JP2004133482A - Method for manufacturing phase mask for worknig optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a phase mask for working optical fiber by which electron-beam lithography of the phase mask having recessed groove pitches changing according to positions can be easily performed. <P>SOLUTION: In the method for manufacturing the phase mask for working optical fibers, diffraction gratings are produced within an optical fiber by the interference fringes of diffracted light of different orders by providing one surface of a transparent substrate with repetition patterns of grid-like recessed grooves 26 and projected lines 27 and irradiating the optical fiber with the diffracted light by the repetition patterns, and a plurality of the patterns A<SB>1</SB>to A<SB>3</SB>in which the pitches of the recessed grooves 26 and the projected lines 27 increase or decrease while keeping specified ratios in the widths thereof are drawn parallel to one another. For this purpose, the drawing data of the basic pattern consisting of one recessed groove 26 and one projected line 27 is formed as a basis, and the patterns consisting of the recessed grooves 26 and the projected lines 27 varying in the pitches are continuously drawn by changing the scale of the drawing data of the basic pattern. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a method of manufacturing a phase mask for processing an optical fiber, and more particularly to a method of manufacturing a phase mask for manufacturing a diffraction grating using an ultraviolet laser beam in an optical fiber used for optical communication or the like.

Optical fibers have revolutionized global communications and have enabled high-quality, high-capacity transoceanic telephone communications. A black diffraction grating is created, and the period of the diffraction grating, the length of the diffraction grating, and the magnitude of the refractive index modulation determine the level of the reflectance of the diffraction grating and the width of the wavelength characteristic. It is known that it can be used as a splitter, a narrow band high reflection mirror used for a laser or a sensor, a wavelength selection filter for removing an extra laser wavelength in a fiber amplifier, and the like.

However, since the attenuation of the quartz optical fiber is minimized and the wavelength suitable for long-distance communication systems is 1.55 μm, in order to use an optical fiber diffraction grating at this wavelength, the grating interval needs to be about 500 nm. It is initially considered difficult to create such a fine structure in the core itself.To make a black diffraction grating in the core of an optical fiber, side polishing, a photoresist process, holographic exposure, reactive ion Many stages of complicated processes such as beam etching were performed. For this reason, the manufacturing time was long and the yield was low.

However, recently, there has been known a method of irradiating an ultraviolet ray to an optical fiber to directly change the refractive index in a core and to form a diffraction grating. It has been gradually implemented with the progress of technology.

In the case of the method using this ultraviolet light, since the lattice spacing is as small as about 500 nm as described above, an interference method of causing two light beams to interfere with each other (condensing a single pulse from an excimer laser to form one diffraction grating surface) A method of writing one point at a time, and a method of irradiating using a phase mask having a grating.

The interference method of causing the two light beams to interfere with each other has a problem in the beam quality in the lateral direction, that is, spatial coherence. The method of writing one point at a time requires precise step control of a submicron size. In addition, it is required to capture a small amount of light and write on many surfaces, and there is also a problem in workability.

For this reason, an irradiation method using a phase mask has been attracting attention as a method capable of coping with the above problem. However, as shown in FIG. 7A, this method forms a concave groove on one surface of a quartz substrate. A KrF excimer laser beam (wavelength: 248 nm) 23 is irradiated on a mask 21 using a phase shift mask 21 provided at a predetermined pitch and at a predetermined depth to directly change the refractive index on the core 22A of the optical fiber 22, A grating (grating) is produced (reference numeral 22B indicates a clad of the optical fiber 22). In FIG. 7A, the interference fringe pattern 24 on the core 22A is enlarged for easy understanding. FIGS. 7B and 7C respectively show a cross-sectional view of the phase mask 21 and a part of a top view corresponding thereto. The phase mask 21 has a binary phase type diffraction grating-like structure in which concave grooves 26 having a repetitive pitch P and a depth D are provided on one surface thereof, and ridges 27 having substantially the same width are provided between the concave grooves 26. It is.

The depth D of the concave groove 26 of the phase mask 21 (the difference in height between the ridge 27 and the concave groove 26) is selected so as to modulate the phase of the excimer laser light (beam) 23 as exposure light by π radian. The zero-order light (beam) 25A is suppressed to 5% or less by the phase shift mask 21, and the main light (beam) emitted from the mask 21 is plus first-order diffracted light including 35% or more of the diffracted light. The light is split into 25B and a minus first-order diffracted light 25C. Therefore, interference fringes of a predetermined pitch are radiated by the plus-first-order diffracted light 25B and the minus-first-order diffracted light 25C, and a change in the refractive index at this pitch is caused in the optical fiber 22.

