JP2011215410A - Optical module and optical detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module and an optical detection method that suppress a rise in manufacturing cost and improve convenience for a user.SOLUTION: The optical module 1 is provided with a light source 11 and an optical fiber 12 having a core 21 which propagates an optical signal emitted from the light source 11. The core 21 includes, longitudinally along the core 21, at least one scattering region 31 which is irradiated with UV light of uniform intensity in the length direction of the core 21. When an optical signal traverses the scattering region 31, the scattering region 31 uses a portion of the optical signal to generate radially-scattered light from the scattering region 31 toward the outside of the optical fiber 12.

Description

  The present invention relates to an optical module including a light source such as a laser element and an optical fiber that propagates light emitted from the light source, and a light detection method for detecting light propagating through the optical fiber.

  Optical fibers are used in a wide range of fields such as optical communications, fiber laser devices, and fiber sensing. The purpose of the optical fiber is to confine light in its core and propagate light as a signal. For this reason, an optical fiber usually has a characteristic that a signal loss in light propagation is small.

  On the other hand, when performing a failure determination of a light source or an optical circuit constituting an optical fiber device using an optical fiber such as a fiber laser or fiber sensing, maintenance of an optical communication network used for optical communication is performed. There are many occasions that need to be detected from outside.

  This is because in such maintenance and failure determination, it is necessary to actually operate the optical communication network and optical fiber equipment, and to check whether the light actually propagates through the optical fiber during the operation. is there.

  However, as described above, the optical fiber has a small signal loss, that is, the amount of leaked light leaking directly from the optical fiber is very small, so it is practical to detect the leaked light directly. It was difficult.

  Therefore, a device capable of positively extracting light from the optical fiber is required so that light propagating through the optical fiber with small signal loss can be detected.

  In consideration of such a situation, an optical monitoring optical fiber is disposed in the vicinity of the fusion-bonding point of the optical fiber to be measured, and leaks from the fusion-connection point of the optical fiber to be measured through the optical fiber for optical monitoring. An optical power monitoring method for monitoring the power of light propagating through an optical fiber to be measured by measuring leakage light has been proposed (see, for example, Patent Document 1).

  In this optical power monitoring method, leakage light leaking from a connection point existing in the optical fiber to be measured is received by the monitoring optical fiber, and the light is guided to the light detection means and measured. By doing so, the power of light propagating through the optical fiber to be measured is monitored.

  There has also been proposed an optical waveguide monitoring method in which a part of light leaking from the core part to the clad part is taken out and the extracted light is converted into an electric signal by a light receiving element (see, for example, Patent Document 2).

  In this optical waveguide monitoring method, a low refractive index portion having a lower refractive index than other portions is formed in the cladding portion. The low refractive index part reflects part of the leaked light leaking from the core part to the clad part, and detects the reflected light from the low refractive index part on the opposite side of the low refractive index part.

  Further, by irradiating the optical fiber with ultraviolet rays, a sland type fiber grating (SFBG) (hereinafter referred to as “sland type FBG”) is formed in the core of the optical fiber, and the sland type FBG is formed. An optical monitor device for detecting a part of the diffracted light that has propagated has been proposed (see, for example, Patent Document 3).

  In this optical monitor device, a sland type FBG is provided with a pattern composed of an ultraviolet irradiation region and a non-ultraviolet irradiation region, which has a length (typically, λ / 2) as long as the wavelength λ of the signal light. The signal light is caused to interfere with the sland type FBG to generate the diffracted light described above.

JP 2006-292673 A (released on October 26, 2006) JP 2005-128099 A (published May 19, 2005) JP 11-133255 A (published May 21, 1999)

  However, in the optical power monitoring method disclosed in Patent Document 1, leakage light leaking from the fusion splicing point due to the connection loss of the splicing splicing point of the optical fiber to be measured is optical fiber for optical monitoring. It is receiving light. For this reason, when the above-mentioned connection loss is small, there is a problem that the amount of leaked light caused by the connection loss is reduced, and the leaked light cannot be monitored.

  In addition, since the generation of leakage light is caused by the connection loss, there is a problem that the amount of such leakage light cannot be adjusted.

  Furthermore, since the leakage direction of the leaked light leaking from the fusion splicing point cannot be adjusted, the light detection means for monitoring the leaked light cannot be arranged at an arbitrary location, and is used for monitoring. There was also a problem of lack of convenience for the elderly.

  In the optical waveguide monitoring method disclosed in Patent Document 2, the light leaked from the core part to the cladding part is taken out and received, so that the amount of light is inevitably small. Similar to the monitoring method, there is a problem that the extracted light may not be monitored.

