JPH04119407U - Optical fiber connection mechanism - Google Patents

Abstract

(57) [Summary] [Purpose] Even if the input end face of the optical fiber is formed at an angle, the laser beam can be aligned with the central axis of the optical fiber without shifting the axes of the optical fiber and the lens system. It can be made parallel. [Structure] An optical fiber connection mechanism 11 is arranged coaxially with the central axis of the fiber 12 and an output side fiber 12 having an end face 12A formed at a predetermined angle with respect to the central axis O. A collimating lens 15 that converts light into parallel light, a condensing lens 17 that converts this parallel light into focused light again via an isolator 16, and a condensing lens 17 that has the same shape as the output side fiber 12 into which this focused light enters, and The end surface 12A with respect to a plane perpendicular to the central axis of the fiber 12.
The input side fiber 14 has an inclined end surface 14A that is plane symmetrical to
It consists of

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention is a fiber that guides light output from a light source in optical communication equipment, etc. and the fiber into which this light enters are connected to each other through a lens system. Concerning connection mechanisms.

0002

[Conventional technology]

Fig. 3 is a schematic configuration diagram showing an optical device having a conventional optical fiber connection mechanism, and Fig. 4 is a schematic diagram for explaining the configuration of a conventional optical fiber connection mechanism, and FIG. FIG. 3 is an explanatory diagram for explaining an improved example of a fiber connection mechanism. Reference numeral 1 in the figure is a light source that emits laser light B. In FIG. This light source 1 is, for example, a laser. A laser diode (not shown) emits laser light B, and this laser light is collected. The light is focused by a light lens (not shown) and enters the optical fiber 2. This incident The laser beam is transmitted through an optical fiber 2 and connected by an optical fiber connection mechanism 3. The signal is transmitted to the optical fiber 4. In the optical fiber connection mechanism 3 shown in FIG. The fiber 2 has an end face 2A formed perpendicularly to the central axis O of the fiber 2. Converts the laser beam B emitted from the fiber 2 into parallel light, which is arranged on the same axis. This is done via the collimating lens 5 (lens system) and the isolator 6 (lens system). A condenser lens 7 (lens system) that converts the parallel light of the similar to the end face 2A of the fiber 2, with respect to the central axis O of both fibers 2 and 4. The fiber 4 has a vertical end face 4A.

0003 In the optical fiber connection mechanism 3 having such a configuration, the fibers 2 and 4 are connected in the same manner. Because it only needs to be placed on the axis, positioning is easy and phase matching is good. It has the advantage of being On the other hand, in such a configuration, the fiber 4 A part of the emitted laser beam B is reflected by this end face 4A and returns to the fiber 2. Elephants occur. When the reflected light returns to light source 1 in this way, the result is This may adversely affect the drive control (not shown) of the laser diode such as noise. There is a problem of To counteract the negative effects of reflected light as described above, the end face of the fiber is made into a sloped surface. It is conceivable that the reflected light is prevented from returning to the input fiber. FIG. 5 shows an end face 8A that is inclined at a predetermined angle with respect to the central axis O of the fiber. and a fiber having an end face 9A formed at an angle. 9. In this example, the end face 9A of the fiber 9 on the input side Since the reflected light does not return to the fiber 8 side, there are no problems such as noise caused by the returned light. It becomes. Also, at an angle that allows phase matching of the incident light with respect to the end surface 9A of the fiber 9. It becomes possible to enter.

0004

[Problem that the idea aims to solve]

However, in the connection mechanism of FIG. 5, the laser beam B guided to the fiber 8 Since the laser beam B is refracted downward in the figure when emitted from the end face 8A, collimation is required. The axes of lens 5, isolator 6, and condensing lens 7 must be shifted from each other. stomach. Therefore, it is difficult to position each lens, etc. and each fiber, making it impractical. There is. Furthermore, since the optical axis of the laser beam is inclined with respect to lenses 5 and 7, etc., The aberration caused by the lens is superimposed on the light incident on the fiber 9, and the light from the final end of the fiber 9 is It becomes necessary to correct aberrations of the emitted light. Therefore, the present invention has been developed for cases where the input end face of an optical fiber is formed at an angle. Even if the laser beam is incident on the optical fiber without shifting the axis of the optical fiber and the lens system, Optical fiber splicer that can phase-match the input to the side fiber. The purpose is to provide a structure.

