JP2002372612A - Scanning type exposure device and manufacturing method for grating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the conventional problem in which distribution of irradiation intensity can not be controlled flexibly at an arbitrary rate of change relative to the longitudinal direction of more than one optical fibers simultaneously exposed. SOLUTION: The device is equipped with a laser beam source 1 for emitting a laser beam; an optical path scanning optical system 2 which emits through an optical path scanning in the x-axis direction the laser beam emitted by the laser beam source 1; a phase mask 4 which has in the x-axis direction a phase-modulation type transmissive diffraction grating having a prescribed period and which diffracts the incident laser beam into a plurality of optical fibers 5 through such diffraction grating; and a beam profile converting optical system 3 which is installed between the optical path scanning optical system 2 and the phase mask 4 and which emits the laser beam from the optical system 2 to the phase mask 4 by converting the laser beam into a vertically-long beam profile BP1 of an elliptical cross section having a short and a long axis in the x- and the y-axis direction respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning type exposure apparatus for manufacturing and manufacturing an optical fiber grating by exposing and scanning an optical fiber with a laser beam, and more particularly to a method for manufacturing a grating. The present invention relates to a scanning type exposure apparatus and a grating manufacturing method capable of simultaneously exposing a light beam to the same.

[0002]

2. Description of the Related Art An optical fiber grating is obtained by giving a periodic refractive index change in the longitudinal direction of an optical fiber, and is a device that reflects only light of a specific wavelength according to the period of the refractive index change. is there. As a manufacturing method of the optical fiber grating, a phase mask method (for example, US Pat.
No. 67588) is well known. The outline of manufacturing an optical fiber grating by the phase mask method is described in detail in, for example, Japanese Patent Application Laid-Open No. 11-326669.

A method of manufacturing an optical fiber grating using a phase mask utilizes a phenomenon that, when ultraviolet light is irradiated on silica glass doped with germanium, the refractive index increases according to the irradiation amount. A phase mask having a plurality of slits formed at regular intervals is provided on the upper surface of an optical fiber having this material as a main component, and the upper surface of the phase mask is irradiated with ultraviolet light vertically. Then, on the lower surface of the phase mask, the 0th-order light traveling straight is suppressed, and interference fringes due to the ± 1st-order diffracted light are formed. As a result, the intensity of the ultraviolet light periodically changes due to the interference fringes. It can be formed on the core of an optical fiber.

Conventionally, since laser light is exposed to each optical fiber one by one, the production efficiency is low, and it is not suitable for mass production of optical fiber gratings. Further, since the amount of change in the refractive index with respect to the irradiation intensity varies depending on the temperature and humidity conditions at the time of irradiation, the filter characteristics of the optical fiber grating often vary with each exposure. Further, it is necessary to scan a laser beam on an optical fiber core of several to several tens μm in the longitudinal direction, and there is a problem that the irradiation intensity fluctuates due to a scanning position error.

As a technique for solving these problems, the following technique has been disclosed in which a plurality of optical fibers are arranged in parallel to perform exposure scanning. FIG. 11 is a diagram showing a configuration of a conventional scanning type exposure apparatus, which is cited from Japanese Patent Application Laid-Open No. 10-319255.

In FIG. 11, 101 is a plurality of optical fibers, 102 is a support, 103 is a phase mask, 104 is a laser light source, 105 is a first lens, 106, 107, and 1
08 denotes a lens group, 109 denotes an aperture, 110 denotes a cylindrical lens, 111 and 112 denote mirrors, and 113 denotes a motor.

In this conventional technique, as shown in FIG. 11, an optical path of a laser beam is fixed, and a support 102 is scanned perpendicularly to a longitudinal direction of a plurality of optical fibers 101 arranged. That is, as shown in FIG. 12, the phase mask 103 and the plurality of optical fibers 101 are fixed on the support 102, and the optical fibers 101 are moved together with the support 102 with respect to the optical path in a direction perpendicular to the longitudinal direction of the optical fibers 101. Scan.
Thus, a plurality of optical fibers 102 can be exposed simultaneously under the same temperature and humidity conditions.

However, when the scanning direction is the optical fiber 10
1 is perpendicular to the longitudinal direction, the irradiation intensity distribution in the longitudinal direction is determined by the irradiation intensity distribution determined by the intensity distribution of the laser beam and the light condensing characteristics of the cylindrical lens 110, and an arbitrary change rate with respect to the longitudinal direction of the optical fiber. It is difficult to control the irradiation intensity distribution flexibly.

The control of the irradiation intensity distribution in the longitudinal direction of the optical fiber is required, for example, in the following cases (A) and (B). (A) The envelope of the refractive index change in the longitudinal direction of the optical fiber has a specific window function (for example, Gaussian function or Cosin function).
When setting the irradiation intensity distribution in the longitudinal direction of the optical fiber so as to obtain a bell-shaped function such as a function) (B) When expanding the exposure range beyond the beam diameter of the laser beam to be irradiated

The method (A) is based on apodization (Ap
This is referred to as “modification”, which suppresses the out-of-band reflectance in the filter characteristics of the optical fiber grating, and is known to have an effect of reducing an unnecessary reflected light level and an effect of reducing a reflectance ripple in a band. In order to perform this apodization method, it is necessary to precisely set the irradiation intensity distribution in the longitudinal direction of the optical fiber.

However, when the light beam diameter is realized by enlarging the light beam diameter, the degree of freedom of the design is significantly restricted because the light beam diameter conversion optical system depends on the aberration and the laser beam intensity profile. Further, it is difficult to change the once determined filter characteristic, and it is also difficult to correct a temporal change of the laser beam profile.

On the other hand, the latter (B) has the effect of expanding the operating bandwidth in the dispersion-compensating optical fiber grating. The dispersion-compensating optical fiber grating changes the grating period continuously in the longitudinal direction of the optical fiber, so that the laser light is reflected at grating positions different depending on the wavelength, and the time required for the laser light to return to the incident end. Is given a delay time difference for each wavelength to perform dispersion compensation.

