CN204086699U - Free space 90-degree optical mixer - Google Patents
Free space 90-degree optical mixer Download PDFInfo
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- CN204086699U CN204086699U CN201420419877.XU CN201420419877U CN204086699U CN 204086699 U CN204086699 U CN 204086699U CN 201420419877 U CN201420419877 U CN 201420419877U CN 204086699 U CN204086699 U CN 204086699U
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- 230000003287 optical effect Effects 0.000 title claims abstract description 29
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- 230000010363 phase shift Effects 0.000 claims abstract description 16
- 238000010008 shearing Methods 0.000 claims description 28
- 230000010287 polarization Effects 0.000 claims description 23
- 238000004026 adhesive bonding Methods 0.000 claims description 6
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- 238000000034 method Methods 0.000 claims 5
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- 101100232265 Candida albicans (strain SC5314 / ATCC MYA-2876) HWP2 gene Proteins 0.000 description 5
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- 101100532512 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) SAG1 gene Proteins 0.000 description 1
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Abstract
The utility model relates to a 90 optical mixers in free space. The device comprises a beam combination unit for combining a signal light beam and a local oscillation light beam, an in-phase balance receiving channel for generating two paths of combined light beams with relative phase shifts of 0 degree and 180 degrees, a quadrature balance receiving channel for generating two paths of combined light beams with relative phase shifts of 90 degrees and 270 degrees, and a receiving unit for receiving the combined light beams with relative phase shifts of 0 degree, 90 degrees, 180 degrees and 270 degrees. The utility model provides a improve accurate, convenient 90 optical mixers in free space who transfers dress.
Description
Technical Field
The utility model belongs to space laser communication field relates to the optical mixer, especially relates to a 90 optical mixer in free space.
Background
The free space 90 degree optical mixer is an optical core device of a free space coherent optical communication terminal, which combines a signal light beam and a local oscillator light beam and decomposes the combined light beam into 4 combined light beams, wherein relative phase shifts of 0 degree, 90 degrees, 180 degrees and 270 degrees are provided between the combined light beam and the combined light beam, or an in-phase balanced receiving channel (two channels of 0 degree and 180 degrees) and a quadrature balanced receiving channel (two channels of 90 degrees and 270 degrees) are generated between the combined light beam and the combined light beam.
The photosensitive surface of the balance receiver of the free space coherent optical communication terminal is generally only dozens of microns, and the two paths of light (I) of the balance receiver+And I-Two paths or Q+And Q-Two paths) of receiving photosensitive surfaces are fixed. The separation between the two light paths of the balanced receiver must therefore be precisely controlled, which often requires several microns. The existing free space optical mixer has the following three disadvantages:
1. it is difficult to precisely control the spacing between the two lights of the balanced receiver;
2. the volume of the device is limited by the distance between two photosensitive surfaces of the balance receiver, so that the device is too small to be installed and adjusted;
3. the four branches are mutually separated, so that the optical distances of the four branches are difficult to control to be equal, and time deviation is easy to generate.
4. The focusing quality of the common lens is difficult to control, and the processing and the assembly and adjustment are difficult.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem that exists among the background art, the utility model provides a free space optical mixer, this mixer utilize improved generation lateral shear interferometer to be difficult to the technical problem that accurate control, volume are limited and four ways output optical path difference are difficult to control in order to solve the interval between balanced receiver two way light among the background art.
The mixer is composed of a lambda/2 wave plate HWP1, a lambda/2 wave plate HWP2, a lambda/4 wave plate QWP, a polarization beam splitter prism PBS, a lambda/2 wave plate HWP3, a lambda/2 wave plate HWP4, a lateral shearing interferometer SAG1, a lateral shearing interferometer SAG2, a self-focusing lens AFL1, a self-focusing lens AFL2, a self-focusing lens AFL3 and a self-focusing lens AFL 4.
The signal light and the local oscillator light are polarized light, and the two paths of light are changed into linearly polarized light forming an angle of 45 degrees with the XZ plane after passing through the lambda/2 wave plate HWP1 and the lambda/2 wave plate HWP2 respectively. Then, the local oscillation light passes through the lambda/4 wave plate QWP, the fast axis of the lambda/4 wave plate forms 45 degrees with the polarization direction of the local oscillation light, the emergent local oscillation light is changed into circular polarization light, and the phase difference between the P wave (parallel component) and the S wave (vertical component) is 90 degrees.