  In the optical monitor device disclosed in Patent Document 3, when the sland type FBG is formed, it is necessary to accurately control (draw) the region where the core portion is irradiated with ultraviolet rays and the region where ultraviolet rays are not irradiated. This is because, in order to form a sland type FBG, a plurality of ultraviolet rays must interfere with each other to form a pattern having a length shorter than the wavelength of the ultraviolet rays.

  For this reason, typically, an expensive diffraction grating called a phase mask has to be used, resulting in an increase in manufacturing cost of the optical monitor device.

  Further, when forming the sland type FBG, it is necessary to incline the optical fiber and perform the above drawing, and the alignment accuracy is required to be very high. This also has a problem that it becomes one of the causes of the increase in the manufacturing cost.

  Furthermore, in order to detect the diffracted light from the sland type FBG, a light receiving element for detecting the diffracted light can be disposed only on the optical path of the diffracted light. Similar to the monitoring method, there is a problem that the convenience of the user for monitoring is lacking.

  The present invention has been made in view of the above problems, and an object thereof is to provide an optical module and a light detection method capable of suppressing an increase in manufacturing cost and improving user convenience. It is in.

  In order to achieve the above object, an optical module according to the present invention includes a light source and an optical fiber having a core portion that propagates signal light emitted from the light source, and the core portion is a length of the core portion. And at least one ultraviolet irradiation region that is irradiated with ultraviolet rays of uniform intensity in the longitudinal direction along the direction, and the ultraviolet irradiation region is the signal when the signal light passes through the ultraviolet irradiation region. A part of the light is used to generate scattered light that is scattered radially from the ultraviolet irradiation region toward the outside of the optical fiber.

  Here, the “uniform intensity in the longitudinal direction” is realized by the ultraviolet irradiation condition without using the phase mask. Therefore, it can be said that the ultraviolet rays having “uniform intensity in the longitudinal direction” are ultraviolet rays that do not use a phase mask, that is, do not have an interference pattern.

  In the above optical module, at least one ultraviolet irradiation region irradiated with ultraviolet rays of uniform intensity in the longitudinal direction is arranged along the longitudinal direction of the core portion.

  In the ultraviolet irradiation area, an increase in scattering center is induced by ultraviolet irradiation with uniform intensity in the longitudinal direction, and a part of the signal light incident on the core from the light source is directed to the outside of the optical fiber from the ultraviolet irradiation area. Scattered radially.

  For this reason, when detecting the scattered light scattered from the ultraviolet irradiation region, the light detection unit can be arranged in any radial direction centering on the ultraviolet irradiation region.

  Further, since the ultraviolet irradiation region is irradiated with ultraviolet rays having a uniform intensity in the longitudinal direction, a phase mask that diffracts and interferes with the ultraviolet rays is not required when the ultraviolet irradiation region is irradiated with ultraviolet rays.

  Therefore, it is possible to improve the convenience for the user that the light detection unit can be arranged in an arbitrary direction while suppressing an increase in the manufacturing cost of the optical module.

  The amount of the scattered light is preferably determined based on at least one of the length of the ultraviolet irradiation region in the longitudinal direction, the ultraviolet intensity of the ultraviolet irradiation, and the irradiation time of the ultraviolet irradiation. .

  In this case, the amount of scattered light scattered from the ultraviolet irradiation region can be determined based on at least one of the length of the ultraviolet irradiation region, the ultraviolet intensity of the ultraviolet irradiation, and the irradiation time of the ultraviolet irradiation. Therefore, the amount of scattered light can be adjusted efficiently.

  The length of the ultraviolet irradiation region in the longitudinal direction is preferably longer than the wavelength of the signal light.

  In this case, even when a plurality of ultraviolet irradiation regions are arranged in the longitudinal direction of the core portion, the scattered light in each ultraviolet irradiation region is not diffracted and each scattered light can be easily detected separately.

  The ultraviolet intensity of the ultraviolet irradiation is preferably uniform within the ultraviolet irradiation surface of the core portion irradiated with the ultraviolet light.

  In this case, the increase of the scattering center induced in the ultraviolet irradiation region becomes uniform in the region, and the scattered light can be scattered uniformly in an arbitrary radial direction centering on the ultraviolet irradiation region.

  It is preferable that the light detection unit further includes a light detection unit that is disposed outside the optical fiber and detects the scattered light, and the light detection unit is disposed in an arbitrary direction extending radially from the ultraviolet irradiation region.

  In this case, when detecting scattered light from the ultraviolet irradiation region, it is not necessary to prepare a light detection unit separately, and even if the installation location of the optical module is moved, the light detection unit is not rearranged, Photodetection by the photodetection unit can be performed.

  The light source includes a plurality of light sources, and the optical fiber includes a plurality of optical fibers that correspond one-to-one to the plurality of light sources, and the plurality of optical fibers are different from each other in each core portion. The light detection unit is configured to detect the scattered light scattered from each of the ultraviolet irradiation regions of each of the core portions of the plurality of optical fibers. preferable.

