CN114967187A - Free space optical isolator - Google Patents
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- CN114967187A CN114967187A CN202210582745.8A CN202210582745A CN114967187A CN 114967187 A CN114967187 A CN 114967187A CN 202210582745 A CN202210582745 A CN 202210582745A CN 114967187 A CN114967187 A CN 114967187A
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- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/09—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on magneto-optical elements, e.g. exhibiting Faraday effect
- G02F1/093—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on magneto-optical elements, e.g. exhibiting Faraday effect used as non-reciprocal devices, e.g. optical isolators, circulators
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Abstract
The invention relates to a free space optical isolator which comprises a Faraday optical rotator magnet system, a magneto-optical crystal, a magnet system fixing sleeve, a Glan-Taylor prism, an adjustable polarizer mounting bracket, a fixing disc, a fixing screw, a gasket and a prism cover. The magnet system has reasonable and compact layout and stable structure, the magnet system enables the magnetic field distributed in the crystal to achieve the optimal result under the condition of small volume through the optimal design of a magnetic circuit, and the problems of low isolation, low transmissivity, non-adjustability of application wavelength and the like of the optical isolator are solved by the design of the shape, the size and the antireflection film of the magneto-optical crystal and the design of a mechanical packaging structure adopting a precision processing process, so that the invention has important engineering practical value.
Description
Technical Field
The invention belongs to the field of optical passive devices, and particularly relates to a free space optical isolator.
Background
With the continuous development of the research of quantum theory and quantum science field, the quantum sensing technology is taken as an important branch field in the quantum science research field, and the breakthrough and development of the field greatly reform and promote the national defense military technology and the living standard of people. The atomic magnetometer technology which utilizes atoms as sensitive media and is based on the characteristics of the ultra-fine structure, spin, energy level transition and the like inherent to the atoms has gained a position of shorthand-first in the field of quantum sensing. In particular, Spin-Exchange Relaxation-Free (SERF) atomic magnetometers have been applied to the medical field of measuring human magnetocardiogram and magnetoencephalography, which is not separated from the outstanding contribution of semiconductor lasers. When the SERF effect of alkali metal atoms in the magnetometer gas chamber is realized, narrow-spectrum laser with corresponding wavelength is needed for pumping, so that the sufficient inhibition of spin exchange relaxation under the condition of high atomic number density is realized. That is, a beam of pumping light with specific wavelength is utilized to polarize atoms, and when the atom spin direction is acted by a magnetic field, Larmor precession is generated, so that the atom spin deviates from the laser direction; the measurement of extremely weak magnetic fields can be achieved by measuring the spin precession of atoms using a beam of detection light of a specific wavelength. Therefore, the development of quantum sensing systems has placed high demands on the frequency and power stability of the laser light source and low noise.
After laser in the laser system is emitted, the laser enters the quantum sensing system, and because optical elements in the light path can form light reflection, the backward incident light enters the laser system along the incident light path. The existence of the backward incident light can cause self-coupling effect in the laser system, and causes phenomena of laser frequency drift, power change, noise increase and the like. A free-space optical isolator is an optical element that allows light to travel in only one direction, typically to prevent unwanted reflected light from being fed back into the laser cavity. The operation of the isolator depends on the faraday effect (created by the magneto-optical effect) which is used for the faraday rotator. Due to the faraday effect, a magnetic field B applied to the faraday rotator causes the plane of polarization of the incident light to rotate. The rotation angle is theta, and the formula is as follows:
θ＝V∫B z dl (1.1)
where V is the verdet constant of the magneto-optical crystal material. The free space optical isolator mainly comprises an input polarizer, a Faraday rotator and an output polarizer, wherein the input polarizer is vertically polarized, and the output polarizer is 45-degree polarized. The incident light is vertically polarized by the input polarizer. The Faraday rotator rotates the polarization of light by 45 degrees, enabling light to be transmitted through the isolator. After the light propagating in the opposite direction passes through the Faraday rotator and the polarization is rotated by 45 degrees, the optical axis of the input polarizer is vertical to the polarization plane of the reverse transmission light, i.e. the reverse transmission light is isolated. Because the quantum sensing system has extremely high requirements on the frequency stability and the power stability of a light source, the free space optical isolator designed by the invention isolates backward incident light by utilizing the reciprocity of the free space optical isolator, and keeps the stability of the frequency and the power of a pumping light source and an optical source for detecting light.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the free space optical isolator overcomes the defects of the free space optical isolator in the prior art, has reasonable component layout and compact structure, optimally designs the magnetic circuit of a magnet system, enables the magnetic field distributed in the crystal to achieve the optimal result under the condition of small volume, and solves the problems of low isolation degree, low transmissivity, non-adjustability of application wavelength and the like of the optical isolator by the design of the shape, the size and the anti-reflection film of the magneto-optical crystal and the design of a mechanical packaging structure adopting a precision machining process.
