CN214097865U - Polarization-independent optical isolator core, optical fiber isolator and semiconductor laser assembly - Google Patents
Polarization-independent optical isolator core, optical fiber isolator and semiconductor laser assembly Download PDFInfo
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- CN214097865U CN214097865U CN202120068974.9U CN202120068974U CN214097865U CN 214097865 U CN214097865 U CN 214097865U CN 202120068974 U CN202120068974 U CN 202120068974U CN 214097865 U CN214097865 U CN 214097865U
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Abstract
The utility model provides a polarization-independent optical isolator core, an optical fiber isolator and a semiconductor laser component, wherein four large-piece optical crystals form a large-piece gluing component according to the sequence of a first birefringent crystal, a half-wave plate, a Faraday rotator and a second birefringent crystal; cutting the large gluing component into small gluing components according to the size required by a single optical isolator core; the small gluing component is installed in the magnetic ring and fixed by glue in the circumferential direction, namely the polarization-independent optical isolator core is formed. Overcome prior art's polarization-independent optical isolator core assembly needs proofreading wedge angle piece angle in the light path, produce the great defect of property ability fluctuation, and the utility model discloses a polarization-independent optical isolator core only needs control cutting accuracy can guarantee product high repeatability and uniformity. The isolator core is arranged between the tail fiber and the lens in the sleeve of the isolator, namely the optical fiber isolator of the utility model is formed. The isolator core is combined with the semiconductor laser to form the laser assembly of the utility model.
Description
Technical Field
The utility model belongs to the technical field of optical device, especially, relate to a polarization-independent optical isolator core and optical fiber isolator, semiconductor laser subassembly.
Background
The optical isolator core is a passive optical device which only allows light to pass through in one direction, and is widely applied to optical communication systems, optical fiber sensing, WDM/CWDM systems, precision optical measurement systems and the like. The optical isolator core can be classified into a polarization-dependent type and a polarization-independent type according to its polarization characteristics. In the prior art, most of polarization-independent optical isolator cores are formed by bonding two birefringent wedge angle pieces (LiNbO 3) and a Faraday crystal (YIG) in a magnetic ring, the method firstly needs to distinguish the crystal axes of the wedge angle pieces, and one side of each wedge angle piece is processed into an inclined plane with a certain angle; secondly, the 3-wafer crystal structure needs to control the angle between the wafers to ensure high isolation of the reverse light; under the action of an external magnetic field, the polarization state of the light beam is rotated by the Faraday magneto-optical rotation effect. The volume of the isolator core with the structure is difficult to control and is very small due to the reasons, and the outer diameter of the current commercially available small isolator core is about 3 mm; the price of the wedge angle sheet and the Faraday is not low, so that the cost of the isolator core is high. The utility model discloses a new construction design for the easy rapid tooling equipment of multi-disc optical crystal, and the volume reduces, has saved manufacturing cost from many aspects.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a multi-disc optical crystal easily rapid tooling equipment, small, the independent optical isolator core of low-cost polarization.
The technical scheme for realizing the purpose of the utility model is that a polarization independent optical isolator core is a small gluing component formed by gluing four optical crystals and is arranged in a magnetic ring. The four optical crystals are respectively a birefringent crystal at two end faces, a half-wave plate in the middle and a Faraday rotator plate. The four optical crystals are all flat plates, and are different from wedge angle plates adopted in the background technology.
The small gluing assembly consisting of the four optical crystals can have two sequential structures.
The first structure is as follows:
the forward transmission direction of the incident light is as follows in sequence: the device comprises a first birefringent crystal, a half-wave plate, a Faraday rotator plate and a second birefringent crystal.
The second structure is as follows:
the forward transmission direction of the incident light is as follows in sequence: the device comprises a first birefringent crystal, a Faraday rotator, a half-wave plate and a second birefringent crystal. That is, the half-wave plate and Faraday rotator plate in the first configuration are interchanged in order.
The small gluing component can be in the shape of quadrangle, polygon, circle, ellipse and the like, and the rectangular shape, particularly the square shape, is optimal in the aspect of processing efficiency; the gluing mode can be optical glue, epoxy glue, ultraviolet glue and the like; preferably, the size of the material is a rectangle with a side of 0.3mm to 3mm or a circle with a diameter of 0.3mm to 3 mm.
The magnetic ring can be various types of magnetic rings in the prior art, and can be closed or semi-closed, such as horseshoe-shaped. The small gluing component is fixed with the inner side of the magnetic ring in a gluing mode in the circumferential direction.
