JPH01280706A - Multiplexing and demultiplexing element - Google Patents

Abstract

PURPOSE:To excellently demultiplex or multiplex light rays in a small spot diameter even to wide band light rays, such as the light of an LED, in a state where both of a high efficiency and low-angle dispersing property are maintained by providing at least two diffraction gratings on an optical path on which multiplexing or demultiplexing the light rays is performed. CONSTITUTION:This multiplexing and demultiplexing element 1 is successively provided with, from an input fiber 2 side, a collimate lens 4, diffraction grating 5, condenser lens 6, and output optical fibers 3a and 3b. The diffraction grating 5 is constituted of a transmissive type double diffraction grating provided with two diffraction gratings 5a and 5b on both sides of its base plate. While the grating surfaces and grating directions of the gratings 5a and 5b are respectively made parallel with each other so that the grating characteristics of the gratings 5a and 5b can be different relatively from each other, the grating pitches of the gratings 5a and 5b are different from each other. When such double diffraction grating 5 is used, the deflection angle DELTAtheta between input light and output light becomes smaller against its large diffracting efficiency and even light rays, such as the light of an LED, having a wide band range can be demultiplexed efficiently without considerably spreading the spot diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a multiplexing/demultiplexing element used in optical communications such as wavelength division multiplexing communications or optical information recording/reproducing devices.

BACKGROUND TECHNOLOGY Although optical communication has become increasingly important in recent years, it is still difficult to say that it has become widespread. This is because optical components are not cheap enough to be compared with electronic components. For example, if LEDs can be used for wavelength division multiplexing communications, it is thought that their cost will be lower and their popularity will increase, but in reality, there is no superior multiplexing/demultiplexing element and LEDs cannot be used for wavelength division multiplexing communications. be.

That is, as an example of a multiplexing/demultiplexing element, there is one using a transmission type diffraction grating as shown in Japanese Patent Application Laid-Open No. 54-5454. More specifically, it consists of a transmission-type hologram that records the interference fringes of two diverging lights, an optical fiber whose end is installed on one side of the hologram, and an optical fiber whose end is installed on the other side of the hologram. and two or more optical input/output elements. In this case, one diffraction grating is used.

Problems to be Solved by the Invention In such a configuration, in order to increase the diffraction efficiency, it is necessary to make the grating pitch small to achieve Bragg diffraction, and to make the depth equal to the pitch. Then,
When splitting broadband light such as LED light, the spot diameter becomes larger than the optical fiber diameter because the pitch is large.

As a result, the coupling loss increases, and there is no point in increasing the diffraction efficiency of the diffraction grating. On the other hand, if the grating pitch is made smaller, the coupling loss becomes smaller, but since the diffraction efficiency becomes smaller, the insertion loss of the entire demultiplexing element ends up becoming larger. Such circumstances are
Even if the diffraction grating described in the above-mentioned publication also has a lens function, there is no difference in the quality of the wood.

That is, the conventional devices do not have both high efficiency and low angular dispersion function, and cannot combine or demultiplex broadband light such as LED light.

Means for Solving the Problem Basically, at least two diffraction gratings are arranged on the optical path where light is multiplexed or demultiplexed.

In this case, these diffraction gratings have relatively the same diffraction characteristics.

Alternatively, it is assumed that the diffraction characteristics are relatively different.

This means that the pitch of at least one diffraction grating is different from that of other diffraction gratings, or that the grating plane of at least one or more diffraction gratings is made non-parallel to the grating plane of other diffraction gratings. By placing it in

Furthermore, a collimating lens that collimates the input light and a condensing lens that condenses the demultiplexed light are provided, or a condensing lens that condenses the input light is provided.

Furthermore, the diffraction grating itself has a lens function.

Alternatively, the lens is provided with a cylindrical light condensing function.

Furthermore, the diffraction grating or the diffraction grating and the lens are arranged on the same substrate.

