CN101009522A - Control method and device for high duplication of making the optical fiber grating - Google Patents

Abstract

The invention relates to a high-repeatability control method and device for fabricating an optical fiber grating. The technology can be used to realize batch and high-repeatability writing of a predetermined wavelength optical fiber grating. The device of the invention includes an ultraviolet laser as the light source of the writing system, a precision scanning platform for controlling the scanning of the ultraviolet light, a series of reflectors and cylindrical lenses for controlling the beam quality, high-precision weights and weight placement boxes. When writing a fiber grating, according to the function of the stress to the offset of the center wavelength, the required stress on the photosensitive fiber at the target wavelength of the grating is obtained, and the weight of the corresponding weight is placed in the weight placement box to ensure that the photosensitive fiber is clamped The device exerts a rated stress on the photosensitive fiber to realize the writing of fiber gratings with precisely adjustable wavelength and high repeatability. Using the same phase mask, the system can realize precise wavelength with a wavelength variation range of 2.4nm and an adjustable length of 0 to 14cm. Fabrication of fiber gratings.

Description

Control method and device for fabricating fiber grating with high repeatability

technical field

The present invention belongs to the fields of optoelectronic technology, optical fiber sensing and optical fiber communication, and specifically relates to a high-repeatability control method and device for fabricating fiber gratings, which involves precise wavelength writing technology of fiber gratings, precise wavelength adjustment technology and The same phase mask can write different fiber grating writing technologies that meet the standard wavelength of the International Telecommunication Union (ITU-T).

Background technique

At present, the fabrication methods of fiber gratings are becoming more and more mature, but the technical problem of obtaining fiber gratings with high repeatability has not been solved. Up to now, the best repeatable fiber grating manufacturing method is the combination of phase mask method and scanning platform. The parameters of batches of optical fibers cannot be exactly the same, which makes the center wavelength of the fiber grating written in the same phase mask different, so the repeatability of the grating performance cannot be guaranteed. In addition, to ensure that the error between the center wavelength of the written fiber grating and the ITU-T standard wavelength is not greater than 0.01nm, the period design of the phase mask is required to be accurate to more than 0.007nm, which places high requirements on the design and production of the phase mask. , is difficult to achieve.

Contents of the invention

The object of the present invention is to provide a high-repeatability control method and device for fabricating fiber gratings, which can realize mass production of low-cost and high-repeatability fiber gratings.

It has been found through research that in the process of writing fiber gratings, if different stresses are applied to the photosensitive fibers, the same mask and photosensitive fibers with the same parameters can be used to produce fiber gratings with different central wavelengths, and when writing fiber gratings The stress exerted on the photosensitive fiber is directly proportional to the nominal wavelength value away from the fiber grating. The so-called nominal wavelength of the fiber grating is the central wavelength of the fiber grating written on a certain photosensitive fiber by a mask plate without applying stress. There is an offset between the center wavelength and the nominal wavelength of the fiber grating produced after stress is applied. As the stress increases, the offset increases, and the offset is a negative value, that is, the greater the applied stress, the fabricated The shorter the center wavelength of the fiber grating. Controlling the stress applied to the photosensitive fiber when writing the fiber grating can control the central wavelength of the produced fiber grating, that is, the central wavelength of the written fiber grating can be precisely controlled, as shown in Figure 2.

The present invention is based on the research above, and designs a high-repeatability control method and device for fabricating fiber gratings.

The technical scheme adopted in the invention is: utilizing the influence of stress on the optical fiber grating on the wavelength of the optical fiber grating to establish a precision photosensitive optical fiber stress control device to realize the manufacture of the highly repeatable optical fiber grating with precise and adjustable wavelength.

The device of the invention comprises an ultraviolet laser, a reflection mirror fixed on a scanning platform, a cylindrical lens, a phase mask, a photosensitive optical fiber holder, a high-precision weight and a weight placement box. The ultraviolet light output by the ultraviolet laser passes through the mirror fixed on the scanning platform, so that the ultraviolet light passes through the cylindrical lens and the phase mask, and exposes the photosensitive optical fiber clamped between the optical fiber holders. The V-groove photosensitive optical fiber clamp The holder is placed on a smooth guide rail, which is connected with the guide rail by an oil-impregnated ball bearing, and can move freely on the guide rail. The other end of the fiber holder is connected to the weight placement box.

The effect and innovation of the present invention are: the weight of the weight is used to strictly control the stress applied on the photosensitive fiber, which can realize the production of optical fiber grating with high repeatability; by applying different stresses on the photosensitive fiber, the same mask can be used to write Fiber Bragg gratings of different wavelengths can be inserted into all fiber gratings with wavelengths in the range of nominal wavelength and nominal wavelength -2.4nm with the same mask while maintaining the quality of fiber gratings without deterioration, which greatly reduces the cost of fiber gratings. production cost.