(4) The pitch of the grating in the optical fiber manufactured using the above-described phase mask 21 was constant, and the pitch of the concave grooves 26 of the phase mask 21 used for the manufacture was also constant.

In order to manufacture such a phase mask, pattern data corresponding to a lattice-shaped groove pitch was prepared and drawn by an electron beam lithography apparatus to prepare a groove-shaped lattice.

Recently, as a black diffraction grating formed in an optical fiber, a chirped grating in which the pitch of the grating linearly or non-linearly increases or decreases according to the position in the direction perpendicular to the grating grooves (the direction of repetition of the grating) is required. It has come to be. Such a grating is used, for example, as a high-reflection mirror having a wide reflection band, a means for adjusting a delay time, or the like.

In this way, a grating in which the grating pitch changes linearly or non-linearly according to the position in the length direction of the optical fiber is to be manufactured using a phase mask by interference between the plus-first-order diffracted light and the minus-first-order diffracted light. In this case, the pitch of the groove of the phase mask also needs to increase or decrease linearly or non-linearly in accordance with the position, as is apparent from the principle of FIG. 7A (the pitch of the groove of the phase mask). Is smaller, the angle between the plus first order diffracted light and the minus first order diffracted light becomes larger, and the pitch of the interference fringes becomes smaller.) Conventionally, in order to form such a phase mask by drawing with an electron beam lithography apparatus, a lot of drawing data is required for drawing a groove or a ridge between the grooves over the entire range of the mask, which makes manufacturing difficult. There are cases.

The present invention has been made in view of such problems of the prior art, and an object of the present invention is to easily perform electron beam writing on a phase mask in which a groove pitch changes according to a position in a direction orthogonal to the groove. It is an object of the present invention to provide a method of manufacturing a phase mask for processing an optical fiber.

Another object of the present invention is to provide a method of manufacturing a phase mask for processing an optical fiber by electron beam lithography, in which the pitch of the groove changes according to the position in the groove direction.

In the method for manufacturing a phase mask for optical fiber processing of the present invention that achieves the above object, a repetitive pattern of a lattice-like concave groove and a convex stripe is provided on one surface of a transparent substrate, and the optical fiber is irradiated with diffracted light by the repetitive pattern. In a method of manufacturing a phase mask for optical fiber processing, in which a diffraction grating is formed in an optical fiber by interference fringes of diffracted light beams of different orders, by drawing a plurality of patterns formed of grooves and ridges having different pitches in parallel. When producing the repetition pattern of the lattice-shaped groove and the ridge, the pitch is based on the drawing data of the basic pattern composed of one groove and the ridge, and the scale of the drawing data of the basic pattern is changed. By successively drawing a pattern consisting of different grooves and ridges, a repetitive pattern of the lattice-like grooves and ridges described above A method characterized in that to produce.

In this case, a plurality of patterns can be drawn in parallel with each other in a direction orthogonal to the groove, or can be drawn in parallel with the direction of the groove.

In the latter case, the deviation width in the direction perpendicular to the groove between the groove of one pattern and the groove of the adjacent pattern may be within the width of one groove at the outermost left and right ends. desirable.

The change according to the position of the pitch of the repetition pattern of the lattice-shaped concave groove and the ridge is determined according to the change of the pitch of the diffraction grating produced in the optical fiber, and the position of the scale of the drawing data of the basic pattern is determined. Is desirably given by a change according to

Further, the number of scanning lines for drawing one of the grooves or ridges and the number of scanning lines for blanking the other in each of the plurality of patterns having the grooves and the ridges having different pitches are the same in any pattern. It is desirable that

(4) Such a repetitive pattern of lattice-shaped concave grooves and convex stripes can be formed by electron beam drawing.

ピ ッ チ Further, the pitch of the repetitive pattern of the lattice-like concave grooves and convex stripes can be changed, for example, between 0.85 μm and 1.25 μm.

It is desirable that the difference between the height of the concave groove and the height of the convex ridge in the repetition pattern of the lattice-shaped concave groove and the convex ridge is such that the phase is shifted by approximately π when ultraviolet rays for optical fiber processing are transmitted.