Function: A double diffraction grating made of at least two diffraction gratings can achieve high diffraction efficiency and the deflection angle between input light and output light, which is a function that cannot be achieved with only one transmission type diffraction grating. It can have the function of becoming smaller. Therefore, by passing through such a double diffraction grating or the like, multiplexing or demultiplexing with both high efficiency and low angular dispersion function is possible, and it can also be used for broadband light such as LED light. At this time, the combined light is at least -t, 1 by a double diffraction grating etc.
Wavelength light that can be diffracted twice and transmitted at least twice or -6
If = is split into wavelength light that can be reflected, the -layer and splitting band can be expanded. In this case, the double diffraction grating may be made of at least two diffraction gratings with relatively different diffraction characteristics, and lenses may be provided on the input and output sides, respectively. If at least two diffraction gratings have the same diffraction characteristics, a condensing lens may be disposed on at least one of the input side and the output side, and the lens on the side can be omitted.

Further, by arranging the diffraction grating on the same substrate, or by arranging the lens in a cylindrical lens configuration on the same substrate as the diffraction grating, duplication etc. can be facilitated.

Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 to 3. For example, the multiplexing/demultiplexing element 1 of this embodiment has different wavelengths λ1. The input fiber 2 emits the input light of λ2 and each of the demultiplexed wavelengths λ1. It is arranged between the output J fibers 3a and 3b into which the light of λ2 is incident. This multiplexing/demultiplexing element 1
is formed by arranging a collimating lens 4, a diffraction grating 5, and a condensing lens 6 in order from the input fiber 2 side,
The diffraction grating 5 is particularly distinctive.

This diffraction grating 5 has two diffraction gratings 5a and 5b on both sides of the substrate.
It is configured as a transmission type double diffraction grating comprising: These diffraction gratings 5a and 5b have their grating planes and grating directions parallel to each other so that their diffraction characteristics are relatively different, but their pitches Δ1. Δ2 is configured differently. The input angle of such diffraction gratings 5a, 5b &
The i-output angle Oo characteristics are shown in FIGS. 2 and 3.

Here, the grating vectors of these diffraction gratings 5a and 5b are respectively (-2π/A,) and 2 (=2π/A2), and the central refractive index of the diffraction grating is n. Then, 2πn. ,
2πn0°r 51ne i −〒−51nOo=K, the relationship 2−−(1) holds true for −.

Such a double diffraction grating 5 has the following advantages. That is, although the diffraction efficiency is high, the deflection angle between the incoming horn light and the output light is small. this is,
This is a function that cannot be achieved with a single diffraction grating as in the past. This is because, in the case of a transmission type diffraction grating, diffraction must occur in the Bragg region in order to increase the diffraction efficiency, but under such Bragg region conditions, the diffraction angle is large, so the deflection angle also becomes large. It is from.

However, in the case of the double diffraction grating 5 having two diffraction gratings 5a and 5b, each one has a large diffraction angle (θi
Since it is in the Bragg region, the diffraction efficiency is high, and by combining two lenses, it is possible to achieve a low deflection angle while maintaining such high efficiency.

In this embodiment, since such a multiplexing/demultiplexing element 1 with high efficiency and a low deflection angle is used, even broadband light such as LED light can be efficiently demultiplexed, and the spot diameter due to the wide band can be reduced. This will not cause a significant spread.

By the way, we will explain how effective it actually is numerically. Now, ignoring the diameter of human fiber 2, 1
It is assumed that a diffraction grating with only one sheet and a two-sheet diffraction grating according to the present embodiment are used, and each value is set as shown in Table 1.

That is, the diffraction grating 5a has a pitch of 1 μm and a pitch of 1.2 μm.
, 5b and 1μ
This is a comparison with the case where a single diffraction grating with only m pitches is used. As a result, the results shown in Table 2 were obtained.

Table 2 Here, the splitting efficiency is the efficiency with which light of each wavelength is diffracted as primary light, and is calculated using S-polarized light, assuming that there is almost no polarization dependence.

The spot diameter is a condenser lens 6 with a focal length of 10 mm.
This is the diameter when the LED light is focused.

In the above results, the noteworthy point is the difference in spot diameter. Now, assuming that the diameter of the input J fiber 2 is 200 μm, on the output side, the double diffraction grating 5 of this embodiment has a diameter of 270 μm, and the conventional single grating has a diameter of 640 μm. . Therefore, the diameter of the output fiber 3 is set to 2
If the coupling efficiency is simply compared in terms of area ratio, the coupling efficiency of the method of this embodiment is about 6 times better. This can be said to be an advantageous effect even if the fact that the demultiplexing factor is somewhat inferior is taken into account.

