JPS593413A - Optical distributor - Google Patents

Abstract

PURPOSE:To prevent the leakage of an optical signal owing to diffracted light by providing the boundary of plural reflection faces in parallel to the direction connecting the positions of an input fiber and an output fiber. CONSTITUTION:An optical fiber array 1 bundled with plural optical fibers constituting input and output ports in parallel in one direction is optically connected to the one end face of a rod lens 2 at 1/4 pitch, and two sheets of light transmittable optical fobides 4a, 4b having inclined faces of angles alpha, pi-alpha in the arranging direction of the input and output ports are butted to the center of the other end face of the lens 2 with the arranging direction of the input and output ports as a boundary line. Reflection faces 5a, 5b are formed on the inclined faces of the respective bodides 4a, 4b. The incident light from the input port is subjected to wavefront division at said boundary line and is dividedly reflected in different directions. The diffracted light generated at the boundary of the faces 5a, 5b having different angles advances in the direction at a right angle to the above-mentioned boundary line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a simple and highly practical optical distributor that does not cause unwanted optical coupling due to light diffraction.

[Technical background of the invention and its problems]

Advances in microprocessors have greatly contributed to the development of economical and reliable distributed processing information systems.

At this time, the information transmission function will play an extremely important role (optical fiber transmission technology that takes advantage of the characteristics of optical fiber, such as broadband, low loss, and non-induction, is expected to play a role in this. In an optical network system responsible for information transmission, it is effective to use an optical splitter in order to improve its reliability.

For example, in a loop network constructed using optical repeaters, an optical distributor having an optical distribution function as shown in FIG. 1 is used. This optical splitter transfers the optical signal input from the trunk input port M1 to the receiving port R of the relay station by 3 dB.
The remaining 3 dB optical signal is output to the next station from the trunk output port M2, and the signal from the transmission port T of the relay station is connected to the trunk output port M2. It is configured such that it is transmitted with a 3 dB coupling to the signal.

Conventionally, an optical demultiplexer that achieves such a demultiplexing function is configured as shown in FIG. 2(a), for example.

That is, input/output port M, 1 # M2 * R, T
An optical fiber array 1 formed by arranging optical fibers parallel to each other in one direction is optically coupled to one end surface of a rod lens 2 having a length of 1/4 pitch, and the apex angle is Total reflection prism 3 slightly smaller than 90°
An optical distributor is constructed by arranging the optical fibers so that the direction of the ridge line is perpendicular to the fiber arrangement direction of the optical fiber array 1. At this time, each port M1 of the optical fiber array 1
+ M2, R, and T are centered at the main output port M2 with respect to the center of the rod lens 2 (the ridge line of the total reflection prism 3, 9a), as shown in FIG. 2(b), and Main line input port M.

and the receiving port ()R are arranged symmetrically, and the transmitting/receiving port ()T and the dummy port ()D are arranged symmetrically. The total reflection prism 3 thus splits the incident light beam into two directions around the ridgeline 3a, as the optical path is schematically shown in FIG. 2(c).

This division action and the input/output ports Ml, M2
.

Depending on the arrangement relationship between R and T, the incident light from the main line input port M1 is divided and guided to the main line capo M2 and the receiving port R, and the incident light from the transmitting port M2 is guided to the main line capo M2 and the receiving port R. The capo) M2 and the dummy po) D are divided and guided.

However, in an optical splitter with such a conventional structure,
In this case, a light beam having a Gaussian light intensity distribution divided into two by the ridge line 3a of the total reflection prism 3 is transmitted in a direction perpendicular to the boundary at a boundary where there is a strong change or a large phase change. input/output capo) Ml + M2,
A relatively large amount of diffracted light is generated in the direction in which the RrTs are arranged. Due to this diffracted light component, the local transmission optical signal input from the transmission port T is guided to the reception port (H), and eventually a signal leakage of, for example, about -37 dB occurs between the transmission and reception ports T and R. There was a problem. This signal leakage has caused problems such as limiting the maximum relay distance in optical fiber optic loop networks.