In the present invention, the drawing data of the basic pattern consisting of one groove and the ridge is basically used, and the pattern consisting of the groove and the ridge having different pitches is continuously drawn by changing the scale of the drawing data of the basic pattern. By doing so, a phase mask for optical fiber processing in which a plurality of patterns each having a concave groove and a convex line having different pitches is arranged in parallel is manufactured, so that the amount of drawing data can be significantly reduced, and the pattern can be easily manufactured. . In addition, a phase mask having an arbitrary pitch arrangement can be manufactured by this method.

Hereinafter, a phase mask for processing an optical fiber and a method of manufacturing the same according to the present invention will be described based on examples.

FIG. 2B is a cross-sectional view of the phase mask 21 having a repetitive pattern of concave grooves 26 and convex ridges 27 for producing a black diffraction grating in an optical fiber in an arrangement as shown in FIG. 7A. . The concave grooves 26 and the convex stripes 27 of the mask 21 are drawn by raster scanning so that the scanning line 28 of the electron beam is directed in the direction along the concave grooves 26 as shown in the top view of FIG. Then, as shown by a broken line in the figure, a case in which the convex groove 27 is produced by exposing the concave groove 26 and blanking the electron beam scan. In the exposure of the entire mask 21, raster scanning is performed in the direction indicated by the double arrow in FIG. 2A, and a predetermined number of scanning lines (in the case of FIG. (5 scans) at the position where the next ridge 27 is to be drawn, blanking the scan by the same number of scanning lines, and repeating this to expose the phase mask 21 of a predetermined length to the electron beam. You.

In the present invention, when the entire mask 21 is exposed by performing the raster scan using the scanning lines 28 of the electron beam as described above, the pitch of the concave grooves 26 or the convex stripes 27 is changed in the direction orthogonal to the grooves 26 or the groove. It increases or decreases linearly or non-linearly according to the position in the direction 26. In this case, the width of the concave groove 26 is increased or decreased in accordance with the change. However, the number of raster scan lines for drawing one concave groove 26 is set to be the same at any position, and the width between the centers of the scan lines 28 is changed. Is increased or decreased according to the change.

FIG. 1 is a top view for explaining a drawing method for linearly or non-linearly increasing or decreasing the pitch of the concave groove 26 or the ridge 27 according to the position in the direction orthogonal to the groove 26. The sampled left end area A ₁ is the pitch P ₁ of the groove 26 or the ridge 27, the sampled central area A ₂ is the pitch P ₂ of the groove 26 or the ridge 27, and the sampled right end area A ₃ Has a pitch P ₃ of the concave grooves 26 or the convex stripes 27. Here, it is assumed that P ₁ <P ₂ <P ₃ . Each concave groove 26 is drawn by raster scanning from the left end to the right end while drawing the scanning line 28 of the electron beam from top to bottom. At that time, even in a region A _1, even in a region A _2, also in the area A _3, the same number of scan lines to draw a single groove 26 (in the case of FIG. 5 lines). Then, scanning is blanked by the same number of scanning lines at the position where the ridge 27 is to be drawn. Therefore, the distance between the centers of the scanning lines 28 changes in the areas A ₁ , A ₂ , A ₃ according to the pitches P ₁ , P ₂ , P ₃ .

When such a drawing method is adopted, the area of the portion of the concave groove 26 that is not exposed by the electron beam between the scanning lines 28 changes depending on the regions A ₁ , A ₂ , and A ₃ , and the electron beam resist ( Although it is conceivable that the unexposed portion remains after the development, the unexposed resist is actually removed with the development of the portion corresponding to the scanning line 28, so that there is no problem at all.

As described above, the pitch of the groove 26 or the ridge 27 of the phase mask 21 is linearly or nonlinearly increased or decreased according to the position in the direction orthogonal to the groove 26, and the width of the groove 26 and the ridge 27 is increased. If a drawing method is used in which the number of raster scan lines for drawing one groove 26 is the same at any position, the basic pattern for one pitch of the mask 21 is used as the drawing data. By simply preparing data and a scale change function for the basic pattern data corresponding to a pitch change function corresponding to a position in a direction orthogonal to the groove 26, the entire pattern of the phase mask 21 can be drawn by electron beam.

