MXPA00005539A - Amplitude mask, and apparatus and method for manufacturing long period grating filter using the same - Google Patents

Abstract

An amplitude mask, and an apparatus and method for manufacturing a long period grating filter using the same, are provided. When a long period grating is manufactured by selectively passing laser light to an optical fiber, the amplitude mask periodically passes laser light to the optical fiber. The amplitude mask includes two masks (300) having periodically alternating pass areas (308) for passing the laser light and nonpass areas for preventing passing of the laser light, wherein the two masks (300) are continuously rotated in opposite directions. The period of the pass area (308) thus continuously changes. In this mask, two masks (300) each having a predetermined period are rotated in opposite directions, to thus provide an amplitude mask period depending on the angle of rotation (a). Thus, the period of the amplitude mask can be continuously changed.

Description

MASK OF AMPLITUDE, AN APPARATUS AND A METHOD TO MANUFACTURE A FILTER OF GRID OF DIFRACTION, OF LONG PERIOD, THAT USES THEMSELVES.

Tea field cni co The present invention relates to a passive element, and more particularly, to an amplitude mask to an apparatus and a method for manufacturing a diffraction grating filter using same.

Background of the Technique With the recent developments in optical communications, a long-period diffraction grating filter, as a passive, optical element, is attracting a lot of attention. The long-period diffraction grating filter couples a core mode, in which light travels through the core of an optical fiber, to a coating mode, and is processed by periodically changing the Refractive index of the core of a REF fiber: 120633 optic which is sensitive to ultraviolet rays. That is, the refractive index of a portion exposed to light increases, and a portion that is not exposed does not change, thus a periodic change in the refractive index is generated. To couple the core mode to the coating mode, the following Equation 1 should be satisfied: Where ß c o is the constant propagation of the kernel mode, ßnCi is the propagation constant of a cladding mode of the rth-th order, y? it is a period of the coupling grid.

When 2rin /? (here, n is a refractive index) is replaced by ß in the Equation 1, Equation 1 becomes nco-nc? =? / ?. According to this, the period? and the refractive index difference (nco-nc?) must be determined to couple a certain wavelength to the coating mode. The difference in the refractive index can be obtained by irradiating, appropriately, an ultraviolet laser towards an optical fiber that is sensitive to ultraviolet rays.

Figure 1 is a block diagram of an apparatus for the manufacture of the conventional long-period diffraction grating filter. With reference to Figure 1, the apparatus for the manufacture of the conventional long-period diffraction grating filter comprises a high emission excimer laser source 100, a mirror 102, a lens 104, a silica mask 106. , and an optical fiber 108. The optical source 100 emits an ultraviolet laser. The mirror 102 changes the path of the laser light emitted by the optical source 100. The lens 104 adjusts the focus of the laser light whose path has been changed by the mirror 102. The silica mask 106 selectively passes the passing laser light. through the lens. The optical fiber 108 has a core in which a long-period diffraction grating is formed, which is irradiated with the laser light passing through the silica mask 106 towards the optical fiber.

When the laser light passes through the lens 104 and radiates towards the optical fiber 108 it is brought into contact with the silica mask 106, the refractive index of the optical fiber 108 changes at regular periods, and the grating is formed. diffraction, of long period, in the optical fiber 108. Here, the light passes through the optical fiber 108 using the optical source 110, and is detected by a detector 112, and in this way the optical characteristics of the filter are obtained of diffraction grating, long period.

In the apparatus for the manufacture of the long-period diffraction grating filter, described above, the silica mask 106 is comprised of chrome shapes obtained by coating and applying chromium Cr onto a silica substrate, the laser light of passes selectively through these forms of chromium. However, the chrome shape has a damage threshold of 100mJ / cm2, which makes it impossible to effectively use the high emission excimer type laser light. In addition, the silica mask is manufactured by forming the chromium forms on the silica substrate, and thus has only one period, which is determined by an initially designed shape. Therefore, amplitude masks having different periods are required in order to obtain diffraction grating filters, of long period, having different periods, with which the manufacturing costs increase.