[Purpose of the invention]

The present invention has been made in consideration of these circumstances, and its purpose is to provide an optical splitter with a simple and highly practical configuration that does not cause optical signal leakage due to diffracted light. be.

[Summary of the invention]

In the present invention, an optical fiber array in which a plurality of optical fibers are bundled in parallel in the axial direction is arranged on one end surface of a lens body consisting of a 1/4 pitch rod lens or an optical lens equivalent thereto, and an optical fiber array is provided on the other end surface. A plurality of reflective surfaces having predetermined reflection angles are provided in areas, and the area divisions of the reflective surfaces are connected, for example, to the image position of the input fiber and the position of the output fiber with respect to the input and output optical fibers whose optical coupling should be avoided. The direction is set in such a way that the influence of diffraction is reduced by, for example, providing a boundary parallel to the direction.

〔Effect of the invention〕

Therefore, according to the present invention, the boundary of the reflecting surface that splits the wavefront of incident light is set approximately parallel to the direction connecting the image position of the input port and the position of the output port, for example, with respect to an input/output port where optical coupling is not desired to occur. By determining the direction, it is possible to suppress the generation of diffracted light in that direction. Therefore, there is no risk of unwanted optical coupling between the input and output ports due to the diffracted light, and optical signal leakage due to the diffracted light is prevented. Therefore, the effects obtained when applied to an optical binox type network are enormous.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

3(a) and 3(b) show a first embodiment of the present invention, in which FIG. 3(a) is a perspective external configuration diagram and FIG. 3(b) is a plan configuration diagram. (in/out capo) MI I MI
#R#T is constructed by optically connecting an optical fiber array 1, which is a plurality of (four) optical fibers bundled in parallel in one direction, to one end surface of a 1/4 pitch rod lens 2. The positional relationship of the input/output port MIIMIIR*T with respect to the rod lens 2 is determined in the same manner as in the conventional structure shown in FIG.

Therefore, on the other end surface of the rod lens 2, there are two translucent optical sheets having inclined surfaces at an angle α (π−α) in the arrangement direction of the input/output ports with respect to the other end surface of the rod lens 2. The bodies 4a, 4b are provided so as to abut against each other at their centers with the direction in which the input/output ports are arranged as a boundary line. and,
Each inclined surface of the two translucent optical bodies 4* and 4b is formed as a reflective surface 5as5b for the incident light from the input port. The reflective surface 5ILe5b is formed using conventionally known means such as vapor deposition of a metal reflective film.

Thus, according to the light distributor having such a structure, the reflective surface 5 a of the reflective optical system formed on the other end surface of the rod lens 2
For the optical input/output port where optical coupling is not desired to occur, +5 b defines the boundary parallel to the direction connecting the image position of the input port (dummy D) and the output port, and divides the reflective area, and the rod lens Since the two end faces have different inclinations, the incident light from the input port is divided into wavefronts at the boundary line, and is reflected in different directions with different inclinations. K becomes. Therefore, each of the above reflecting surfaces is 5 m long.

If the inclination of 5b and the arrangement of the input/output ports are appropriately set to optimal conditions, the incident light from the main line capo) M2 and the receiving port R, and the incident light from the transmitting port T. The light is connected to the main output port M2 and the dummy port) D
They will be guided to each other. It becomes possible to achieve optical coupling between the tabs and the input/output ports.

Further, at this time, the diffracted light generated at the boundary between the reflecting surfaces 5a and 5b having different angles will proceed in a direction perpendicular to the boundary line. Therefore, the diffracted light does not reach an output port where coupling is not desired, and unwanted coupling between input and output ports and leakage of optical signals do not occur here.

By adopting this unique structure in which the boundary line of the reflecting surfaces 5am 5b that splits the wavefront of the incident light is provided in the direction in which the input/output ports are arranged, it is possible to greatly simplify and effectively eliminate the adverse effects of diffracted light. It can be prevented. Therefore, using this optical distributor, it is possible to effectively construct a loop-like network based on the optical path-pass method.