FIG. 3 is a top view for explaining a drawing method for linearly or non-linearly increasing or decreasing the pitch of the groove 26 or the ridge 27 according to the position of the groove 26 in the direction of the groove 26. the pitch P ₁ of the region B ₁ in the lower direction grooves 26 or ridges 27 along the pitch P ₂ in the region B ₂ thereon in a direction along the groove 26 is recessed groove 26 or projections 27, the groove 26 direction region B ₃ thereon the concave groove 26 or projections 27 pitch P ₃ of along, ..., pitch P of the region B ₇ under the direction of the upper end along the groove 26 recessed groove 26 or ridge 27 _7, the regions B ₈ in the direction of the upper end along the grooves 26 have a pitch P ₈ of the groove 26 or ridge 27. Here, it is assumed that P ₁ > P ₂ > P ₃ >...> P ₇ > P ₈ . Each groove 26 of one area B _n (n = 1 to 7) is drawn from top to bottom by raster scanning of an electron beam, and the next area B _{n + 1} is drawn in the same manner to form all areas. Drawing is performed on the concave grooves 26 of B _{1 to} B ₈ . At this time, the number of scanning lines for drawing one concave groove 26 is the same in any of the regions B _{1 to} B ₈ (five in the case of the drawing). Then, scanning is blanked by the same number of scanning lines at the position where the ridge 27 is to be drawn. Therefore, the distance between the centers of the scanning lines 28 changes in the regions B _{1 to} B ₈ according to the pitches P _{1 to} P ₈ .

In the case of employing such a drawing method, it varies with the electronic area of the portion which was not exposed by the beam area B ₁ .about.B ₈ between the scanning lines 28 in the recessed groove 26 parts, electron beam resist (see FIG. 6 Although it is conceivable that the unexposed portion remains after the development, there is no problem since the unexposed resist is actually removed with the development of the portion corresponding to the scanning line 28.

  As described above, the pitch of the groove 26 or the ridge 27 of the phase mask 21 is linearly or non-linearly increased or decreased according to the position in the direction of the groove 26, and the width of the groove 26 and the ridge 27 is changed according to the change. If a drawing method is used in which the number of raster scan lines for drawing one groove 26 is the same at any position, basic pattern data for one pitch of the mask 21 is used as drawing data. By simply preparing a scale change function for the basic pattern data corresponding to a change function of the pitch according to the position in the direction of the groove 26, the entire pattern of the phase mask 21 can be drawn by the electron beam.

As shown in FIG. 3, the phase mask 21 in which the pitch of the groove 26 or the ridge 27 is linearly or non-linearly increased or decreased according to the position of the groove 26 in the direction of the groove 26 is a black mask formed in an optical fiber. It is suitable for manufacturing a grating in which the pitch increases or decreases linearly or non-linearly depending on the position in the direction of the grating groove. Such a grating is suitable, for example, for making the reflection wavelength different depending on the position in the optical fiber. Further, since the grooves 26 and the ridges 27 of the phase mask 21 extend in the direction perpendicular to the plane of FIG. 7A, by adjusting the position of the phase mask 21 in the direction perpendicular to the plane of FIG. It can also be used to selectively adjust the pitch of the grating produced in the optical fiber 22.

In the case of the drawing method shown in FIG. 3, the shift width of the groove 26 in one area _{Bn and} the groove 26 in the next area _{Bn + 1 in} the direction orthogonal to the groove 26 is as shown in FIG. In addition, it is necessary to set the above-mentioned scale change function so that the outermost ends on the left and right sides are also within the width of one groove 26. In addition, the drawing between the areas _Bn and _{Bn + 1} adjacent to each other may be in contact with each other, but when they are partially overlapped with each other, the groove 26 and the ridge 27 can be connected smoothly. So desirable.

