JP2006338058A - Optical waveguide member and optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the tolerance of setup positioning error of an optical multiplexer/demultiplexer which uses a multi-mode optical waveguide. <P>SOLUTION: For this sake, the present invention is designed to couple the multi-mode optical waveguide with a single-mode optical waveguide directly. In another configuration of this invention, there is provided between both optical waveguides a single-mode optical waveguide having its length set to be approximately equal to zero, or equal or approximately equal to the period of interference between the 0th-order mode and a radiative higher-order mode of the single-mode optical waveguide. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical waveguide member and an optical module, and more particularly to an optical multiplexer / demultiplexer, an optical multiplexer / demultiplexer, and an optical module using the same.

  From the viewpoint of increasing the speed and capacity of optical communications, a wavelength division multiplexing (WDM) system has attracted attention. In a WDM system, an optical multiplexer / demultiplexer is an indispensable element. In particular, elements of the type used in combination with a single-mode fiber are particularly important. This is because when a single mode fiber is used, an optical signal can be transmitted with less waveform degradation (deterioration of the signal).

  Conventionally, as such an element, for example, Applied Physics Letter (Appl. Phys. Lett.), Vol. 61, no. 15, pp. 1754-1756, 1992. Is known (Non-Patent Document 1).

  FIG. 13 is a plan view of such a representative example. In this element, a single-core waveguide 10 having a single core, a multi-mode waveguide 2 and a single-mode waveguide array 3 having four cores are coupled in series on the substrate 1 in the optical axis direction. . When this element is operated as, for example, a branching filter, the single mode fiber 4 is coupled to one core side and light is incident on the single mode waveguide 10. This light excites a plurality of modes when entering the multi-mode waveguide 2 and is branched into four by interference between the modes, and the single-mode waveguide array 3 to the four-core single mode. To the fiber 4 '.

Japanese Patent Laid-Open No. 10-48458 Applied Physics Letter (Appl. Phys. Lett.), Vol. 61, no. 15, pp. 1754-1756, 1992

  In the element of the above conventional example, a single mode waveguide 10 is provided between the single-core single-mode fiber 4 and the multimode waveguide 2 so that light is incident on the center of the multimode waveguide 2. I am trying to. However, in this case, if there is a misalignment between the element and the single mode fiber 4 on the single core side, a radiative higher order mode (higher order mode) 14 is generated in the single mode waveguide 10. Is excited. The high-order mode light 14 and the zero-order mode light 13 interfere with each other. At this time, since the light propagation meanders (since the distribution of the light fluctuates during beam propagation), the position and traveling direction of the light input to the multimode waveguide 2 can be changed from the central axis even if the positional deviation is slight. It may shift greatly. 14thly, the relationship of the central axis 11 of the single mode fiber 4 at this time, the central axis 12 of the single mode waveguide 10, and the peak position 15 of light intensity is shown. Other parts are denoted by the same reference numerals as in FIG. In this case, the optical output between channels varies greatly. For this reason, when mounting the element, high alignment accuracy is required, and it is difficult to reduce the mounting cost by using a simple passive alignment method.

  In view of such circumstances, an object of the present invention is to provide an optical multiplexer / demultiplexer that can be mounted in a module by a low-cost passive alignment method with a large tolerance for mounting displacement with respect to a single-mode fiber. .

  JP-A-10-48458 reports an example in which a multimode fiber is directly coupled to a multimode waveguide (Patent Document 1). However, this example only relates to a technique using a multimode fiber.

  A typical embodiment of the present invention is characterized in that the multimode waveguide 2 and the single-core single-mode fiber 4 are directly optically coupled. The optical waveguide member of the present application can be used as an optical multiplexer or an optical demultiplexer. The direction in which light is introduced into the optical waveguide member differs depending on whether the optical waveguide member is used as an optical multiplexer or an optical demultiplexer. Furthermore, a desired optical member and optical element can be provided at the entrance or exit depending on the purpose.

An embodiment of the present invention includes at least a multimode optical waveguide and a plurality of single mode optical waveguides optically coupled to a first end face of the multimode optical waveguide, and the first mode of the multimode optical waveguide is the first mode. An optical waveguide member characterized in that a second end surface opposite to one end surface can be optically coupled to a single mode fiber.
In the present invention, it is important to set the length of the single mode optical waveguide that is optically coupled to the second end face of the multimode optical waveguide. The setting method will be described in detail below.