  In this case, since scattered light from a plurality of optical fibers can be detected, the presence or absence of signal light propagating to the plurality of optical fibers can be determined.

  In each of the plurality of optical fibers, it is preferable that the ultraviolet irradiation region is arranged in each core portion based on a unique arrangement pattern.

  In this case, since the scattered light patterns from the plurality of optical fibers are different, the presence / absence of signal light propagating to each of the plurality of optical fibers can be determined.

  The light detection method according to the present invention is a light detection method using an optical fiber including at least one ultraviolet irradiation region irradiated with ultraviolet rays of uniform intensity in the longitudinal direction along the longitudinal direction of the core portion. A detecting step for detecting scattered light radially scattered from the ultraviolet irradiation region toward the outside of the optical fiber, and a signal propagating through the optical fiber when the scattered light is detected in the detecting step. A determination step of determining that light is present.

  In the above-described light detection method, at least one ultraviolet irradiation region irradiated with ultraviolet rays of uniform intensity in the longitudinal direction is arranged along the longitudinal direction of the core portion.

  In the ultraviolet irradiation area, an increase in scattering center is induced by ultraviolet irradiation with uniform intensity in the longitudinal direction, and a part of the signal light incident on the core from the light source is directed to the outside of the optical fiber from the ultraviolet irradiation area. Scattered radially.

  For this reason, when detecting the scattered light scattered from the ultraviolet irradiation region, the light detection unit can be arranged in any radial direction centering on the ultraviolet irradiation region.

  Further, since the ultraviolet irradiation region is irradiated with ultraviolet rays having a uniform intensity in the longitudinal direction, a phase mask that diffracts and interferes with the ultraviolet rays is not required when the ultraviolet irradiation region is irradiated with ultraviolet rays.

  Therefore, it is possible to improve the convenience for the user that the light detection unit can be arranged in an arbitrary direction while suppressing an increase in the manufacturing cost of the optical module.

  The optical module of the present invention includes a light source and an optical fiber having a core portion that propagates signal light emitted from the light source, and the core portion extends in the longitudinal direction along the longitudinal direction of the core portion. Including at least one ultraviolet irradiation region irradiated with ultraviolet rays of uniform intensity, wherein the ultraviolet irradiation region uses the part of the signal light when the signal light passes through the ultraviolet irradiation region; Scattered light that is scattered radially from the ultraviolet irradiation region toward the outside of the optical fiber is generated.

  The light detection method of the present invention is a light detection method using an optical fiber including at least one ultraviolet irradiation region irradiated with ultraviolet rays of uniform intensity in the longitudinal direction along the longitudinal direction of the core portion. A detection step for detecting scattered light radially scattered from the ultraviolet irradiation region toward the outside of the optical fiber, and signal light that propagates through the optical fiber when the scattered light is detected in the detection step And a determination step of determining that there is.

  Therefore, it is possible to suppress an increase in manufacturing cost and improve user convenience.

It is a figure which shows schematic structure of the optical module which concerns on one Embodiment of this invention, (a) is a top view of the optical module, (b) is an enlarged view of the A section of (a). It is explanatory drawing for demonstrating the photon detection method which concerns on one Embodiment of this invention. It is explanatory drawing for demonstrating the formation method of the scattering area | region arrange | positioned at the core part of the optical fiber of the said optical module. It is explanatory drawing for demonstrating the formation method of FBG. It is a figure which shows schematic structure of the optical module which concerns on other embodiment of this invention. It is a figure which shows schematic structure of the optical module which concerns on other embodiment of this invention.

(Embodiment 1)
One embodiment of the present invention will be described with reference to FIGS. Configurations other than those described in the following specific embodiments may be omitted as necessary, but are the same as the configurations described in the other embodiments. For convenience of explanation, members having the same functions as those shown in each embodiment are given the same reference numerals, and the explanation thereof is omitted as appropriate.

  1A and 1B are diagrams illustrating a schematic configuration of an optical module according to Embodiment 1 of the present invention, in which FIG. 1A is a top view of the optical module, and FIG. 1B is an enlarged view of a portion A in FIG. is there.

  An optical module 1 according to an embodiment of the present invention includes a light source 11 and an optical fiber 12 as shown in FIG.

  For example, a semiconductor laser element can be used as the light source 11. In this case, the light source 11 is connected to a laser driving device (not shown), and a driving current is input from the laser driving device. The light source 11 has an emission surface that emits laser light, and the emission surface is disposed to face the tip of the optical fiber 12. The light source 11 oscillates when a drive current is input from the laser driving device, and emits laser light from the emission surface by the oscillation. The light source 11 may be a solid laser element in which an amplification medium crystal is disposed in a cavity in which a mirror is disposed, or may be an LED (light emitting diode).

