CN217305596U - Adjustable optical fiber coupling device - Google Patents
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- CN217305596U CN217305596U CN202220987308.XU CN202220987308U CN217305596U CN 217305596 U CN217305596 U CN 217305596U CN 202220987308 U CN202220987308 U CN 202220987308U CN 217305596 U CN217305596 U CN 217305596U
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Abstract
The utility model discloses an optical fiber coupling device with adjustable, include: the laser instrument for launch laser beam, it has set gradually in the direction that laser instrument sent laser beam: the combined zoom module comprises a zoom lens, a fixed lens and a compensation lens which are sequentially arranged along the emitting direction of the laser beam, the distances between the zoom lens and the fixed lens and between the fixed lens and the compensation lens can be adjusted, the zoom lens and the compensation lens are biconcave lenses, and the fixed lens is a biconvex lens; and the optical fiber coupling module comprises a first collimator and an optical fiber which are sequentially arranged along the emitting direction of the laser beam. The utility model discloses be provided with the combination zoom module that three groups of lenses constitute, through adjusting the distance between the lens in the combination zoom module to when keeping the collimation nature of laser instrument outgoing laser, the beam shaping that can the continuous adjustment incident laser compares, and then realizes the continuous change of laser beam size, improves the coupling efficiency of optic fibre.
Description
Technical Field
The utility model relates to a laser technical field, concretely relates to fiber coupling device with adjustable.
Background
The optical fiber coupling in the optical experiment includes building a light path and coupling laser into the optical fiber. The method comprises the steps of building a light path in the first step, knowing specific parameters of a laser system in advance, such as the type of a laser, the working wavelength, the beam waist size and the like, and designing a corresponding lens to perform beam shaping. At present, a biconvex lens combination is often used for beam shaping in experiments, and as shown in fig. 1, the size of a light beam can be adjusted only by a biconvex lens confocal plane at a fixed magnification. And the second step is to couple the laser into the optical fiber, and the specific steps are to adjust the distance between two lenses in the double-lens group to match the beam waist position and precisely adjust the laser incidence direction to couple the laser into the single-mode polarization-preserving optical fiber. The space mode matching of the laser and the optical fiber can be improved by reasonably adjusting the optical path, so that the coupling efficiency of the optical fiber is improved. And finally, calculating the optical fiber coupling efficiency of the system by detecting the optical power of the incident laser and the emergent laser.
Most of the current commercial fiber couplers used for fiber coupling have two main problems: firstly, the commercial optical fiber coupler cannot be accurately matched with the laser parameters of a user, so that the optical fiber coupling efficiency is difficult to achieve the optimum; and secondly, when the laser parameters of a user are changed, the parameters of the optical fiber coupling device need to be changed, but the user cannot freely replace the lens in the coupler, so that the optical fiber coupling device is inconvenient to be applied in practice.
SUMMERY OF THE UTILITY MODEL
In order to overcome the defects of the prior art, the utility model aims to provide an adjustable optical fiber coupling device realizes the continuous adjustment of light beam size 0.5x ~ 2x multiplying power when guaranteeing laser collimation, and then ensures to obtain higher optical fiber coupling efficiency under different laser parameters.
In order to solve the above problem, the utility model discloses the technical scheme who adopts as follows:
an adjustable fiber optic coupling device, comprising:
the laser instrument for launch laser beam the laser instrument sends laser beam's direction and has set gradually:
the combined zoom module comprises a zoom lens, a fixed lens and a compensation lens which are sequentially arranged along the emitting direction of the laser beam, the distances between the zoom lens and the fixed lens and between the fixed lens and the compensation lens are adjustable, the zoom lens and the compensation lens are biconcave lenses, and the fixed lens is a biconvex lens;
and the optical fiber coupling module comprises a first collimator and an optical fiber which are sequentially arranged along the emitting direction of the laser beam.
As a preferred embodiment of the present invention, the combined zoom module is connected to a servo motor displacement table for adjusting a distance between every two adjacent lenses.
As a preferred embodiment of the present invention, the focal length of the variable power lens and the focal length of the compensation lens are both-25 mm, and the focal length of the fixed lens is 20 mm.
As a preferred embodiment of the present invention, the coupling device further includes an isolator for ensuring stability of the light source, the isolator is disposed along the emitting direction of the laser beam between the compensation lens and the first collimator.