The utility model also provides a fiber isolator. Including tail fiber, lens, according to logical light direction, will the utility model discloses a polarization-independent isolator core is fixed in between relative tail fiber terminal surface and the lens terminal surface. The structure and combination mode of the tail fiber and the lens can adopt any mode in the prior art.
The optical fiber isolator is a reflection type isolator, the outer side of the lens is provided with a reflector, the tail fiber is double optical fibers, and the polarization-independent isolator core of the utility model is fixed between one of the optical fiber end faces which are opposite and the lens end face which is opposite to the optical fiber isolator core, and does not shield the other optical fiber. According to the light path design, the polarization-independent isolator core can be shielded by emergent optical fibers or incident optical fibers.
The utility model also provides a semiconductor laser subassembly. In order to prevent reflected light from affecting a resonant cavity of a laser, so that output light is interfered, an isolator is generally required to isolate the reflected light, the output of a conventional laser is generally linearly polarized light, and the isolator is generally a polarization-dependent isolator. It is common practice to use a stack of three plates of polarizer plate + faraday rotation plate + polarizer plate to form isolation of reflected light. The polarization isolator needs to enable the polarization direction of the first polaroid to be parallel to the polarization direction output by the laser, and light can be smoothly emitted.
The utility model discloses a semiconductor laser subassembly uses aforementioned polarization-independent isolator core, promptly: semiconductor laser subassembly includes semiconductor laser, and the place ahead of its resonant cavity sets up the utility model discloses a polarization-independent isolator core.
Because the polarization-independent isolator core can cause displacement with the same size for the reflected light of two polarization states, the reflected light can not enter the resonant cavity of the semiconductor laser. Due to the adoption of the polarization-independent design, the output polarization state direction of the laser can be not considered, and the difficulty of process assembly is reduced. The resonant cavity of the semiconductor laser is generally very small, generally several microns to tens of microns, and can be regarded as a point source similar to a fiber core of an optical fiber, and only a thin crystal is needed to generate enough reverse displacement so as to achieve the purpose of isolation.
The manufacture of the small gluing component of the utility model can adopt the following method: and the four large-plate optical crystals are glued in the order of the first birefringent crystal, the half-wave plate, the Faraday rotator plate and the second birefringent crystal or in the order of the first birefringent crystal, the Faraday rotator plate, the half-wave plate and the second birefringent crystal to form the large-plate gluing assembly. The gluing method can adopt gluing processes such as optical glue, epoxy glue, ultraviolet glue and the like.
And cutting the large glued assembly into small glued assemblies according to the size required by the single optical isolator core.
The principle of the optical isolator core of the present invention is explained below:
taking the first structure as an example: when light is transmitted in the forward direction, a beam of light is decomposed into two beams of parallel light with the same transmission direction and orthogonal polarization directions through the first birefringent crystal; the polarization directions of the two beams of light are rotated in the same direction by a certain angle through a half-wave plate; the Faraday rotator rotates the two beams of light in the same direction by a certain angle, and the Faraday rotator is a non-reciprocal element; the two beams of light are combined into one beam by the second birefringent crystal.
When light is transmitted reversely, the light firstly enters the second birefringent crystal, and is converted into two beams of parallel light to be transmitted after exiting the second birefringent crystal; after passing through the Faraday rotator in the magnetic field, the polarization states of the two beams of light are respectively converted due to the non-reciprocity of the Faraday rotator; after passing through the half-wave plate, the polarization directions of the two beams of light are converted in the same direction; at this time, the polarization state of the two beams of light is the same as that of the emergent first birefringent crystal; the two beams of light deviate again after passing through the first birefringent crystal, so that one beam of light cannot be synthesized, and the purpose of reverse light isolation is achieved.
The second structure is the same principle as the first structure except that the order of light passing through the half-wave plate and the faraday rotator plate is different.
In the prior art, two birefringent wedge angle pieces are needed, so that a large glued assembly cannot be processed firstly, and small glued assemblies need to be glued one by one. The optical crystal used by the utility model is a flat-plate crystal plate, which can be firstly glued into a large gluing component and then cut into small gluing components with required sizes, thus greatly improving the production efficiency; the assembly of polarization-independent optical isolator core of prior art in the light path needs proofreading wedge angle piece angle, and it is undulant great to produce property ability, and the utility model discloses a polarization-independent optical isolator core only needs control cutting accuracy can guarantee product high repeatability and uniformity.