  The optical fiber 12 includes a triple structure of a core portion 21, a cladding portion 22 outside the core portion 21, and a covering portion (not shown) that covers them. The optical axis of the laser light emitted from the light source 11 and the optical axis of the core part 21 of the optical fiber 12 are such that the laser light emitted from the light source 11 is introduced to the core part 21 of the optical fiber 12 as much as possible. It is aligned.

For example, silica glass (silicon dioxide: SiO ₂ ) can be used for the core portion 21 and the cladding portion 22 of the optical fiber 12. The refractive index of the core portion 21 is higher than the refractive index of the cladding portion 22. For this reason, the signal light, which is light incident on the core portion 21 from the light source 11, can propagate through the core portion 21 while being efficiently confined in the core portion 21.

(Scattering region)
In general, when germanium (Ge) is added to the core portion of an optical fiber and an ultraviolet ray having a wavelength of about 240 nm (for example, 248 nm) is irradiated onto a partial region of the core portion, the refractive index of the partial region increases. It is known that the scattering center increases in a part of the region. It is generally considered that the two phenomena of increasing the refractive index and increasing the scattering center occur independently of each other. In addition to germanium, the additive may be titanium oxide (TiO ₂ ), boron (B), or the like.

  In the optical module 1 according to the present embodiment, the phenomenon of increasing the scattering center among the two phenomena described above is used. That is, a part of the core portion 21 of the optical fiber 12 is irradiated with ultraviolet rays, and the scattering center in the part of the region is increased. Then, the signal light is propagated to a region where the increase of the scattering center is induced, and at the time of the propagation, a part of the signal light is scattered in the region where the increase of the scattering center is induced. That is, scattered light scattered from the core portion 21 is generated.

  The core portion 21 of the optical fiber 12 has at least one scattering region (ultraviolet irradiation region) 31 as shown in FIG. The scattering region 31 is arranged so as to occupy a partial region of the core portion 21 along the longitudinal direction of the core portion 21, in other words, the waveguide direction of the signal light incident from the light source 11. Has been.

  This scattering region 31 utilizes the phenomenon described above. First, as described above, germanium is added to the core portion 21 of the optical fiber 12, and the concentration thereof is 3 to 3. 10 wt% is preferable.

  As shown in FIG. 1B, the scattering region 31 is a region irradiated with ultraviolet rays along the longitudinal direction of the core portion 21, and is not irradiated with ultraviolet rays. It arrange | positions so that it may be pinched | interposed into the area | region 32 and the ultraviolet irradiation non-irradiation area | region 33.

  Therefore, for example, the signal light incident on the core portion 21 of the optical fiber 12 from the light source 11 propagates through the ultraviolet non-irradiated region 32 and reaches the interface between the ultraviolet non-irradiated region 32 and the scattering region 31. After passing through the interface, it propagates through the scattering region 31 and reaches the interface between the scattering region 31 and the ultraviolet non-irradiated region 33. Then, after passing through the interface, it propagates through the ultraviolet non-irradiated region 33 and the remaining region of the core portion 21 that follows.

  When signal light is incident on itself, the scattering region 31 scatters a part of the signal light based on the phenomenon described above. Further, when the scattering region 31 scatters a part of the light, the scattering region 31 radiates in all directions around the scattering region 31, that is, scatters radially.

  As shown in FIG. 1B, the scattering region 31 has a length L in the longitudinal direction of the core portion 21. The length L is longer than the wavelength of the signal light incident on the core portion 21 from the light source 11, and is preferably 1 to 50 mm.

In addition, the intensity of the ultraviolet light applied to the scattering region 31 is preferably 0.5 to ² mJ / mm ² , more preferably 1 mJ / mm ² when the ultraviolet light is emitted from a pulse light source having a repetition frequency of 100 Hz. a mm ^2.

  Furthermore, the irradiation time of the ultraviolet rays is preferably 0.5 to 300 seconds, more preferably 30 seconds.

(Light detection method)
Next, a light detection method according to an embodiment of the present invention will be described. FIG. 2 is an explanatory diagram for explaining the light detection method according to the present embodiment.

  As described above, the signal light incident on the core portion 21 of the optical fiber 12 from the light source 11 propagates through the ultraviolet non-irradiated region 32, the scattering region 31, and the ultraviolet non-irradiated region 33 in this order.

  At this time, as shown in FIG. 2, in the scattering region 31, when the signal light is incident on and propagates, a part of the signal light is radially scattered.

  Thus, the scattered light scattered from the core part 21 of the optical fiber 12 is imaged using the imaging device 41 arrange | positioned at the upper right in FIG. 2, for example. The result that the imaging device 41 has captured the scattered light means that the signal light propagates through the core portion 21 of the optical fiber 12.

