JP3192609U - Optical multiplexer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical combiner which can be used without wasting light emitted from a plurality of light sources as much as possible. SOLUTION: A plurality of light sources 10 and 10, a plurality of optical fibers 40 and 40 propagating light emitted from a plurality of light sources, respectively, and a plurality of optical fibers connected to each exit end of the optical fiber and having a length in the optical axis direction. It is provided with a plurality of rod lenses 50, 50 having a meandering cycle of the propagating light inside the m / 4 (m is an odd number of 1 or more), and a condensing lens 61 connected to the plurality of rod lenses. It is characterized by that. [Selection diagram] Fig. 1

Description

  The present invention relates to an optical multiplexing device that combines light emitted from a plurality of light sources.

  Conventionally, a plurality of light emitting elements are coupled to sub optical fibers, and the other ends of the sub optical fibers are aligned and arranged so that they are parallel to each other. A method of combining an optical fiber with a light-emitting element that makes light from the fiber incident on the main optical fiber has been proposed (second page, lower left column, second to seventh rows, etc. of Patent Document 1).

  According to this conventional coupling method, even if the coupling efficiency between the individual light emitting elements (light emitting diodes) and the main optical fiber is slightly sacrificed, the main optical fiber has a sufficiently large optical signal input necessary for transmission. (The second page, lower left column, line 7 to line 10 of Patent Document 1, etc.).

Japanese Patent Laid-Open No. 58-11918

  In recent years, however, there is a further need for an apparatus that can collect light emitted from a plurality of light sources onto an optical fiber without wasting it as much as possible.

  Therefore, an object of the present invention is to provide an optical multiplexing device that can be used without wasting light emitted from a plurality of light sources as much as possible.

  According to the present invention, the above problem is solved by the following means.

The present invention is connected to a plurality of light sources, a plurality of optical fibers for propagating light emitted from the plurality of light sources, and an output end of the plurality of optical fibers, respectively, and the length in the optical axis direction is the length of the propagation light. m _1/4 of the meandering period (m ₁ is 1 or more odd number) and a plurality of rod lenses is, the plurality of connected condenser lens to the rod lens, an optical multiplexing device characterized by comprising a is there. The “meandering cycle” indicates a cycle (pitch length) P when light meanders and propagates inside the rod lens.

  The present invention is the above-described optical multiplexing device, wherein the condenser lens is a rod lens.

Further, the present invention is a condenser lens, the length of the optical axis direction, m _2/4 meander period of the propagating light therein (m ₂ is 1 or more odd number) and the rod lens, the condenser In the above-described optical multiplexing device, an optical fiber is connected to the exit end of the lens.

  The present invention is the above-described optical multiplexing device characterized in that a rod lens is connected to the output end of the optical fiber connected to the output end of the condenser lens.

  The present invention is the above-described optical multiplexing device, wherein the wavelengths of the light emitted from the plurality of light sources are 500 nm or less.

  According to the present invention, it is possible to provide an optical multiplexing device that can be used without wasting light emitted from a plurality of light sources as much as possible.

1 is a schematic side view of an optical multiplexing device according to a first embodiment of the present invention. It is a schematic side view of the optical multiplexer which concerns on 2nd Embodiment of this invention. It is a schematic side view of the optical multiplexing apparatus which concerns on 3rd Embodiment of this invention. It is a schematic side view of the optical multiplexing apparatus which concerns on 4th Embodiment of this invention. It is a schematic side view of the optical multiplexing apparatus which concerns on 5th Embodiment of this invention. It is a schematic sectional drawing (an optical axis is included) of a rod lens.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated, referring attached drawing.

[Optical multiplexer 1 according to the first embodiment of the present invention]
FIG. 1 is a schematic side view of an optical multiplexing device according to the first embodiment of the present invention.