The polarizing beam splitter PBS functions to reflect S-waves and transmit P-waves. After the signal light S wave and the local oscillation light P wave entering the I branch pass through the 1/2 wave plate HWP3, the polarization directions of the signal light S wave and the local oscillation light P wave rotate by 45 degrees, the signal light forms-45 degrees with an XZ surface, and the local oscillation light forms 45 degrees with the XZ surface. Therefore, the direction of the P wave component of the signal light is the same as that of the P wave component of the local oscillation light, and the direction of the S wave component of the signal light is opposite to that of the S wave component of the local oscillation light.
The transverse shearing interferometer is formed by gluing two semi-pentagonal prisms with different thicknesses, wherein one part of a gluing surface is plated with a polarization beam splitting film, and the other part of the gluing surface is plated with an anti-reflection film. The P wave component of the signal light and the P wave component of the local oscillator light enter I through the transverse shearing interferometer+Branch addition, the S wave component of the signal light and the S wave component of the local oscillator light enter I-By subtracting branches, thus corresponding to I+Branch and I-There is a phase difference of 180 between the branches. Simultaneous lateral shearing interferometer+Branch and I-The two beams of light in the branch are cut apart by a distance which can be accurately controlled during the adjustment of the interferometer. Due to the nature of the lateral shearing interferometer, I+And I-The optical paths of the branches in the interferometer are equal. In the same way, Q+Branch and Q-The branches also conform to the above properties.
I+Branch, I-Branch, Q+Branch, Q-The outgoing beams of the branches are focused on the detector by a self-focusing lens respectively. The aperture of the self-focusing lens is only a few millimeters generally, and the size of a focused beam diffuse spot is equivalent to that of a photosensitive surface of the detector.
The technical scheme of the utility model is that: a free space 90-degree optical mixer comprises a beam combination unit for combining a signal light beam and a local oscillator light beam, an in-phase balance receiving channel for generating two paths of combined light beams with relative phase shifts of 0 degree and 180 degrees, an orthogonal balance receiving channel for generating two paths of combined light beams with relative phase shifts of 90 degrees and 270 degrees, and a receiving unit for receiving the combined light beams with relative phase shifts of 0 degree, 90 degrees, 180 degrees and 270 degrees;
it is characterized in that:
a transverse shearing interferometer is respectively arranged on the in-phase balance receiving channel and the orthogonal balance receiving channel; the transverse shearing interferometer comprises two semi-pentagonal prisms with different thicknesses, the light beam combined by the beam combining unit is sheared into two light beams by the transverse shearing interferometer, and the distance between emergent lights of the two light beams can be controlled by translating the two semi-pentagonal prisms in a gluing plane during adjustment;
the incidence area of the cementing surface of the transverse shearing interferometer is plated with a polarization beam splitting film, and the transmission area is plated with an antireflection film;
the in-phase balanced receiving channel and the orthogonal balanced receiving channel have the same structure;
the receiving unit respectively receives the relative phase shift combination light beam of 0 degrees, 90 degrees, 180 degrees and 270 degrees through the focusing of a second self-focusing lens, a third self-focusing lens, a first self-focusing lens and a fourth self-focusing lens;
the beam splitting unit comprises a second wave plate, a fifth wave plate and a third wave plate which are sequentially arranged on the local oscillation light path, and a first wave plate and a fourth wave plate which are sequentially arranged on the signal light path; and a polarization beam splitter prism is also arranged at the intersection of the local oscillation light path and the signal light path.
The utility model has the advantages that:
1. the utility model discloses a spacing accurate control between balanced receiver two way light has been realized to modified lateral shear interferometer.
2. The utility model discloses a light path structure size no longer is subject to balanced receiver two-channel interval, and the device volume can suitably increase in order to conveniently install and transfer.
3. Two paths of light of the same balanced receiving channel are equal in shearing optical path through the transverse shearing interferometer, so that the four paths of light path control equality is simplified into the fact that the optical paths between the two balanced receiving channels are equal. Namely, the utility model discloses make four branch road optical distances equal more easily. The higher the requirement to each path of optical path difference that space laser communication system transmission rate is, the utility model discloses a this advantage is more important.
4. The two sides of the self-focusing lens are both flat, so that the self-focusing lens is convenient to mount and has excellent focusing quality.
Drawings
FIG. 1 is a schematic diagram of the present invention;
FIG. 2 is a diagram of an optical system according to the present invention;
FIG. 3 is a schematic diagram of a middle polarization lateral shearing interferometer of the present invention;
the device comprises a first wave plate 1, a second wave plate 2, a third wave plate 3, a fourth wave plate 4, a polarization beam splitter prism 5, a first self-focusing lens 6, a second self-focusing lens 7, a third self-focusing lens 8, a fourth self-focusing lens 9, a lateral shearing interferometer 10 and a fifth wave plate 11.
Detailed Description
Referring to fig. 1-2, a free space 90 ° optical mixer includes a beam combining unit for combining a signal light beam and a local oscillator light beam, an in-phase balanced receiving channel for generating two combined light beams with relative phase shifts of 0 ° and 180 °, an orthogonal balanced receiving channel for generating two combined light beams with relative phase shifts of 90 ° and 270 °, and a receiving unit for receiving the combined light beams with relative phase shifts of 0 °, 90 °, 180 °, and 270 °; a transverse shearing interferometer 10 is respectively arranged on the in-phase balance receiving channel and the orthogonal balance receiving channel; the lateral shearing interferometer 10 comprises two semi-pentagonal prisms with different thicknesses, the light beam combined by the beam combination unit is sheared into two light beams by the lateral shearing interferometer 10, and the distance between the emergent light of the two light beams can be controlled by the translation of the two semi-pentagonal prisms in the gluing plane during adjustment; the incidence area of the bonding surface of the transverse shearing interferometer 10 is plated with a polarization beam splitting film, and the transmission area is plated with an antireflection film; the in-phase balanced receiving channel and the orthogonal balanced receiving channel have the same structure; the receiving unit is used for receiving the relative phase shift combined light beam of 0 degrees, 90 degrees, 180 degrees and 270 degrees through the focusing of a second self-focusing lens 7, a third self-focusing lens 8, a first self-focusing lens 6 and a fourth self-focusing lens 9 respectively; the beam splitting unit comprises a second wave plate 2, a fifth wave plate 11 and a third wave plate 3 which are sequentially arranged on the local oscillation light path, and a first wave plate 1 and a fourth wave plate 4 which are sequentially arranged on the signal light path; and a polarization beam splitter prism 5 is also arranged at the intersection of the local oscillation optical path and the signal optical path.
When the local oscillation laser enters the system, the polarization direction of the local oscillation laser is parallel to the XZ plane, and certain angular deviation is allowed. By adjusting 1/2 wave plate HWP2, the fast axis of the wave plate HWP2 is 22.5 degrees with the polarization direction of the local oscillator laser, and the polarization direction XZ of the local oscillator laser after passing through HWP2 forms an angle of 45 degrees. The fast axis direction of the 1/4 wave plate QWP is parallel to the XZ plane, i.e. the fast axis direction of the QWP is 45 degrees to the polarization direction of the local oscillator light. The local oscillation light passes through 1/4 wave plate QWP and becomes circularly polarized light, and the phase difference between P wave and S wave is 90 deg. Then the local oscillation light passes through the polarization beam splitter prism, the P wave is transmitted to enter the I branch, and the S wave is reflected to enter the Q branch. Therefore, a phase difference of 90 degrees is generated between the local oscillation light of the I branch and the local oscillation light of the Q branch.
Similarly, the fast axis of HWP1 is 22.5 ° to the polarization direction of the signal light, and the polarization direction XZ of the signal light after passing through HWP1 is 45 ° by adjusting 1/2 wave plate HWP1, i.e., the P-wave component is equal to the S-wave component. Then, the signal light passes through the polarization beam splitter prism, the P wave is transmitted to enter the Q branch, and the S wave is reflected to enter the I branch.
After the signal light S wave and the local oscillation light P wave entering the I branch pass through the 1/2 wave plate HWP3, the polarization directions of the signal light S wave and the local oscillation light P wave rotate by 45 degrees, the signal light forms-45 degrees with an XZ surface, and the local oscillation light forms 45 degrees with the XZ surface. Therefore, the direction of the P wave component of the signal light is the same as that of the P wave component of the local oscillation light, and the direction of the S wave component of the signal light is opposite to that of the S wave component of the local oscillation light. After passing through the transverse shearing interferometer, the P wave component of the signal light and the P wave component of the local oscillator light enter the I+Branch addition, the S wave component of the signal light and the S wave component of the local oscillator light enter I-By subtracting branches, thus corresponding to I+Branch and I-The inter-branch difference frequency components are 180 ° out of phase. For the same reason Q+Branch and Q-There is also a phase difference of 180 between the branches.
I+Branch and I-The distance between the two beams in the branch, i.e. the shearing amount of the interferometer, is accurately controlled by the adjustment interferometer. Two prisms of the interferometer are glued by using photosensitive glue. During adjustment, a beam of laser with the polarization direction of 45 degrees is incident into the transverse shearing interferometer, an analyzer (45 degrees with an XZ surface) is arranged at the emergent end of the transverse shearing interferometer, and a digital camera is placed at a distance behind the analyzer. Two beams of light, i.e. I, sheared by the lateral shearing interferometer+And I-The two light paths will interfere at the focal plane of the digital camera. And displaying the interference fringe pattern in real time by using a computer. Theoretical calculation of N0CCD pixel number M of digital camera occupied by interference fringe0：
Wherein,
λ is the laser wavelength of the laser output,
f is the focal length of the digital camera,
d is the size of the CCD pixel,
Δ is the amount of lateral shear required for design.
The two glued and uncured prisms are relatively moved in a small amount to read N0The interference fringes account for the number M of CCD pixels of the digital camera. Until the number M of CCD pixels is M0And stopping moving, and carrying out illumination curing on the bonding surface to position the two prisms. Interferometric lateral shearing interferometer, I+Branch and I-The theoretical precision of the branch distance can reach 1 wavelength of the adopted laser.
I+Branch, I-Branch, Q+Branch, Q-The outgoing beams of the branches are focused on the detector by a self-focusing lens respectively, and the size of the focused diffuse beams of the beams is equivalent to that of the photosensitive surface.
Claims (5)
1. A free space 90-degree optical mixer comprises a beam combination unit for combining a signal light beam and a local oscillator light beam, an in-phase balance receiving channel for generating two paths of combined light beams with relative phase shifts of 0 degree and 180 degrees, an orthogonal balance receiving channel for generating two paths of combined light beams with relative phase shifts of 90 degrees and 270 degrees, and a receiving unit for receiving the combined light beams with relative phase shifts of 0 degree, 90 degrees, 180 degrees and 270 degrees;
the method is characterized in that:
the in-phase balance receiving channel and the orthogonal balance receiving channel are respectively provided with a transverse shearing interferometer; the transverse shearing interferometer comprises two semi-pentagonal prisms with different thicknesses, the light beam combined by the beam combining unit is sheared into two light beams through the transverse shearing interferometer, and the distance between the emergent light of the two light beams can be controlled by the two semi-pentagonal prisms in the gluing plane in translation during adjustment.
2. A free-space 90 ° optical mixer according to claim 1: the method is characterized in that: and a polarization beam splitting film is plated on the incident area of the transverse shearing interferometer delta cemented surface, and an antireflection film is plated on the transmission area.
3. A free-space 90 ° optical mixer according to claim 2: the method is characterized in that: the in-phase balanced receiving channel and the quadrature balanced receiving channel are identical in structure.
4. A free-space 90 ° optical mixer according to claim 3: the method is characterized in that: the receiving unit respectively receives the relative phase shift combined light beam of 0 degrees, 90 degrees, 180 degrees and 270 degrees through the focusing of the second self-focusing lens, the third self-focusing lens, the first self-focusing lens and the fourth self-focusing lens.
5. A free-space 90 ° optical mixer according to claim 4: the method is characterized in that: the beam splitting unit comprises a second wave plate, a fifth wave plate and a third wave plate which are sequentially arranged on the local oscillation light path, and a first wave plate and a fourth wave plate which are sequentially arranged on the signal light path; and a polarization beam splitter prism is also arranged at the intersection of the local oscillation light path and the signal light path.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420419877.XU CN204086699U (en) | 2014-07-28 | 2014-07-28 | Free space 90-degree optical mixer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201420419877.XU CN204086699U (en) | 2014-07-28 | 2014-07-28 | Free space 90-degree optical mixer |
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| CN204086699U true CN204086699U (en) | 2015-01-07 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104297936A (en) * | 2014-07-28 | 2015-01-21 | 中国科学院西安光学精密机械研究所 | Free space 90-degree optical mixer |
| CN107132663A (en) * | 2017-06-14 | 2017-09-05 | 长春理工大学 | 90 ° of frequency mixers of spatial light that splitting ratio adaptively regulates and controls |
-
2014
- 2014-07-28 CN CN201420419877.XU patent/CN204086699U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104297936A (en) * | 2014-07-28 | 2015-01-21 | 中国科学院西安光学精密机械研究所 | Free space 90-degree optical mixer |
| CN107132663A (en) * | 2017-06-14 | 2017-09-05 | 长春理工大学 | 90 ° of frequency mixers of spatial light that splitting ratio adaptively regulates and controls |
| CN107132663B (en) * | 2017-06-14 | 2019-05-07 | 长春理工大学 | 90 ° of frequency mixers of spatial light that splitting ratio adaptively regulates and controls |
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| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20150107 Termination date: 20190728 |