As the utility model discloses preferred embodiment, the fiber coupling module still includes the second collimator of further collimation to laser, the second collimator sets up optic fibre is kept away from on the one end of first collimator and is located laser beam jets out the direction.
In a preferred embodiment of the present invention, the optical fiber is a single-mode polarization maintaining fiber.
Compared with the prior art, the beneficial effects of the utility model reside in that:
the utility model discloses be provided with the combination zoom module that three groups of lenses constitute, through adjusting the distance between the lens in the combination zoom module to when keeping the collimation nature of laser instrument outgoing laser, the beam shaping that can the continuous adjustment incident laser compares, and then realizes the continuous change of laser beam size, improves the coupling efficiency of optic fibre.
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Drawings
FIG. 1-is a schematic diagram of a prior art adjustable fiber coupling device;
fig. 2-is a schematic structural diagram of an adjustable optical fiber coupling device according to the present invention;
fig. 3-is a schematic diagram of a three-element lens set zoom optical system according to the present invention;
fig. 4-is a graph of the relationship between the distance between the lenses and the beam shaping ratio of the present invention.
The reference numbers illustrate: 1. a laser; 2. a combined zoom module; 3. a fiber coupling module; 4. a variable power lens; 5. fixing a lens; 6. a compensation lens; 7. a first collimator; 8. an optical fiber; 9. a second collimator; 10. an isolator.
Detailed Description
The adjustable optical fiber coupling device provided by the present application, as shown in fig. 2, includes a laser 1, a combined zoom module 2 and an optical fiber coupling module 3. The laser 1 is used for emitting a laser beam, and since the output beam size of the laser 1 is not matched with the first collimator 7, the beam of the laser 1 needs to be shaped and output in order to make the laser 1 better applicable. The direction in which the laser 1 emits the laser beam is sequentially provided with:
the combined zoom module 2 comprises a zoom lens 4, a fixed lens 5 and a compensating lens 6, wherein the zoom lens 4, the fixed lens 5 and the compensating lens 6 are sequentially arranged along the direction of emitting laser beams, the distances between the zoom lens 4 and the fixed lens 5 and between the fixed lens 5 and the compensating lens 6 are adjustable, the zoom lens 4 and the compensating lens 6 are double-concave lenses, and the fixed lens 5 is a double-convex lens.
The optical fiber coupling module 3 comprises a first collimator 7 and an optical fiber 8, and the first collimator 7 and the optical fiber 8 are sequentially arranged along the emitting direction of the laser beam. Preferably, the optical fiber 8 is a single-mode polarization maintaining fiber, a common single-mode fiber cannot maintain a polarization state, the polarization state is greatly affected by external factors (temperature, pressure, vibration, etc.), and the polarization maintaining fiber itself has a large birefringence to largely eliminate external interference, so that a linear polarization state can be maintained. Further preferably, the fiber coupling module further includes a second collimator 9 for further collimating the laser, and the second collimator 9 is disposed at an end of the optical fiber 8 away from the first collimator 7 and located in the emitting direction of the laser beam, and is used for further collimating the laser. The optical fiber collimator is an important component in an optical original device, is generally applied to an optical communication system, consists of a single-mode tail fiber and a lens, and has the characteristics of low insertion loss, high return loss, small light beam divergence angle, light weight, easiness in assembly and the like. The optical fiber collimator emits the divergent light beams at the end of the optical fiber in parallel or converges the parallel light beams into the optical fiber so as to improve the coupling efficiency of the optical fiber system.
Utilize the utility model discloses realize that laser beam size is high-efficient, continuous and stable adjusts and carry out fiber coupling's step as follows:
the adjustable range of the shaping ratio M of the combined zoom module 2 is generally 0.5 x-2 x, and the shaping ratio M actually required is calculated according to the requirement of mode matching, so that the distance D between the lens groups is determined 1 And D 2 Wherein is f 1 `,f 2 `,f 3 The focal length of the three-component lens is calculated according to the formula (1):
the zoom lens 4 and the compensation lens 6 are moved to corresponding distances, the laser beam size can be adjusted according to the required shaping ratio,
after shapingThe laser beam can be used for optical fiber coupling, and two reflectors can be used for adjusting the laser to be injected into an optical fiber collimator. As shown in FIG. 2, the fiber coupling efficiency can be measured by measuring T 2 And T 3 The optical power at the location is post-calculated.
