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US 5,963,359 AGranted
Wavelength conversion device employing non-diffracting beam
AssigneeOki Electric Industry Co., Ltd.
InventorsKeisuke Shinozaki, Chang-Qing Xu, Hironori Sasaki
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Abstract
A non-diffracting beam generator converts coherent light from a semiconductor laser into a small, intense, non-diffracting beam, which is directed into a non-linear optical element. The non-linear optical element converts this beam to light of a different wavelength. The non-linear optical element is a bulk element, not having an internal waveguide, and not requiring precise alignment of the non-diffracting beam. The non-diffracting beam preferably has a length matching the thickness of the non-linear optical element.
Claims31
A non-diffracting beam generator, comprising:
- a first optical system having a certain effective aperture, for focusing incident light to an annular image with a diameter less than half of said effective aperture, wherein said first optical system comprises a first zone plate, and
- a second optical system for generating a non-diffracting beam from said annular image, wherein said second optical system comprises:
- a first lens for collimating light from the annular image into a tubular parallel beam;
- and
- a second lens for generating said non-diffracting beam from the tubular parallel beam.
2 more elements
A non-diffracting beam generator, comprising:
- a first optical system having a certain effective aperture, for focusing incident light to an annular image with a diameter less than half of said effective aperture, and a second optical system for generating a non-diffracting beam from said annular image, wherein said second optical system comprises:
- a ring-shaped toroidal lens for collimating light from said annular image into a tubular parallel beam;
- and
- an axicon lens for generating said non-diffracting beam from said tubular parallel beam.
1 more element
A non-diffracting beam generator, comprising:
- a first optical system having a certain effective aperture, for focusing incident light to an annular image with a diameter less than half of said effective aperture, and
- a second optical system for generating a non-diffracting beam from said annular image, wherein said second optical system comprises:
- a second zone plate for collimating light from said annular image into a tubular parallel beam;
- and
- an axicon lens for generating said non-diffracting beam from said tubular parallel beam.
2 more elements
A non-diffracting beam generator, comprising:
- a first optical system having a certain effective aperture, for focusing incident light to an annular image with a diameter less than half of said effective aperture, and
- a second optical system for generating a non-diffracting beam from said annular image, wherein said second optical system comprises:
- a ring-shaped toroidal lens for collimating light from said annular image into a tubular parallel beam;
- and
- a third zone plate for generating said non-diffracting beam from said tubular parallel beam.
2 more elements
A non-diffracting beam generator, comprising:
- a first optical system having a certain effective aperture, for focusing incident light to an annular image with a diameter less than half of said effective aperture, and a second optical system for generating a non-diffracting beam from said annular image, wherein said second optical system consists of a single zone plate.
A device for converting coherent light of a first wavelength, emitted by a semiconductor laser, to light of a second wavelength, comprising:
- a non-diffracting beam generator for receiving said coherent light of said first wavelength and generating from said coherent light a non-diffracting beam on a certain optic axis, wherein said non-diffracting beam generator directs said coherent light toward said optic axis at a uniform angle .theta.;
- a half-mirror for mixing the coherent light of said first wavelength with coherent light of a fourth wavelength,
- a bulk non-linear optical element disposed on said optic axis, for receiving said non-diffracting beam, and transmitting said non-diffracting beam in an unconfined manner while converting said non-diffracting beam from said first wavelength to said second wavelength, wherein said non-linear optical element:
- performs second-harmonic generation and difference-frequency generation,
- produces a phase mismatch .DELTA.k.sub.D with respect to light of said first wavelength, said second wavelength, and said fourth wavelength propagating parallel to said optic axis, and
- has a periodic domain inversion structure with a period .LAMBDA. measured parallel to said optic axis, where
- .LAMBDA.=(2.pi./.DELTA.k.sub.D).
4 more elements
A device for converting coherent light of a first wavelength, emitted by a semiconductor laser, to light of a second wavelength, comprising:
- a non-diffracting beam generator for receiving said coherent light of said first wavelength and generating, from said coherent light, a non-diffracting beam on a certain optic axis;
- and
- a bulk non-linear optical element disposed on said optic axis, for receiving said non-diffracting beam, and transmitting said non-diffracting beam in an unconfined manner while converting said non-diffracting beam from said first wavelength to said second wavelength, wherein said non-linear optical element performs second-harmonic generation, wherein said non-linear optical element has a quasi-phase-matching structure and performs quasi-phase-matching for light of said first wavelength and light of said second wavelength, further comprising means for creating a phase delay in part of the non-diffracting beam, to compensate for dimensional error in the quasi-phase-matching structure.
A device for converting coherent light of a first wavelength, emitted by a semiconductor laser, to light of a second wavelength, comprising:
- a non-diffracting beam generator for receiving said coherent light of said first wavelength and generating from said coherent light, a non-diffracting beam on a certain optic axis, wherein said non-diffracting beam generator has a flat surface for receiving said coherent light from said semiconductor laser,
- a reflective coating on said flat surface that partially reflects light of said first wavelength and transmits light of other wavelengths, for providing optical feedback to said semiconductor laser, thereby causing said semiconductor laser to operate at said first wavelength and
- a bulk non-linear optical element disposed on said optic axis, for receiving said non-diffracting beam, and transmitting said non-diffracting beam in an unconfined manner while converting said non-diffracting beam from said first wavelength to said second wavelength, wherein said non-linear optical element performs second-harmonic generation.
