JPS5999414A - Optical circuit parts - Google Patents

Abstract

PURPOSE:To improve reliability by rotating eccentric tubes of which the central axis in the cylindrical hollow part deviates from the central axis of the outside diameter in the holes of a holder, and inserting lenses for incidence and exit into the hollow parts of the eccentric tubes after making the central axis in the hollow part roughly coincident with the optical axis of a light beam. CONSTITUTION:Seven cylindrical holes are provided in a stainless steel holder 8, which is a heptagonal column, from a member 12 for fixing the position of optical fibers toward the center of the holder. Tubes 7 which have the diameter slightly smaller than the inside diameter of said holes and of which the central axis O of the outside diameter deviates from the central axis O' in the cylindrical hollow part 7' are inserted into the respective holes of the holder. Cylindrical lenses 1' having the outside diameter slightly larger than the inside diameter of the hollow part and the refractive index distribution which decreases roughly proportionally with the square of the distance from the central axis are inserted into the hollow parts 7' of the tubes 7. The lenses 1' make the light from input optical fibers into parallel light or focus the light beam to exit fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to optical circuit components used in optical fiber cable communication systems, and more particularly to the structure of passive optical circuit components that perform optical branching, multiplexing, and optical path switching.

Passive optical circuit components include optical branching and coupling devices that branch and combine optical signals, optical switches that switch optical signals, and optical multiplexers and demultiplexers that multiplex multiple optical signals with different wavelengths. The configuration of such passive optical circuit components includes a coupling part with an optical fiber,
The main components are the waveguide part that guides and transmits the light beam from the optical fiber, and the functional part that splits, combines, or deflects the light beam. Some passive optical circuit components have two parts integrated into one. Passive optical circuit components with this type of configuration can be roughly divided into components that use a lens component with a uniform refractive index distribution that transmits a parallel beam as a waveguide section They can be classified into those that are composed of optical waveguides and those that are composed of some other type of optical waveguide.Using optical waveguides generally requires advanced microfabrication technology, and sufficient characteristics cannot be obtained (in many cases, they are not). On the other hand, use the lens (・
In this case, as shown in Fig. 1, the number of components is larger than 1, and the components of the input optical fiber 31% lens 1, the optical functional element 2, and the output optical fiber 32 are all placed at individual optimal positions with high precision. There is a need to. One way to do this is to fix the cylinder without adjustment using mechanical parts with precision. However, the cost will be extremely high, and in some cases it may not be possible to divide the cost.
Conventionally, the approximate position was determined using an optical mechanism component, a certain adjustment space was provided, the position of the component was finely adjusted within the adjustment space, and the component was fixed with a fixing material 5 such as an adhesive. However, the fixing material 5 such as adhesive has a large volume change due to thermal or temporal changes, so if the adjustment space is filled with adhesive, the reliability of the lens-shaped passive optical component will not necessarily be sufficient. There was a drawback.

The object of the present invention is to enable the position adjustment of lens components, and to require almost no adjustment space to be filled with fixing materials such as adhesives. Our objective is to provide passive optical circuit components.

According to the present invention, at least one optical fiber for input, at least one optical fiber for output, an input lens for converting the output beam from the input optical fiber into a parallel beam, and a lens for converting the output beam from the input optical fiber into a parallel beam. an 8-injection lens that focuses the light and makes it enter the output optical fiber; at least one optical functional element inserted between the input and output lenses; a holder having a plurality of holes for arranging lenses for use in the incident light; An optical circuit component including an eccentric tube having a hollow portion for fixing an exit lens, and in which the eccentric tube is adjusted and fixed by rotating with respect to the hole is obtained.

The optical functional element mentioned above is an interference film filter that splits and multiplexes the light beam from the input lens to each output lens. There are elements such as elements and elements using optical path switching means.