  Therefore, it can be determined that the signal light is propagated to the core portion 21 of the optical fiber 12 based on the result that the imaging device 41 has captured the scattered light.

  Such a determination may be performed through the human eye with the imaging result of the imaging device 41, or may be performed by computer processing based on the image processing result of the imaging result.

  Further, in the light detection method according to the present embodiment, as shown in FIG. 2, the imaging device 41 can be arranged in an arbitrary direction extending radially from the scattering region 31. As described above, the scattering region 31 scatters the scattered light in all directions around itself.

  Therefore, the imaging device 41a arranged at the upper left in FIG. 2 or the imaging device 41b arranged at the lower left in FIG. 2 is the imaging device 41c arranged at the lower right in FIG. Also, it becomes possible to image the scattered light.

  That is, when the user confirms whether or not the signal light is actually propagating through the optical fiber 12, the imaging devices 41 and 41 a to 41 c for detecting the scattered light are spread radially from the scattering region 31. It can be arranged in any direction.

  Therefore, for example, even when the optical module 1 is stored in a housing (not shown) and the direction in which the imaging devices 41 and 41a to 41c can be arranged is limited, imaging is performed in the limited direction. The devices 41 and 41a to 41c can be arranged to detect the scattered light. By doing so, it is possible to improve the convenience of the user when confirming whether or not the signal light is actually propagating through the optical fiber 12.

  In FIG. 2, the imaging device 41 arranged at the upper right in FIG. 2, the imaging device 41a arranged at the upper left in FIG. 2, the imaging device 41b arranged at the lower left in FIG. 2, and the lower right in FIG. Although the imaging device 41c arranged is shown, the present embodiment is not limited to these positions. In short, the imaging devices 41 and 41a to 41c may be arranged in any direction that spreads radially from the scattering region 31 so that the scattered light scattered radially from the scattering region 31 can be imaged.

  Further, the number of the imaging devices 41 and 41a to 41c that capture the scattered light is not limited to one. For example, you may use the two imaging devices 41 and 41b arrange | positioned in a mutually different direction, such as the imaging device 41 arrange | positioned at the upper right in FIG. 2, and the imaging device 41b arrange | positioned at the lower left in FIG. In this case, it becomes possible to more reliably capture the scattered light.

(Method for forming scattering region)
Next, a method for forming the scattering region 31 will be described. FIG. 3 is an explanatory diagram for explaining a method of forming the scattering region 31. FIG. 4 is an explanatory diagram for explaining a method of forming an FBG as a comparative example of the scattering region 31.

  As shown in FIG. 3, the scattering region 31 is a partial region of the core portion 21 of the optical fiber 12 that has been irradiated with the ultraviolet rays 53 as described above. The ultraviolet rays 53 are applied to a region where the scattering region 31 is formed in the longitudinal direction of the core portion 21 of the optical fiber 12. For example, if the length of the scattering region 31 in the longitudinal direction of the core portion 21 is L, the ultraviolet rays 53 are irradiated to the core portion 21 through the mask 50 having a slit of length L.

  Here, when ultraviolet rays pass through the slit as described above, the diffraction effect tends to spread more than the length of the slit.

  For this reason, the mask 50 can use the combination of the two masks 51 and 52, for example. If it does so, it becomes possible to make the length L of the area | region irradiated with the ultraviolet-ray 53 in the longitudinal direction of the core part 21 into a desired value more correctly.

  In FIG. 3, a combination of two masks 51 and 52 is used, but of course, the number of masks may be three or more. In short, it is only necessary that the length L of the region irradiated with the ultraviolet rays 53 in the longitudinal direction of the core portion 21 can be set accurately.

  As described above, the core portion 21 and the cladding portion 22 of the optical fiber 12 are covered with the covering portion. The covering portion is formed of a resin material or the like, and for example, a thermosetting silicone resin having a high ultraviolet transmittance can be used. Specific examples include dimethyl silicone resin. The thermosetting silicone resin has a transmittance of about 90% with respect to an ultraviolet ray having a wavelength of 244 nm.

  In this case, the ultraviolet rays 53 reach the core portion 21 of the optical fiber 12 even if the ultraviolet rays 53 are irradiated through the covering portion. Therefore, when forming the scattering region 31 in the core portion 21 of the optical fiber 12, it is not necessary to remove the covering portion from the optical fiber 12.

  On the other hand, instead of the above-described resin having a high ultraviolet transmittance, the coating portion can be made of an ultraviolet-absorbing ultraviolet curable resin that is used for coating a general optical fiber. Preferably, an epoxy-based or urethane acrylate-based ultraviolet curable resin can be used.