  As shown in FIG. 1, in the optical multiplexing device 1 according to the first embodiment of the present invention, light emitted from a plurality of light sources 10 is propagated through a plurality of optical fibers 40 and collected by a condenser lens 61. .

  Rod lenses 30 and 50 are connected to an incident end and an emission end of the optical fiber 40, respectively. The light emitted from the light source 10 is collimated by the collimator lens 20 and enters the rod lens 30.

  Details will be described below.

(Light source 10)
As the light source 10, a plurality of semiconductor laser elements, light emitting diodes, and the like are used. When the dispersion (the property that the refractive index varies depending on the wavelength) of the material of the condenser lens or the chromatic aberration of the condenser lens can be ignored, the wavelengths λ of the light emitted from the plurality of light sources may be different. Further, when a semiconductor laser element is used as the light source, particularly when a wavelength λ is a relatively short wavelength, specifically when a wavelength of 500 nm or less is used, dust collection tends to occur when the light density increases. It is possible to make it difficult to collect dust by condensing light by the configuration as in the implementation.

(Collimator lens 20)
The collimator lens 20 turns the light emitted from the light source 10 into parallel light.

(Rod lens 30)
The rod lens 30 is a lens having a length L ₃₀ in the optical axis direction of m _0/4 (m ₀ is an odd number equal to or greater than 1) having a meandering period P ₃₀ of propagating light therein, and has a refractive index of the optical axis ( It is a cylindrical gradient index lens that is the highest on the central axis and lowers toward the periphery.

  More specifically, the refractive index of the optical axis (the center of the circle) is highest in the cross section (circle) perpendicular to the optical axis of the cylindrical lens made of a translucent member, and is continuous from the optical axis toward the outer circumferential direction. The lens has a low refractive index.

  Such a rod lens 30 is connected to the incident end of the optical fiber 40, collects the light emitted from the collimator lens 20, and causes the light to enter the optical fiber 40.

The refractive index n ₃₀ of the rod lens 30 is not constant, and the refractive index n _{30 at} the position of the radius r ₃₀ centered on the optical axis is expressed by the following equation (1).
n ₃₀ = n ₀₃₀ (1-g ₃₀ ² r ₃₀ ^q / 2) (1)
Here, g ₃₀ is a constant representing the light collecting ability of the rod lens 30, and n ₀₃₀ is a refractive index on the optical axis of the rod lens 30 with respect to the wavelength λ of the light source. q is a distribution constant, and when q = 2, the refractive index changes in a quadratic curve.

When q = 2, if the refractive index at a radius d ₃₀ of a cross section (circle) perpendicular to the optical axis of the rod lens 30 is n _d30 , the numerical aperture NA ₃₀ (Numerical Aperture) of the rod lens 30 is NA ₃₀ = ( n ₀₃₀ ² _−nd 30 ² ) ^1/2 , and a constant g ₃₀ indicating the light condensing capability of the rod lens ₃₀ is expressed by the following equation (2).
_{g 30 = (NA 30 / d} 30) {2 / (n 030 2 + n 030 n d30)} 1/2 ··· (2)

The inner rod lens when light is serpentine period P ₃₀ of the cycle (pitch length) when propagating serpentine sinusoidal, can be expressed by the following equation (3).
P ₃₀ = 2π / g ₃₀ (3)

Additionally (2) and (3), the meandering period _{P 30} is represented by the following equation (4).
_{P 30 = πd 30 {2n 030} / (n 030 -n d30)} 1/2 ··· (4)

  Then, the parallel light emitted from the collimator lens 20 is collected by the rod lens 30 and is incident on the incident end of the optical fiber 40.

Incidentally, the numerical aperture NA ₃₀ of the rod lens 30 is preferably equal to or less than the numerical aperture of the optical fiber. Thereby, light can be efficiently incident on the optical fiber 40.

  According to the optical multiplexing device 1 according to the first embodiment of the present invention, since the rod lens 30 is connected to the incident end of the optical fiber 40, light dust collection is prevented from occurring at the incident end of the optical fiber 40. be able to.