Generally, optical fibers are the lightest and smallest optical circuit components connected to optical fibers, and there is no need to fine-tune the position of all components when aligning the optical axis with the optical eyer. (・In other words, heavy and large lenses and optical functional elements should be mechanically positioned or only roughly adjusted, and the final fine adjustment of the optical system should be made by finely adjusting the position of the optical fiber. It is desirable from the viewpoint of reliability that the center axis of the cylindrical hollow part is deviated from the central axis of the outer diameter of the tube (hereinafter referred to as an eccentric tube), which is rotated in the hole of the holder, and the hollow part After the central axis of the eccentric tube is roughly aligned with the optical axis of the light beam from the optical functional element that enters one end surface of the eccentric tube, an input/output lens is inserted into the hollow part of the eccentric tube to coarsely adjust the optical axis. After coarse adjustment, the human output optical fiber is connected to the end surface of the input/output lens so that the optical axis of the input/output optical fiber connected to the end surface of the input/output lens matches the central axis of the input/output lens. By doing so, highly reliable coupling with optical functional elements, lenses, and optical fibers can be realized.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a perspective plan view of an optical multiplexer/demultiplexer showing an embodiment of the present invention, and FIG. 3 is a sectional view of FIG. 2 taken along line a-a'. Input optical fiber 3.

The multiplexed parallel light beams from the six output optical fibers 3i
The light beams from the optical fibers other than the optical fiber 3 are multiplexed into the optical fiber 3 by demultiplexing into (i=2 to 7), or vice versa. The optical fiber position fixing member 12 has seven cylindrical holes provided inside the heptagonal column holder 8 (made of stainless steel) toward the center of the holder. , a tube (eccentric tube) 7 which has an outer diameter slightly smaller than the inner diameter of the hole, and in which the central axis O of the outer diameter is offset from the central axis O' of the cylindrical hollow part 7' (Fig. 3). are respectively inserted into the holes of the holder.

The hollow part 7' (Fig. 3) in the eccentric tube 7 has an outer diameter slightly larger than the inner diameter of the hollow part, and has a refractive index distribution that decreases approximately in proportion to the square of the distance from the central axis. A cylindrical lens 1' is inserted. The cylindrical regime 1' collimates the light from the input optical fiber and focuses the light beam onto the output fiber. Approximately in the center of the holder 8, there is a heptagonal prism 9 and on each side thereof an interference film filter 11 for transmitting only a light beam of a specific wavelength, and an optical path between the central axis of the outer diameter of the eccentric tube and the prism is adjusted. spacer 1
0 is laminated and integrated, and is closely fixed to the bottom of the holder 8, and the optical axis alignment is roughly adjusted to efficiently couple the optical fibers 3□ to 37, the cylindrical lens 1', and the spacer 10, respectively. The multiplexed parallel light beams from the fiber 3 are connected to six output optical fibers 3□ to 3. for each wavelength. can be efficiently separated.

Here, a method for coarsely adjusting the optical axis will be explained with reference to FIG.

Before inserting a lens into the cylindrical hollow part 7' of the eccentric tube 7, the eccentric tube is rotated around its outer diameter axis O while observing the parallel light beam passing through the hollow part 7'. The distance between the center and the center of the hollow portion 7' should be minimized.

Generally, as shown in FIG. 4, the coupling loss of the parallel light beam 6 to the optical fiber 3 when the position of the optical fiber 3 is optimally adjusted with respect to the distance X between the parallel light beam 6 and the center axis of the lens 1 is The range of X in which the coupling loss does not increase as shown in Figure 5 (
x<d) always exists. This interval d provides the accuracy required when coarsely adjusting the lens. Therefore, as shown in FIG. If there is an optical axis in the second layer, coarse adjustment of the optical axis can be performed with minimum coupling loss.After adjusting the cylindrical lens 1 in the hollow part 7', ′
Insert the holder 8 and eccentric tube 7 with a fixing material such as adhesive.
The lens and eccentric tube are fixed by filling the minute gap between the cylindrical lens 1' and the holder 8' with the same fixing material.

At this time, since the volume of the fixing material is minute and the cylindrical lens 1' and the hollow part 7' have a coaxial structure, the position of the lens becomes stable over time. If the optical axis of the parallel light beam passes through a plane other than the dotted hatched area in FIG. 3, the distance oo' (referred to as eccentricity amount) between the central axis O' of the hollow part and the tube axis O of the eccentric tube is d.