FIG. 5 is a diagram schematically showing the drawing method of the present invention as compared with the case of the conventional technique. This drawing corresponds to the drawing method of FIG. 1, but the drawing method of FIG. 3 is substantially the same. When the pitch of the concave groove 26 or the ridge 27 of the phase mask 21 is linearly or non-linearly increased or decreased according to the position, according to the conventional drawing method, as shown in FIG. A large number of drawing pattern data A, B, C, D, E,... V, W, X, Y, Z must be prepared according to the position, and the amount of drawing data becomes enormous. . On the other hand, in the drawing method of the present invention, the basic pattern data A and the position x (the position in the direction orthogonal to the groove 26 in FIG. 1 and the position in the direction of the groove 26 in FIG. 3) are set. A corresponding scale change function β (x) is prepared, and at the time of drawing, as shown in FIG. 5A, A × β (x) = A _n and the basic pattern data A according to the position. It is sufficient to use the apparatus at a reduced scale, and the amount of drawing data can be reduced, and drawing can be simplified. In FIG. 1 and FIG. 5A, the drawing range in the vertical direction differs depending on the position because the scale in the vertical direction consisting only of the horizontal direction is also changed at the same time. In this case, the vertical drawing range can be aligned at all positions.

As a specific example, drawing data for one pitch consisting of 0.125 μm address units and ten scanning lines is prepared as basic pattern data, and the scale is (desired grid pitch) / (0.125 × 10 ). Using the reduced scale and the basic pattern data, an electron beam lithography apparatus draws an image on an electron beam resist applied on a transparent substrate. Hereinafter, an embodiment of a method for manufacturing a phase mask of the present invention using such a drawing method will be described.

FIG. 6 is a sectional view showing the steps of this embodiment. 6, reference numeral 10 denotes a phase mask blank, 11 denotes a quartz substrate, 12 denotes a chromium thin film, 12A denotes a chromium thin film pattern, 12B denotes a chromium thin film opening, 13 denotes an electron beam resist, 13A denotes a resist pattern, and 13B denotes a resist opening. , 14 are electron beams (beams), 21 is a phase mask, 26 is a concave groove, and 27 is a ridge.

First, as shown in FIG. 6A, a blank 10 was prepared by sputtering a chromium thin film 12 having a thickness of 150 mm on a quartz substrate 11 by sputtering. The chromium thin film 12 is useful for preventing charge-up when irradiating the electron beam resist 13 with the electron beam 14 in a later step, and serves as a mask when forming the concave groove 26 in the quartz substrate. Controlling the thickness is also important from the viewpoint of resolution, and a thickness of 100 to 200 mm is appropriate.

Next, as shown in FIG. 6 (b), an electron beam resist RE5100P (manufactured by Hitachi Chemical Co., Ltd.) was used as the electron beam resist 13 to a thickness of 400 nm and dried.

Thereafter, as shown in FIG. 6C, the electron beam resist 13 was described with an electron beam lithography system MEBESIII (manufactured by ETEC) at an exposure amount of 1.2 μC / cm ² with reference to FIGS. Thus, the pitch of the grooves 26 is linearly increased from the left to the right or from the front to the back of the figure according to the position in the direction orthogonal to the grooves 26 or the position in the direction of the grooves 26, and While the width of the ridge 27 is increased in accordance with the change, the number of raster scan lines for drawing one concave groove 26 is set to 5 at any position, so that the number of scan lines of the electron beam 14 is reduced. Exposure was performed while sequentially controlling the width of.

After exposure, baking at 90 ° C. for 5 minutes (PEB: Post Exposure Baking), and then developing the electron beam resist 13 with 2.38% concentration of TMAH (tetramethylammonium hydroxide), as shown in FIG. A desired resist pattern 13A was formed. The post-exposure bake (PEB) is for selectively increasing the sensitivity of the portion irradiated with the electron beam 14.

Next, using the resist pattern 13A as a mask, dry etching was performed using CH ₂ Cl ₂ gas to form a chromium thin film pattern 12A as shown in FIG.

Next, as shown in FIG. 6F, the quartz substrate 11 was etched to a depth of 240 nm using CF ₄ gas using the chromium thin film pattern 12A as a mask. The control of the depth is performed by controlling the etching time, and the etching can be performed by controlling the depth within a range of 200 to 400 nm.

Thereafter, as shown in FIG. 6 (g), the resist pattern 13A is peeled off with sulfuric acid at 70 ° C. Then, as shown in FIG. 6 (h), the chromium thin film pattern 12A is formed with a ceric ammonium nitrate solution. After etching and removing, and after a cleaning process, a line (convex stripe 27) & space (line 27) having a depth of 240 nm and a pitch linearly changing from 0.85 μm to 1.25 μm in the direction orthogonal to the groove 26 or in the direction of the groove 26. The phase mask 21 with the concave groove 26) was completed.