Description of the invention To solve the above problems, it is an object of the present invention to provide an amplitude mask that is comprised of two coupled masks, each of which has a regular period and whose periods are consecutively changed by rotating the two masks in opposite directions to one another. predetermined amount, and an apparatus and method for manufacturing a long-period diffraction grating filter using them.

Accordingly, in order to achieve the previous project, an amplitude mask is provided to periodically pass the laser light to an optical fiber, comprising: two masks having step areas that alternate periodically to let the laser light pass and non-step areas to prevent the passage of laser light, where the two masks are continuously rotated in opposite directions, and thus the period of the passage area changes continuously.

To achieve the above project, an apparatus for the manufacture of the diffraction grating filter, of long period comprising; an optical laser source to emit laser light; an amplitude mask portion whose period is controlled by overlapping both masks of which each has a predetermined period and rotates the two overlapping masks at a predetermined angle, and which selectively passes the laser light to an optical fiber in which it is formed a long period grid, this according to the controlled period; and means for rotating the two masks at a predetermined angle in opposite directions.

To achieve the above project, an apparatus for the manufacture of the long-period diffraction grating filter is provided, comprising: a laser optical source; a mirror to change the trajectory of the laser light emitted by the laser optical source; a lens to adjust the focus of the laser light whose trajectory has been changed; an amplitude mask portion whose period is controlled by overlapping the two masks of which, each having a predetermined period and rotating the two overlapping masks at a predetermined angle, and selectively allowing laser light through the lens to a fiber optics in which a period grid is formed, this according to the controlled period; a detector for detecting a coupling peak of a long-period diffraction grating filter formed in the optical fiber, and a controller for controlling the period of the amplitude mask to obtain a coupling peak wavelength, this receiving a wavelength in the coupling peak from the detector.

To achieve the above project, a method for the manufacture of the long-period diffraction grating filter is provided, comprising the steps of: overlapping the two masks in each of which the passing regions pass through the light laser and alternating with regions that do not pag, rotate the two masks in opposite directions; radiate the 1? 7 laser towards 1 a_ optical fiber via the passage regions formed in predetermined periods in the two rotated masks and forming a grid of di frac, long period, in the optical fiber; and measure the coupling peak due to the diffraction grating, of a long period that the light passes through the optical fiber in which the diffraction grating has been formed, of a long period, and control the angle of rotation to which the two masks have been rotated so that the measured coupling peak is achieved at a desired wavelength.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram schematically illustrating an assembly for the manufacture of the long-period diffraction grating filter; Figure 2 illustrates the structure of a mask to form the present invention; Figure 3 illustrates the result of the two masks of Figure 2 rotating at a predetermined Angle in different directions to obtain a desired period; Figure 4 shows the determination of the period of an amplitude mask according to the angle of rotation in Figure 3; Figure 5 illustrates two masks rotated by an angle greater than that of Figure 3; Figure 6 is a graph showing the variation of the period of the amplitude mask depending on the angle of rotation (a) when using a mask that has a period? 0 of lOOμm; and Figure 7 is a block diagram schematically illustrating an apparatus for the manufacture of the long-period diffraction grating filter using an amplitude mask portion in accordance with the present invention.

Best way to carry out the invention Figure 2 shows the structure of a mask to form the present invention. Figure 3 shows the two masks of figure 2 rotating at a predetermined angle in opposite directions to obtain a desired period. The mask of figure 2 is comprised of the passage areas 202 so that the light passes in periods of (? 0 = 2d) of hundreds of μm and the non-passage areas 204 in a thin metal substrate 200 of about 0.2mm of thickness, that is to say, a stainless substrate. The region of passage 202 is formed by laser lithography of carbon dioxide or by chemical etching. The metallic substrate 200 removes the restrictions imposed by a damage threshold, which allows the use of a high-energy ultraviolet laser as an optical source. The laser passes through the passage area 202, thereby increasing the refractive index of an optical waveguide. The non-step area 204, which is a metal portion, blocks the passage of ultraviolet light.