For this reason, the wavelength range in which the dispersion can be compensated is determined by the writing range of the optical fiber grating. For example, a grating length of 10 cm is required for dispersion compensation with a bandwidth of 1.4 nm. In order to further increase the bandwidth, it is necessary to increase the grating length, and it is difficult to uniformly irradiate the laser beam by expanding the luminous flux diameter over such a wide range. It is disadvantageous from the point of view.

In addition, in the prior art, since the core spacing in a plurality of optical fibers is not considered, there is a problem that a component of the irradiated laser light that contributes to a change in the refractive index is small. For example, core diameter 10μ
When two optical fibers having a cladding diameter of 125 μm are arranged in close contact with each other, the projected area ratio of the core to the cladding per unit length is about 1:12, and the irradiation utilization efficiency of laser light exposed with uniform intensity is It is as low as 5%.

[0015]

Since the conventional scanning exposure apparatus and grating manufacturing method are configured as described above, the irradiation intensity distribution can be set to any value in the longitudinal direction of a plurality of optical fibers to be simultaneously exposed. There was a problem that it was not possible to flexibly control the rate of change.

Further, the conventional scanning type exposure apparatus and grating manufacturing method do not take into account the core spacing of a plurality of optical fibers, and therefore have a problem that the efficiency of laser beam irradiation during simultaneous exposure is low. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and enables simultaneous exposure scanning of a plurality of optical fibers and laser beam scanning in the longitudinal direction of the optical fibers, thereby improving production efficiency. It is an object of the present invention to configure a scanning exposure apparatus and a grating manufacturing method that simultaneously realize uniform filter characteristics and flexible control of irradiation intensity distribution in the longitudinal direction of an optical fiber.

Further, the present invention provides a scanning type exposure apparatus and a grating manufacturing method capable of improving the utilization efficiency of laser light irradiation at the time of simultaneous exposure in consideration of the core spacing of a plurality of optical fibers. The purpose is to do.

[0019]

A scanning exposure apparatus according to the present invention includes a laser light source that emits laser light, and an optical path scanning optical system that scans the laser light emitted by the laser light source in the scanning direction and emits the light. A phase mask having a transmission type diffraction grating of a phase modulation type formed at a predetermined period in the scanning direction and diffracting the incident laser light, provided between the optical path scanning optical system and the phase mask, A beam profile conversion optical system that converts a laser beam emitted by an optical path scanning optical system into a vertically elongated beam profile having an elliptical cross section having a short axis and a long axis in the arrangement direction of the optical fibers, and emits the beam to a phase mask. Is provided.

In the scanning exposure apparatus according to the present invention, the beam profile conversion optical system is position-scanned in the scanning direction in synchronization with the optical path scanning of the laser beam emitted from the optical path scanning optical system.

In the scanning type exposure apparatus according to the present invention, a beam profile conversion optical system is composed of two achromatic prisms which convert the laser beam emitted from the optical path scanning optical system into a vertically long beam profile and emit the laser beam. It is like that.

In the scanning exposure apparatus according to the present invention, the beam profile conversion optical system is constituted by two cylindrical lenses which convert the laser beam emitted from the optical path scanning optical system into a vertically long beam profile and emit the beam. It was made.

A scanning exposure apparatus according to the present invention includes a first phase mask having a first phase modulation type transmission diffraction grating formed in a first cycle in a scanning direction, and a first phase mask formed in a second cycle. A second phase modulation type transmission diffraction grating in the arrangement direction, and a plurality of periods of the maximum intensity of interference fringes generated in the arrangement direction by laser light diffracted through the second phase modulation type transmission diffraction grating. And a second phase mask having a second period determined so as to coincide with the core interval of the optical fiber. The phase mask includes a first phase modulation type transmission diffraction grating and a second phase mask.
The laser light emitted from the beam profile conversion optical system is diffracted into a plurality of optical fibers via the phase modulation type transmission diffraction grating.

In the scanning exposure apparatus according to the present invention, a first phase mask and a second phase mask are integrated to form a phase mask.

A scanning exposure apparatus according to the present invention has a first phase modulation type transmission diffraction grating formed in a first period in a scanning direction and a second phase modulation type diffraction grating formed in a second period. Type transmission grating in the arrangement direction, and the cycle of the maximum intensity of the interference fringes generated in the arrangement direction by the laser beam diffracted through the second phase modulation type transmission grating is equal to or greater than the number of optical fibers. A phase mask is composed of one two-dimensional phase mask having a second period determined so as to coincide with the core interval, and a first phase modulation type transmission diffraction grating and a second phase modulation type transmission diffraction grating are formed. The laser beam emitted from the beam profile conversion optical system is diffracted through the optical system and irradiates a plurality of optical fibers.

In the scanning exposure apparatus according to the present invention, a plurality of cylindrical lenses each having a condensing lens function only in the arrangement direction are arrayed, and a plurality of condensing lines are formed on a plurality of condensing lines generated on a rear focal plane. The optical fiber is provided in front of the phase mask along the optical fiber, and the phase mask includes a cylindrical lens array in which the distance to the plurality of optical fibers is matched with the focal length of the cylindrical lens.

In the scanning exposure apparatus according to the present invention, a phase mask is formed integrally with a cylindrical lens array.

According to the scanning exposure apparatus of the present invention, a beam splitter mirror for splitting a laser beam incident from a beam profile conversion optical system at a predetermined incident angle into two optical paths in an array direction and emitting the split laser beam is provided at a predetermined interval from each other. Two mirrors for reflecting the laser light split into two by the beam splitter mirror to the phase mask and causing two light beams to interfere with each other on the plurality of optical fibers by the facing reflecting surfaces; The predetermined incident angle or the predetermined interval is adjusted so that the cycle of the maximum intensity of the interference fringe coincides with the core interval of the plurality of optical fibers.