Next, a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. Here, only the double diffraction grating 7 is shown.

In comparison with the double diffraction grating 5 of the above embodiment, the pitches of the two diffraction gratings 7a and 7b are the same, but by using a wedge-shaped substrate instead of a parallel substrate, the diffraction gratings 7a and 7b are
The diffraction characteristics of the two diffraction gratings 7a and 7b are made relatively different by tilting the grating planes of the diffraction gratings so as not to be parallel to each other. In this case, the relationship between the lattice vectors, K2, etc. is as shown in FIG. That is, it can be seen that the same effects as in the above embodiment can be obtained.

In the structure of this embodiment, the relationship between the input angle θj of light of a certain wavelength within the diffraction grating and the output J angle (diffraction angle) θ0 is expressed by the following equation.

k, 5inOi + kllsinθi' = K,
−(2)k, 5in (to θi′180)+,
5in(Oo-ΔQ')=K2--(3) Therefore, the angle θi' is the first-order diffraction angle, k. Assuming that is a propagation constant within the diffraction grating, the angle ΔO' corresponds to the inclination of the two diffraction gratings 7a and 7b planes.

Next, a third embodiment of the present invention will be explained with reference to FIG. In this embodiment, the double diffraction grating 8 itself, which includes the diffraction gratings 8a and 8b, also has a lens function (convergence performance), and by making it serve both as a collimating lens and a condensing lens, the collimating lens 4 and the condensing lens are combined. This eliminates the need for a separate optical component called the lens 6. That is, the multiplexing/demultiplexing element 1 of this embodiment is composed of one optical component, which is a double diffraction grating 8 including diffraction gratings 8a and 8b.

Furthermore, a fourth embodiment of the present invention will be explained with reference to FIG. In this embodiment, a diffraction grating 10, a collimating lens 11, and a condensing lens 1 are placed on the same substrate 9 using a thick film waveguide structure.
This is an integral structure of 2 and 2. That is, the collimating lens 11 has a waveguide type cylindrical lens configuration, that is, a two-stage waveguide type collimating lens], 1a, llb
Similarly, the condenser lens 12 has a cylindrical lens configuration, that is, a two-stage waveguide type collimating lens 12a.
, 12b. Transmission type diffraction gratings 10 are provided on opposing end surfaces of the waveguide type collimating lenses llb and 12a, respectively.
a and 10 b to form a double diffraction grating 10. Here, the diffraction gratings 10a and 10b are the diffraction gratings 5a
, 5b type, or diffraction gratings 7a, 7b type. With such a waveguide configuration, light is confined in a direction perpendicular to the surface of the substrate 9 and is demultiplexed in the same manner as in the embodiment described above.

According to this embodiment, the optical elements constituting the multiplexing/demultiplexing element 1 are integrally manufactured on the same substrate 9, so if it is to be duplicated, a mold is made and thermosetting resin and electromagnetic wave hardening material are used. It can be easily reproduced using resin or the like.

Note that the two diffraction gratings constituting the double diffraction grating are not limited to the above-mentioned combination, and even if the grating pitches are different, the grating planes may not be parallel to each other.

The point is that the diffraction characteristics may be made relatively different depending on the actual configuration of the multiplexing/demultiplexing element.

Further, a fifth embodiment of the present invention will be explained with reference to FIG.

In the embodiment described above, the double diffraction grating was explained as a transmission type, but in this embodiment, two reflection type diffraction gratings 13 are used.
A double diffraction grating consisting of a and 13 b] 3 is used.

Note that even in such a reflective configuration, the structure, operation, etc. are similar to those of the transmissive configuration.

Furthermore, in these embodiments, the multiplexing function can be achieved by switching the directions of the input and output sides.