In the present invention, the amplitude mask is comprised of two masks of Figure 2 which are fixed, and which are overlapped in a rotation support (not shown), and subsequently each rotates exactly. Figure 3 shows two masks 300 rotated by a °. Here, the reference number 302 is the direction of an optical waveguide fiber, the reference numbers 304 and 306 represent the first and second substrates each rotated by a °, the reference-number 308 represents the region for the laser to pass, and? represents the period of the amplitude mask according to the present invention.

As shown in Figure 4, the period? of the amplitude mask is determined with respect to the angle of rotation (a), as follows: xcosa = a, = a2 xsin2a = cf a _? = cfcosct stn x (2) 2? ncosa? - srn2a where ? e s the period of the mask Figure 5, shows the masks 500 rotated by ß ° that is greater than the angle of rotation of (°) of Figure 3. Here, the reference number 502 is the direction of an optical fiber t > a wave guide. It can be seen that the period of the amplitude mask becomes smaller as the angle of rotation becomes larger than in Figure 3. Figure 6 is a graph showing a variation of the diffraction grating period of an amplitude mask depending on the angle of rotation (a), when his wears a mask that has a period? of lOOμm. With reference to figure 6, the diffraction grating period of the amplitude mask can be controlled continuously from 140 μm, through 60 μm at a rotation angle of 10 °, above 600 μm (when a is 0 °, the infinity period).

Figure 7 is a block diagram schematically illustrating an apparatus for manufacturing the long-period diffraction grating filter using a portion of an amplitude mask in accordance with the present invention. Referring to FIG. 7, the apparatus for manufacturing the long-period diffraction grating filter includes an excimer-type laser optical source 700, a mirror 702, a lens 704, an amplitude mask portion 706, a optical fiber 708, an optical source 710, a detector 712, and a controller 417. The mirror 702 changes the path of the laser light emitted by the excimer type laser source 700. The lens 704 adjusts the focus of the laser light whose trajectory it is changed by the mirror 702. The portion of the amplitude mask 706 selectively passes the laser light passed through the lens, and is comprised of two masks of figure 2 which are fixed, and are overlapped in a rotation support (not shown), to then rotate exactly. The optical fiber 708 has a core in which a long-period diffraction grating is formed, which is irradiated by the laser light passing through the amplitude mask 706. The detector 712 detects the optical characteristics passed through the optical fiber 708 on which the long-period diffraction grating has been formed. The controller 714 controls the portion period of the amplitude mask 706 in accordance with a coupling peak that is detected by the detector 712.

Here, the coupling peak means that a suppression ratio becomes maximum, since a core mode of each wavelength is coupled to a coating mode in a long-period diffraction grating.

The manufacture of the long-period mesh grid filter using the long-period grid filter manufacturing apparatus will now be described. First, the laser light generated by the excimer type laser optical source 700 is radiated to the optical fiber 708 by contacting the portion of the amplitude mask 706, via the mirror 702 and the lens 704. The refractive index of a portion of the optical fiber irradiated by the laser light passed through the portion of the mask of amplitude 706 is changed so that a diffraction grating of a long period is formed. At this time, the optical fiber 708 in which the long-period diffraction grating has formed, passes the light generated by the optical source 710, and the detector 712 detects the intensity of the wavelength of the passing light through optical fiber 708. Controller 714 controls the period of the amplitude mask in order to obtain a desired coupling peak wavelength from optical fiber 708.