According to the grating manufacturing method of the present invention, a laser beam emitted from a laser light source is scanned in a longitudinal direction, and an elliptical section having a short axis and a long axis in a scanning direction and an arrangement direction of a plurality of optical fibers, respectively. The laser beam is converted into a vertically elongated beam profile, the converted laser beam is diffracted, and the diffracted laser beam is applied to a plurality of optical fibers arranged in parallel in the longitudinal direction.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a diagram showing a configuration of a scanning exposure apparatus according to Embodiment 1 of the present invention. In FIG. 1, 1
Is a laser light source that emits laser light of a single wavelength, 2 is an optical path scanning optical system that scans and emits laser light from the laser light source 1 in the scanning direction, and 3 is a beam of laser light from the optical path scanning optical system 2. A beam profile conversion optical system for converting and shaping the profile and emitting the beam; 4 a phase mask for diffracting the laser beam from the beam profile conversion optical system 3 by a phase modulation type transmission diffraction grating having a predetermined period;
Reference numeral 5 denotes a plurality of optical fibers.

In FIG. 1, the z-axis is arranged in the emission direction of the laser beam from the phase mask 4, the x-axis is arranged in the scanning direction, and the y-axis is arranged in the direction orthogonal to the x-axis and the z-axis. The optical fibers 5 are arranged such that their longitudinal directions are overlapped in the x-axis direction (scanning direction) and in the y-axis direction (arrangement direction).

In FIG. 1, reference numeral BP0 denotes a symmetric beam profile, and reference numeral BP1 denotes a vertically long beam profile, which schematically shows the beam profile of the laser beam. When the symmetric beam profile BP0 is cut along a plane orthogonal to the z-axis, the cut surface becomes a perfect circle. On the other hand, when the longitudinal beam profile BP1 is cut along a plane orthogonal to the z-axis, the cut surface is in the x-axis direction and
It has an elliptical cross-sectional shape having a short axis and a long axis in the axial direction.

A laser beam traveling from the laser light source 1 to the optical path scanning optical system 2 and a laser beam traveling from the optical path scanning optical system 2 to the beam profile conversion optical system 3 have a symmetric beam profile BP0. The laser light emitted from the beam profile conversion optical system 3 to the phase mask 4 and the optical fiber 5 has a vertically long beam profile BP1. That is, the laser beam has a symmetric beam profile B
The beam profile is converted from P0 into a vertically long beam profile BP1 by the beam profile conversion optical system 3.

Next, the operation will be described. Laser light source 1
The laser beam having the symmetrical beam profile BP0 emitted from the optical path scanning optical system 2 enters the optical path scanning optical system 2. The optical path scanning optical system 2 includes:
The optical path of the incident laser light is scanned in the x-axis direction and emitted. At this time, the parallelism and the deflection angle of the beam are not changed. When the laser beam having the symmetric beam profile BP0 emitted from the optical path scanning optical system 2 is received, the beam profile conversion optical system 3 outputs the longitudinal beam profile BP.
The laser beam is converted into one laser beam and emitted to the phase mask 4.

FIGS. 2 and 3 show a first configuration example and a second configuration example of the beam profile conversion optical system 3, respectively. The same reference numerals as those in FIG. 1 indicate corresponding parts. In FIG. 2, reference numerals 3P1 and 3P2 denote achromatic prisms, respectively, and the beam profile conversion optical system 3 is configured by an anamorphic optical system in which two achromatic prisms 3P1 and 3P2 are combined. By using the achromatic prisms 3P1 and 3P2 in this manner, the beam profile conversion optical system 3 can be configured simply and compactly.

In FIG. 3, reference numerals 3L1 and 3L2 denote cylindrical lenses, respectively. The beam profile conversion optical system 3 includes cylindrical lenses 3L1 and 3L.
2 are combined. Thus, even if the cylindrical lenses 3L1 and 3L2 are used, the beam profile conversion optical system 3 can be simplified and downsized.

As described above, according to the configuration examples shown in FIGS. 2 and 3,
Before and after the beam profile conversion, the beam profile is converted while maintaining the parallelism of the beam and the deflection angle of the beam. At this time, the beam profile conversion optical system 3 has a width equal to or longer than the scanning distance in the x-axis direction in order to always realize the same beam profile conversion characteristic with respect to the optical path scanning in the x-axis direction by the optical path scanning optical system 2. And fixed to the optical path.

The position scanning of the beam profile conversion optical system 3 in the scanning direction may be performed in synchronization with the scanning of the laser beam by the optical path scanning optical system 2. By doing so, the size of the beam profile conversion optical system 3 can be reduced to about the beam diameter of the laser light, and the cost can be reduced. In addition, even if a wavefront aberration that varies depending on the manufacturing accuracy of the beam profile conversion optical system 3 is parasitic for each portion, the beam profile conversion optical system 3
, The laser beam always passes through the same part of the beam profile conversion optical system 3, so that the influence of the above-mentioned parasitic wavefront aberration can be reduced.

FIG. 4 is a diagram showing a configuration of a scanning type exposure apparatus according to Embodiment 1 of the present invention, in which a plurality of optical fibers 5 are irradiated with a laser beam having a vertically long beam profile BP1 via a phase mask 4. FIG. Laser light source 1 to beam profile conversion optical system 3
The configuration up to this point is not shown.

As shown in FIG. 4, the laser beam having the converted longitudinal beam profile BP1 enters a phase mask 4 having a periodic refractive index change in the x-axis direction as a phase modulation type transmission diffraction grating. In the vicinity of the exit surface of the phase mask 4, ± 1 having an angle equal to the absolute value with respect to the incident direction.
Next-order diffracted light D is emitted, and interference fringes I are generated in the x-axis direction. An interference fringe I whose period is determined by the pitch of the phase mask 4 (the period of the phase modulation type transmission diffraction grating).
Is applied to the photosensitive fiber core of each optical fiber 5 to periodically change the core refractive index.

A plurality of photosensitive fiber cores are arranged so that the longitudinal direction is the x-axis direction, and the converted beam having the longitudinal beam profile BP1 is composed of a plurality of optical fibers 5.
Irradiate all of the cores. Thus, simultaneous exposure can be performed on a plurality of optical fibers 5 in a state where the temperature condition, the humidity condition, and the irradiation time are made common, and the production efficiency can be improved.

