CN214310972U - Device for preparing optical fiber grating - Google Patents

Abstract

The application discloses device for preparing fiber grating, through predetermineeing temperature distribution on photosensitive optic fibre, use the phase template method to make linear chirp grating on predetermineeing the regional distribution volume of increasing of accurate control's photosensitive optic fibre, the preparation is accomplished the back, closes the carbon dioxide laser instrument, and then photosensitive optic fibre temperature recovery is even, and the temperature change process makes optic fibre take place nonlinear contraction to realize the preparation of nonlinear chirp grating. The device for preparing the fiber grating can reduce the difficulty of the process for preparing the grating, and has the advantages of simple operation, low cost and good compatibility.

Description

Device for preparing optical fiber grating

Technical Field

The present application relates to the field of optical information technology, and particularly, but not exclusively, to an apparatus for manufacturing a fiber grating.

Background

The advent of a Chirped Pulse Amplification (CPA) system enables a laser focusing power density to be increased in a flying manner. Fiber gratings are important optical devices in chirped pulse amplification systems. There are various methods for manufacturing the fiber grating, and among them, the phase-templating method is one of the methods commonly used at present. But to compensate for third-order dispersion in the system, it is often necessary to use nonlinear chirp techniques. At present, two methods of applying a predetermined stress/non-uniformly distributed temperature field on a linear chirped grating or a phase template with non-linear chirp are mainly adopted to prepare the grating. The former has influence on the process and reliability of the product, and the precise control difficulty is higher in the long-term use process; the latter has higher manufacturing cost, and the same phase template can only manufacture the grating with preset dispersion, so the compatibility is poor.

SUMMERY OF THE UTILITY MODEL

The embodiment of the application mainly aims to provide a device for preparing a fiber grating, and aims to realize grating writing by adopting parts such as a photosensitive fiber, a laser and the like, so that the difficulty of a grating preparation process is reduced, and the device is simple to operate, low in cost and good in compatibility.

In a first aspect, an embodiment of the present application provides an apparatus for manufacturing a fiber grating, including: the device comprises an ultraviolet laser, a beam shaping system, a reflector, a cylindrical lens, a phase template, a photosensitive optical fiber and a carbon dioxide laser; the ultraviolet laser forms an output beam; the output light beam passes through a light beam shaping system and is shaped into a collimated light beam with a pure light spot; the collimated light beam is reflected by the reflecting mirror and is incident to the cylindrical lens; the condenser lens focuses the collimated light beam and forms focused light; after the focused light penetrates through the phase template, interference fringes are formed; the interference fringe irradiates the photosensitive optical fiber; the carbon dioxide laser outputs a laser beam, and the laser beam irradiates the photosensitive optical fiber.

The device for preparing the fiber grating is characterized in that the linear chirped grating is manufactured on the photosensitive fiber in the region distribution increasing amount which is accurately controlled in a preset mode by using a phase template method through presetting the temperature distribution/increasing amount on the photosensitive fiber, and after the linear chirped grating is manufactured, the carbon dioxide laser is turned off, so that the temperature recovery of the photosensitive fiber is uniform, and the nonlinear contraction of the fiber is realized in the temperature change process, thereby realizing the preparation of the nonlinear chirped grating. The device for preparing the fiber grating can reduce the difficulty of the process for preparing the grating, and has the advantages of simple operation, low cost and good compatibility.

Drawings

FIG. 1 is a schematic diagram of an apparatus for manufacturing a fiber grating according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a carbon dioxide laser and its operation according to the present application;

FIG. 3 is another schematic diagram of a carbon dioxide laser and its operation according to the present application;

FIG. 4 is a schematic view of the scanning speed of the scanning galvanometer of the carbon dioxide laser along the axial direction.

Reference numerals:

an ultraviolet laser-1; a beam shaping system-2; a reflector-3; a cylindrical lens-4; phase template-5; a photosensitive optical fiber-6; carbon dioxide laser-7; carbon dioxide laser body-71; scanning galvanometer-72.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the examples described herein in one possible implementation are for the purpose of illustration only and are not intended to limit the present application. In the present application, the embodiments and features of the embodiments may be arbitrarily combined with each other without conflict.

In the description of the embodiments of the present application, suffixes such as "module", "part", or "unit" used to denote elements are used only for facilitating the description of the present application, and have no peculiar meaning by themselves. Thus, "module", "component" or "unit" may be used mixedly.