A device for converting coherent light of a first wavelength, emitted by a semiconductor laser, to light of a second wavelength, comprising:
- a non-diffracting beam generator for receiving said coherent light of said first wavelength and generating, from said coherent light, a non-diffracting beam on a certain optic axis, wherein said non-diffracting beam generator has a flat surface, normal to said optic axis, for receiving said coherent light,
- a phase shifter disposed on said flat surface, and having a shape symmetrical about said optic axis, for creating a phase delay in part of the coherent light entering said non-diffracting beam generator, and
- a bulk non-linear optical element disposed on said optic axis, for receiving said non-diffracting beam, and transmitting said non-diffracting beam in an unconfined manner while converting said non-diffracting beam from said first wavelength to said second wavelength, wherein said non-linear optical element performs second-harmonic generation.
A device for converting coherent light of a first wavelength, emitted by a semiconductor laser, to light of a second wavelength, comprising:
- a non-diffracting beam generator for receiving said coherent light of said first wavelength and generating, from said coherent light, a non-diffracting beam on a certain optic axis, wherein said non-diffracting beam generator includes
- a first optical system having a certain effective aperture, for receiving said coherent light from said semiconductor laser and focusing said coherent light to an annular image with a diameter less than half of said effective aperture, and
- a second optical system for generating said non-diffracting beam from said annular image;
- and
- a bulk non-linear optical element disposed on said optic axis, for receiving said non-diffracting beam, and transmitting said non-diffracting beam in an unconfined manner while converting said non-diffracting beam from said first wavelength to said second wavelength, wherein said non-linear optical element performs second-harmonic generation.
2 more elements
A device for converting coherent light of a first wavelength, emitted by a semiconductor laser, to light of a second wavelength, comprising:
- a non-diffracting beam generator for receiving said coherent light of said first wavelength and generating, from said coherent light, a non-diffracting beam on a certain optic axis;
- a bulk non-linear optical element disposed on said optic axis, for receiving said non-diffracting beam, and transmitting said non-diffracting beam in an unconfined manner while converting said non-diffracting beam from said first wavelength to said second wavelength, wherein said non-linear optical element performs second-harmonic generation;
- an axicon collimator for receiving light of said second wavelength from said non-linear optical element, and forming said light of said second wavelength into a second tubular parallel beam;
- and
- a first convex lens for focusing said second tubular parallel beam to a super-resolved spot.
2 more elements
A device for converting coherent light of a first wavelength, emitted by a semiconductor laser, to light of a second wavelength, comprising:
- a non-diffracting beam generator for receiving said coherent light of said first wavelength and generating, from said coherent light, a non-diffracting beam on a certain optic axis,
- a bulk non-linear optical element disposed on said optic axis, for receiving said non-diffracting beam, and transmitting said non-diffracting beam in an unconfined manner while converting said non-diffracting beam from said first wavelength to said second wavelength, wherein said non-linear optical element performs second-harmonic generation, and
- a fourth zone plate for receiving light of said second wavelength from said non-linear optical element, and focusing said light of said second wavelength to a super-resolved spot.
A device for converting coherent light of a first wavelength, emitted by a semiconductor laser, to light of a second wavelength, comprising:
- a non-diffracting beam generator for receiving said coherent light of said first wavelength and generating, from said coherent light, a non-diffracting beam on a certain optic axis, wherein said non-diffracting beam generator directs said coherent light toward said optic axis at a uniform angle .theta.;
- and
- a bulk non-linear optical element disposed on said optic axis, for receiving said non-diffracting beam, and transmitting said non-diffracting beam in an unconfined manner while converting said non-diffracting beam from said first wavelength to said second wavelength, wherein said non-linear optical element performs second-harmonic generation, wherein
- said non-linear optical element has a coherence length 1.sub.c with respect to light of said first wavelength and light of said second wavelength propagating parallel to said optic axis, and
- said non-linear optical element has a periodic domain inversion structure with a period .LAMBDA. measured parallel to said optic axis, where
- .LAMBDA.=2l.sub.c =(.lambda./2)/(n.sub.sh -n.sub.f cos .theta.).
- 30.
4 more elements
A device for converting coherent light of a first wavelength, emitted by a semiconductor laser, to light of a second wavelength, comprising:
- a non-diffracting beam generator for receiving said coherent light of said first wavelength and generating, from said coherent light, a non-diffracting beam on a certain optic axis, wherein said non-diffracting beam generator directs said coherent light toward said optic axis at a uniform angle .theta.;
- a half-mirror for mixing the coherent light of said first wavelength with coherent light of a third wavelength,
- a bulk non-linear optical element disposed on said optic axis, for receiving said non-diffracting beam, and transmitting said non-diffracting beam in an unconfined manner while converting said non-diffracting beam from said first wavelength to said second wavelength, wherein said non-linear optical element:
- performs second-harmonic generation and sum-frequency generation,
- produces a phase mismatch .DELTA.k.sub.S with respect to light of said first wavelength, said second wavelength, and said third wavelength propagating parallel to said optic axis, and
- has a periodic domain inversion structure with a period .LAMBDA. measured parallel to said optic axis, where
- .LAMBDA.=(2.pi./.DELTA.k.sub.S).
4 more elements
A wavelength conversion method comprising the steps of:
- generating a non-diffracting beam including light of a first wavelength:
- directing said non-diffracting beam into a bulk non-linear optical element having a quasi-phase-matching structure, which converts said first wavelength to a second wavelength, said non-diffracting beam being directed toward an arbitrary point on a surface of said nonlinear optical element and not coupled into a waveguide:
- and
- creating a phase delay in part of said non-diffracting beam, to compensate for dimensional error in said quasi-phase-matching structure.
1 more element
Dependencies are inferred from the claim text.