The polarization-independent optical isolator core of prior art is angle sensitive type optical device, mainly is applied to middle and small size device, the utility model discloses polarization-independent optical isolator core is displacement sensitive type device, can be applied to more extensive optical fields such as subminiature.
Drawings
FIG. 1 is a schematic view of a large glued assembly;
fig. 2 is a perspective view of the present invention;
fig. 3 is a schematic structural diagram of a first embodiment of a polarization independent isolator core of the present invention;
fig. 4a and 4b are optical path diagrams of a first embodiment of a polarization independent isolator core according to the present invention;
fig. 5 is a schematic diagram of a second embodiment of a polarization independent isolator core according to the present invention;
fig. 6a and 6b are optical path diagrams of a second embodiment of the polarization independent isolator core of the present invention;
fig. 7a and 7b are schematic views of a first embodiment of the fiber isolator of the present invention;
fig. 8 is a schematic view of a second embodiment of the fiber isolator of the present invention;
fig. 9a and 9b are schematic diagrams of a semiconductor laser module according to the present invention, in which fig. 9a shows emitted light and fig. 9b shows reflected light.
Wherein: 1. the device comprises a small chip gluing component, 11, a first birefringent crystal, 12, a half-wave plate, 13, a Faraday rotator, 14, a second birefringent crystal, 2, a magnetic ring, 3, an isolator core, 4, a tail fiber, 41, a first optical fiber, 41, a second optical fiber, 5, a lens, 6, a sleeve, 7, a reflector, 8, a semiconductor laser, 81 and a resonant cavity.
Detailed Description
(I) polarization independent isolator core
The first embodiment is as follows:
as shown in FIG. 1, a large glued assembly is glued in the light passing direction according to the stacking sequence and the design direction of a first birefringent crystal 11, a half-wave plate 12, a Faraday rotator 13 and a second birefringent crystal 14. In this example, the above four optical crystals have a length and width of 11mm × 11mm, and other sizes may be used as required; the gluing adopts a light glue process, and can also adopt processes such as epoxy glue, ultraviolet glue and the like.
The large-piece adhesive assembly is cut into small-piece adhesive assemblies 1 in the size required by the size of a single optical isolator core. The die bonder assembly is sized as desired, typically between 0.3mm by 0.3mm to 3mm by 3mm, in this case 1mm by 1 mm.
And installing the small gluing component 1 into the magnetic ring 2, and fixing the small gluing component 2 with glue at the circumferential direction and the inner side of the magnetic ring. The magnetic ring is usually made of zinc and manganese materials, and other materials with the magnetizing function such as iron powder can also be used. In this case, the adhesive is an epoxy type adhesive, and an acryl type or other method for fixing the optical elements may be used. After fixing, become to become the utility model discloses a polarization independent optical isolator core.
Materials and parameters of the four optical crystals:
wherein the first birefringent crystal 11, the second birefringent crystal 14: can be made of lithium niobate (LiNbO 3), and other alternative materials include yttrium vanadate, cryolite, quartz, ruby, etc. crystals of the same type having birefringence effect; the crystal axis of the birefringent crystal is set to be 48 degrees, and the crystal axis can be set to be different angles such as 45 degrees, 40 degrees and the like according to requirements; the large birefringent crystal is processed into a square sheet with the size of 11 multiplied by 11mm, and can be processed into other sizes; the birefringent crystal needs to match the refractive indexes of an air surface and a glue surface, so that the antireflection film is plated on one surface of the birefringent crystal, the antireflection film is plated on the other surface of the birefringent crystal, and otherwise, the front surface and the back surface are not distinguished.
Wherein the half-wave plate 12: the material can be made of crystal, and can also be made of the same material with double refraction effect such as quartz; the optical axis of the half-wave plate is set to be 22.5 degrees, and can also be set to be other angles such as 45 degrees, 50 degrees and the like, and the optical axis mainly depends on the rotation angle of the Faraday rotator plate; thickness d of half-wave plate, from formula
And δ = (2n +1) pi, n = (0, ± 1, ± 2, …), where δ is the phase difference of o light and e light, and λoIs the wavelength of the incident light, noAnd neRespectively, the wavelength of the crystal pair is lambda in vacuumoThe principal refractive indices of o-light and e-light of (1); during manufacturing, the thickness of d needs to satisfy the above two formulas; and coating an antireflection film on the half-wave plate two-way light surface.