Further, the beam profile conversion optical system 3 uses the beam profile conversion optical system 3 until the irradiation intensity on the core center of the plurality of optical fibers 5 becomes equal.
P1 is extended in the y-axis direction. Alternatively, the symmetric beam profile BP0 is temporarily expanded, only the portion where the intensity distribution can be regarded as flat is cut out, and then the beam is expanded again in the y-axis direction to obtain the longitudinal beam profile BP1.
And Thereby, the irradiation energy conditions for the cores of the plurality of optical fibers 5 can be shared, the exposure conditions for the plurality of optical fibers 5 can be unified, and the filter characteristics of the optical fiber grating can be made uniform.

On the other hand, by using the optical path scanning optical system 2,
The laser beam can be scanned in the longitudinal direction of the optical fibers 5 while maintaining the exposure conditions for the plurality of optical fibers 5.
Thereby, the exposure range in the longitudinal direction of the optical fiber 5 can be expanded to be equal to or larger than the light flux diameter in the x-axis direction. By expanding the exposure range in the x-axis direction, the operation bandwidth of the dispersion-compensating optical fiber grating can be increased. Therefore, a plurality of dispersion-compensating optical fiber gratings having an increased operating bandwidth can be manufactured at the same time, and the production efficiency can be improved.

Further, by changing the scanning speed in the x-axis direction, the irradiation intensity distribution in the x-axis direction can be controlled. By controlling the irradiation intensity distribution, apodization can be realized, and the out-of-band reflected light of the optical fiber grating can be suppressed and the in-band reflected ripple can be reduced. Therefore, a plurality of optical fiber gratings having improved filter characteristics by apodization can be manufactured at the same time, and the production efficiency can be improved.

As described above, according to the first embodiment, the laser light source 1 for emitting laser light and the laser light source 1
Has an optical path scanning optical system 2 that scans the emitted laser beam in the x-axis direction and emits it, and a phase modulation type transmission diffraction grating having a predetermined period in the x-axis direction. A phase mask 4 for diffracting the optical fiber 5 through a transmission type diffraction grating of a phase modulation type, and provided between the optical path scanning optical system 2 and the phase mask 4, and have a short axis in the x-axis direction and the y-axis direction. And a beam profile conversion optical system 3 for converting a laser beam emitted from the optical path scanning optical system 2 into a beam profile and emitting the laser beam to the phase mask 4 to a vertically long beam profile BP1 having an elliptical cross section having a major axis and a long axis, respectively. Therefore, simultaneous exposure of a plurality of optical fibers 5 and laser beam scanning in the longitudinal direction of the optical fibers 5 become possible, thereby improving the production efficiency and making the filter characteristics uniform.
The effect is obtained that flexible control of the irradiation intensity distribution in the longitudinal direction of the optical fiber 5 can be realized at the same time.

Further, according to the first embodiment, the beam profile conversion optical system 3 is position-scanned in the x-axis direction in synchronization with the optical path scanning of the laser beam emitted from the optical path scanning optical system 2. In addition to the effect that the beam profile conversion optical system 3 can be reduced in size, the size reduction of the beam profile conversion optical system 3 can reduce the cost, and the parasitic wavefront aberration of the beam profile conversion optical system 3 can be reduced. The effect of reduction can be obtained.

Further, according to the first embodiment, the laser beam emitted from the optical path scanning optical system 2 is converted into a vertically elongated beam profile BP1 and emitted.
Since the beam profile conversion optical system 3 is constituted by the achromatic prisms 3P1 and 3P2, the effect that the beam profile conversion optical system 3 can be simply and small-sized can be obtained.

Further, according to the first embodiment, the laser beam emitted from the optical path scanning optical system 2 is converted into a vertically elongated beam profile BP1 and emitted.
Since the beam profile conversion optical system 3 is constituted by the cylindrical lenses 3L1 and 3L2,
The effect is obtained that the beam profile conversion optical system 3 can be configured simply and compactly.

Embodiment 2 FIG. 5 is a diagram showing a configuration of a scanning type exposure apparatus according to Embodiment 2 of the present invention, showing a state in which a laser beam having a vertically long beam profile BP1 exposes a plurality of optical fibers 5 via a phase mask 4. I have. The same reference numerals as those in FIG. 1 denote corresponding components, and the configuration from the laser light source 1 to the beam profile conversion optical system 3 is omitted in the drawing.

In FIG. 5, reference numerals 4X and 4Y denote phase masks, respectively. One phase mask (first phase mask) 4
X is a transmission type diffraction grating of the phase modulation type (first transmission type diffraction grating) in the x-axis direction (scanning direction), and the other phase mask (second phase mask) 4Y is the y-axis direction (array). Direction), a phase modulation type transmission diffraction grating (second phase modulation type transmission diffraction grating) is periodically formed, and the phase mask 4 is composed of phase masks 4X and 4Y. The feature of the second embodiment is that two phase masks 4X and 4Y each having a periodic structure in the x-axis direction and the y-axis direction are used.

Next, the operation will be described. When the laser beam having the vertically long beam profile BP1 emitted from the beam profile conversion optical system 3 enters the phase mask 4Y, y
The light is emitted as ± 1st-order diffracted light D1 in the axial direction from the phase mask 4Y. The ± 1st-order diffracted light D1 becomes an interference fringe I1 in the phase mask 4X, and ± 1st-order diffracted light D2 having the same absolute value with respect to the x-axis direction and the y-axis direction is emitted from the phase mask 4X. . And this ±
The first-order diffracted light D2 irradiates the optical fiber 5 with interference fringes I2 formed in a lattice in the x-axis direction and the y-axis direction.

Regarding the periodicity of the interference fringes I2 in the x-axis direction, a desired change in the refractive index is given as in the first embodiment. A periodic change in the core refractive index of the optical fiber 5 can be written in the x-axis direction by the interference fringe intensity whose period is determined by the pitch (first period) of the phase modulation type transmission diffraction grating of the phase mask 4X.

