium for splitting an input light beam into two parallel displaced components having orthogonal polarization and equal intensity; an electro-optic medium exhibiting a field-dependent anisotropy; guide means for defining a light path for said first beam component through said electro-optic medium and for defining a light path for said second beam component, said guide means including reflective means contiguous with opposite boundaries of said electro-optic medium for causing said first beam light path to be reiterative; parallel spaced electrode means arranged across said field-dependent anisotropic medium for establishing an electric field transverse to said first beam light path upon application of a signal voltage thereto for phase modulating at least a component of said first beam component; means for reuniting said beam components to form an output beam; and analyzing means in said output beams for resolving said beam components in a common plane to cause an intensity modulation of said output beam.

Claim 6

An electro-optic modulator for modulating a polarized laser beam, comprising: aN optical beamsplitter comprising an anisotropic medium for splitting an input light beam into two parallel displaced components having orthogonal polarization and equal intensity; an electro-optic medium exhibiting a field-dependent anisotropy; guide means for defining a light path for said first beam component through said electro-optic medium and for defining a light path for said second beam component, said guide means including reflective means contiguous with opposite boundaries of said electro-optic medium for causing said first beam light path to be reiterative; parallel spaced electrode means arranged across said field-dependent anisotropic medium for establishing an electric field transverse to said first beam light path upon application of a signal voltage thereto for phase modulating at least a component of said first beam component; means for reuniting said beam components to form an output beam; and analyzing means in said output beams for resolving said beam components in a common plane to cause an intensity modulation of said output beam.

Claim 7

The apparatus defined by claim 4 wherein said reflective means includes means for returning said beam components back along their respective reiterative light paths, and wherein said beamsplitter is effective, due to its anisotropic properties, to accomplish said reunion of said beam components.

Claim 8

The apparatus defined by claim 5 wherein a Glan prism is located in a common input-output path thus formed for plane polarizing said beam input beam and for acting as said analyzing means in said output beam.

Claim 9

The apparatus defined by claim 4 wherein said anisotropic beamsplitter-recombiner medium is also field-dependent, and wherein said apparatus includes bias control means for applying an adjustable but substantially unvarying electric field across said splitter-recombiner medium.

Claim 10

The apparatus defined by claim 7 wherein said bias control means comprises means for extracting a portion of the energy from said output beam, photodetection means positioned to receive said output beam portion, means responsive to said photodetection means for developing a DC bias signal the magnitude of which characterizes the output from said photodetection means, and means responsive to said DC bias signal for establishing an electric field transversely across said beamsplitter-recombiner medium.

Claim 11

An electro-optic modulator for modulating a polarized laser beam, comprising: an optical beamsplitter comprising an anisotropic medium for splitting an input light beam into two parallel displaced components having orthogonal polarization; first and second electro-optic media each exhibiting a field-dependent anisotropy; guide means for defining first and second light paths for said beam components through said first and second electro-optic media, respectively, said guide means including reflective means contiguous with opposite boundaries of said first and second media for establishing respective reiterative light paths through said media; parallel spaced electrode means arranged across each of said first and second electro-optic media to establish respective electric fields of opposite polarity transversely across said first and second light paths upon application of signal voltages thereto for phase modulating at least a component of each of said component beams; means for reuniting said beam components to form an output beam; and analyzing means in said output beam for resolving said beam components in a common plane to cause an intensity modulation of said output beam.

Claim 12

An electro-optic modulator for modulating a polarized laser beam, comprising: an optical beamsplitter comprising an anisotropic medium for splitting an input light beam into two parallel displaced components having orthogonal polarization; first and second electro-optic media each exhibiting a field-dependent anisotropy; guide means for defining first and second light paths for said beam components through said first and second electro-optic media, respectively, said guide means including reflective means contiguous with opposite boundaries of said first and second media for establishing respective reiterative light paths through said media; parallel spaced electrode means arranged across each of said first and second electro-optic media to establish respective electric fields of opposite polarity transversely across said first and second light paths upon application of signal voltages thereto for phase modulating at least a component of each of said component beams; means for reuniting said beam components to form an output beam; and analyzing means in said output beam for resolving said beam components in a common plane to cause an intensity modulation of said output beam.

Claim 13

The apparatus defined by claim 9 wherein said reflective means includes means for returning said beam components back along their respective reiterative paths, and wherein said beamsplitter is effective due to its anisotropic properties to accomplish said reunion of said beam components.

Claim 14

The apparatus defined by claim 10 wherein said anisotropic beamsplitter-recombiner medium is also field-dependent, and wherein said apparatus includes bias control means for applying an adjustable but substantially unvarying electric field across said splitter-recombiner medium.

Claim 15

The apparatus defined by claim 11 wherein said bias control means comprises: sampling means for sampling said output beam at predetermined intervals; photodetection means positioned to receive said samples; means responsive to said photodetection means for developing a DC bias signal the magnitude and polarity of which characterizes the output from said photodetection means; and means responsive to said DC bias signal for establishing an electric field transversely across said beamsplitter medium.

Claim 16

The apparatus defined by claim 12 wherein said means responsive to said photodetection means includes a comparator circuit responsive to the output of said photodetection means and to a reference voltage representing the known output of said photodetection means at a predetermined operating point of said modulator for producing a DC signal characterizing the output of said photodetection means relative to said reference voltage.

Claim 17

The apparatus defined by claim 3 wherein a Glan prism is located in a common input-output path formed for plane polarizing said input beam and for acting as said analyzing means in said output beam.