FIGS. 4(a) and 4(b) show a second embodiment of the present invention. This embodiment differs from the previous embodiment in that the reflective optical system provided on the other end surface of the rod lens 2 is
The lower half or the upper half of the surface with different angles is the reflective surface 7a
* Two translucent optical bodies 6 a serving as 7 b *
It is located at the point formed by joining 6b. That is, the light-transmitting optical body 6a has a lower half of its back surface as a reflective surface 7a, and the back surface is used as a bonding surface to which the light-transmitting optical body 6b is bonded. Then, a reflective surface 7b is formed on the entire back surface or the upper half of the translucent optical body 6b, and a boundary line is formed in the reflective surface 7b at a different angle from the optical body 6a in a direction parallel to the arrangement direction of the input/output ports. The shell is formed by dividing the area into two.

According to this configuration, the relationship between the reflective surfaces 7a*7b and the input/output ports via the rod lens 2 is equivalent to that of the previous embodiment, and therefore similar effects can be achieved.

Further, FIGS. 5(a) and 5(b) show a third embodiment of the present invention, in which a reflective optical system is connected to an input/output port on the front and back surfaces of a translucent optical body 80 having a predetermined inclined surface. Areas are divided in the direction parallel to the arrangement direction and each reflective surface 91 #9
b.

It goes without saying that even with such a configuration, the same effects as those of the previous embodiments can be achieved. In this case,
Of course, the reflective surface 9a provided on the surface of the translucent optical body 8 may be directly formed on the other end surface of the rod lens 2.

Thus, as described above for the optical splitter according to the present invention in each of the embodiments, according to the present invention, it is possible to prevent signal leakage between input and output ports caused by diffracted light. Therefore, it is possible to increase the optical path function and the allowable transmission loss in the optical distribution network.

In addition, since the transmission output of the own station is not looped back to the own station, the ill C8MA-CD (Carrler S
@nseMultiple Accems-Col item 5
This has great practical effects, such as greatly improving the performance of path-based optical networks based on the Alon Deteetlon method.

Note that the present invention is not limited to the above embodiments. In the example, the wave front is divided into two parts, but the wave front is divided into two parts.
The same can be applied to K which performs wavefront division more than division.

In addition, the boundary line of the reflective surface does not necessarily have to be set parallel to the arrangement direction of the input/output ports; for input/output ports where optical coupling is not desired, the boundary line of the reflective surface should be set approximately parallel to the direction connecting the image position of the input port and the position of the output port. The reflective surface area may be divided by defining boundaries to suppress diffracted light in that direction. In short, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of the drawings] Figure 1 is a diagram showing the basic light distribution relationship of the optical distributor, Figure 2
Figures (a) to (e) are diagrams showing the configuration and operation of a conventional optical distributor, and Figures 3 (a) and (b) to Figure 5 (a). (b) is a diagram showing the configuration of an optical distributor of different embodiments according to the present invention. 1... Optical fiber array, 2... Rod lens, 3
... Total reflection prism, 4 pieces m4bm6a+6be8・
・Translucent optical body, 5ae5be7h, 7bm91L
#9 b”’Reflecting surface, Mt + Ml + R
＃T”・Input/output port. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 (C) 11- Figure 3 (a) (b) Figure 4 (a) (b)

Claims (2)

[Claims] (1) A lens body consisting of a 1/4 pitch length Lot 9 lens or an optical lens system equivalent thereto, and a plurality of optical fibers arranged on one end surface of the lens body are arranged in parallel in the axial direction. An optical fiber array comprising a bundled optical fiber array and a plurality of reflecting surfaces each having a predetermined reflection angle provided on the other end surface of the lens body, and for input/output optical fibers in which optical coupling in the optical fibers should be avoided. A light distributor characterized in that each of the reflective surfaces is divided into regions in a direction in which the influence of diffraction is reduced. (2) Area division of the reflective surface, regarding the input and output optical fibers whose optical coupling should be avoided, the direction connecting the position of the image of the input optical fiber determined by the lens body and the reflective surface with a predetermined angle, and the position of the output optical fiber. 2. The light distributor according to claim 1, wherein the reflecting surface is divided by defining area boundary lines substantially parallel to the area boundary line.