  Further, according to the optical multiplexing device 1 according to the first embodiment of the present invention, parallel light is incident on the incident end of the rod lens 30 instead of condensed light.

  However, the collimated light has a lower energy density than the collected light.

  Therefore, according to the optical multiplexing device 1 according to the first embodiment of the present invention, it is possible to prevent light dust collection from occurring at the incident end of the rod lens 30.

  The rod lens 30 and the incident end of the optical fiber 40 are connected by, for example, fusion or an adhesive.

(Optical fiber 40)
The optical fiber 40 has rod lenses 30 and 50 connected to the incident end and the emission end, respectively, and propagates the light emitted from the light source 10.

(Rod lens 50)
The rod lens 50 is connected to the output end of the optical fiber 40.

Rod lens 50, the length _{L 50 P 50 × m 1/4 (} P 50 is the period (pitch length when the light inside the rod lens 50 propagates meandering sinusoidal) _{(m 1} is 1 or more The light emitted from the optical fiber 40 is converted into parallel light and is incident on the condensing lens 61.

  The rod lens 50 provided at such a position preferably has a numerical aperture greater than or equal to the numerical aperture of the optical fiber 40. Thereby, light can be efficiently incident on the rod lens 50.

  Note that the rod lens 50 and the output end of the optical fiber 40 are connected by, for example, fusion or adhesive.

(Condenser lens 61)
The condenser lens 61 is connected to the plurality of rod lenses 50. The condensing lens 61 condenses the parallel light respectively emitted from the plurality of rod lenses 50.

  The rod lenses 50 connected to the emission ends of the optical fibers 40 are bundled so that their optical axes are parallel to each other, and are bundles having an optical axis parallel to the optical axis of each rod lens 50.

  The bundled rod lenses 50 and the condenser lens 61 are connected so that their optical axes are parallel to each other by fusion, an adhesive, or the like.

  According to the optical multiplexing device 1 according to the first embodiment of the present invention described above, light incident on the condenser lens 61 is simply emitted from the emission end via the optical fiber 40 (opening of the optical fiber 40). Light that spreads and propagates according to the number).

  That is, light that has propagated only in the optical fiber without using the rod lens spreads and propagates in accordance with the numerical aperture of the optical fiber. For this reason, even if such light is incident on the condenser lens 61, most of the light cannot be efficiently collected by the condenser lens 61, and thus cannot be effectively used on the exit end side of the condenser lens 61. , Become useless.

  However, according to the optical multiplexing device 1 according to the first embodiment of the present invention, the light emitted from the exit end of the optical fiber 40 (the light propagating in accordance with the numerical aperture of the optical fiber 40) is transmitted by the rod lens 50. The collimated light is incident on the condenser lens 61.

  Therefore, according to the optical multiplexing device 1 according to the first embodiment of the present invention, most of the light incident on the condenser lens 61 is collected by the condenser lens 61, and on the output end side of the condenser lens 61. Can be used.

  Therefore, according to the optical multiplexing device 1 according to the first embodiment of the present invention, it is possible to provide an optical multiplexing device that can be used without wasting light emitted from the plurality of light sources 10 as much as possible.

[Optical multiplexer 2 according to the second embodiment of the present invention]
FIG. 2 is a schematic side view of an optical multiplexing device according to the second embodiment of the present invention.

  As shown in FIG. 2, the optical multiplexing device 2 according to the second embodiment of the present invention is different from the optical multiplexing device 1 according to the first embodiment of the present invention in that the condensing lens is a rod lens 62. To do.

  When the condensing lens is the rod lens 62, each rod lens 50 connected to the output end of the optical fiber 40 can be easily connected to the condensing lens 62.

  Further, when the condensing lens is the rod lens 62, it is easy to adjust the optical axes of the rod lenses 50 and the condensing lens 62 connected to the emission end of the optical fiber 40.