[0005]

[Means to solve the problem]

The structure of the present invention to achieve the above object is to connect fibers that transmit light to each other. A connection mechanism for optical fibers that is optically connected via a lens system, and is a coaxial The opposing end surfaces of the two fibers are symmetrical to the plane perpendicular to the central axis. It has a sloped surface, and one fiber end is located between the end faces of both fibers. A lens system is provided that focuses the light emitted from one surface onto the other fiber end surface. It is characterized by being

[0006]

[Effect]

According to the present invention having the above configuration, the fiber is formed at a predetermined angle with respect to the central axis of the fiber. The laser beam emitted from the output side fiber with the A lens system placed coaxially with the center axis converts the light into parallel light and further It is converted into focused light. This focused light has an end face that has the same shape as the end face of the output side fiber. and is disposed in plane symmetry with a plane perpendicular to the central axis of the exit fiber. The light is incident on the end face of the fiber. Therefore, the phase of the light is matched to the end face of the fiber on the input side. The fibers and lenses can be placed coaxially. This also improves ease of assembly.

[0007]

【Example】

An embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a layout diagram showing an optical fiber connection mechanism according to an embodiment of the present invention, and Fig. 2 shows its parts. This is an enlarged view. The optical fiber connection mechanism 11 shown in FIG. An end face 1 from which the emitted light is guided and is inclined at a predetermined angle with respect to the central axis. The output side fiber 12 has an output power of 2A and is arranged coaxially with the central axis O of the fiber 12. The collimating lens 15 converts the emitted light into parallel light, and the collimating lens 15 converts the emitted light into parallel light. A condensing lens 17 converts the condensed light into condensed light again via the isolator 16, and this condensed light is The input fiber has the same shape as the output fiber 12 (the end face 1 of the output fiber 12 2A), and The fiber 12 is inclined symmetrically with the end surface 12A with respect to a plane perpendicular to the central axis O of the fiber 12. The input side fiber 14 has an end face 14A having a vertical angle.

[0008] Next, the operation of the optical fiber connection mechanism with the above configuration will be explained with reference to FIG. do. First, as shown in Fig. 1, the laser beam B emitted from the fiber 12 is collimated. The torrent lens 15 converts the parallel light into parallel light, and the isolator 16 converts the parallel light into parallel light. The condenser lens 17 converts the light into a convergent light again. This focused light enters the input fiber 14. The light is incident on the central axis O. At this time, the end face 14A of the input side fiber 14 is at a predetermined angle. Since it is formed to be inclined, the light reflected from the end face 14A is directed to the output side fiber 12. Do not return to direction A. Therefore, this reflected light will not return to the light source 1, and the laser - No adverse effects such as noise on diode drive control (not shown) Become.

[0009] Further, the optical axis of the laser beam B emitted from the end face 12A of the emission side fiber 12 is B0. It is bent downward in the figure as shown in , and then proceeds parallel to the central axis O as shown in B1. The optical axis is further focused in the B2 direction by the condenser lens 17, and the input fiber 1 The light is incident on the center of the end surface 14A of No. 4. The end surface 14A and the end surface 12A are perpendicular to the central axis O. Since it is plane symmetrical with respect to the plane, the optical axis incident at the angle of optical axis B2 is at the end surface 14A. The light is refracted toward the central axis O of the incident side fiber 14. Therefore, to the input fiber 14 Phase matching of the incident laser beam B can be achieved. In addition, the optical axis B0 of the laser beam B emitted from the input fiber 12 is located at the end surface 12A. Since the optical axis B0 is incident on the collimating lens 15 at an angle, the laser beam is refracted. Aberrations occur in the laser light B due to the collimating lens 15. However, this The difference is that the condensing lens 17 directs the laser beam B in a direction symmetrical to the collimating lens 15. This will be canceled out by being focused.