It should be noted that although functional blocks are partitioned in a schematic diagram of an apparatus and a logical order is shown in a flowchart, in some cases, the steps shown or described may be performed in a different order than the partitioning of blocks in the apparatus or the order in the flowchart. The terms first, second and the like in the description and in the claims, and the drawings described above, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. In addition, unless otherwise expressly limited, terms such as set, mounted, connected and the like are to be construed broadly, and those skilled in the art can reasonably determine the specific meanings of the above terms in the examples of the present application in combination with the details of the technical solutions.

Referring to fig. 1, fig. 1 is a diagram illustrating an apparatus for manufacturing a fiber grating according to an embodiment of the present application. As shown in fig. 1, the apparatus for preparing a fiber grating at least comprises: the device comprises an ultraviolet laser 1, a beam shaping system 2, a reflector 3, a cylindrical lens 4, a phase template 5, a photosensitive optical fiber 6 and a carbon dioxide laser 7.

The uv laser is turned on to produce an output beam, L1, which is incident on the beam shaping system 2. The beam shaping system 2 shapes the output light beam L1 and outputs a collimated light beam L2. The collimated light beam L2 enters the mirror 3, and is reflected by the mirror 3 to be directed to the cylindrical lens 4. The collimated light beam L2 passes through the rod lens 4 and forms a focused light beam L3. The focused light L3 is emitted toward the phase mask 5, and after passing through the phase mask 5, the ± 1 st order diffracted light forms interference fringes. A photosensitive optical fiber 6 is placed behind the phase template 5 and is arranged in the region of the interference fringes. The carbon dioxide laser 7 outputs a laser beam L4, passes through a scanning galvanometer, and irradiates the photosensitive optical fiber 6.

The reflecting mirror 3 is fixed on the electric control translation table through the mirror seat, so that the reflecting mirror 3 can scan along the axial direction of the collimated light beam L2 at variable speed according to the preparation requirement, and the apodization of the fiber bragg grating is realized.

Wherein, the scanning galvanometer can be controlled in a programmable way. Through the programming control of the scanning galvanometer, the laser beam L4 is rapidly scanned back and forth along the axial direction on the photosensitive optical fiber 6, thereby realizing the heating of the photosensitive optical fiber 6. The scanning speed of the laser beam L4 is different at different positions, so that the photosensitive optical fiber 6 reaches a preset temperature distribution condition in the axial direction.

In one possible embodiment, the uv laser 1 may be an excimer laser or a solid state laser. The laser emission wavelength of the ultraviolet laser 1 can be any wavelength between 193nm and 355nm, preferably 193nm, 213nm, 248nm, 266nm and 355 nm; coherence length greater than 1.5mm, beam mass M²Less than 1.6.

In a possible implementation mode, the beam shaping system 2 comprises necessary optical elements such as a lens, a diaphragm, a slit, a pinhole and the like, and shapes the output beam L1 of the ultraviolet laser 1 into a collimated beam L2 with the diameter of 0.5 mm-6 mm and a pure light spot.

In one possible embodiment, the reflecting surface of the mirror 3 makes an angle of 45 ° with the incident collimated light beam L2, and turns the collimated light beam L2 by 90 ° and then emits the collimated light beam to the cylindrical lens 4.

In one possible embodiment, the cylindrical lens 4 is an ultraviolet quartz cylindrical lens evaporated with an antireflection film or an uncoated film with a corresponding wavelength, so as to focus the collimated light beam into horizontal light.

In one possible embodiment, the interference fringes formed after passing through the phase mask 5 have a fringe period that is half the period of the phase mask, preferably chirp fringes.

In a possible embodiment, the refractive index of the photosensitive fiber 6 is modulated to accommodate the writing requirements.

In one possible embodiment, the carbon dioxide laser 7 is a laser wave that outputs a laser beam L4 of preferably 10.6 um.

Referring to fig. 2 and 3, fig. 2 and 3 are schematic diagrams of a carbon dioxide laser and an operation thereof provided by an embodiment of the present application. Fig. 2 and 3 show components such as a carbon dioxide laser main body 71, a scanning galvanometer 72, a laser beam L4, and a photosensitive optical fiber 6.