In order to solve the technical problems, the invention adopts the technical scheme that:
a free space optical isolator comprises a Faraday optical rotator magnet system, a magneto-optical crystal, a Glan Taylor prism, a magnet system fixing sleeve, an adjustable polarizer mounting bracket, a fixing disc, a fixing ferrule, a fixing screw, a gasket and a prism cover; wherein, the Faraday rotator magnet system is a cylinder with a clear aperture and composed of a radial magnetization ring and an anti-axial magnetization ring; the magneto-optical crystal is a core component of the free space optical isolator, generates Faraday effect and generates Faraday rotation on linearly polarized light under uniform strong magnetic field distribution; the Glan Taylor prism is used as an input polarizer and an output polarizer and is fixed on the adjustable polarizer mounting bracket, and the input transmissivity and the reverse isolation of the free-space optical isolator are influenced by the optical axis space azimuth angle error of the Glan Taylor prism; the magnet system fixing sleeve is used as an adjustable mechanical packaging structure, on one hand, the inner wall of the magnet system fixing sleeve is glued with the cylindrical surface of the Faraday rotator magnet system, and on the other hand, the fixing disc is rotatably installed through threads and is used for fixing two bottom surfaces of the Faraday rotator magnet system; the adjustable polarizer mounting bracket can rotate precisely, and after the optical axis space azimuth angle is adjusted to a set value, the adjustable polarizer mounting bracket is fixed on two sides of the magnet system fixing sleeve through threads, a fixing ferrule and a fixing screw on the fixing disc; the gasket is used for protecting the mounting bracket for mounting the adjustable polarization device and preventing abrasion; the prism cover is used for sealing the magnet system fixing sleeve to form a closed structure, the Glan Taylor prism is protected, and the light-passing aperture is reserved.
Further, the size of a required magnetic field and the size of a uniform area are determined according to the wavelength and the diameter of a light beam, and the Verdet constant, the light transmission length and the transverse size of the magneto-optical crystal, and then an optimal magnetic circuit of the free-space optical isolator is designed.
Further, the optimum magnetic circuit makes the faraday effect in all places in the magneto-optical crystal stable and suppressed, and realizes smaller size design of the magneto-optical crystal and reduction of dependency of verdet constant, with optimum performance while keeping miniaturization.
Furthermore, Tb is adopted as the magneto-optical crystal 3 Ga 5 O 12 The crystal material has a small expansion coefficient, and the photoelastic effect caused by stress deformation is reduced; the light-passing surface of the light-emitting diode is plated with a double-quarter antireflection film.
Furthermore, the Glan Taylor prism and the adjustable polarizer mounting bracket precisely rotate to adjust the optical axis angle value of the axial space direction, so that the isolation and the anti-reflection rate of the free space optical isolator are improved; when the wavelength is changed, the adjustable polarizer mounting bracket is rotationally adjusted to keep the isolation constant at the peak value.
Further, the magnet system fixing sleeve encapsulates and fixes the main structure of the free space optical isolator, and protects the Faraday rotator magnet system and the Glan-Taylor prism from being displaced and damaged due to external force.