0010 Also, for each lens 15 and 17, the laser beam B is deviated from the central axis O. It progresses in a state where it is shifted from the position. Therefore, in the following, the numerical aperture of the lens and the fiber The relationship with numerical aperture will be explained. As shown in FIG. 2, the inclination angle of the end face 12A of the output side fiber 12 is α. Then, the optical axis B01 of the laser beam from the light source (not shown) is parallel to the axis of the fiber 12. (on the axis of the fiber in this example), this optical axis B01 is at the end face 12A. The incident angle of incidence is α (V is a perpendicular to the end surface 12A). Therefore, the end surface 12A The exit angle β is (sin β=n1·sin α). However, n1 is is the refractive index of bar 12. Let β1 be the angle of this output optical axis B0 from the central axis O ( β1=β−α). Further, the numerical aperture of the laser beam B emitted from the end face 12A is (sin γ). At this time, the collimating lens 15 cannot take in the laser beam B. In order to achieve this, the minimum value of the numerical aperture NA of the collimating lens 15 must be as shown in the following formula. It is necessary to

[0011] NA=n・sin(β1+γ) (Formula 1) However, n=1 (refractive index of air)

0012 A collimator with a numerical aperture greater than or equal to the minimum numerical aperture (NA) determined by the above (Formula 1) If a torrent lens is used, the laser beam B0 from the light source will be refracted by an angle β and emitted. Even in this case, all of the laser beam B0 can be taken in. Also, condensing lens Regarding No. 17, the lens has a numerical aperture greater than or equal to the minimum numerical aperture determined by (Formula 1). If you use 4A and can be incident parallel to the central axis of the input fiber 14. Ru. Therefore, for example, if the inclination angle (α) of the end face 12A of the output side fiber 12 is 7° In this case, the central axis O of the laser beam B0 emitted from the end face 12A of the fiber 12 is The angle β1 between them is 3.2°. Also, the numerical aperture of a normal optical fiber is 0.15. Therefore, the angle γ is 8.63°. Therefore, it can capture laser light. The minimum numerical aperture of the lens 15 is from (formula 1)

[0013] NA=sin(3.2°+8.63°)=0.205

[0014] Therefore, if a collimating lens 15 with a numerical aperture of 0.205 or more is used, the light source can be It is possible to take in all of the laser beam B0. Also, similar to this, the aperture If a condensing lens 17 with a number of 0.205 or more is used, the collimating lens 15 All of the laser beams that have been made into parallel beams are focused on the end face 14A, and the input side fiber is 14 can be incident parallel to the central axis. As detailed above, according to the optical fiber connection mechanism of one embodiment of the present invention, the optical The fibers 12 and 14, the collimating lens, and the condensing lens 17 are arranged on the axis O. The laser beam emitted from the optical fiber 12 can be aligned with the axis of the optical fiber 14 again. It can be made parallel. Note that in the above embodiment, the collimating lens 15 and the focusing lens are provided between the fibers 12 and 14. Although the optical lens 17 is provided, for example, if it is not necessary to make the light beam parallel, the end surface 12 Between A and 14A is a finite system condensing lens, that is, diffused emitted light from the end surface 12A. It is also possible to provide a single or multiple lenses that can focus light on the end surface 14A.

[0015]

[Effect of the idea]

As described above, according to the present invention, the input end face of the optical fiber is formed at an angle. Even if the optical fiber and lens system are We provide an optical fiber connection mechanism that allows the input of light parallel to the central axis of the optical fiber. can be provided.

[Brief explanation of drawings]

FIG. 1 is a lens layout diagram showing an optical fiber connection mechanism according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view for explaining the relationship between the refraction angle of a laser beam and the numerical aperture (angle) of a lens.

FIG. 3 is a schematic configuration diagram showing an optical device having a conventional optical fiber connection mechanism.

FIG. 4 is a schematic diagram for explaining the configuration of a conventional optical fiber connection mechanism.

FIG. 5 is a diagram for explaining an improved example of a conventional optical fiber connection mechanism.

[Explanation of symbols]

11 Optical fiber connection mechanism 12,14 Optical fiber 15 Collimating lens 17 Condensing lens

Claims (1)

[Scope of utility model registration request] Claim 1: An optical fiber connection mechanism for optically connecting fibers that transmit light to each other via a lens system, wherein the opposing end surfaces of two coaxially located fibers are aligned with a plane perpendicular to the central axis. A lens system is provided between the end faces of both fibers to focus the light emitted from one fiber end face and make it incident on the other fiber end face. An optical fiber connection mechanism characterized by: