JPS6366513A - Optical multiplexer/demultiplexer - Google Patents

Abstract

PURPOSE:To obtain an optical multiplexer/demultiplexer having a high separation capacity of signal light by providing grooves crossing each other on a plane substrate and closely bringing a spherical lens incorporating a filter film into contact with grooves and providing a filter film on the wall face of the groove crossing the optical axis of reflected light of the filter film in the spherical lens. CONSTITUTION:A first groove 20 and a second circular groove 22 placed in the middle of the groove 20 are formed on a plane substrate 18 consisting of a plate glass, and a first spherical lens 24 whose half bodies a filter 26a inclined at an angle theta in the direction of the optical axis is interposed between is closely brought into contact with a second groove 22 and is fixed to the groove 20 at intersections 24a-24d. A groove parallel with the first groove 20 and a circular groove are provided on one side of the first spherical lens 24, and a second spherical lens 34 similar to the lens 24 is closely brought into contact with this circular groove, and a third similar spherical lens 50 is provided in a position distant from the lens 24, and optical fibers 38, 42, and 46 covered with ferrules 40, 44, and 48 are connected to exit sides of respective lenses. Filters 26b and 26c are arranged between lenses 24 and 34, and the light is transmitted between lenses 24 and 34.

Description

Detailed Description of the Invention: --I The positioning accuracy of the ball lens is improved by forming grooves that intersect with each other on a flat substrate and placing a ball lens having a filter film therein in close contact with the intersection of the grooves. In addition, by providing at least one filter film member on the wall surface of the groove that intersects with the reflection optical axis of the filter film, crosstalk between light transmitted through the filter film and the same reflected light is reduced. let

The present invention relates to an optical multiplexer/demultiplexer for a wavelength-coupled communication system.
In particular, it relates to an optical multiplexer/demultiplexer configured on a single substrate.

In recent years, the application of optical fibers to J3 transmission lines in public communications has been actively studied in various fields. Among these, a bidirectional image transmission system using wavelength division multiplexing technology is being developed and attracting attention as a model for applying optical fibers to subscriber systems.

This system utilizes the low loss characteristics of optical fiber over a wide wavelength range to transmit multiple signals in one direction or in both directions through a single optical fiber, and is capable of transmitting multiple signals in one direction or in both directions, including optical multiplexers and demultiplexers. It is believed that once the mass productivity of each component is established, it will be used as an epoch-making system. An optical multiplexer/demultiplexer is connected to both ends of an optical fiber in order to combine and separate the transmitted signal light and the received signal light, and usually consists of a heavy board with lenses and filter films for wavelength separation. There was a demand for something with a simple configuration and high wavelength separation performance.

Conventional technology Figure 2 shows the basic configuration of a conventional optical multiplexer/demultiplexer.

This optical multiplexer/demultiplexer includes a second lunse 4 that converts the light emitted from the optical fiber 2 into parallel light beams, and a dielectric multilayer film on the surface of the lunse 4, which is arranged at a predetermined incident angle on the emitted optical axis of the second lunse 4. 6
The filter film 8 is formed with a filter film 8 , a second lens 10 that collects light transmitted through the filter film 8 , and a third lens 12 that collects light reflected from the filter film 8 . Filter membrane 8
acts as a filter for incident light with wavelength/transmission characteristics as shown in Figure 3, allowing light of wavelengths lower than a specific wavelength, e.g. The light of λ2 is reflected. Therefore, lens 1
By providing appropriate light-receiving water droplets at the respective focal positions of the optical fiber 2 and the lens 12, the multiplexed signal lights of wavelengths λ1 and λ2 entering from the optical fiber 2 are separated by the filter film 8 and then separated independently by the respective light-receiving elements. It becomes possible to receive light. Furthermore, by changing the light receiving element provided at the focal position of the lens 10 among the two light receiving elements to a light emitting element having the wavelength λ1, the light having the wavelength λ2 from the optical fiber 2 can be provided at the focal position of the lens 12. λ1 received by the light receiving element and emitted from the light emitting element
It also becomes possible to guide the light into the optical fiber 2.

On the other hand, in recent improved optical multiplexers/demultiplexers, attempts have been made to configure the filter film integrally with the lens for the purpose of downsizing the device.

FIG. 4 shows a top view of this filter film integrated ball lens 14, in which the glass ball lens is cut along a plane that includes its center point, and the dielectric multilayer film 16 is formed on one cut surface. It can be obtained by closely adhering to the shape of. This filter film integrated ball lens 14 is used, for example, as the lens 4 and filter film 8 of an optical combiner/demultiplexer shown in FIG.

Problems to be Solved by the Invention) Although the optical multiplexer/demultiplexer using the filter film-integrated ball lens 14 achieves miniaturization of the device, it is difficult to precisely position the filter film-integrated ball lens 14. In order to do this, complicated work was required due to the equipment configuration, and there were problems such as making it unsuitable for four productions. In addition, in general, optical multiplexers/demultiplexers that use filter films as means for splitting multiplexed signal light have only one filter film, which causes transmitted light to leak into the photometer. It has an essential shortcoming of not having good performance in terms of π, and there has been a need to improve this.