Next, the sixth embodiment of the present invention will be described in FIGS. 9 to 11.
This will be explained using figures. The multiplexing/demultiplexing element 14 of this embodiment is also
It is arranged between the fiber 2 and the output fibers 3a and 3b, but in this example it consists of a condensing lens 5 located on the input side J and a diffraction grating 16. Here, this diffraction grating 16 is constructed as a transmission type double diffraction grating having two diffraction gratings 16a and 16b on both sides of the substrate.

According to equations (2) and (3) described above, it is also possible to set this deflection angle to O. In this case, the output angle is the same for each wavelength, but as shown in FIG. 11, each light beam is moved in parallel for each wavelength, and in this case as well, it is possible to separate the beams. That is, at this time, the broadband property can be ignored.

In this way, also in this embodiment, the number of wavelengths to be demultiplexed increases, and the degree of multiplexing of wavelength division multiplexing communication can be increased. In particular, since broadband light such as LEDs is also targeted,
This will further contribute to the construction of an inexpensive multiplex communication system. Furthermore, in comparison with the first to fifth embodiment methods described above, in principle, the broadband nature of the wavelength of light has only a very slight influence, so efficiency can be further improved, and optical lens components (The condenser lens 15 may be provided only on the input side and only on the output side), and there is no need to provide two lenses like the lenses 4 and 6. Therefore, it can be made smaller, the stability of the multiplexing/demultiplexing element 14 can be increased, and the arrangement can be easily adjusted.

Furthermore, a seventh embodiment of the present invention will be explained with reference to FIG. In this embodiment, as in the case of the fourth embodiment, a diffraction grating 18 and a condensing lens 19 are integrally constructed on the same substrate 17 using a thick film waveguide type structure. That is, the condensing lens 19 has a waveguide type cylindrical lens configuration, that is, a two-stage waveguide type collimating lens 19a,
Consisting of 19 b. Then, transmission type diffraction gratings 18a and 18b are formed on opposing end faces of the waveguide type collimating lens 19b and the waveguide 20, respectively, to form a double diffraction grating 18. Here, the diffraction gratings 18a and 18b are the diffraction grating 1.
6a or 1.6b type may be used. With such a waveguide configuration, light is confined in a direction perpendicular to the surface of the substrate 17 and is demultiplexed as in the sixth embodiment.

According to this embodiment, the optical elements constituting the multiplexing/demultiplexing element 14 are integrally manufactured on the same substrate 17. Therefore, in case of duplication, a mold is made and thermosetting resin and electromagnetic wave hardening material are used. It can be easily reproduced using resin or the like.

Next, a fourth embodiment of the present invention is shown in FIGS. 13 to 18.
This will be explained using figures. This embodiment is a further modification of the first to fifth embodiments described above. First, according to the embodiments described above, it is possible to use a wideband multiplexing/demultiplexing element such as an LED. However, since both methods take diffracted light that has been diffracted twice, the light to be demultiplexed needs to have a somewhat similar wavelength, which limits the demultiplexing band. Focusing on this point, this embodiment uses two diffraction gratings 21a with relatively different diffraction characteristics as shown in FIG.

21b, that is, a diffraction grating structurally similar to that shown in the first to fifth embodiments (for example, the one shown in FIG. 1 or FIG. 4). ), the incident multiplexed light is split into light with a wavelength that can be diffracted twice and light with a wavelength that can be transmitted twice (reversible, multiplexing in the opposite direction) ). A multiplexing/demultiplexing element 22 is constructed using such a double diffraction grating 21 as a main body, for example, in the same manner as in the case of FIG.

For example, when separating short wavelength light λS and long wavelength light λL as shown in FIG. 13, the short wavelength light λS is separated by the diffraction grating 2
is diffracted twice by the diffraction gratings 21a and 21b.
5(1-1), and long wavelength light λI.

passes through the diffraction grating 21 and is converted into 2 by the diffraction gratings 21a and 21b.
The signal is transmitted twice and demultiplexed as λt, (0-0).

This was achieved by combining the advantage of a double diffraction grating, which has small dispersion of diffraction angles, and the advantage of a diffraction grating with a fine pitch structure, that almost all long wavelength light is transmitted. It is something. That is, when the two are combined, it has a feature that the demultiplexing band is wide and the diffraction angle when demultiplexing broadband light such as LED light is small.