Compared with the prior art, the invention has the advantages that:
1) the free space optical isolator is designed on the basis of miniaturization, the magnetic circuit is optimally designed, so that a strong magnetic field is distributed in the range of a light transmission aperture of 10mm, the magnetic field strength B reaches 1.32T and is higher than the remanence Br of a magnetic body structure per se by 1.25T, good uniformity is achieved in the axial direction and the transverse direction, the Faraday effect in the magneto-optical crystal is stable no matter in the cross section or in the axial direction, and the Faraday rotation angle of each point is 45 degrees. The uniform distribution of the strong magnetic field inhibits the depolarization distortion phenomenon of the magneto-optical crystal, reduces the dependence of the isolation index on the high Verdet constant of the magneto-optical crystal and reduces the cost of the core component of the magneto-optical crystal.
2) The magneto-optical crystal designed by the invention selects a crystal material Tb with a small expansion coefficient 3 Ga 5 O 12 And the photoelastic effect caused by stress deformation is reduced. The light-passing surface is plated with a double-quarter-layer antireflection film, so that the reflectivity of 780nm wavelength laser passing through the magneto-optical crystal is less than 0.14%, and the reflectivity of 795nm wavelength laser passing through the magneto-optical crystal is less than 0.15%. The Verdet constant of the magneto-optical crystal is reduced to 60 when 780nm wavelength laser passes through, and the growth cost of the magneto-optical crystal is reduced.
3) The adjustable mechanical packaging structure designed by the invention provides support and mounting reference for optical isolator components. The magnetic body fixing sleeve and the fixing disc are used for fixing the magnetic body structure of the Faraday optical rotator, so that the magnetic circuit is prevented from being changed due to the displacement of the magnetic body structure caused by external force damage or extrusion, and the Faraday optical rotation effects at all positions in the crystal are inconsistent. The polarizer mounting bracket is used as a carrier for fixing the input polarizer and the output polarizer, can be rotatably adjusted and is fixed by the fixing ferrule and the fixing screw, so that the polarizer mounting bracket is prevented from rotating and deviating or falling off in the use process. The prism cover is screwed into the sleeve through threads to protect the prism.
4) The magnetic material of the invention is mainly neodymium iron boron, which has the advantages of large coercive force, higher remanence, large magnetic energy product, low cost and the like. During magnetizing, the remanence Br value can be accurately controlled, and the demagnetization is not easy to occur.
5) The main structure of the mechanical packaging structure adopts the duralumin material, and the surface anodic oxidation blackening treatment is carried out, so that the weight of the whole structure is reduced, the structure volume is reduced, the wear resistance, the corrosion resistance and the insulativity of the whole structure are effectively improved, and the mechanical packaging structure has important engineering practical value.
In conclusion, the components of the invention have reasonable and compact layout and stable structure, so that the magnet system can achieve the optimal result of the magnetic field distributed in the crystal under the condition of small volume through the optimal design of the magnetic circuit, and the problems of low isolation degree, low transmissivity and the like of the optical isolator are solved by the design of the shape, the size and the anti-reflection film of the magneto-optical crystal and the design of the mechanical packaging structure adopting the precision processing technology, thereby having important innovation and engineering practical value.