[Optical multiplexer 3 according to the third embodiment of the present invention]
FIG. 3 is a schematic side view of an optical multiplexing device according to the third embodiment of the present invention.

  As shown in FIG. 3, in the optical multiplexing device 3 according to the third embodiment of the present invention, an optical fiber 70 is connected to an exit end of a condensing lens that is a rod lens 62, and the optical fiber 70. This is different from the optical multiplexing device 2 according to the second embodiment of the present invention in that a rod lens 80 is connected to the emission end of the optical multiplexer.

Here, the condenser lens which is a rod lens 62, the length _{L 62, P 62 × m 2/4} (m 2 is 1 or more odd number) have a length of, the incident parallel light Are condensed and made incident on the optical fiber 70 connected to the exit end of the condenser lens 62. P ₆₂ is a meandering period (pitch length) when light is meandering and propagating in a sinusoidal shape inside the condenser lens (rod lens) 62. The numerical aperture of the condenser lens 62 is preferably equal to or less than the numerical aperture of the optical fiber 70, and the numerical aperture of the rod lens 80 is preferably equal to or greater than the numerical aperture of the optical fiber 70.

  According to the optical multiplexing device 3 according to the third embodiment of the present invention, since the optical fiber 70 is connected to the exit end of the condenser lens 62, the optical multiplexing device 3 multiplexes by drawing the optical fiber 70. Light becomes easy to use in various places.

  Further, according to the optical multiplexing device 3 according to the third embodiment of the present invention, the rod lens 80 is connected to the optical fiber 70 connected to the output end of the condenser lens 62, so that the optical fiber 70 is connected to the output end of the optical fiber 70. Thus, light dust collection can be prevented.

  The condenser lens 62 and the optical fiber 70 can be connected by, for example, fusion or adhesive. The optical fiber 70 and the rod lens 80 can be connected by, for example, fusion or an adhesive.

[Optical multiplexer 4 according to the fourth embodiment of the present invention]
FIG. 4 is a schematic side view of an optical multiplexing device according to the fourth embodiment of the present invention.

  As shown in FIG. 4, the optical multiplexing device 4 according to the fourth embodiment of the present invention condenses the light emitted from the light source 10 by a spherical gradient index lens 90 and enters the optical fiber 40. This is different from the optical multiplexing device 1 according to the first embodiment of the present invention in which the light emitted from the light source 10 is collimated by the collimator lens 20 and enters the rod lens 30.

  The light emitted from the light source 10 may be guided to the optical fiber 40 as in the optical multiplexing device 4 according to the fourth embodiment of the present invention.

[Optical multiplexer 5 according to the fifth embodiment of the present invention]
FIG. 5 is a schematic side view of an optical multiplexing device according to the fifth embodiment of the present invention.

  As shown in FIG. 5, the optical multiplexing device 5 according to the fifth embodiment of the present invention is configured such that the light emitted from the light source 10 is directly incident on the rod lens 100 by the collimator lens 20. This is different from the optical multiplexing device 1 according to the first embodiment of the present invention in which the parallel light is incident on the rod lens 30.

  The light emitted from the light source 10 may be guided to the optical fiber 40 as in the optical multiplexing device 5 according to the fifth embodiment of the present invention.

  The rod lens 100 has a length and a numerical aperture that allow light propagating through the rod lens 100 to be collected on the optical fiber 40.

[Rod lens]
FIG. 6 is a schematic cross-sectional view of the rod lens.

A rod lens is a cylindrical gradient index lens that has the highest refractive index on the optical axis (center axis) and decreases toward the periphery. The refractive index n inside the rod lens is not constant, and the refractive index n at the position of the radius r centered on the optical axis is expressed by the following equation (5).
n = n ₀ (1-g ² r ^q / 2) (5)
Here, g is a constant representing the condensing ability of the rod lens, and n ₀ is a refractive index on the optical axis of the rod lens with respect to the wavelength λ of the light source. q is a distribution constant, and when q = 2, the refractive index changes in a quadratic curve.