Now, FIG. 14 shows a diffraction diaphragm of the diffraction grating 21 of this embodiment. First, as shown in the above embodiment, a certain light, that is, the light indicated by the propagation constant kA in FIG. 14, is diffracted twice by the diffraction gratings 21a and 21b. On the other hand, the other light, that is, the light indicated by the propagation constant kB, is made non-diffractive. In other words, the light with a propagation constant of 1 (B) is not diffracted by the first diffraction grating 21a.
As shown in FIG. 4, if the relationship ∆= and −kB−sinOl− holds: ■3≧O, then light with a propagation constant kB becomes completely impossible to diffract. Here, as in the previous case, K is the initial grating 2
The lattice constant of 1a and Oj are the input angles.

If such a relationship is satisfied, light of a certain wavelength will be diffracted twice by the diffraction grating 21, and light of a certain wavelength will be transmitted twice, so that the output light will be as shown in FIG. will be demultiplexed.

For example, as shown in FIG. 16, the short wavelength light λS
++ λS21~. One group λsn and long wavelength light λI
The same is true when demultiplexing the combined light consisting of , 1
Group of short wavelength light λS++ λS21~. λsn passes through the diffraction grating 21, is diffracted twice (1-1) and demultiplexed by the diffraction gratings 21a, 2], b, and the long wavelength light λL is separated by the diffraction grating 21a, 2], b.
1, the light beam passes through the diffraction gratings 21a and 2lb twice, and is separated from the diffraction output light group as λL(0-0).

In addition, even if the structure is not configured to satisfy the above formula, the propagation constant k
If the light B is significantly separated from the Bragg condition, a similar demultiplexing effect can be obtained.

=21- Furthermore, if there are a plurality of lights that satisfy the above condition, each of the lights in one group travels in the same direction after passing through the two diffraction gratings twice. Therefore, these one group of multiplexed lights transmitted through the diffraction grating 21 may be newly demultiplexed using a separate demultiplexing element. At this time, after demultiplexing using the diffraction grating 21 of this embodiment, if the transmitted output light is mixed with light of multiple wavelengths, it is sufficient to perform further demultiplexing.

That is, such a demultiplexing step may be repeated as many times as necessary using a plurality of demultiplexing elements.

For example, as shown in FIG. 16, short wavelength light λS++λS
21~. One group of λS□ and long wavelength light λL++ λL
If multiplexed light consisting of a group of z+ to λLn is to be demultiplexed, two diffraction gratings 23 and 24 equivalent to the diffraction grating 21 may be used. That is, a group of short wavelength lights λ
S++ λ821~. λsn passes through the diffraction grating 23 and is demultiplexed by being diffracted twice (1-1) by the diffraction gratings 23a and 23b, while the longer wavelength brother λL++
λf2. ~． One group, λLn, transmits all light as shown by (0-0), and separates it from light on the short wavelength side. After that, a group of long wavelength lights λL+ transmitted through the first diffraction grating 23
+λI, 2. ~． λLn may be separated by passing through the second diffraction grating 24 and being diffracted twice by the diffraction gratings 24a and 24b.

Now, as a specific example, the pitch of the diffraction grating 23a on the input side is 0.6 μm, and the pitch of the diffraction grating 23b on the output side is 0.6 μm.
For the first diffraction grating 23 of 62μ■, the entrance J angle is 30'
0.5μm, 0. 6μm, 0.7pm,
1. , 3(un, 1.4μm, 1.5pm
Consider the case where multiplexed light of six different wavelengths is input.

In this case, the light that satisfies the above equation and cannot be diffracted is three types of light on the long wavelength side, 1.3 μm, 1.4 μm, and 1.5 μm, and these wavelength lights are transmitted through the diffraction grating 23 and are Since the light with wavelengths of 0.5 μm, 0.6 μm, and 0.7 μm is diffracted twice, it is separated from the former. Then, it is necessary to demultiplex the transmitted light again, but for this demultiplexing, the pitch of the diffraction grating 24a on the input end is 1.4 μm, and the pitch of the diffraction grating 24b on the output side J is 1.45 μm. When using the diffraction grating 24, the diameter is 1.3 μm. ．． 4 μm, 1.
The three types of light of 5 μm are each diffracted twice and separated as in the above-described embodiment. In this way, the demultiplexing band is expanded and the multiplicity of optical communications etc. can be dramatically improved.