Drawings
FIG. 1 is a schematic diagram of a free-space optical isolator according to the present invention;
figure 2 is a block diagram of a faraday rotator magnet system with optimized magnetic circuit of the present invention;
FIG. 3 is an axial cross-sectional view of a Faraday rotator magnet system of the present invention, FIG. 3(a) is an axial cross-sectional view, FIG. 3(b) is a finite element simulation of magnetic field, and FIG. 3(c) is a simulation of magnetic circuit;
in the figure: 1-Faraday rotator magnet system, 2-magneto-optic crystal, 3-Glan Taylor prism, 4-magnet system fixing sleeve, 5-adjustable polarizer mounting bracket, 6-fixing disk, 7-fixing ferrule, 8-fixing screw, 9-gasket, 10-prism cover, 11-central axial magnetizing ring, 12-radial outward magnetizing ring, 13-lens rubber snap ring and 14-reverse axial magnetizing ring.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the respective embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The free space optical isolator of the present invention is structured as shown in fig. 1, and includes a faraday rotator magnet system 1, a magneto-optical crystal 2, a glan-taylor prism 3, a magnet system fixing sleeve 4, an adjustable polarizer mounting bracket 5, a fixing disk 6, a fixing collar 7, a fixing screw 8, a washer 9 and a prism cover 10. A magneto-optical crystal 2 is placed at the center of a clear aperture of the Faraday optical rotator magnet system 1 to form a Faraday optical rotator; the magnet system fixing sleeve 4 is used for gluing the inner wall to the cylindrical surface of the Faraday rotator magnet system 1 on one hand, and rotatably installing the fixing disk 6 through threads on the other hand so as to fix the two bottom surfaces of the Faraday rotator magnet system 1. The adjustable polarizer mounting bracket 5 can rotate precisely, and after the optical axis attitude is adjusted to a set value, the adjustable polarizer mounting bracket is extruded and fixed on two sides of the magnet system fixing sleeve 4 through threads on the fixing disc 6, the fixing ring 7 and the fixing screw 8. The gasket 9 serves to protect the adjustable polarizer mounting bracket 5 from abrasion. The prism cover 10 is used to seal the magnet system fixing sleeve 4, to form a closed structure, to protect the prism, and to leave a clear aperture.
The magneto-optical crystal 2 is a core component of the free space optical isolator, generates a Faraday effect, and generates Faraday rotation on linearly polarized light under uniform strong magnetic field distribution. The magneto-optical crystal adopts Tb 3 Ga 5 O 12 A crystalline material having a crystal orientation selected to be [001 ]]The expansion coefficient is small, and the photoelastic effect caused by stress deformation is reduced. A double-quarter-layer antireflection film is plated on a light passing surface, and the thickness of a double-quarter-wavelength (800nm wavelength) layer is designed for pump light (795nm) and detection light (780nm) applied to an atomic magnetometer, so that internal reflection of 780nm wavelength and 795nm laser is extremely small, and depolarization distortion errors are suppressed. And a magneto-optical crystal 2 with optimized size design is placed in a specific length range of the central position of the through aperture of the Faraday rotator magnet system 1.
The two Grating Taylor prisms 3 are respectively used as an input polarizing device and an output polarizing device and are fixed on the adjustable polarizing device mounting bracket 5, and the error of the optical axis space azimuth angle of the two Grating Taylor prisms influences the input transmissivity and the reverse isolation degree of the free space optical isolator. The Glan Taylor prism 3 and the adjustable polarizer mounting bracket 5 thereof can accurately rotate and adjust the optical axis angle value of the axial space direction, and the isolation degree and the anti-reflection rate of the optical isolator are improved. When the wavelength is changed, the isolation is kept unchanged at the peak value through adjustment. When the linearly polarized light passing through is perpendicular to the optical axis, the light energy is isolated and passes through when coincident. And the included angle of the optical axes of the two Glan Taylor prisms 3 in the spatial direction is controlled to be 45 degrees in a precise mode, and the input transmission and reverse isolation effects are optimal at the moment.
The magnet system fixing sleeve 4 is an adjustable mechanical packaging structure. The adjustable mechanical packaging structure packages and fixes the main structure of the free space optical isolator, and protects the Faraday optical rotator magnet system 1 and the Glan Taylor prism 3 from being displaced and damaged due to external force.
Figure 2 is a block diagram of a faraday rotator magnet system with optimized magnetic circuit of the present invention. The main principle of the free space optical isolator is based on the Faraday effect, wherein the Faraday effect means that when linearly polarized light passes through a magneto-optical crystal distributed with a magnetic field with certain intensity, the light vector of the linearly polarized light rotates to a certain degree, the Faraday rotation angle is theta, and the formula is (1.1).