  As shown in FIG. 6, the light of wavelength λ incident on the rod lens travels in a sine wave shape or a cosine wave shape with a pitch length P as a period.

  That is, as shown in FIG. 6 (a), when the condensed light is incident on the rod lens, the incident light propagates through the rod lens in a sine wave shape, and is approximately P × m / 4 (m Becomes parallel light at an odd length of 1 or more.

  On the other hand, as shown in FIG. 6 (b), when parallel light is incident on the rod lens, the incident light propagates in the rod lens in a cosine wave shape, and approximately P × m / 4 of the rod lens (P is the rod lens). The light is condensed at a period of time in which light propagates in a sinusoidal shape, m is an odd number of 1 or more.

  In addition, although the magnitude | size of the rod lenses 30, 50, 80, 100 is not specifically limited, In the optical multiplexing apparatuses 1-5 which concern on 1st Embodiment-5th Embodiment of this invention, a rod lens 30, 50, 100 have the same diameter as the optical fiber 40, and the rod lens 80 has the same diameter as the optical fiber 70. This makes it easy to adjust the optical axis between the rod lens and the optical fiber.

  As mentioned above, although the optical multiplexing apparatuses 1-5 which concern on 1st Embodiment-5th Embodiment of this invention were demonstrated, the optical multiplexing apparatuses 1-5 which concern on these embodiments are the wavelengths of the light radiate | emitted from the light source 10. FIG. It can be particularly preferably used when λ is 500 nm or less, that is, when light having a wavelength of 500 nm or less is multiplexed.

  Light having a wavelength of 500 nm or less has a high energy density because it is a relatively short wavelength, and when it is collected and incident or emitted, optical dust collection becomes significant. However, the optical multiplexing according to each embodiment This is because according to the devices 1 to 5, light dust collection can be effectively prevented.

  As mentioned above, although embodiment of this invention was described, these description is related to an example of this invention, and this invention is not limited at all by these description.

  The present invention can be used as a fiber laser excitation light source, a laser processing light source, a projector light source, optical communication field, processing and inspection such as marking and welding, industrial use such as fiber laser excitation, medical use, printing, etc. It can be used in various fields such as consumer use.

DESCRIPTION OF SYMBOLS 1 Optical multiplexer 2 Optical multiplexer 3 Optical multiplexer 4 Optical multiplexer 5 Optical multiplexer 10 Light source 20 Collimator lens 30 Rod lens 40 Optical fiber 50 Rod lens 61 Condensing lens 62 Condensing lens (rod lens)
70 Optical fiber 80 Rod lens 90 Spherical gradient index lens 100 Rod lens

Claims (5)

Multiple light sources;
A plurality of optical fibers each propagating light emitted from the plurality of light sources;
Are connected to the exit end of said plurality of optical fibers, the length of the optical axis direction, and a plurality of rod lenses is m _1/4 meander period of the propagating light therein (m ₁ is 1 or more odd number) ,
A condensing lens connected to each of the plurality of rod lenses so that an optical axis thereof is parallel to each of the plurality of rod lenses;
An optical multiplexing device comprising:   2. The optical multiplexing device according to claim 1, wherein the condensing lens is a rod lens. The condenser lens, the length of the optical axis direction, a rod lens of the length of the m _2/4 meander period of the propagating light therein (m ₂ is 1 or more odd number), of the condenser lens The optical multiplexing device according to claim 2, wherein an optical fiber is connected to the emission end.   The optical multiplexing device according to claim 3, wherein a rod lens is connected to an output end of an optical fiber connected to an output end of the condenser lens. 5. The optical multiplexing device according to claim 1, wherein a wavelength of light emitted from each of the plurality of light sources is 500 nm or less.