In order to explain the inventive idea of the present invention, the relationship between the single-mode waveguide length on one core side and the insertion loss is illustrated. FIG. 15 shows the single-core single-mode waveguide length L _IN and insertion loss when the duplexer having the single-mode waveguide and the single-core single-mode fiber 4 are shifted by 1.0 μm in the horizontal direction. Is calculated by calculation. The calculation was based on the beam propagation method. The insertion loss is an optical loss associated with inserting the optical waveguide member of the present invention into the optical path.
FIG. 15 also shows a typical device structure of the present invention, that is, the characteristics when L _IN = 0. CH4 to CH4 show characteristic examples of the single-mode optical waveguide on the 4-core side. In this example, the losses of the single mode optical waveguides CH1 and CH4 located on the outside are larger than those of CH2 and CH3. However, it is understood that the variation in insertion loss of each channel becomes extremely small at a predetermined period. The present invention uses a configuration in which this single-core single-mode optical waveguide is eliminated, or an optical waveguide length that greatly reduces the variation in characteristics of each channel even when this single-mode optical waveguide is used. According to such an element structure of the present invention, variation in insertion loss between channels when a duplexer having a single mode waveguide and a single-core single-mode fiber 4 are displaced in the horizontal direction is the worst of conventional elements. It can be seen that the value can be reduced by nearly 5 dB. As described above, the configuration in which the multimode waveguide 2 and the single-core single-mode fiber 4 are optically coupled directly is most preferable. It can be confirmed from the aspect of characteristics and manufacturing.

  Hereinafter, the period in which the variation of the optical waveguide characteristic is extremely reduced and various embodiments of the present invention will be described.

As seen in Figure 15, the single-core side Shingurumo - de waveguide length L _IN outside case is zero, almost no inter-channel insertion loss difference at 200μm or 250μm period L _IN is present. As shown in FIG. 14, this period is a period of interference between the 0th mode 13 and the radioactive higher mode 14, and the difference between the propagation constants of both modes is π. Is equal to the value obtained by dividing.

Thus, in the present invention, L _IN may be set to n times the period of this interference (n = 0, 1, 2,...). This is because when designing a multi-mode interference (MMI) type multiplexer / demultiplexer, not only the waveguide mode is considered as in the prior art, but also the radiation mode is included. Equivalent to consideration.

As a result of the interference, the inter-channel insertion loss difference periodically changes in a trigonometric manner with respect to L _IN . For this reason, even if L _IN differs from the structure of n times the interference period by a predetermined small value with respect to the interference period, the inter-channel insertion loss difference can be kept low. And the characteristic can be made into a desired value.

That is, it is possible to achieve sufficient object of the present invention the L _IN as within 1/5 of the interference period. In other words, it can be said that this L _IN is substantially within 40 μm. According to this condition, for example, a module for 10 Gb Ethernet (registered trademark) can be sufficiently applied.

Further, L _IN may be in a range from n−1 / 5 times the interference period to n + 1/5 times the interference period (n = 0, 1, 2,...). In other words, it can be said that L _IN may be within a range of ± 40 μm from n times the interference cycle (n = 0, 1, 2,...). Even in this case, the inter-channel insertion loss variation can be reduced by about 3 dB from the conventional worst value.

More desirably, L _{IN is set} to a range within 1/10 of the interference period. In other words, it is more desirable that L _IN be within 20 μm.

Or, the same effect, L _IN a, can be obtained. However in the range of n + 1/10 times the n-1/10 times the interference period of the period of the interference (n = 0,1,2 ...). In other words, it can be more desirable if L _IN is set within a range of n times (n = 0, 1, 2,...) Of the interference period within ± 20 μm. In this case, it can be expected that the inter-channel insertion loss variation is reduced by nearly 4 dB compared to the conventional worst value.

  In the case of the above description, the high-order mode 14 that interferes with the 0th-order mode 13 is an odd-order. A value obtained by dividing 2π by the difference in propagation constants may be used.

  In carrying out the present invention, the central axis of the multi-mode waveguide coincides with the central axis of the single-mode waveguide optically coupled to the second end face of the multi-mode waveguide. It is optically preferable. This form is the same in various modifications of the present invention.

  In the above description, the example of the optical waveguide member of the present invention has been described as a duplexer. However, the operating principle is the same between the duplexer and the multiplexer except that the traveling direction of light is reversed. Therefore, even when the element of the present invention is used as a multiplexer, a large mounting position deviation tolerance can be ensured as in the duplexer.