Therefore, the performance indexes of the free-space optical isolator, i.e., isolation and transmittance, are greatly dependent on the faraday effect, and thus the magnetic circuit needs to be designed. The Faraday magnetic circuit design is that for the structural design of the Faraday optical rotator magnet system 1, the size and the uniform area size of a required magnetic field are determined according to the wavelength and the diameter of a light beam and the Verdet constant, the light passing length and the transverse size of the magneto-optical crystal 2, and then the optimal structure and the optimal magnetic circuit of the miniaturized permanent magnet of the free-space optical isolator are designed. Theoretical calculation, numerical simulation and error analysis are carried out on the magnetic circuit design, the length and the diameter of the magneto-optical crystal 2 are determined by designing the strength value and the uniformity of an axial magnetic field and the uniformity of a transverse magnetic field on the magneto-optical crystal, and then the isolation and the transmissivity of the optical system are determined.
Specifically, the following requirements are designed for the magnetic circuit of the free-space optical isolator:
(1) the strength of the axial magnetic field is ensured to be large enough, so that the product of the magnetic field integral of the length of the magneto-optical crystal and the Verdet constant of the crystal is just 45 degrees, and the reverse isolation effect is optimal at the moment;
(2) the good uniformity of the axial magnetic field is ensured, the position of the magneto-optical crystal 2 is favorably calibrated, and the crystal length is more easily designed;
(3) the magnetic field uniformity on the cross section area of the magneto-optical crystal is ensured, so that the Faraday rotation angles at all positions on the cross section are kept consistent when light beams pass through the magneto-optical crystal.
The invention adopts Halbach array theory, and makes the magnetic bodies with different magnetizing directions arranged and combined regularly, so that the formed cylinder has a strong magnetic field in a specific range of the center of the clear aperture, and can be obtained by calculation, and figure 2 is the structure of a Faraday optical rotator magnet system 1 with an optimal magnetic circuit, which is composed of three parts: an anti-axial magnetized ring having a length of L0, an outer diameter of R and an inner diameter of R is used as the central axial magnetized ring 11. The 10 radially outward magnetized sectors form a radially outward magnetized ring 12 having a thickness of L1, an outer diameter of R, and an inner diameter of R1, and are placed at the input end. The 10 radially inward magnetized sectors form a counter-axial magnetized ring 14 with a thickness of L1, an outer diameter of R, and an inner diameter of R1 at the output end. Two lens rubber snap rings 13 with the length of L1, the outer diameter of R1 and the inner diameter of R are respectively embedded in a radial magnetization ring 12 and an anti-axial magnetization ring 14 which are radially outward to form an input end auxiliary magnetization ring and an output end auxiliary magnetization ring. Which are respectively arranged at the left side and the right side of a central axial magnetizing ring 11 to form a cylindrical magnet system with a clear aperture (i.e. the inner diameter is r), namely a Faraday rotator magnet system 1. The magnet system arranged according to a certain rule ensures that the magnetic field is uniformly distributed in a specific area on the clear aperture, and the magnetic field intensity B in the area is greater than the remanence Br of the magnet structure. The Faraday rotator magnet system 1 is a cylinder with a clear aperture and composed of radial magnetized rings and axial magnetized rings, and is arranged and combined according to a rule according to a MagicSphere design method in a halbach array theory, so that a magnetic circuit is optimized. The optimal magnetic circuit can be generated, so that the Faraday effect at each position in the magneto-optical crystal is kept stable and suppressed, the magneto-optical crystal is designed in a smaller size, the dependency of the Verdet constant is reduced, and the performance is optimal while the miniaturization is kept. The Faraday rotator magnet system 1 is made of NdFeB N40.
The free space optical isolator is realized as follows:
in a first step, an optimal magnetic circuit of the free-space optical isolator is designed, i.e. the faraday rotator magnet system 1 is designed. The magnetic circuit of faraday rotator magnet system 1 enables the creation of a magnetic circuit that optimizes the performance of the free-space optical isolator while involving the design of parameters such as shape, size, verdet constant, etc. of magneto-optical crystal 2. An anti-axial magnetized ring having a length of L0, an outer diameter of R and an inner diameter of R is used as the central axial magnetized ring 11. The 10 radially outward magnetized sectors form a radially outward magnetized ring 12 having a thickness of L1, an outer diameter of R, and an inner diameter of R1, and are placed at the input end. The 10 radially inward magnetized sectors form a counter-axial magnetized ring 14 with a thickness of L1, an outer diameter of R, and an inner diameter of R1 at the output end. Two lens rubber snap rings 13 with the length of L1, the outer diameter of R1 and the inner diameter of R are respectively embedded in a radial magnetization ring 12 and an anti-axial magnetization ring 14 which are radially outward to form an input end auxiliary magnetization ring and an output end auxiliary magnetization ring. Which are respectively arranged at the left side and the right side of a central axial magnetizing ring 11 to form a cylindrical magnet system with a clear aperture (i.e. the inner diameter is r), namely a Faraday rotator magnet system 1.