If this embodiment is generalized, if there are many more wavelength groups of light, the configuration shown in FIG. 17 may be adopted in accordance with FIG. 16. That is, a required number of diffraction gratings 24A to 24N may be provided on the transmitted light group output side of the second diffraction grating 24.

If the function shown in FIG. 16 is to be implemented as a thick film waveguide type integrated structure according to FIG. 7, the structure may be configured as shown in FIG. 17. That is, in the configuration shown in FIG. 7, a part of the waveguide type collimating lens 1.2a is also extended to the optical path side of the light transmitted through the diffraction grating 10, and the condenser lens 25 is installed on the transmitted output side.
is configured as a waveguide-type cylindrical lens, that is, integrally configured with two-stage waveguide-type collimating lenses 25 a and 25 b.
, 25a are respectively provided with transmission type diffraction gratings 26a, 2.
6b to form a double diffraction grating 26. That is, this diffraction grating 26 corresponds to the diffraction grating 24, and the diffraction grating 10
corresponds to the diffraction grating 23.

Next, the ninth embodiment of the present invention is shown in FIGS. 19 and 20.
This will be explained using figures. This embodiment uses the idea of the above-mentioned embodiment in the sixth or seventh embodiment. Although the basic operation is the same, for example, when configured according to FIG. 17, two diffraction gratings 27 and 28 corresponding to the diffraction gratings 23 and 24 are used. , 27b are relatively the same as in the case of FIG. 9, and the diffraction gratings 28a of the diffraction grating 28,
The diffraction characteristics of 28b are also relatively the same. As a result, only one condensing lens 11 is provided on the input side, and the lens on the output side is omitted.

In the case of this embodiment as well, if this function is to be implemented in a thick film waveguide type integrated structure according to FIG. 13, it may be constructed as shown in FIG. 20. That is, in the configuration shown in FIG. 13, the waveguide 20 is separated into a diffraction side and a transmission side, and the transmission side is separated into waveguides 20a and 20b, and transmission type diffraction gratings 29a and 29b are respectively installed on the opposing end faces of the waveguides 20a and 20b. Forming a double diffraction grating 2
It becomes 9. That is, this diffraction grating 29 is the diffraction grating 28
The diffraction grating 18 corresponds to the diffraction grating 27.

Further, an embodiment of the tactician of the present invention will be explained with reference to FIGS. 21 to 23. In this example, in order to achieve further miniaturization,
Two stages of diffraction gratings 27, 28 (or 23, 24) are arranged close to each other so that the light split by the first diffraction grating 27 passes through the next diffraction grating 28. In the case of using the diffraction gratings 27 and 28 of the above embodiment, the 22nd
As shown in the figure, a condenser lens 11 may be provided at the input end.

In this case as well, if we generalize this example, if there are many more wavelength groups of light, the 23rd wavelength group according to FIG.
It can be configured as shown in the figure. That is, the second diffraction grating 28
The required number of diffraction gratings 28A to 28N (28N
(Only shown in the figure) may be provided.

Furthermore, an embodiment of the strategist of the present invention will be explained with reference to FIG. In this embodiment, the double diffraction grating structure of the seventh or strategist embodiment is replaced with two diffraction gratings 29a according to the case of FIG.
, 29b is constructed as a reflective double diffraction grating 29. The structure itself may remain as shown in FIG. 8, or may be based on the idea of the second embodiment. In any case, some of the combined light is diffracted twice by the diffraction gratings 29a and 29b and output, as in the case of FIG.
Some other light is reflected twice by the diffraction gratings 29a and 29b.
(corresponding to the above-mentioned transmission), and is output and separated from the former.

Note that in any of the embodiments, the demultiplexing function and the multiplexing function are relative, and if multiplexing is required, input and
All you have to do is replace the output side.

Effect Since the present invention includes at least two diffraction gratings as described above, it is possible to achieve both high efficiency and low angular dispersion, which are impossible with only one diffraction grating.
Even when dealing with broadband light such as ED light, it is possible to perform good demultiplexing or multiplexing without expanding the spot diameter. By diffracting and having a certain light transmitted or reflected at least twice, it is possible to easily expand the demultiplexing or multiplexing band, and by combining at least two diffraction gratings with relatively different diffraction characteristics. However, by combining at least two diffraction gratings with the same relative diffraction characteristics, it is also possible to omit the lens on the input side or the output side.
Furthermore, not only can the diffraction grating itself be placed on the same substrate, but also duplication can be facilitated by forming a lens, such as a cylindrical lens, in a waveguide type on the same substrate as the diffraction grating. .

[Brief explanation of the drawing]

FIG. 1 is a schematic front view showing a first embodiment of the present invention, and FIG.
The figure is a schematic front view showing an enlarged part of the diffraction grating, Figure 3 is a vector diagram showing the characteristics of input angle - output angle, and Figure 4 shows the second embodiment of the present invention. FIG. 5 is a vector diagram showing the input angle-output angle characteristics, FIG. 6 is a schematic front view showing the third embodiment of the present invention, and FIG. 7 is a fourth embodiment of the present invention. FIG. 8 is a schematic front view showing a fifth embodiment of the present invention; FIG. 9 is a schematic front view showing a sixth embodiment of the present invention; FIG. 10 is a diffraction grating. 11 is a schematic front view when the deflection angle is 0, FIG. 12 is a schematic perspective view of an integrated configuration example showing the seventh embodiment of the present invention, and FIG. 13 is a schematic front view of the seventh embodiment of the present invention. A schematic front view showing an example of
Fig. 14 is a vector diagram, Figs. 15 and 16 are a schematic front view showing a multiplexed example, Fig. 17 is a general front view showing a more generalized example, and Fig. 18 is a schematic perspective view showing an example of an integrated configuration. ,
FIG. 19 is a schematic front view showing a ninth embodiment of the present invention, FIG. 20 is a schematic perspective view showing an example of an integrated configuration, and FIG. 21 is a schematic front view showing an embodiment of the schemer of the present invention. Figure 22 is a schematic front view, Figure 23 is a generalized front view, and Figure 24 is a generalized front view.
The figure is a schematic front view showing an embodiment of the strategist of the present invention. 4 ・Collimating lens, 5a, 5b...diffraction grating,
6... Condenser lens, 7a, 7b... Diffraction grating, 8.
・Co 30=

Claims (1)

[Scope of Claims] 1. A multiplexing/demultiplexing element comprising at least two diffraction gratings disposed on an optical path for multiplexing or demultiplexing light. 2. A multiplexing/demultiplexing element characterized in that at least two diffraction gratings having relatively the same diffraction characteristics are arranged on an optical path for multiplexing or demultiplexing light. 3. A multiplexing/demultiplexing element characterized in that at least two diffraction gratings having relatively different diffraction characteristics are arranged on an optical path for multiplexing or demultiplexing light. 4. The multiplexing/demultiplexing element according to claim 3, wherein the pitch of at least one diffraction grating is different from that of the other diffraction gratings. 5. The multiplexing/demultiplexing element according to claim 3, wherein the grating plane of at least one diffraction grating is arranged non-parallel to the grating plane of other diffraction gratings. 6. The multiplexing/demultiplexing element according to claim 1, 3, 4, or 5, further comprising a collimating lens for collimating the input light and a condensing lens for condensing the demultiplexed light. 7. The multiplexing/demultiplexing element according to claim 1, 2, 3, 4, or 5, further comprising a condensing lens for condensing input light. 8. The multiplexing/demultiplexing element according to claim 1, 2, 3, 4, or 5, wherein the diffraction grating itself has a lens function. 9. The multiplexing/demultiplexing element according to claim 6, 7 or 8, wherein the lens has a cylindrical light focusing function. 10. The multiplexing/demultiplexing device according to claim 1, 2, 3, 4, or 5, characterized in that the diffraction gratings are arranged on the same substrate. 11. The multiplexing/demultiplexing device according to claim 6, 7, 8 or 9, wherein the diffraction grating and the lens are arranged on the same substrate.