  In the present invention, it is important that the single mode fiber is directly coupled to the multimode waveguide to improve the tolerance of the mounting position shift of the multiplexer / demultiplexer.

  If the optical waveguide member and element of the present invention are used, module mounting by an inexpensive passive alignment method can be performed, so that a low-cost optical module can be obtained.

  According to the embodiment of the present invention, it is possible to provide an optical waveguide member having a large mounting displacement tolerance, for example, an optical multiplexer / demultiplexer.

  Embodiments of the present invention are listed below.

  FIG. 1 shows a first embodiment of the present invention. This figure is a schematic top view of the element. The element of this embodiment can be used as an optical multiplexer or an optical demultiplexer. In this embodiment, a multi-mode waveguide 2 and a four-core single-mode waveguide array 3 are optically coupled on a substrate 1. A single mode fiber 4 is optically directly coupled to the end surface of the multimode waveguide 2 on the side not coupled to the single mode waveguide array 3. For this reason, in this structure, as described above, even when the alignment between the multi-mode waveguide 2 and the single-mode fiber 4 is misaligned, the variation in insertion loss between channels can be kept low. it can. As seen in this example, it is important to couple a single mode fiber directly to a multimode waveguide.

  FIG. 2 shows a second embodiment of the present invention. This figure is a schematic top view of the element. This embodiment is an example of an optical transmission module. In this embodiment, similarly to the first embodiment, the multi-mode waveguide 2 and the four-core single-mode waveguide array 3 are optically coupled on the substrate 1. A single mode fiber 4 is optically directly coupled to the end surface of the multimode waveguide 2 on the side not coupled to the single mode waveguide array 3. In this module, a V-groove 6 for positioning and fixing the single-mode fiber 4 is provided on the same substrate 1 as the element of the first embodiment. The V-groove 6 is provided along the axial direction of the optical fiber. For example, a silicon substrate is typically used as the substrate 1. In this case, the V-groove, that is, a groove having a V-shaped cross section, is processed with high accuracy by anisotropic etching of silicon crystal. A groove structure obtained by anisotropic etching of a silicon crystal is commonly called a V-groove. However, in an actual form, there may be a form similar to a U-shape, or a form in which these shapes are modified in addition to an accurate V-shape. Including this form, the term “V-groove” or “V-shaped” is used in the description of the present application. Since the configuration of the substrate having such a V-shaped groove structure is known in the art, detailed description thereof is omitted. Of course, these can take other measures.

  Further, in this example, a dicing groove 7 is formed in order to adjust the end face of the V groove 6. In addition, four distributed feedback (DFB) type semiconductor lasers 5 having different oscillation wavelengths are mounted on the substrate 1 and optically coupled to the single mode waveguide array 3. The DFB type semiconductor laser 5 is connected to the transmission LSI 40 via the wiring 41 and driven. In this module, light of different wavelengths oscillated from the four DFB type semiconductor lasers 5 can be combined and transmitted to the single mode fiber 4 with low loss and with reduced loss difference between channels. Further, this module can be operated as a reception module when a waveguide type photodiode is used instead of the DFB type semiconductor laser and a reception LSI is used instead of the transmission LSI. Also in this case, a large mounting position deviation tolerance with respect to the inter-channel insertion loss difference can be obtained. Also in this example, as described above, it is important to directly couple the single mode fiber 4 to the multimode waveguide 2.

FIG. 3 shows a perspective view of an example in which the second embodiment is fabricated using a Si substrate and a polymer waveguide. In the figure, the LSI portion is omitted. In this module, the multi-mode waveguide 2 and the single-mode waveguide array 3 shown in FIG. 2 are clad layers composed of lower polymers (hereinafter abbreviated as lower polymer clad layers). ) 22, a polymer core layer (hereinafter abbreviated as polymer core layer) 23 and an upper polymer clad layer (hereinafter abbreviated as upper polymer clad layer) 24. This polymer waveguide is formed on a Si substrate 20 having a silicon dioxide film (hereinafter abbreviated as SiO ₂ film) 21 on its surface. The other parts are the same as in the second example. That is, the optical fiber 4 is positioned and mounted in the V groove 8. A dicing groove 7 is formed in order to adjust the end face of the V groove 6. Each of the four-core single-mode waveguides 231, 232, 233, and 234 is connected to the DFB semiconductor lasers 51, 52, 53, and 54.