  In this case, when forming the scattering region 31 in the core portion 21 of the optical fiber 12, it is necessary to remove the covering portion from the optical fiber 12. For example, the coating part may be irradiated with an ultraviolet beam in a pulse shape, the coating part may be heated, and burned. Since the ablation is easily caused, the covering portion can be easily removed. This ultraviolet irradiation can be performed by, for example, irradiating the coating portion with an ultraviolet beam such as an excimer laser in a pulse shape.

  Here, an FBG formation method will be described as a comparative example of the scattering region 31. Below, the method to form said FBG is demonstrated with respect to the optical fiber 112 which has the core part 121 and the clad part 122 of the same structure as the core part 21 and the clad part 22 of the optical fiber 11, respectively.

  As shown in FIG. 4, the phase mask 61 can be used when forming the FBG in the core portion 121 of the optical fiber 112. The ultraviolet rays 62 are applied to the core portion 121 through the phase mask 61.

  When the FBG is formed, the ultraviolet rays 62 are diffracted by the periodic diffraction grating of the phase mask 61, and the + 1st order diffracted light and the −1st order diffracted light interfere with each other to generate interference fringes. Moreover, the refractive index of the core part 121 of the part which produced this interference fringe rises. Note that second-order or higher-order diffracted light may be used as ultraviolet diffracted light.

  When an FBG is formed using such a phase mask 61, diffracted light from adjacent openings in the periodic diffraction grating of the phase mask 61 interferes with each other, so that each opening These images can be separated from each other.

  That is, in order to form a pattern having a length shorter than the wavelength of the ultraviolet ray 62 by causing a plurality of diffracted lights to interfere with each other, the ultraviolet ray irradiation region 131 irradiated with the ultraviolet ray 62 is used with such a phase mask 61. The other regions that are not irradiated with the ultraviolet rays 62 are controlled (drawn) with high accuracy.

  Here, the difference between such an FBG and the scattering region 31 will be described.

  (1) In the FBG, it is required to significantly change the refractive index of the core portion 121 of the optical fiber 112. In FIG. 4, as shown in part C, the refractive index difference at the interface between the ultraviolet irradiation region 131 and the region not irradiated with the ultraviolet light 62 adjacent to each other is Δn2.

  As described above, in the present embodiment, the refractive index difference Δn1 at the interface between the scattering region 31 and the ultraviolet non-irradiated region 32 and the refractive index difference Δn1 at the interface between the scattering region 31 and the ultraviolet non-irradiated region 33 are It is very small. This is because the scattering region 31 is intended to increase the number of scattering centers that scatter a part of the signal light propagating through the scattering region 31. Therefore, as in the case of the FBG, the refraction is conspicuous in the scattering region 31. This is because it does not require rate change.

  Therefore, the increase in the refractive index induced in the scattering region 31 is smaller than the increase in the refractive index induced in the ultraviolet irradiation region 131 of the FBG.

  That is, the irradiation time and intensity of the ultraviolet rays 53 irradiated to the scattering region 31 and the irradiation time and intensity of the ultraviolet rays 62 irradiated to the ultraviolet irradiation region 131 of the FBG are respectively required purposes, that is, an increase in refractive index. Since the increase in scattering center is different from that of the scattering center, it is completely different.

  (2) When the FBG is formed, the phase mask 61 described above is used. This phase mask 61 is very expensive due to the cost required for forming the fine periodic diffraction grating. .

  Further, when the FBG is a sland type FBG, for example, a state in which the periodic diffraction grating formed in the phase mask 61 shown in FIG. 4 is arranged so as to be inclined with respect to the optical axis direction of the optical fiber 112. Then, the core 121 of the optical fiber 112 is irradiated with ultraviolet light through the phase mask 61.

  In this case, the alignment accuracy between the phase mask 61 and the optical fiber 112 is required to be very high. This is also one of the factors that increase the FBG formation cost.

  On the other hand, a mask 50 provided with slits may be used to form the scattering region 31. Since the mask 50 is simply provided with slits, it is less expensive than the phase mask 61 described above. Is.

  In addition, high-precision alignment like FBG is not required.

  Therefore, the formation cost of the scattering region 31 is lower than the formation cost of the FBG.

  (3) The FBG diffracts part of the signal light propagating through itself, but the diffracted light is emitted in the diffraction direction of the FBG. Therefore, the diffracted light diffracted from the core portion 121 of the optical fiber 112 is radiated only in a predetermined direction centered on the FBG.

  For this reason, when it is going to detect the diffracted light of FBG, the light detection part can be arranged only in the diffraction direction of the diffracted light.

  On the other hand, as described above, the scattering region 31 radiates a part of the signal light propagating through itself in all directions around itself, that is, scatters radially.