The present invention was created in view of these problems, and aims to provide an optical multiplexer/demultiplexer that can easily position the filter membrane integrated ball lens 14 with high precision and has high signal light separation performance. There is.

Means for Solving the Problems The problems of the prior art described above can be solved by configuring the optical multiplexer/demultiplexer as follows.

A first groove and a second groove that intersect with each other are formed on a flat substrate.

A first sphere having a filter film on a plane including substantially the center point thereof is located on four intersections between the intersection lines of adjacent wall surfaces of the first groove and the second groove and the surface of the plane substrate. Place the lens in a fixed position.

At least one Noirta film member is installed on the second wall surface in parallel with the filter film of the first spherical lens.

Each of the above members is arranged such that the reflected light from the filter film of the light incident on the first ball lens 110 along the first groove is filtered through the filter film member parallel to the filter film of the first ball lens. The film is positioned so as to be incident on a second spherical lens having a flat surface that includes substantially the center point thereof.

According to the present invention, there are four intersections between the intersections of adjacent wall surfaces of mutually intersecting grooves formed on a plane substrate and the surface of the plane substrate, that is, four vertices of a rectangle or square on the plane. Since the first spherical lens is fixedly arranged so that the first spherical lenses are in contact with each other, the distance from the flat substrate to the center point of the first spherical lens can be set with high precision, allowing precise optical axis adjustment. become.

In addition, since the light reflected by the filter film of the light incident on the first ball lens is made to enter the second ball lens via the filter film member, the light that entered the first ball lens is reflected twice or more. The light is reflected repeatedly and enters the first spherical lens, and the second ray of light having the same wavelength as the light transmitted through the first spherical lens
Leakage into the ball lens can be kept to a minimum. Since this filter membrane member is numbered on the wall surface of the groove formed in the flat substrate, it is not necessary to configure the device as a single member, contributing to miniaturization of the device.

Embodiments Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

Referring to FIG. 1, there is shown a plan view of the main parts of an optical multiplexer/demultiplexer to which the present invention is applied. Reference numeral 18 denotes a flat substrate made of a plate glass material having a flat surface, and a first groove 20 is formed on the surface of the flat substrate 18 in a predetermined linear direction (referred to as the horizontal direction 2 or less in the figure). has been done. Reference numeral 22 denotes a second groove formed on the planar substrate 18 in a direction perpendicular to the first Fi 20 (hereinafter, this direction will be referred to as 8 directions). The intersections of these first grooves 20 and second grooves 22, that is, the four intersections 24a of the intersection lines of the wall surfaces of the first groove 20 and the wall surfaces of the second groove 22 and the surface of the planar substrate 18.
, 24b, 24c, and 24d, the first spherical lens 24 is fixedly arranged so as to be in contact with the intersection. The first spherical lens 24 is formed by cutting a glass spherical lens along a plane that includes its center point, providing a filter film 26a made of a dielectric multilayer film on one cut surface, and then closely contacting the lens to its original shape. The filter film 26a is positioned so as to be perpendicular to the flat substrate and form a predetermined angle θ in the B direction.

40 is a cylindrical ferrule made of, for example, a ceramic material, and the optical fiber 3 is inserted into the center hole of this ferrule 40.
8 is fitted. The diameter of the ferrule 40 is set so that the center line of the optical fiber 38 is at the same height as the center point of the first spherical lens 24 when placed in close contact with the groove 20, and the end face 40a, that is, the optical fiber 38 is positioned such that the end face of the lens is located at the focal point of the first spherical lens 24.

Therefore, the light that has traveled through the optical fiber 38 is incident on the first spherical lens 24 and transmitted through the filter film 26a or reflected by the filter film 26a, and then is emitted as a parallel light beam.

The second groove 22 has a stepped portion 28 below the first spherical lens 24 in FIG. 1, and the filter II! Filter film members 26b and 26G having the same spectral characteristics as 26a are filter II! It is provided in parallel with 26a. These filter membrane members 26b.

26C, for example, SiO2 and T on a thin film glass material.
It can be formed by alternately laminating dielectric materials having different refractive indexes such as i02, and the surface of this thin film glass material opposite to the laminated side is attached to both sides of the stepped portion 28 by means such as glass solder. They can be attached closely by gluing them. Further, the positions of the filter film members 26b and 26c are set so that the reflected light from the filter film 26a is reflected by the filter film member 26b and guided to the filter film member 26c.

34, like the first spherical lens 24, are four vertices of a rectangle formed at the intersections of the second groove 22 and a groove 32 formed on the flat substrate 18 orthogonally to the second groove 22. 34a,
34b, 34c, and 34d, and this second spherical lens 34 has a filter film 26d having the same spectral characteristics as the filter film 26a of the first spherical lens 24. The filter membrane 26d is the filter membrane 26a1.
The light that is set parallel to the filter shield member 26b and the filter film member 26G and enters the second ball lens 34 from the optical fiber 38 via the first ball lens 24 and the filter film members 26b and 26c is reflected by the filter film 26d. The light is reflected and exits from the second spherical lens 34.