  With this module configured in this way, the characteristic that the tolerance of displacement with respect to the single-mode fiber 4 was 1.0 μm or more was obtained. That is, the variation between channels is 0.5 dB or less. The operating wavelength band is an example of 1.3 μm.

  FIG. 4 shows a method for producing the optical waveguide portion of the module. Other areas are omitted in the figure. They are sufficient to be produced in the usual way. FIG. 4 is a sectional view of the main part of the element shown in the order of the manufacturing process.

For the optical waveguide, a Si substrate 20 on which an SiO ₂ film 21 is formed is prepared, and a lower polymer cladding layer 22 and a polymer core layer 23 are formed on the SiO ₂ film 21 (FIG. 4A). Thereafter, the polymer core layer 23 is etched by a known method so as to correspond to each of the four-core single mode waveguides 231, 232, 233, and 234 (FIG. 4B). When the upper polymer cladding layer 24 is formed on the substrate thus prepared, an optical waveguide portion is formed by the polymer waveguide (FIG. 4C). Examples of typical polymers used in such configurations include, for example, polyimide, polysiloxane, epoxy resin, acrylate resin, or fluorinated organics of these resins. For example, a fluorinated polymer.

  The V-groove 6 in the module silicon substrate 20 can be obtained, for example, by anisotropic wet etching using a KOH solution.

  As an example of a specific application, the core of the optical waveguide is about 6.5 μm × 6.5 μm, the refractive index of the cladding is about 1.525, and the refractive index difference between the cladding and the core is less than 0.4%. About 5%. The wavelength band used for the optical module is, for example, about 1250 nm to 1375 nm. In general, in 10 GbE-WWDM, four wavelengths having a center wavelength of 1257.7 nm, 1300.2 nm, 1324.7 nm, and 1349.2 nm are used.

  In the above description, the case where the DFB type semiconductor laser and the waveguide type photodiode are used has been described. However, other types of semiconductor lasers, photodiodes, or others may be used depending on the requirements of the optical system. These optical elements can be used.

  FIG. 5 shows a third embodiment of the present invention. This embodiment is an example in which a single mode fiber 4 is optically coupled to a single mode waveguide array 3 instead of the DFB type semiconductor laser 5 in the form of the second embodiment. Since other configurations are the same as those in the above examples, detailed description is omitted. This embodiment can be used as a multiplexer or a demultiplexer. In this embodiment, all or some of the optical fibers optically coupled to the single mode waveguide array 3 may be multimode fibers. In this case, the present embodiment can be operated as a duplexer.

  FIG. 6 shows a fourth embodiment of the present invention. The element of the present embodiment is an example in which the substrate of the optical module is composed of a plurality of members. That is, in this example, it has the 2nd board | substrate 8 different from the board | substrate 1 with which the multimode waveguide 2 and the single mode waveguide array 3 are formed. A second single mode waveguide array 9 is formed on the second substrate 8. Other configurations are the same as the example of FIG.

  This embodiment is an example in which the second single mode waveguide array 9 is optically coupled to the single mode waveguide array 3 in place of the DFB type semiconductor laser 5 in the second embodiment. This embodiment can also be used as a multiplexer or a duplexer. Here, when the element of this embodiment is used as a duplexer, it is formed by a multi-mode waveguide array or a multi-mode waveguide and a single-mode waveguide instead of the single-mode waveguide array 9. It is also possible to use a waveguide array.

  FIG. 7 shows a fifth embodiment of the present invention. This embodiment is an example of a multiplexer. The present embodiment is an example in which the end surface of the single-mode fiber 4 in the optical module shown as the second embodiment on the side not coupled to the multi-mode waveguide 2 is coupled to the multi-mode fiber 30. . In this case, since the single mode can be incident on the center of the multimode fiber 30 from the single mode fiber 4, the waveguide mode can be efficiently excited in the multimode fiber 30. Other configurations are the same as in the example of FIG. As described above, the present invention is also effective when used for optical transmission by a multimode fiber.

  In the present invention, the number of single mode waveguides in the single mode waveguide array 3 is arbitrary, and it is not always necessary to limit the number to four as shown in the drawings used in the description of the above embodiments. FIG. 8 shows an example having seven single mode waveguides as a sixth embodiment.