Ap 1 i c ab i 1 i d Industrial In the mask of amplitude according to the present invention, the masks, each of which has a regular period, rotate in opposite directions, such that they have a period that depends on the angle of rotation. Thus, the period of the amplitude mask can be changed continuously. In addition, in the manufacture of the long-period diffraction xle grating filter, an amplitude mask is adopted whose period is adjustable instead of the silica mask having only one period, in this way a wavelength of coupling peak that is sensitive to the period.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the manufacture of the objects to which it refers.

Having described the invention as above, property is claimed as contained in the following:

Claims (9)

1. An amplitude mask, to periodically pass laser light to an optical fiber, when a long-period diffraction grating is manufactured, selectively passing the laser light to the optical fiber, characterized in that it comprises: two masks having an area in passing they alternate periodically to let the laser light pass, and to prevent the passage of laser light. where JLa s two masks rotate continuously in opposite directions, and in this way the period of the step area changes continuously.

2. The mask of amplitude of larei indication 1, characterized in that the substrate of the mask is formed of a metal.

3. The amplitude mask COJCLO as claimed in claim 1, characterized in that the period (?) Of the amplitude mask is determined as follows: 2? 0cosa? - sin2a where? 0 is the period of the mask, and the a is the rotation angle of the two masks

4. An apparatus for the manufacture of a diffraction grating filter, period l a r g, characterized p ^ comprising: a laser optical source for emitting laser light; an amplitude mask portion whose period is controlled by overlapping the two masks, each of which has a predetermined period and the two top faces rotate overlapped to a predetermined angle, and which allow selective passing of the laser light towards an optical fiber, in which the diffraction grating of a long period is formed, in accordance with the controlled period; and rotation means for the two masks to rotate at a predetermined angle in opposite directions.

5. The apparatus for manufacturing the filter, of diffraction grating, of long period, as claimed in the rei indication 4, characterized in that it also comprises: a second optical source; a detector for detecting a coupling peak of the diffraction grating filter, of long period, coming from one end towards an optical fiber in which a diffraction grating has been formed, of long period, when the light generated by the second optical source is incidental on the other end of the optical fiber in which the long-period diffraction grating has been formed; and a controller for controlling the rotation means, to obtain a desired coupling peak wavelength, receiving a wavelength at the coupling peak of the detector.

6. The apparatus for the manufacture of the long-period diffraction grating filter, as claimed in claim 4, characterized in that the substrate material of the mask is a metal.

7. The apparatus for the manufacture of the long-period mesh grid filter, as claimed in the claim 5, characterized in that the period (?) Of the amplitude mask is determined as follows: 2 / ^ 00801? sin2s e n d o n d e n e r p e d o f th e face a is the angle of rotation of the masc.

8. The apparatus for the manufacture of the long-period diffraction grating filter, characterized in that it comprises a laser optical source; a mirror to change the trajectory of the laser light emitted by the laser optical source; a lens to adjust the focus of the laser light whose trajectory has been changed; an amplitude mask portion whose period is controlled by overlapping the two masks, of which each has a predetermined period and the two overlapping masks rotate at a predetermined angle, which selectively passes the laser light passing through the lenses towards an optical fiber, in which a diffraction grating is formed, of long period, in accordance with the controlled period; a detector for detecting a coupling spike of a long period grating filter fo rmed on the optical fiber; and a controller for controlling the period of the amplitude mask to obtain a desired coupling peak wavelength by receiving a wavelength at the coupling peak from the detector.

9. A method for the manufacture of a long-period diffraction grating filter, characterized in that it comprises the steps of: overlapping the two masks in each of which the passage regions, passed by the laser light alternates with the regions that do not allow passage, and the two masks rotate in opposite directions; irradiating the laser light to an optical fiber via the passage regions formed in predetermined periods in the two rotated masks, and forming a long-period diffraction grating in the optical fiber; and measuring a coupling peak due to the long period grid passing light through the optical fiber in which the long period grid is formed, and controlling the angle of rotation in which the two masks have been rotated , so that the coupling peak is obtained at a desired wavelength.