48 is a ferrule in which the optical fiber 46 is fitted into the center hole and placed in close contact with the groove 32 like the ferrule 40; It is positioned at the focal point on the output optical axis of the two-ball lens 34.

On the other hand, on the right side of the first ball lens 24 on the paper, that is, on the extension line of the transmission optical axis of this lens, there is a first groove 20 and a first groove 20.
The four vertices 50a, 50b of a rectangle are formed at the intersections with the grooves 52 which are perpendicular to the vertices 20 of the rectangle.

A third spherical lens 50 is provided which is closely fixed to 50c and 50d, and this third spherical lens 50 has a filter E326e having the same spectral characteristics as the filter film 26a of the first spherical lens 24 in parallel with the filter 26a. have. 4
2 is an optical fiber provided coaxially with the optical fiber 38, and like the optical fiber 38, the first
It is securely fixed in the groove 20 of.

Next, the operation of the optical multiplexer/demultiplexer having the above-described configuration will be described in the case where it is used as an optical demultiplexer.

The multiplexed signal lights with wavelengths λ 1 and λ 2 are incident on the first spherical lens 24 via the optical fiber 38 . The filter film 26a functions to transmit the light of λ1 and reflect the light of λ2, and the transmitted and reflected light is converted into parallel rays and guided to the third ball lens 50 and the filter film member 26b, respectively. The light incident on the third ball lens 50 is filtered through the filter film 26d.
When transmitting the light, the crosstalk component of the wavelength λ2 is removed, and then the light is emitted, and is received by a photoelectric conversion element (not shown) via the optical fiber 42. On the other hand, the reflected light of wavelength λ2 guided by the filter film member 26b has its crosstalk component of wavelength λ1 removed when reflected by the filter film members 26b and 26C, enters the second ball lens 34, and enters the filter film 26d. When the light is reflected by the light, the crosstalk component is further removed and the light is emitted from the second ball lens 34. The emitted light of λ2 is received by a charge conversion element (not shown) via the optical fiber 46. In this way, the optical fiber 3
The multiplexed signal lights of wavelengths λ and λ2 from
It becomes possible to receive the light as single wavelength signal light of λ2 and λ2 via the optical fibers 42 and 46, respectively.

Furthermore, for example, if the aforementioned light-receiving element connected to one end of the optical fiber 42 is replaced with a light-emitting element (not shown) having a wavelength λ1, and this light-emitting element is driven with a predetermined electric signal, the signal light is transmitted to the optical fiber 42, the third Since the light is guided to the optical fiber 38 through the ball lens 50 and the first ball lens 24, bidirectional communication is possible using the single optical fiber 38.

In this manner, in this embodiment, highly accurate positioning is possible simply by placing each ball lens at the intersection of the grooves, so complicated operations such as optical axis adjustment are not required.

Further, the filter membrane members 26b and 26c are connected to the second groove 22.
Since it is provided on both sides corresponding to the stepped portion 28, there is no need to arrange an independent member on the optical axis, and the device can be made more compact.

Note that the flat substrate 18 and the first ball lens 24 used in this example
, the second spherical lens 34, the third spherical lens 50, and each ferrule 40, 44, 48 are desirably formed from materials having approximately the same coefficient of thermal expansion for the purpose of stable operation of the device.

Effects of the Invention As described in detail above, the present invention has the effect that the ball lens can be easily positioned with 8 precision and that it is possible to provide an optical multiplexer/demultiplexer with high signal light separation performance. play.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an optical multiplexer/demultiplexer that does not show a preferred embodiment of the present invention. FIG. 2 is a diagram showing the basic configuration of a conventional optical multiplexer/demultiplexer. FIG. 3 is a diagram showing a filter! FIG. 4 is a side view of a filter film-integrated ball lens used in a conventional improved optical multiplexer/demultiplexer. 2.38.42.46...Optical fiber, 18...Planar substrate, 26a, 26b, 26c. 26d, 26e...filter membrane, 40.44.48...ferrule. 1 (The basics of 1 minute use of the next optical system) 2nd obstacle 1 Filter 4 - looking through - Lens 14 shell V side view Figure 4 1

Claims (1)

[Claims] First grooves (20) intersecting each other on a flat substrate (18)
and a second groove (22), and four intersections between the intersection lines of adjacent wall surfaces of the first groove (20) and the second groove (22) and the surface of the planar substrate (18). (24a), (24b), (24c), (24d)
Above, a filter membrane (26a
) is fixedly arranged, and the reflected light by the filter film (26a) of the light incident on the first ball lens (24) along the first groove (20) is A filter membrane (26d) parallel to the filter membrane (26a) is inserted through at least one filter membrane member provided parallel to the filter membrane (26a) on the wall surface of the second groove (22).
) is made to enter a second spherical lens (34) on a plane including substantially its center point.