In the present embodiment, the carbon dioxide laser main body 71 emits a collimated laser beam L4 having a wavelength of 10.6 μm and a spot diameter of about 0.5mm to 1 mm. The collimated laser beam L4 passes through the scanning galvanometer 72 to adjust the direction of transmission. Here, the laser beam L4 may be irradiated to an arbitrary position of the photosensitive fiber 6. In this particular embodiment, the laser beam L4 is rapidly scanned back and forth along the area to be inscribed of the photosensitive fiber 6. The precision photosensitive fiber 6 keeps the photosensitive fiber 6 from any contact with the phase template 5, avoiding heating or damaging the phase template 5. Since quartz has a high absorption efficiency for the carbon dioxide laser 7, the photosensitive fiber 6 absorbs the laser beam L4 and heats up under the irradiation of the laser beam L4. The irradiation time of the photosensitive optical fiber 6 at different positions is controlled by the scanning galvanometer 72, so that the photosensitive optical fiber 6 absorbs different heat at different positions, thereby achieving the purpose of accurately controlling the temperature distribution of the photosensitive optical fiber 6. The amount of the rise of each region of the photosensitive fiber 6 at this time can be calculated by the thermal expansion coefficient of the silica fiber being 5.5X 10-7/DEG C. On the contrary, after the required preset increment is calculated according to the dispersion compensation requirement, the increment can be accurately controlled through the irradiation amount of the laser beam L4.

To describe the apparatus for manufacturing a fiber grating in further detail, another embodiment of the apparatus for manufacturing a fiber grating will be described below.

In the present embodiment, the ultraviolet laser 1 is a solid laser with an operating wavelength of 266nm, and collimated light beam L2 with a diameter of 3mm and a beam quality M is obtained after passing through the beam shaping system 2²Is 1.5. The mirror 3 passes through an electrically controlled moving platform. In the process of manufacturing the grating, the reflecting mirror 3 scans back and forth to realize raised cosine apodization. The phase template 5 is a principle that the center period is 709nm, the linear chirp quantity is 5.5nm/cm and the order of +/-1 is adopted. The photosensitive optical fiber 6 is a high-photosensitivity PM980 optical fiber after high-pressure hydrogen loading. The scanning speed of the carbon dioxide laser scanning galvanometer 72 along the axial direction of the photosensitive optical fiber 6 is shown in figure 4. The speed is fastest when the center of the photosensitive optical fiber 6 is scanned, the speed for scanning the two sides is slower, so that the temperature of the center position of the photosensitive optical fiber 6 is lowest, the temperature of the two sides is gradually increased, the manufacture of the nonlinear chirped fiber Bragg grating is finished, the dispersion parameter is 12.3ps/nm, and the third-order dispersion value is 0.6ps³。

The preferred embodiments of the present application have been described above with reference to the accompanying drawings, and are not intended to limit the scope of the claims of the application accordingly. Any modifications, equivalents and improvements which may occur to those skilled in the art without departing from the scope and spirit of the present application are intended to be within the scope of the claims of the present application.

Claims (7)

1. An apparatus for preparing a fiber grating, the apparatus comprising: the device comprises an ultraviolet laser, a beam shaping system, a reflector, a cylindrical lens, a phase template, a photosensitive optical fiber and a carbon dioxide laser;

the ultraviolet laser outputs a light beam;

the beam shaping system receives the output beam and shapes the output collimated beam;

the reflector reflects the collimated light beam;

the cylindrical lens focuses the collimated light beam after reflection and forms focused light;

after the focused light penetrates through the phase template, interference fringes are formed;

the photosensitive optical fiber is disposed in a region where the interference fringes are formed, the interference fringes being irradiated to the photosensitive optical fiber;

the carbon dioxide laser outputs a laser beam, and the laser beam irradiates the photosensitive optical fiber.

2. The apparatus of claim 1, further comprising:

an electrically controlled translation stage;

the mirror is fixed to the electrically controlled translation stage;

the mirror is capable of variable speed scanning along the collimated beam axis.

3. The apparatus of claim 1 or 2, wherein the carbon dioxide laser comprises:

the scanning galvanometer is controlled in a programmable way;

the laser beam irradiates a photosensitive optical fiber after passing through the scanning galvanometer;

and the laser beam is scanned along the axis on the photosensitive optical fiber by controlling the scanning galvanometer.

4. The apparatus of claim 1, wherein:

the reflecting surface of the reflector forms an angle of 45 degrees with the collimated light beam before incidence;

the collimated light beam after being reflected by the reflecting mirror forms a 90-degree angle with the collimated light beam before incidence.

5. The apparatus of claim 1, wherein:

the phase template is a linear chirp phase template;

the fringe period of the interference fringes is half of the phase template period.

6. The apparatus of claim 1, wherein:

the output light beam wavelength is 193 nm-355 nm.

7. The apparatus of claim 1, wherein:

the diameter of the collimated light beam is 0.5 mm-6 mm.

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