  For this reason, when it is going to detect the scattered light scattered from the scattering region 31, the light detection part can be arrange | positioned in the arbitrary directions centering on the scattering region 31, unlike the case of FBG.

  (4) When forming the FBG, the interference fringes of the ultraviolet rays 62 by the periodic diffraction grating of the phase mask 61 are used. This is because the FBG has a fine structure in which an ultraviolet irradiation region 131 irradiated with the ultraviolet rays 62 and other regions not irradiated with the ultraviolet rays 62 are repeatedly arranged.

  On the other hand, as described above, the scattering region 31 has a length L in the longitudinal direction of the core portion 21, and the length L is the wavelength of the signal light incident on the core portion 21 from the light source 11. Is longer.

  For this reason, unlike the case of FBG, it is not necessary to interfere with the ultraviolet ray 53, and the scattering region 31 may be irradiated with the ultraviolet ray 53 having a uniform intensity in the longitudinal direction of the core portion 21.

  Therefore, as described in (2) above, the phase mask 61 is unnecessary.

  The above “uniform strength in the longitudinal direction” means that the intensity of the ultraviolet rays 53 is uniform along the longitudinal direction of the core portion 21. As described above, this “uniform strength in the longitudinal direction” is realized by the ultraviolet irradiation condition without using the phase mask. For this reason, the ultraviolet ray 53 having “uniform intensity in the longitudinal direction” can be referred to as an ultraviolet ray 53 that does not use a phase mask, that is, has no interference pattern.

  As described above in (1) to (4), the scattering region 31 shown in FIG. 3 and the ultraviolet irradiation region 131 shown in FIG. 4 are completely different in configuration and effect. .

(Embodiment 2)
In the drawings described below, there may be illustrated modifications corresponding to the above-described components. About these modified examples, by adding the alphabets a, b, c... To the reference numerals (numerals) added to the corresponding components described above, it is shown that they are modified examples while clarifying the correspondence. And The same applies to Embodiment 3 below.

  FIG. 5 is a diagram showing a schematic configuration of an optical module according to Embodiment 2 of the present invention. The optical module 2 according to the present embodiment includes a light source 11a, a light source 11b, a light source 11c, a light source 11d, an optical fiber 12a, an optical fiber 12b, an optical fiber 12c, and an optical fiber 12d.

  The light source 11a makes the signal light incident on the core portion 21a of the optical fiber 12a. The light source 11b makes the signal light incident on the core portion 21b of the optical fiber 12b. The light source 11c makes signal light incident on the core portion 21c of the optical fiber 12c. The light source 11d makes signal light incident on the core portion 21d of the optical fiber 12d.

  That is, each of the light source 11a, the light source 11b, the light source 11c, and the light source 11d and the optical fiber 12a, the optical fiber 12b, the optical fiber 12c, and the optical fiber 12d have a one-to-one correspondence.

  The optical fiber 12a has one scattering region 31a in its core portion 21a. The optical fiber 12b has two scattering regions 31b in its core portion 21b. The optical fiber 12c has three scattering regions 31c in its core portion 21c. The optical fiber 12d has four scattering regions 31d in its core portion 21d.

  That is, each of the optical fiber 12a, the optical fiber 12b, the optical fiber 12c, and the optical fiber 12d has a scattering region arrangement pattern in which the respective scattering regions 31a, 31b, 31c, and 31d are arranged. These arrangement patterns are unique to each of the optical fiber 12a, the optical fiber 12b, the optical fiber 12c, and the optical fiber 12d.

  Therefore, the detection result of the scattered light scattered from each optical fiber 12a, 12b, 12c, and 12d differs for each optical fiber 12a, 12b, 12c, and 12d.

  Specifically, the optical fiber 12a scatters scattered light radially from one scattering region 31a. The optical fiber 12b scatters scattered light radially from each of the two scattering regions 31b. The optical fiber 12c scatters scattered light radially from each of the three scattering regions 31c. The optical fiber 12d scatters scattered light radially from each of the four scattering regions 31d.

  Therefore, for example, when the scattered light scattered from each of the optical fibers 12a, 12b, 12c, and 12d is detected using the imaging device 41 as described in FIG. 2, each of the optical fibers 12a, 12b, 12c, and The detection result of the scattered light from 12d becomes a different detection pattern for each optical fiber 12a, 12b, 12c, and 12d.

  Therefore, based on the detection patterns that differ for each of the optical fibers 12a, 12b, 12c, and 12d, the optical detection as described above can be simultaneously performed for each of the optical fibers 12a, 12b, 12c, and 12d. Is possible.

(Embodiment 3)
FIG. 6 is a diagram showing a schematic configuration of an optical module according to Embodiment 3 of the present invention. The optical module 3 according to this embodiment includes a light source 11e, an optical fiber 12e, a light detection unit 71, and a determination unit 72.