On the other hand, the periodicity of the interference fringes I2 in the y-axis direction matches the pitch of the phase modulation type transmission diffraction grating of the phase mask 4Y (the second period) so as to match the core interval of the plurality of optical fibers 5. ) And make the maximum point of the interference intensity coincide with the core center. Thereby, compared with the case where only the phase mask 4 of the first embodiment is used, the laser beam irradiated on the portion other than the core of the optical fiber 5, for example, the clad portion can be concentrated on the core portion. Therefore, it is possible to improve the efficiency of using laser light for giving a change in the refractive index to the core, so that the exposure time can be reduced as compared with the first embodiment, and the production efficiency can be further improved.

In FIG. 5, the phase masks 4X and 4Y are installed at spatially separated positions. However, these two phase masks 4X and 4Y may be adhered and integrated. By doing so, the two phase masks 4X and 4
Alignment for arranging Y at right angles is not required, so that cost reduction by reducing the alignment adjustment mechanism and improvement in installation accuracy can be achieved.

Further, as shown in FIG. 6, a single phase mask (two-dimensional phase mask) 4XY may be provided with the refractive index periods in the x-axis direction and the y-axis direction. In this case, in the x-axis direction and the y-axis direction, the period of the phase modulation type transmission diffraction grating (the first phase modulation type transmission diffraction grating, the second phase modulation type transmission diffraction grating) (first period). (The cycle, the second cycle) may be determined in the same manner as in the case of the phase masks 4X and 4Y. Even in this case, the two phase masks 4
Alignment for arranging X and 4Y at right angles is not required, so that cost reduction and improvement in installation accuracy can be achieved by reducing the alignment adjustment mechanism.

As described above, according to the second embodiment, the first phase mask 4X having the first phase modulation type transmission diffraction grating formed in the first period in the x-axis direction,
An interference fringe generated in the y-axis direction by a laser beam diffracted through the second phase modulation type transmission type diffraction grating having a second phase modulation type transmission type diffraction grating formed in a period in the y-axis direction. And a second phase mask 4Y having a second cycle determined so that the cycle of the maximum intensity of the first phase coincides with the core interval of the plurality of optical fibers 5. The first phase modulation type transmission diffraction grating In addition, since the laser light emitted from the beam profile conversion optical system 3 is diffracted to a plurality of optical fibers 5 via the second phase modulation type transmission diffraction grating, the efficiency of laser light irradiation is improved. As a result, the exposure time can be shortened, and the production efficiency can be further improved.

According to the second embodiment, the phase mask 4 is constructed by integrating the first phase mask 4X and the second phase mask 4Y, so that the installation accuracy of the phase mask 4 is improved. That is, the cost can be reduced by reducing the number of parts and the alignment adjustment mechanism.

Further, according to the second embodiment, the first
A first phase modulation type transmission diffraction grating formed in the second cycle in the x-axis direction;
Having a phase modulation type transmission type diffraction grating in the y-axis direction.
The second period is set such that the period of the maximum intensity of the interference fringes generated in the y-axis direction by the laser light diffracted through the phase modulation type transmission diffraction grating coincides with the core interval of the plurality of optical fibers 5. The phase mask 4 is composed of two two-dimensional phase masks 4XY, and is emitted from the beam profile conversion optical system 3 via the first phase modulation type transmission diffraction grating and the second phase modulation type transmission diffraction grating. Since the laser beam thus obtained is diffracted into a plurality of optical fibers 5, the number of phase masks 4 can be reduced, the laser beam irradiation utilization efficiency can be improved, and the exposure time can be shortened. The effect that the production efficiency can be further improved is obtained.

Embodiment 3 FIG. 7 is a diagram showing a configuration of a scanning type exposure apparatus according to Embodiment 3 of the present invention, showing a state in which a laser beam having a vertically long beam profile BP1 exposes a plurality of optical fibers 5 via a phase mask 4. I have. The same reference numerals as those in FIGS. 1 and 5 denote corresponding elements, and the laser light source 1 is used to convert the beam profile conversion optical system 3
The configuration up to this point is not shown.

In FIG. 7, reference numeral 6 denotes the y-axis direction (array direction).
This is a cylindrical lens array formed by arraying a plurality of cylindrical lenses each having a condensing lens function, and is disposed in front of the phase mask 4 having the one-dimensional periodic structure used in the first embodiment. The parallel light that has entered the cylindrical lens array 6 is condensed on a line on the rear focal plane of the cylindrical lens array 6.

A plurality of optical fibers 5 are arranged along a plurality of converging lines generated on the rear focal plane of the cylindrical lens array 6, and the distance between the cylindrical lens array 6 and the optical fiber 5 is determined by the length of the cylindrical lens. Set up to match the focal length. Cylindrical lens array 6
The laser light distributed between the cores of the optical fibers 5 can be efficiently radiated to the cores of the optical fibers 5 by the light condensing action of the optical fiber 5.

On the other hand, the refractive index change direction of the phase mask 4 is
As in the first embodiment, the optical fiber 5 is set in the longitudinal direction (x-axis direction, scanning direction). ± 1 generated in phase mask 4
Interference fringes I of the next-order diffracted lights D are generated on the emission side of the phase mask 4, whereby an intensity distribution having periodicity in the longitudinal direction of the optical fiber 5 can be realized.

By combining the cylindrical lens array 6 and the phase mask 4, it becomes possible to efficiently irradiate the core of the optical fiber 5 with laser light having a periodic intensity distribution in the longitudinal direction. In addition, by using the optical path scanning optical system 2 and scanning in the x-axis direction while maintaining the exposure conditions for the plurality of optical fibers 5, the exposure range in the x-axis direction can be expanded, and the dispersion-compensating optical fiber grating Operating bandwidth can be increased.

Further, by changing the scanning speed in the x-axis direction, the irradiation intensity distribution in the x-axis direction can be controlled. Apodization can be realized by controlling the irradiation intensity distribution. Proper apodization has the effect of suppressing the out-of-band reflected light of the optical fiber grating and reducing the in-band reflected ripple.

Therefore, a plurality of optical fiber gratings having improved filter characteristics by apodization can be manufactured at the same time, and the irradiation efficiency of laser light for giving a change in the core refractive index can be improved as compared with the first embodiment. Therefore, the exposure time can be shortened, and the production efficiency can be further improved.