And secondly, designing a magneto-optical crystal 2, wherein parameters such as the shape and size, the Verdet constant and an antireflection film of the magneto-optical crystal 2 are designed by a Faraday rotation angle formula according to the size of the magnetic field intensity and the length of the uniformity distribution range on the basis of the magnetic circuit design. The material adopts Tb 3 Ga 5 O 12 A crystalline material. The light-passing surface is plated with a double-quarter antireflection film, so that the internal reflection of light in the magneto-optical crystal 2 is reduced, and the transmittance of the magneto-optical crystal is increased to the maximum extent. Arranged in the center, axial direction and light-passing direction of the light-passing aperture of the Faraday rotator magnet system 1. Under the action of a uniform strong magnetic field, the linearly polarized light passing through is rotated by a specific angle. The Faraday rotation angle equation is (1.1).
And thirdly, designing a magnet system fixing sleeve 4 serving as an adjustable mechanical packaging structure, wherein the magnet system fixing sleeve 4 is used for gluing a magnetic body on the inner wall, and fixing discs 6 are rotatably arranged on two sides of the magnet system fixing sleeve through threads, so that the magnet system is fixed, and the magnetic circuit change caused by part vibration and external force extrusion deformation is prevented. The Glan Taylor prism 3 is arranged on the prism mounting bracket and is mounted at two sides of the magnet system fixing sleeve 4, after adjustment and rotation, the two fixing ferrules 7 with threads are fixed through screws, and the adjusted optical axis space azimuth angle is kept unchanged. The structure of the prism cover 10 is screwed into the magnet system fixing sleeve 4 through threads, plays a role in protecting the Glan Taylor prism 3, forms a shell of the free space optical isolator with the magnet system fixing sleeve 4, isolates main components from the outside, and only leaves a clear aperture.
FIG. 3 is an axial cross-sectional view of a Faraday rotator magnet system of the present invention, FIG. 3(a) is an axial cross-sectional view, FIG. 3(b) is a finite element simulation of magnetic field, and FIG. 3(c) is a simulation of magnetic circuit. The strong magnetic field is uniformly distributed in a certain range at the center of the clear aperture.
Those skilled in the art will appreciate that the invention may be practiced without these specific details. It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (6)
1. A free-space optical isolator, comprising: the device comprises a Faraday optical rotator magnet system (1), a magneto-optical crystal (2), a Glan Taylor prism (3), a magnet system fixing sleeve (4), an adjustable polarizing device mounting bracket (5), a fixing disc (6), a fixing ferrule (7), a fixing screw (8), a gasket (9) and a prism cover (10); wherein the Faraday rotator magnet system (1) is a cylinder with a clear aperture and is composed of a radial magnetization ring and an anti-axial magnetization ring; the magneto-optical crystal (2) is a core component of the free space optical isolator, generates a Faraday effect, and generates Faraday rotation on linearly polarized light under uniform strong magnetic field distribution; the Glan Taylor prism (3) is used as an input polarizer and an output polarizer and is fixed on the adjustable polarizer mounting bracket (5), and the error of the optical axis space azimuth angle of the Glan Taylor prism affects the input transmissivity and the reverse isolation of the free space optical isolator; the magnet system fixing sleeve (4) is used as an adjustable mechanical packaging structure, on one hand, the inner wall of the magnet system fixing sleeve is glued with the cylindrical surface of the Faraday optical rotator magnet system (1), and on the other hand, the fixing disc (6) is rotatably installed through threads and is used for fixing two bottom surfaces of the Faraday optical rotator magnet system (1); the adjustable polarizer mounting bracket (5) can rotate precisely, and after the optical axis space azimuth angle is adjusted to a set value, the adjustable polarizer mounting bracket is fixed on two sides of the magnet system fixing sleeve (4) through threads on the fixing disc (6), a fixing ferrule (7) and a fixing screw (8); the gasket (9) is used for protecting the adjustable polarizer mounting bracket (5) from abrasion; the prism cover (10) is used for sealing the magnet system fixing sleeve (4) to form a closed structure, the Glan Taylor prism (3) is protected, and the light-passing aperture is reserved.