Description of drawings

Figure 1 Current fiber grating phase mask writing system

Figure 2 The relationship between the stress added to the photosensitive fiber and the deviation from the nominal wavelength of the fiber grating when writing the fiber grating

Fig. 3 Fiber Bragg grating writing system with high repeatability control method for fabricating fiber Bragg gratings

Figure 4 Probability distribution of the difference between the target wavelength and the actual measured wavelength of the fiber grating

Detailed ways

As shown in Figure 1: Usually the existing fiber grating phase mask method writes the ultraviolet light 2 output by the ultraviolet laser 1 through the mirror 3 fixed on the scanning platform 4, so that the ultraviolet light 2 passes through the cylindrical lens 5 and the phase The mask plate 6 is exposed to the photosensitive optical fiber 7 clamped between the optical fiber holders 8 and 9, and the scanning platform 4 is driven by a computer through the GBIP interface, so that the ultraviolet light 2 scans the entire photosensitive optical fiber 7, and the desired length can be written. fiber grating.

Fig. 3 shows a fiber grating writing system with precise wavelength tunability and a high-repeatability control method for fabricating fiber gratings according to the present invention. The difference between the fiber grating writing system and the usual fiber grating writing system is that: the photosensitive fiber holder (V-groove) 9 of the fiber grating writing system is placed on a smooth guide rail, and the optical fiber The holder 8 is fixed, and the holder 9 is connected with the guide rail through an oil-impregnated ball bearing 10, and can move freely on the guide rail. The other end of the optical fiber holder 9 is connected to the weight placement box 11, and by adding weights of different weights, the stress applied to the photosensitive optical fiber can be precisely controlled. The detailed steps are as follows:

Step 1, select the mask plate and photosensitive optical fiber for writing the grating.

In step 2, the photosensitive optical fiber is placed in the optical fiber holder 8, 9 without any stress applied thereto.

Step 3, the ultraviolet light 2 output by the ultraviolet laser 1 passes through the mirror 3 fixed on the scanning platform 4, so that the ultraviolet light 2 passes through the cylindrical lens 5 and the phase mask 6, and is clamped between the optical fiber holders 8 and 9 Expose the photosensitive optical fiber 7 between them to obtain the central wavelength of the fiber grating without stress, that is, the nominal wavelength of the fiber grating.

Step 4, add a certain weight to the weight box 11, select the photosensitive optical fiber with the same parameters, that is, apply appropriate stress to the photosensitive optical fiber through the ball bearing, and obtain the central wavelength of the fiber grating under the stress.

Step 5, according to the center wavelength of the grating obtained in steps 3 and 4, determine the required stress to be applied when fabricating the fiber grating with the desired target wavelength.

In step 6, the selected stress is used to realize the fabrication of multiple optical fiber gratings with high repeatability.

Claims (2)

1. A control method and device for making fiber gratings with high repeatability, characterized in that the device of the present invention includes an ultraviolet laser (1), a mirror (3) fixed on a scanning platform (4), a cylindrical lens (5) , phase mask (6), photosensitive fiber holders (8) and (9), high-precision weights and weight placement boxes (11); the ultraviolet light (2) output by the ultraviolet laser (1) is fixed on The mirror (3) on the scanning platform (4) makes the ultraviolet light (2) pass through the cylindrical lens (5) and the phase mask (6), and the pair is clamped between the fiber holders (8) and (9) The photosensitive optical fiber (7) is exposed; the optical fiber holder (8) is fixed, and the optical fiber holder (9) is placed on a smooth guide rail, which is connected with the guide rail through an oil-containing ball bearing (10), and can be placed on the guide rail. Free to move, the other end of the optical fiber holder (9) is connected to the weight placement box (11). 2. The high-repeatability control method and device for fabricating an optical fiber grating according to claim 1, characterized in that, by precisely controlling the tension of the photosensitive optical fiber when writing the grating, the required target wavelength of the optical fiber grating is obtained, and through precise Control the different tensions on the photosensitive optical fiber, and use the same mask to write fiber gratings with different target wavelengths; Specifically: By introducing stress to the photosensitive optical fiber during the process of writing the grating, using the same phase mask, under the condition of ensuring the quality of the fiber grating, it is possible to write within the range from the nominal wavelength to the nominal wavelength -2.4nm All fiber gratings; Only one of the two fiber holders is fixed, and the other one can move on the smooth guide rail through the ball bearing. A certain stress is applied to the photosensitive fiber through the ball bearing, and the fiber grating of the target wavelength can be written; Phase-shifted FBG or sampled FBG target products can be written by changing the stress applied to the photosensitive fiber one or more times during the writing process.

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