In FIG. 7, the cylindrical lens array 6
Although FIG. 8 shows a case in which the phase mask 4 and the phase mask 4 are installed at a spatially separated position, the cylindrical lens array 6 and the phase mask 4 may be closely mounted and integrally installed as shown in FIG. . This eliminates the need for alignment for aligning the relative azimuth between the cylindrical lens array 6 and the phase mask 4 at a right angle, and has the effects of reducing costs by reducing the alignment adjustment mechanism and improving the installation accuracy.

As described above, according to the third embodiment, a plurality of cylindrical lenses each having a condensing lens function only in the y-axis direction are arrayed, and a plurality of condensing lenses formed on the rear focal plane are formed. A plurality of optical fibers 5 are provided in front of the phase mask 4 along the light beam, and a cylindrical lens array 6 in which the distance to the plurality of optical fibers 5 is matched with the focal length of the cylindrical lens is used. Is provided, it is possible to improve the utilization efficiency of laser beam irradiation, and it is possible to shorten the exposure time, thereby further improving the production efficiency.

According to the third embodiment, since the phase mask 4 is formed integrally with the cylindrical lens array 6, the effect of improving the installation accuracy of the phase mask 4 is obtained. The effect of reducing costs by reducing the number of points and the alignment adjustment mechanism can be obtained.

Embodiment 4 FIG. 9 is a diagram showing a configuration of a scanning exposure apparatus according to Embodiment 4 of the present invention, showing a state in which a laser beam having a vertically long beam profile BP1 exposes a plurality of optical fibers 5 via a phase mask 4. I have. The same reference numerals as those in FIGS. 1 and 5 denote corresponding elements, and the laser light source 1 is used to convert the beam profile conversion optical system 3
The configuration up to this point is not shown.

In FIG. 9, reference numeral 7 denotes a beam splitter mirror for splitting a laser beam incident from the beam profile conversion optical system 3 at a predetermined incident angle. Reference numerals 8A and 8B denote mirrors, each having a reflecting surface facing each other at a predetermined interval, and transmitting the laser light split by the beam splitter mirror 7 to a plurality of optical fibers 5 via a phase mask 4. And reflect each. Embodiment 4
In this example, a beam splitter mirror 7 and two mirrors 8A and 8B are provided between a beam profile conversion optical system 3 and a phase mask 4 having a one-dimensional periodic structure. Achieve irradiation intensity.

Next, the operation will be described. First, the vertically elongated beam profile B by the beam profile conversion optical system 3 is used.
The parallel beam converted into P1 is split by the beam splitter mirror 7 into two optical paths in the y-axis direction (array direction).
Each longitudinal beam profile BP1 divided into two optical paths
The laser beams A and BP1B are reflected by the mirrors 8A and 8B, respectively, and interfere with two light beams on the plurality of optical fibers 5. Beam splitter mirror 7 and mirrors 8A and 8B
And the two beams interfere with each other, the longitudinal direction (x
An interference fringe parallel to the axial direction and the scanning direction is generated. By adjusting the pitch of the interference fringes to the interval between the centers of the cores of the optical fiber 5, it is possible to expose the center of the core with a high irradiation intensity.

On the other hand, the direction of change in the refractive index of the phase mask 4 is
As in the first embodiment, the optical fiber 5 is set in the longitudinal direction (x-axis direction, scanning direction). ± resulting from phase mask 4
An interference fringe I2 between the first-order diffracted lights is generated on the emission side of the phase mask 4, whereby an intensity distribution having periodicity in the longitudinal direction of the optical fiber 5 can be realized.

As shown in FIG. 10, interference fringes between ± first-order diffracted lights by the phase mask 4 in the x-axis direction and interference fringes due to two-beam interference occur in the y-axis direction. On the plurality of optical fibers 5, interference fringes I2 are generated in a lattice shape. The interval between the interference fringes due to the two-beam interference in the y-axis direction includes the incident angle of the laser beam on the beam splitter mirror 7, the interval between the respective reflection surfaces of the mirrors 8A and 8B,
That is, since the adjustment can be performed by adjusting the angle at which the two light beams intersect, even when the interval between the plurality of optical fibers 5 is changed, the adjustment can be performed so that the high irradiation intensity point is located at the center of the core. Thus, when the distance between the optical fibers 5 is changed or when the distance is shifted, fine adjustment can be made by the angle at which the two light beams intersect.

Further, by using the optical path scanning optical system 2 to scan in the x-axis direction while maintaining the exposure conditions for the plurality of optical fibers 5, the exposure range in the x-axis direction can be expanded, and the dispersion compensation type The operating bandwidth of the optical fiber grating can be increased.

Further, by changing the scanning speed in the x-axis direction, the irradiation intensity distribution in the x-axis direction can be controlled. Apodization can be realized by controlling the irradiation intensity distribution. Appropriate apodization has the effect of suppressing the out-of-band reflected light of the optical fiber grating and reducing the in-band reflected ripple.

Therefore, a plurality of optical fiber gratings having improved filter characteristics by apodization can be manufactured at the same time, and the use efficiency of irradiation light for giving a change in the core refractive index can be improved as compared with the first embodiment. Therefore, the exposure time can be shortened, and the production efficiency can be further improved.

As described above, according to the fourth embodiment, the beam splitter mirror 7 which divides the laser beam incident from the beam profile conversion optical system 3 at a predetermined incident angle into two optical paths in the y-axis direction and emits the split laser beam. And two mirrors 8A, which reflect the laser beams split by the beam splitter mirror 7 by the reflecting surfaces facing each other at a predetermined interval to the phase mask 4 to cause two light beams to interfere with each other on the plurality of optical fibers 5. 8B, the predetermined incident angle or the predetermined interval is adjusted so that the cycle of the maximum intensity of the interference fringes generated in the y-axis direction by the two-beam interference coincides with the core interval of the plurality of optical fibers 5. , Laser light irradiation efficiency can be improved, and the effect that the exposure time can be shortened and the production efficiency can be further improved is obtained,
Further, when the distance between the optical fibers 5 is changed,
Can be dealt with even if there is a gap in the distance.