2. A free-space optical isolator as claimed in claim 1 wherein: and determining the size of a required magnetic field and the size of a uniform area according to the wavelength and the diameter of the light beam and the Verdet constant, the light passing length and the transverse size of the magneto-optical crystal (2), and further designing an optimal magnetic circuit of the free-space optical isolator.
3. A free-space optical isolator as claimed in claim 2 wherein: the optimal magnetic circuit makes the Faraday effect in all places in the magneto-optical crystal (2) keep stable and restrain, and realizes the smaller size design of the magneto-optical crystal (2) and reduces the dependency of Verdet constant, and the performance is optimal while keeping miniaturization.
4. A free-space optical isolator as claimed in claim 1 wherein: the magneto-optical crystal (2) adopts Tb 3 Ga 5 O 12 The crystal material has a small expansion coefficient, and the photoelastic effect caused by stress deformation is reduced; the light-passing surface of the light-emitting diode is plated with a double-quarter antireflection film.
5. A free-space optical isolator as claimed in claim 1 wherein: the Glan Taylor prism (3) and the adjustable polarizer mounting bracket (5) precisely rotate to adjust the optical axis angle value of the axial space direction, so that the isolation and the anti-reflection rate of the free space optical isolator are improved; when the wavelength is changed, the adjustable polarizer mounting bracket (5) at one end of the rotary adjustment enables the isolation to keep the peak value unchanged.
6. A free-space optical isolator as claimed in claim 1 wherein: the magnet system fixing sleeve (4) encapsulates and fixes the main structure of the free space optical isolator, and prevents the Faraday rotator magnet system (1) and the Glan-Taylor prism (3) from being displaced and damaged due to external force.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN118295159A (en) * | 2024-06-05 | 2024-07-05 | 西南应用磁学研究所(中国电子科技集团公司第九研究所) | Gel-free Faraday rotator |
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|---|---|---|---|---|
| CN101900892A (en) * | 2010-06-23 | 2010-12-01 | 福建福晶科技股份有限公司 | Wavelength tunable opto-isolator |
| CN201765403U (en) * | 2010-06-17 | 2011-03-16 | 西北工业大学 | Device for realizing optical isolation in optical experiment and optical fiber communication system |
| CA3007581A1 (en) * | 2017-06-07 | 2018-12-07 | Shin-Etsu Chemical Co., Ltd. | Optical isolator and semiconductor laser module |
| CN214278570U (en) * | 2021-02-05 | 2021-09-24 | 光越科技(深圳)有限公司 | Compact optical isolator |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201765403U (en) * | 2010-06-17 | 2011-03-16 | 西北工业大学 | Device for realizing optical isolation in optical experiment and optical fiber communication system |
| CN101900892A (en) * | 2010-06-23 | 2010-12-01 | 福建福晶科技股份有限公司 | Wavelength tunable opto-isolator |
| CA3007581A1 (en) * | 2017-06-07 | 2018-12-07 | Shin-Etsu Chemical Co., Ltd. | Optical isolator and semiconductor laser module |
| CN214278570U (en) * | 2021-02-05 | 2021-09-24 | 光越科技(深圳)有限公司 | Compact optical isolator |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118295159A (en) * | 2024-06-05 | 2024-07-05 | 西南应用磁学研究所(中国电子科技集团公司第九研究所) | Gel-free Faraday rotator |
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