By selecting an eccentric tube with an appropriate amount of eccentricity from among the eccentric tubes of 3d, ..., (2m+t)d, it is possible to freely control the parallel light beam incident on any location on the end surface of the eccentric tube. Coarse adjustment of the lens position is possible.

After performing the same rough adjustment for all other eccentric tubes and inserting and fixing the cylindrical lens 1' into the hollow part of the eccentric tube, the optical fiber 3. Connect ~37. At that time, the optical fiber 31~
The optical axis of lens 37 and the central axis of cylindrical lens 1' are connected so as to coincide with each other.

Similar sprouts can be obtained by using a diffraction grating instead of the interference film filter for wavelength selection used in the above embodiment. Alternatively, a half mirror may be used instead of the interference film filter to serve as an optical branching coupler.

Furthermore, if the integrated interference film filter, prism, and spacer in the above embodiments of the present invention is replaced with an optical path switching element, it can also be used as an optical switch.

As described above, in contrast to conventional lens-type passive optical circuit components that do not require advanced technology but have a large number of parts and are insufficiently reliable, the lens-type passive optical circuit components of the present invention The position adjustment and fixing of parts becomes stable over heat and over time, resulting in high reliability.

Furthermore, ultra-high precision machining of mechanical components is no longer necessary, making it possible to achieve not only high reliability but also low prices. Therefore, the lens-shaped passive optical circuit component according to the present invention can be widely used in practical optical communication systems, and its industrial value is extremely high.

[Brief explanation of the drawing]

FIG. 1 is a side view showing the structure of a conventional lens-type passive optical component, FIG. 2 is a perspective front view of an optical multiplexer showing an embodiment of the present invention, and FIG. 4 and 5, which are cross-sectional views taken along a plane, are diagrams for explaining the coupling loss to the optical fiber with respect to the irradiation position of the parallel light beam onto the lens. 1...Lens, 1'...Selfoc lens, 2...Optical system functional element, 3゜~3□・
...Optical fiber, 4...Base, 5...
...Fixing material, 6...Parallel beam, 7.
... Yushin tube, 8 ... Holder, 9 ...
... Heptagonal prism, 10 ... Spacer, 11
...Interference membrane filter. Koshirae 1 Figure 2 Figure 7 7 Hana 3 Figure 4 Parallel beam 2 degrees center axis 5 Figure 5 L vortex)

Claims (5)

[Claims] (1) At least one input optical fiber and at least one
The output optical fiber of the book, the input optical fiber, the input lens that converts the output beam from the input optical fiber into a parallel beam, and the output lens that focuses the parallel beam and makes it enter the output optical fiber. At least one optical functional element inserted between a lens, the input/output lens, and a holder that fixes the optical functional element and is provided with a plurality of holes in which the input lens or the output lens is arranged. and an eccentric tube having an outer diameter slightly smaller than the diameter of the hole, and a hollow portion having a central axis located eccentrically with respect to the central axis of the outer diameter and fixing the entrance lens or the exit lens. An optical circuit component including an eccentric tube which is adjusted and fixed by rotating with respect to the hole. (2) The optical functional element includes a prism, an interference film filter disposed on the side surface of the prism, and faces an end face of the input/output lens to adjust the optical path between the central axis of the input/output lens and the prism. The optical circuit component according to claim (1), which is a multiplexing/demultiplexing element having a spacer. (3) The optical functional element includes a prism and a spacer that faces the end face of the input/output lens arranged on the side surface of the prism and adjusts the optical path between the central axis of the input/output lens and the prism. - The optical circuit component according to Claim No. (1) Present V, which is a demultiplexing element. (4) The optical functional element includes a light beam prism from the input lens, a half mirror disposed on the side surface of the prism, and a central axis of the input/output lens that faces the end face of the input/output lens. Claim No. 1, which is an optical branching element having a spacer that adjusts the optical path with the prism.
Optical circuit components listed in section. (5) The optical circuit component according to claim (1), wherein the optical functional element is an optical path switching element.