[0078]

As described above, according to the present invention, a laser light source for emitting laser light, an optical path scanning optical system for scanning the laser light emitted from the laser light source in the scanning direction and emitting the laser light, A phase mask having a transmission type diffraction grating of a phase modulation type, which is formed at a predetermined period and diffracts the incident laser light, and is provided between the optical path scanning optical system and the phase mask, the scanning direction and a plurality of light beams. A beam profile conversion optical system that converts a laser beam emitted by the optical path scanning optical system into a beam profile and emits the laser beam to a phase mask into a vertically long beam profile having an elliptical cross section having a short axis and a long axis in the fiber arrangement direction, respectively. As a result, simultaneous exposure of a plurality of optical fibers and laser beam scanning in the longitudinal direction of the optical fibers can be performed, thereby improving production efficiency and filling. Effect that uniformity of characteristics and the optical fiber longitudinal direction of the irradiation intensity distribution for flexible control and at the same time can be realized.

According to the present invention, the beam profile conversion optical system is position-scanned in the scanning direction in synchronization with the optical path scanning of the laser beam emitted from the optical path scanning optical system. In addition to the effect that the beam profile conversion optical system can be downsized, the effect that the cost can be reduced and the parasitic wavefront aberration of the beam profile conversion optical system can be reduced can be obtained.

According to the present invention, the beam profile conversion optical system is constituted by the two achromatic prisms which convert the laser beam emitted from the optical path scanning optical system into a vertically long beam profile and emit the laser beam. The advantage is that the beam profile conversion optical system can be configured simply and compactly.

According to the present invention, the beam profile conversion optical system is constituted by the two cylindrical lenses which convert the laser light emitted from the optical path scanning optical system into a vertically long beam profile and emit the beam. The effect is obtained that the beam profile conversion optical system can be configured simply and compactly.

According to the present invention, the first phase mask having the first phase modulation type transmission type diffraction grating formed in the first period in the scanning direction and the second phase modulation formed in the second period are provided. Type transmission grating in the arrangement direction, and the cycle of the maximum intensity of the interference fringes generated in the arrangement direction by the laser beam diffracted through the second phase modulation type transmission grating is equal to or greater than the number of optical fibers. A phase mask is composed of a second phase mask having a second period determined so as to match the core interval, and is transmitted through a first phase modulation type transmission diffraction grating and a second phase modulation type transmission diffraction grating. Since the laser beam emitted from the beam profile conversion optical system is diffracted into a plurality of optical fibers, the efficiency of laser beam irradiation can be improved, and the exposure time can be shortened and production efficiency can be reduced. Can be further improved Say the effect can be obtained.

According to the present invention, the first phase mask and the second phase mask
Since the phase mask is configured by integrating the phase mask, the effect of improving the installation accuracy of the phase mask is obtained, and the effect of reducing the cost by reducing the number of components and the alignment adjustment mechanism is obtained.

According to the present invention, the transmission type diffraction grating of the first phase modulation type formed in the first period is provided in the scanning direction, and the transmission type diffraction grating of the second phase modulation type formed in the second period is provided. The diffraction grating is arranged in the arrangement direction, and the period of the maximum intensity of the interference fringes generated in the arrangement direction by the laser light diffracted through the second phase modulation type transmission diffraction grating coincides with the core interval of the plurality of optical fibers. One 2
A phase mask is formed from the two-dimensional phase mask, and diffracts the laser light emitted from the beam profile conversion optical system via the first phase modulation type transmission diffraction grating and the second phase modulation type transmission diffraction grating. Since the irradiation to a plurality of optical fibers, the number of phase masks can be reduced, and the efficiency of laser beam irradiation can be improved.
The effect is obtained that the exposure time can be shortened and the production efficiency can be further improved.

According to the present invention, a plurality of cylindrical lenses each having a condensing lens function only in the arrangement direction are arrayed, and a plurality of optical fibers are arranged on a plurality of condensing lines generated on the rear focal plane. The phase mask has a cylindrical lens array that is provided in front of the phase mask so as to extend along the optical fiber, and the distance to the plurality of optical fibers matches the focal length of the cylindrical lens. As a result, the exposure time can be shortened and the production efficiency can be further improved.

According to the present invention, since the phase mask is formed integrally with the cylindrical lens array, the effect of improving the installation accuracy of the phase mask can be obtained, and the number of parts and the alignment adjustment mechanism can be reduced. The effect that cost can be reduced is obtained.

According to the present invention, a beam splitter mirror that splits a laser beam incident from a beam profile conversion optical system at a predetermined incident angle into two optical paths in an array direction and emits the split beam, and a reflecting surface facing each other at a predetermined interval And two mirrors that respectively reflect the laser light split into two by the beam splitter mirror to the phase mask and cause two light beams to interfere on a plurality of optical fibers. Since the predetermined incident angle or the predetermined interval is adjusted so that the cycle of the intensity matches the core interval of the plurality of optical fibers, the efficiency of use of laser light irradiation can be improved, and the exposure time can be reduced. This has the effect of being able to further improve production efficiency, and there are cases where the spacing between optical fibers is changed or the spacing between optical fibers is misaligned. Effect that it is possible to cope with a case.

According to the present invention, the laser beam emitted from the laser light source is scanned in the longitudinal direction, and a vertically long elliptical sectional shape having a short axis and a long axis in the scanning direction and the arrangement direction of the plurality of optical fibers, respectively. Converted to a beam profile, then diffracted the converted laser light, and then irradiate the diffracted laser light to a plurality of optical fibers arranged in parallel in the longitudinal direction. Simultaneous exposure and laser beam scanning in the longitudinal direction of the optical fiber are possible, improving the production efficiency, uniformizing the filter characteristics, and simultaneously realizing flexible control of the irradiation intensity distribution in the longitudinal direction of the optical fiber. can get.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a scanning exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a first configuration example of a beam profile conversion optical system.

FIG. 3 is a diagram illustrating a second configuration example of the beam profile conversion optical system.

FIG. 4 is a diagram showing a configuration of a scanning exposure apparatus according to Embodiment 1 of the present invention.