Wherein the faraday rotator 13: can be made of yttrium iron garnet crystals, and also can be made of other materials with magneto-optical rotation effect; the polarization rotation angle is set to be 45 degrees, and can also be set to be other angles such as 40 degrees and 30 degrees, and the like, and the polarization rotation angle is matched with the half-wave plate for use; the polarizer rotation angle is determined by the formula θ = VBL, where V is the verdet constant, related to the dielectric properties and the frequency of the light wave, B is the magnetic field strength, and L is the faraday rotator thickness; and the two-way light surface of the Faraday rotation sheet is coated with an antireflection film.
The optical principle of this embodiment is seen in the light path diagrams, fig. 4a and 4 b. Wherein fig. 4a shows forward light and fig. 4b shows reverse light.
After being incident to the first birefringent crystal in the forward direction, one beam of light is decomposed into two beams of light, namely o light and e light, wherein the o light is transmitted along the original direction, and the e light is deflected; the two beams of light are changed into two beams of parallel light to be transmitted after being emitted out of the first birefringent crystal; after passing through the half-wave plate, the polarization states of the o light and the e light are respectively converted, and in the example, the polarization directions of the o light and the e light are clockwise rotated by 45 degrees; after passing through a Faraday rotator in a magnetic field, the polarization states of o light and e light are respectively converted, the polarization directions of the o light and the e light are clockwise rotated by 45 degrees, and at the moment, the polarization states of the two beams of light are orthogonal to the polarization state of the two beams of light when the two beams of light exit from the first birefringent crystal; after passing through the second birefringent crystal, the original e light is birefringent again and is combined with the o light to form a beam of light.
When light is transmitted reversely, the light firstly enters the second birefringent crystal, is divided into o light and e light, and is converted into two parallel light beams after exiting the second birefringent crystal for transmission; after passing through the Faraday rotator in the magnetic field, the polarization states of o light and e light are respectively converted due to the non-reciprocity of the Faraday rotator, and in the example, the polarization directions of the o light and the e light are counterclockwise rotated by 45 degrees; after passing through the half-wave plate, the polarization states of the two beams of light are converted, the polarization directions of the two beams of light rotate clockwise by 45 degrees, and at the moment, the polarization states of the two beams of light are the same as the polarization states of the two beams of light when the two beams of light exit the first birefringent crystal; the two beams of light deviate again after passing through the first birefringent crystal, so that one beam of light cannot be synthesized, an incident light path is avoided, and the purpose of reverse optical isolation is achieved.
Example two
Referring to fig. 5, the present embodiment is different from the first embodiment in that four optical crystals are glued in the order of the first birefringent crystal 11, the faraday rotator 13, the half-wave plate 12, and the second birefringent crystal 14 along the light passing direction. I.e. the half-wave plate 12 and faraday rotator 13 in the first embodiment are interchanged. The rest of this embodiment is the same as the first embodiment.
The optical principle of this embodiment is seen in the light path diagrams, fig. 6a and 6 b. Wherein fig. 6a shows forward light and fig. 6b shows reverse light. Except for the difference in the order of the half-wave plate and the Faraday rotator, they are the same as those of the first embodiment, and thus are not described in detail.
(II) optical fiber isolator
Example one
As shown in fig. 7 a. The utility model provides a pair of optical fiber isolator. Including tail fiber 4, lens 5, will the utility model discloses a polarization-independent isolator core 3 is fixed in between 4 terminal surfaces of tail fiber and the 5 faces of lens end in opposite directions. The light transmission direction in this example is from the lens 5 to the pigtail 4, and the direction of the polarization-independent isolator core 3 is adapted to the light transmission direction. In this example the pigtail 4 and the lens 5 are both placed in a ferrule 6. The structure and combination of the pigtail 4 and the lens 5 can be any of those known in the art.
In fig. 7b, the light transmission direction is opposite to that of fig. 7a, and the light is transmitted from the pigtail 4 to the lens 5, and accordingly, the direction of the polarization-independent isolator core 3 is opposite to that of fig. 7 a. The rest is the same as in fig. 7 a.
Example two
As shown in fig. 8. The optical fiber isolator in this example is a reflection type isolator, the outer side of the lens 5 is provided with a reflecting mirror 7, the tail fiber 4 is a double-fiber tail fiber and is provided with a first optical fiber 41 and a second optical fiber 42, and the polarization independent isolator core 3 is fixed between the end surface of the first optical fiber 41 and the end surface of the lens 5 opposite to the first optical fiber and does not shield the other second optical fiber 42. According to the light path design, the polarization-independent isolator core 3 can be shielded by emergent optical fibers or incident optical fibers.