  As the light detection unit 71, for example, a PD can be used. When the signal light is incident on the core 21e of the optical fiber 12e from the light source 11e and the scattering region 31e scatters part of the signal light radially, the light detection unit 71 detects the scattered light.

  The light detection unit 71 can be arranged in any radial direction centered on the scattering region 31e. This is because the scattered light scattered from the scattering region 31e is scattered radially with the scattering region 31e as the center, as described above.

  Therefore, for example, the light source 11e, a part of the optical fiber 12e on the light source 11e side, the light detection unit 71, and the determination unit 72 are stored in a housing (not shown). The degree of freedom may be small. Even in such a case, the light detection unit 71 can be disposed at a position where the scattered light scattered from the scattering region 31e can be detected.

  The determination unit 72 determines the presence or absence of signal light propagating through the core portion 21e of the optical fiber 12e based on the detection result from the light detection unit 71. When the determination unit 72 receives the detection result that the scattered light is detected from the light detection unit 71, the determination unit 72 determines that the signal light propagates through the core portion 21e of the optical fiber 12e based on the detection result. To do.

  In addition, when the light detection unit 71 is the imaging device 41 described with reference to FIG. 2, the determination unit 72 performs image processing on the imaging result of the imaging device 41 and determines the presence or absence of signal light based on the image processing result. May be. In this case, for example, under the condition where the signal light propagates through the core portion 21e of the optical fiber 12e, the scattered light from the scattering region 31e is imaged by the imaging device 41, and a reference image is formed by image processing the imaging result. You just have to. If it does so, the determination part 72 can perform said determination by the comparison with the reference | standard image, and can attain speeding-up of a determination process.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The present invention can be used for an optical module used for a fiber laser, an LD module, or the like.

1, 2, 3 Optical module 11, 11a, 11b, 11c, 11d, 11e Light source 12, 12a, 12b, 12c, 12d, 12e, 112 Optical fiber 21, 21a, 21b, 21c, 21d, 21e, 121 Core part 22 , 22a, 22b, 22c, 22d, 22e, 122 Clad part 31, 31a, 31b, 31c, 31d, 31e Scattering region (ultraviolet irradiation region)
32, 33, 131 Ultraviolet non-irradiated area 41, 41a, 41b, 41c Imaging device 50, 51, 52 Mask 53, 62 Ultraviolet 61 Phase mask 71 Photodetection unit 72 Determination unit

Claims (8)

A light source;
An optical fiber having a core portion for propagating signal light emitted from the light source,
The core portion includes at least one ultraviolet irradiation region irradiated with ultraviolet rays of uniform intensity in the longitudinal direction along the longitudinal direction of the core portion,
The ultraviolet irradiation region is a scattered light that is scattered radially from the ultraviolet irradiation region to the outside of the optical fiber by using a part of the signal light when the signal light passes through the ultraviolet irradiation region. An optical module characterized by generating   The amount of the scattered light is determined based on at least one of the length of the ultraviolet irradiation region in the longitudinal direction, the ultraviolet intensity of the ultraviolet irradiation, and the irradiation time of the ultraviolet irradiation. The optical module according to claim 1.   3. The optical module according to claim 1, wherein a length of the ultraviolet irradiation region in the longitudinal direction is longer than a wavelength of the signal light and is 1 to 50 mm.   The optical module according to any one of claims 1 to 3, wherein the ultraviolet intensity of the ultraviolet irradiation is uniform within an ultraviolet irradiation surface of the core portion irradiated with the ultraviolet light. A light detection unit that is disposed outside the optical fiber and detects the scattered light;
5. The optical module according to claim 1, wherein the light detection unit is arranged in an arbitrary direction extending radially from the ultraviolet irradiation region. The light source includes a plurality of light sources,
The optical fiber includes a plurality of optical fibers corresponding to each of the plurality of light sources on a one-to-one basis,
Each of the plurality of optical fibers includes at least one of the ultraviolet irradiation regions in a different number from each other in each core part,
The optical module according to claim 5, wherein the light detection unit detects the scattered light scattered from each of the ultraviolet irradiation regions of the core portions of the plurality of optical fibers.   The optical module according to claim 6, wherein in each of the plurality of optical fibers, the ultraviolet irradiation region is arranged in each of the core portions based on a unique arrangement pattern. A method of detecting light using an optical fiber including at least one ultraviolet irradiation region irradiated with ultraviolet rays of uniform intensity in the longitudinal direction along the longitudinal direction of the core part,
A detection step of detecting scattered light scattered radially from the ultraviolet irradiation region toward the outside of the optical fiber;
And a determination step of determining that there is signal light propagating through the optical fiber when the scattered light can be detected in the detection step.

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