FIG. 5 is a diagram showing a configuration of a scanning exposure apparatus according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a scanning exposure apparatus according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a scanning exposure apparatus according to a third embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of a scanning exposure apparatus according to a third embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a scanning exposure apparatus according to a fourth embodiment of the present invention.

FIG. 10 is a diagram for explaining an operation of a scanning exposure apparatus according to a fourth embodiment of the present invention.

FIG. 11 is a diagram showing a configuration of a conventional scanning exposure apparatus.

FIG. 12 is a diagram for explaining the operation of a conventional scanning exposure apparatus.

[Explanation of symbols]

Reference Signs List 1 laser light source, 2 optical path scanning optical system, 3 beam profile conversion optical system, 4 phase mask, 4X phase mask (first phase mask), 4Y phase mask (second phase mask), 4XY phase mask (two-dimensional phase mask) , 5
Multiple optical fibers, BP0 symmetric beam profile, BP1, BP1A, BP1B longitudinal beam profile, 3P1, 3P2 achromatic prism, 3L1, 3L
2 cylindrical lens, 6 cylindrical lens array, 7 beam splitter mirror, 8A, 8B mirror, D, D1, D2 diffracted light, I, I1, I2 interference fringe.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takaaki Kase 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Minoru Hashimoto 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 3 Rishi Electric Co., Ltd. F-term (reference) 2H049 AA34 AA59 AA62 2H050 AA07 AC82 AC84

Claims (11)

[Claims] 1. A scanning exposure apparatus that irradiates a laser beam to a plurality of optical fibers whose longitudinal directions are arranged in parallel with each other with the longitudinal direction as a scanning direction, wherein: a laser light source that emits the laser light; An optical path scanning optical system that emits the laser light emitted from the laser light source by scanning the optical path in the scanning direction and an optical path scanning optical system that is formed at a predetermined period in the scanning direction and diffracts the incident laser light; A phase mask having a diffraction grating, provided between the optical path scanning optical system and the phase mask, having an elliptical cross-sectional shape having a short axis and a long axis in the scanning direction and the arrangement direction of the plurality of optical fibers, respectively. A beam profile in which the laser beam emitted by the optical path scanning optical system is converted into a vertically elongated beam profile and emitted to the phase mask. Scanning exposure apparatus characterized by comprising a 換光 science system. 2. The scanning exposure apparatus according to claim 1, wherein the beam profile conversion optical system performs position scanning in a scanning direction in synchronization with optical path scanning of laser light emitted from the optical path scanning optical system. 3. A beam profile conversion optical system comprising two achromatic prisms for converting a laser beam emitted from an optical path scanning optical system into a vertically long beam profile and emitting the beam profile. 2. The scanning exposure apparatus according to claim 1. 4. The beam profile conversion optical system is composed of two cylindrical lenses that convert the laser beam emitted from the optical path scanning optical system into a vertically long beam profile and emit the beam profile. The scanning exposure apparatus according to any one of the preceding claims. 5. A phase mask comprising: a first phase modulation type transmission diffraction grating formed in a first period in a scanning direction; and a second phase modulation formed in a second period. Of the interference fringes generated in the arrangement direction by a laser beam diffracted through the second phase modulation type transmission diffraction grating in the arrangement direction. A second phase mask that defines the second period so as to match the fiber core spacing, the first phase modulation type transmission diffraction grating, and the second phase mask.
2. The scanning exposure apparatus according to claim 1, wherein the laser beam emitted from the beam profile conversion optical system is diffracted to the plurality of optical fibers via the phase modulation type transmission diffraction grating. 6. The scanning exposure apparatus according to claim 5, wherein the phase mask is formed by integrating the first phase mask and the second phase mask. 7. A phase mask having a first phase modulation type transmission type diffraction grating formed in a first period in a scanning direction and a second phase modulation type transmission type diffraction grating formed in a second period. Having a diffraction grating in the arrangement direction,
The second cycle is set so that the cycle of the maximum intensity of the interference fringes generated in the arrangement direction by the laser light diffracted through the second phase modulation type transmission diffraction grating coincides with the core interval of the plurality of optical fibers. A laser which is composed of one determined two-dimensional phase mask and is emitted from the beam profile conversion optical system via the first phase modulation type transmission diffraction grating and the second phase modulation type transmission diffraction grating. 2. The scanning exposure apparatus according to claim 1, wherein the light is diffracted and irradiates the plurality of optical fibers. 8. A phase mask is formed by arraying a plurality of cylindrical lenses each having a condensing lens function only in the arrangement direction, and a plurality of optical fibers on a plurality of condensing lines generated on a rear focal plane. 2. The scanning type according to claim 1, further comprising: a cylindrical lens array provided in front of the phase mask so as to extend along the optical axis and having a distance to the plurality of optical fibers coincident with a focal length of the cylindrical lens. Exposure equipment. 9. The scanning exposure apparatus according to claim 8, wherein the phase mask is formed integrally with the cylindrical lens array. 10. A beam splitter mirror which divides laser light incident from a beam profile conversion optical system at a predetermined incident angle into two optical paths in an arrangement direction and emits the divided laser light, and a reflecting surface facing each other at a predetermined interval, thereby forming the beam. Two mirrors that respectively reflect the laser light split into two by the splitter mirror to the phase mask and cause two light beams to interfere on a plurality of optical fibers, and the maximum intensity of interference fringes generated in the arrangement direction due to the two light beam interferences 2. The scanning exposure apparatus according to claim 1, wherein the predetermined incident angle or the predetermined interval is adjusted so that a period of the optical fiber coincides with a core interval of the plurality of optical fibers. 11. A grating manufacturing method for irradiating a plurality of optical fibers arranged in parallel with a longitudinal direction with a laser beam with the longitudinal direction as a scanning direction and applying a grating to the plurality of optical fibers. While scanning the laser light emitted from in the longitudinal direction, the laser beam is converted into a vertically long beam profile of an elliptical cross-section having a short axis and a long axis in the scanning direction and the arrangement direction of the plurality of optical fibers, A method for manufacturing a grating, comprising diffracting the converted laser light, and irradiating the diffracted laser light to the plurality of optical fibers arranged in parallel with the longitudinal direction.