The structure and combination of the pigtail 4 and the lens 5 can be any of those known in the art.
(III) semiconductor laser module
As shown in fig. 9a and 9 b. The utility model discloses a semiconductor laser subassembly, including semiconductor laser 8 and the irrelevant isolator core 3 of aforementioned polarization that sets up in its resonant cavity 81 preceding light path. As shown in fig. 9a, the emergent light passes through the polarization-independent isolator core 3 and then continues to be transmitted along the emergent direction; as shown in fig. 9b, the reflected light is shifted by the polarization independent isolator core 3 and does not enter the cavity 81.
Claims (8)
1. A polarization independent optical isolator core, characterized by: comprises a small gluing component (1) formed by gluing four optical crystals and a magnetic ring (2); the small gluing component (1) is arranged in the magnetic ring (2); two outer sides of the four optical crystals are respectively provided with a birefringent crystal, and the middle part of the four optical crystals is provided with a half-wave plate (12) and a Faraday rotator plate (13).
2. A polarization independent optical isolator core as claimed in claim 1, wherein: the four optical crystals are sequentially a first birefringent crystal (11), a half-wave plate (12), a Faraday rotator plate (13) and a second birefringent crystal (14) along the light passing direction.
3. A polarization independent optical isolator core as claimed in claim 1, wherein: the four optical crystals are sequentially a first birefringent crystal (11), a Faraday rotator (13), a half-wave plate (12) and a second birefringent crystal (14) along the light passing direction.
4. A polarization independent optical isolator core as claimed in claim 1, wherein: the small gluing component (1) is a rectangle with the side length of 0.3mm to 3mm or a circle with the diameter of 0.3mm to 3 mm.
5. A polarization independent optical isolator core as claimed in claim 1, wherein: the magnetic ring (2) is closed or semi-closed, and the circumference of the small gluing component (1) is fixed with the inner circumference of the magnetic ring (2) by glue.
6. An optical fiber isolator comprises a tail fiber (4) and a lens (5), and is characterized in that: a polarization-independent isolator core (3) according to any one of claims 1 to 5, being fixed between the end face of the pigtail (4) and the end face of the lens (5) opposite thereto.
7. A fibre optic isolator according to claim 6, wherein: the optical fiber isolator is a reflection-type isolator, a reflector (7) is arranged on the outer side of the lens (5), the tail fiber (4) is a double-fiber tail fiber and is provided with a first optical fiber (41) and a second optical fiber (42), and the polarization-independent isolator core is fixed between the end face of the first optical fiber (41) and the end face of the lens (5) opposite to the first optical fiber in the opposite direction without blocking the second optical fiber (42).
8. A semiconductor laser package characterized by: comprising a semiconductor laser (8) and a polarization-independent isolator core (3) according to one of claims 1 to 5 arranged in front of its resonant cavity (81).
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113900286A (en) * | 2021-10-11 | 2022-01-07 | 光炬科技(深圳)有限责任公司 | Manufacturing method of SMT type optical isolator |
| CN116316002A (en) * | 2023-01-05 | 2023-06-23 | 上海飞博激光科技股份有限公司 | Pulse fiber laser device integration module, system and method thereof |
| WO2024066048A1 (en) * | 2022-09-28 | 2024-04-04 | 四川华岭光子科技有限公司 | Optical path coupling assembly and optical module having optical path coupling assembly |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113900286A (en) * | 2021-10-11 | 2022-01-07 | 光炬科技(深圳)有限责任公司 | Manufacturing method of SMT type optical isolator |
| CN113900286B (en) * | 2021-10-11 | 2024-03-29 | 光炬科技(深圳)有限责任公司 | Manufacturing method of SMT type optical isolator |
| WO2024066048A1 (en) * | 2022-09-28 | 2024-04-04 | 四川华岭光子科技有限公司 | Optical path coupling assembly and optical module having optical path coupling assembly |
| CN116316002A (en) * | 2023-01-05 | 2023-06-23 | 上海飞博激光科技股份有限公司 | Pulse fiber laser device integration module, system and method thereof |
| WO2024146268A1 (en) * | 2023-01-05 | 2024-07-11 | 上海飞博激光科技股份有限公司 | Device integration module and method for pulsed fiber laser, and pulsed fiber laser system |
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