The utility model discloses a basic operating principle is: the beam size of the laser is adjusted through the combined variable-power module, and mode matching between the laser and a specific optical fiber is achieved. The following will explain the principle details of the lens combination for adjusting the laser size:
(1) combined zoom Module 2 parameters
Firstly, the parameters of the lens are explained as follows: assuming that the lenses used are thin lenses, the image principal plane and the object principal plane can be considered to coincide. When the object space and the image space of the optical system are the same, the object space focal length and the image space focal length have a simple relationship of f ═ f'. In the diagram, to indicate distance, a negative parameter is indicated by adding a negative sign to a positive value.
Then, a certain description is made on the parameters of the combined zoom module 2: as shown in fig. 3, the combined zoom lens module is a zoom lens 4, a fixed lens 5 and a compensation lens 6, d 1 ，d 2 Respectively, the distances from the variable power lens 4 to the fixed lens 5 and from the fixed lens 5 to the compensation lens 6, q is the moving distance of the variable power lens 4, e is the moving distance of the compensation lens 6, and takes a positive value when the lens moves rightward and takes a negative value when the lens moves leftward. In fig. 3, the magnification-varying lens 4 and the compensation lens 6 are moved leftward by distances of-q and-e, respectively.
(2) Collimation zoom moving distance
The gaussian formula for an ideal optical element is listed for the fixed lens 5, as in formula (2):
in the laser system, the incident light and the emergent light are collimated parallel light, and it can be considered that the light is emitted from the object side focus of the zoom lens 4 and passes through the image side focus of the compensation lens 6, and the following specific calculation formula can be obtained by using the information in fig. 3, as formula (3):
the above formula is substituted into a gaussian formula to obtain a specific calculation formula as formula (4):
when the collimation of the emergent light can be obtained through calculation and simplification, the movement e of the compensation lens is the following specific calculation formula, such as formula (5):
(3) combined zoom module 2 shaping ratio
The vertical axis magnification is defined as the ratio of the image distance to the absolute value of the object distance, and the specific calculation formula is shown as formula (6):
m＝-l/l (6)
the optical system composed of a plurality of lenses, the combined focal length is equal to the product of the focal length of the first lens and the vertical axis magnification of the rear lens, and the specific calculation formula is as the formula (7):
f′ 12 ＝f′ 1 m 2 (7)
the vertical axis magnification of the fixed lens 5 can be expressed by the focal length, and the specific calculation formula is as formula (8):
as shown in fig. 3, the incident light has a height h 1 Height of emergent light is h 3 Let u be the object-side aperture angle of the fixed lens 5 and u' be the image-side aperture angle, and have the following specific calculation formula, as shown in formula (9):
the shaping ratio is the ratio of the emergent light to the incident light height, and the specific calculation formula is shown as formula (10):
calculating the shaping ratio M requires knowing the transaxial magnification M of the fixed lens 5 2 (q) is carried out. The vertical axis magnification m of the fixed lens 5 can be obtained by analyzing the imaging property of the variable power lens 4 and the fixed lens 5 group by using a lens-by-lens calculation method 2 (q) image A of the preceding lens using Newton's or Gaussian formula for each lens from the first lens 1 Object A of the latter lens 2 . The method requires determining a transition formula between two adjacent lenses. The focal length and focal point of each lens, the principal point position, and the relative position between the lenses are known, as shown in the relationship diagram of the two lenses shown in dashed outline in fig. 3. The following transition relationship is provided between two adjacent lenses, and is specifically expressed by formula (11):
Δ 1 is the image space focus F of the zoom lens 4 1 To the fixed lens 5 object focus F 2 A distance of, i.e. Δ 1 ＝F 1 `F 2 Referred to as the optical spacing. The relationship between the optical spacing and the principal plane spacing can be seen from the dashed box in fig. 3, as shown in equation (12):
Δ 1 ＝d 1 -f 1 +f 2 (12)
f 'is' 12 The total image space focal length of the two lenses and the object space focal length of the two lens groups are in relation, as shown in formula (13):
f` 1 for fixing the image focal length of the lens, f ″ 2 The image focal length of the lens is fixed. The vertical axis magnification can be expressed by the following specific formula (14):
after the lens is moved, the distance between the lenses is changed to d 1 Q, the magnification of the beam becomes the following specific formula (15):
the system shaping ratio is the following specific formula (16):
according to the formulas of the shaping ratio M and the movement amount e, the following specific formula (17) can be obtained as a movement rule: .