Although the phase mask for processing an optical fiber and the method of manufacturing the same according to the present invention have been described above based on the embodiments, the present invention is not limited to these embodiments, and various modifications are possible. In the above description of the present invention, a raster scan type electron beam lithography apparatus is used. However, the present invention may be applied to a case where a vector scan type apparatus or another method is used. Can be.

FIG. 4 is a top view for explaining a first drawing method used in the manufacturing method of the present invention. It is a figure which shows the electron beam drawing method used in the manufacturing method of a phase mask, and the cross section of a phase mask. FIG. 9 is a top view for explaining a second drawing method used in the manufacturing method of the present invention. FIG. 11 is a diagram for explaining a shift width between concave grooves in adjacent regions in a second drawing method. FIG. 4 is a diagram schematically illustrating a drawing method according to the present invention, as compared with the case according to the related art. FIG. 4 is a cross-sectional view showing a step of one embodiment of the method for manufacturing a phase mask of the present invention. It is a figure for explaining optical fiber processing and a phase mask used for it.

Explanation of reference numerals

Reference Signs List 10 phase mask blank 11 quartz substrate 12 chrome thin film 12A chrome thin film pattern 12B chrome thin film opening 13 electron beam resist 13A resist pattern 13B resist opening 14 electron beam (beam)
21 phase shift mask 22 optical fiber 22A optical fiber core 22B optical fiber clad 23 KrF excimer laser light 24 interference fringe pattern 25A 0th order light (beam)
25B ... plus one scanning line A ₁ to A-order diffracted light 25C ... minus first-order diffracted light 26 ... groove 27 ... projections 28 ... electron beam ₃ ... region B ₁ .about.B ₈ ... region P ₁ to P ₈ ... Pitch

Claims (9)

A repetitive pattern of lattice-like concave grooves and convex stripes is provided on one surface of a transparent substrate, and a diffraction grating is formed in the optical fiber by irradiating the optical fiber with the diffracted light according to the repetitive pattern and interference fringes of diffracted light of different orders. In the method of manufacturing a phase mask for optical fiber processing, when preparing a repetitive pattern of the lattice-shaped groove and the ridge by drawing a plurality of patterns consisting of grooves and ridges having different pitches in parallel, Based on the drawing data of the basic pattern consisting of one groove and a ridge, the pattern of the groove and the ridge having the different pitch is continuously drawn by changing the scale of the drawing data of the basic pattern. A method of manufacturing a phase mask for processing an optical fiber, wherein a repetitive pattern of the above-mentioned lattice-shaped concave grooves and convex stripes is produced. 2. The method of manufacturing a phase mask for optical fiber processing according to claim 1, wherein the plurality of patterns are drawn in parallel in a direction perpendicular to the groove. 2. The method according to claim 1, wherein the plurality of patterns are drawn in parallel with each other in a groove direction. The deviation width in the direction orthogonal to the groove between one groove of one pattern and the groove of the adjacent pattern is within the width of one groove at the left and right outermost ends. 4. The method for producing a phase mask for optical fiber processing according to item 3. The change according to the pitch position of the repetitive pattern of the lattice-shaped concave grooves and the convex stripes is determined according to the change in the pitch of the diffraction grating produced in the optical fiber, and the scale of the drawing data of the basic pattern is reduced. 2. The method of manufacturing a phase mask for optical fiber processing according to claim 1, wherein the phase mask is provided by a change according to a position. The number of scanning lines for drawing one of the grooves or ridges of each of the plurality of patterns including the grooves and the ridges having different pitches and the number of scanning lines for blanking the other are the same in any of the patterns. The method for manufacturing a phase mask for processing an optical fiber according to any one of claims 1 to 5, wherein: The method of manufacturing a phase mask for processing an optical fiber according to claim 1, wherein the repetitive pattern of the lattice-like concave grooves and the convex stripes is formed by electron beam lithography. The phase mask according to any one of claims 1 to 7, wherein a pitch of the repetition pattern of the lattice-shaped concave groove and the convex stripe varies between 0.85 µm and 1.25 µm. Manufacturing method. The difference between the height of the concave groove and the height of the convex stripe of the repetition pattern of the lattice-shaped concave groove and the convex stripe is characterized in that the phase is shifted by approximately π when ultraviolet rays for optical fiber processing are transmitted. The method for producing a phase mask for processing an optical fiber according to claim 1.

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