Under the condition that the focal lengths of the three lenses are known and the distances between the lenses are known, the moving amount q of the zoom lens and the moving amount e of the compensation lens can be calculated according to the shaping ratio M required by design, and then the lenses are adjusted.
For the condition of manually adjusting the distance between the lenses, the distance between the lenses is not too short or too long due to manual coarse adjustment, and a more appropriate distance between the lenses can be kept under the condition that the focal lengths of the zoom lens 4 and the compensation lens 6 are both-50 mm and the focal length of the fixed lens 5 is 50 mm. Calculating to obtain the distance D between the lens groups 1 、D 2 The table of the relationship with the shaping ratio records the following lens position points corresponding to several commonly used shaping ratios among the lens groups, thereby realizing the continuous adjustment of the 0.5 x-2 x multiplying power of the laser beam.
TABLE 1 distance D between lens groups 1 、D 2 Relation with shaping ratio
Preferably, the combined zoom module 2 is connected with a servo motor displacement table, the distance between every two lenses is adjusted, and the zoom lens and the compensation lens can be continuously moved to corresponding positions by the servo motor displacement table according to a distance formula, so that the size of the laser beam can be continuously adjusted more accurately compared with manual adjustment.
Further preferably, the focal lengths of the variable power lens 4 and the compensation lens 6 are both-25 mm, and the focal length of the fixed lens 5 is 20 mm. For the precise adjustment of the servo motor, the movement range of the lens is not required to be too large, and therefore the focal length of the lens should be as short as possible, after the lens provided by the research manufacturer, the focal lengths of the selected zoom lens 4 and the compensation lens 6 are both-25 mm, the lens group with the focal length of the fixed lens 5 being 20mm is more suitable, and the function relationship of the obtained distance is the following specific formula (18):
calculating to obtain the distance D between the lens groups 1 、D 2 The shaping ratio is shown in table 2:
TABLE 2 distance D between lens groups 1 、D 2 In relation to the shaping ratio
Plotting the function yields a plot of the distance between the lenses versus the shaping ratio, as shown in FIG. 4.
Preferably, the coupling device further comprises an isolator 10 for ensuring the stability of the light source, the isolator 10 is disposed between the compensation lens 6 and the first collimator 7 along the emitting direction of the laser beam, in the transmission line of the optical communication system, there are many reflected lights with different degrees of end faces which are transmitted back along the optical fiber, which causes the self-coupling stage effect between the optical path systems, which causes the unstable operation of the laser 1, and this back light also causes the deterioration of the transmission performance of the system, and eventually causes the generation of bit errors, and the isolator 10 is used for isolating the back light returned from the optical communication system, thereby ensuring the stable operation of the light source.
The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention cannot be limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are all within the protection scope of the present invention.
Claims (6)
1. An adjustable fiber optic coupling device, comprising:
the laser instrument for launch laser beam the laser instrument sends laser beam's direction and has set gradually:
the combined zoom module comprises a zoom lens, a fixed lens and a compensation lens which are sequentially arranged along the emitting direction of the laser beam, the distances between the zoom lens and the fixed lens and between the fixed lens and the compensation lens are adjustable, the zoom lens and the compensation lens are biconcave lenses, and the fixed lens is a biconvex lens;
and the optical fiber coupling module comprises a first collimator and an optical fiber which are sequentially arranged along the emitting direction of the laser beam.
2. The adjustable fiber coupling device of claim 1, wherein the combined zoom module is connected with a servo motor displacement stage for adjusting the distance between each two adjacent lenses.
3. The adjustable fiber coupling device of claim 2, wherein the focal lengths of the variable power lens and the compensating lens are both-25 mm, and the focal length of the fixed lens is 20 mm.
4. The adjustable fiber coupling device of claim 1 or 2, further comprising an isolator to stabilize the light source, the isolator being disposed between the compensation lens and the first collimator.
5. The adjustable optical fiber coupling device according to claim 1 or 2, wherein the optical fiber coupling module further comprises a second collimator for further collimating the laser light, the second collimator being disposed at an end of the optical fiber far from the first collimator and in the emitting direction of the laser beam.
6. The adjustable fiber coupling device of claim 1 or 2, wherein the optical fiber is a single mode polarization maintaining fiber.
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| CN202220987308.XU CN217305596U (en) | 2022-04-26 | 2022-04-26 | Adjustable optical fiber coupling device |
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