  In the present invention, a single mode waveguide 10 having a finite length in the vicinity of 0 μm may be provided between the multimode waveguide 2 and the single mode fiber 4. FIG. 9 shows a multiplexer / demultiplexer having this structure as a seventh embodiment. Also in this case, as described above, a large mounting position deviation tolerance can be obtained. The length of the single-mode waveguide 10 is described as “finite length in the vicinity of 0 μm”, but more specifically, it has been described in detail in the section for solving the problem. Further, the allowable range has been described with reference to the fifteenth.

  Further, the following form is practically useful. That is, it means that the median of the allowable range of the length of the single mode waveguide optically coupled to the second end face of the multimode waveguide is the zero-order intrinsic mode of the single mode waveguide. This is an optical waveguide member having a value obtained by dividing π by a difference in propagation constant between the first mode and the radioactive first mode. Alternatively, the median of the allowable range of the length of the single mode waveguide optically coupled to the second end face of the multimode waveguide is the zero-order intrinsic mode of the single mode waveguide. This is an optical waveguide member having a value obtained by dividing 2π by the propagation constant difference between the second mode and the radioactive secondary mode. A form in which such an optical waveguide member is used in various optical modules is useful.

  In addition, in the optical waveguide member, it is practical that the central axis of the multi-mode waveguide coincides with the central axis of the single-mode waveguide optically coupled to the second end face of the multi-mode waveguide. Is preferable.

  FIG. 10 shows an eighth embodiment of the present invention. This embodiment is an example of a transmission or reception module using the elements of the seventh embodiment. This module can be operated as a multiplexing / demultiplexing module if a single mode fiber or a single mode waveguide is coupled to the single mode waveguide array 3 instead of an optical element.

  In the present invention, a single-mode waveguide 10 is provided between the multi-mode waveguide 2 and the single-mode fiber 4, and the length of the single-mode waveguide 10 is reduced between the zero-order mode and the radioactive mode. You may make it the period of the interference with a higher mode, or the vicinity of the period. FIG. 11 shows a ninth embodiment having this structure. Also in this case, as described above, a large mounting position deviation tolerance can be obtained. The more specific length of the single-mode waveguide 10 has been described in detail in the section for solving the problems.

  FIG. 12 shows a tenth embodiment of the present invention. This embodiment is an example of a transmission or reception module using the elements of the ninth embodiment.

  In addition, this module can be operated as a multiplexing / demultiplexing module if a single mode fiber or a single mode waveguide is coupled to the single mode waveguide array 3 instead of an optical element.

  The present invention is effective regardless of the materials of the substrate, the waveguide, and other components, and is not limited to the case described in the above embodiments. The present invention is effective regardless of the positioning and fixing method of the single mode fiber, the optical element, the waveguide and other components, and is not limited to the case described in the above embodiment.

Hereinafter, various forms of the length of the single mode optical waveguide optically coupled to the second end face of the multimode waveguide that can be used in the present invention are listed and listed. In addition, the form shown only by specific numbers, such as 20 micrometers or less and 40 micrometers or less, was excluded.
(1) a multimode optical waveguide, a plurality of first single-mode optical waveguides optically coupled to the first end face of the multimode optical waveguide, and the first end face of the multimode optical waveguide; At least one second single-mode optical waveguide optically coupled to the opposite second end face, and the length of the at least one second single-mode optical waveguide is the second N-1 / 5 to n + 1/5 times the interference period between the zero-order intrinsic mode and the radioactive higher-order mode of the single-mode waveguide (where n = 0, 1, 2,...) Or a value obtained by dividing π by the propagation constant difference between the zeroth-order intrinsic mode and the radioactive higher-order mode of the second single-mode waveguide. -1/5 times to n + 1/5 times (where n = 0, 1, 2,...) (However, a positive number), Is n−1 / 5 times to n + 1/5 times the value obtained by dividing 2π by the propagation constant difference between the zeroth-order intrinsic mode and the radioactive higher-order mode of the second single-mode waveguide. (Where n = 0, 1, 2,...) (In this case, a positive number).
(2) The length of the single-mode optical waveguide optically coupled to the second end face of the multi-mode waveguide is such that the zero-order intrinsic mode and the radiative high-order mode of the single-mode waveguide (1) to n + 1/10 times (where n = 0, 1, 2,...) (Where n is a positive number). The optical waveguide member according to 1).
(3) a multimode optical waveguide, a plurality of single mode optical waveguides optically coupled to the first end face of the multimode optical waveguide, and the opposite side of the first end face of the multimode optical waveguide A single-mode optical waveguide optically coupled to a second end face; and an optically coupled second end face of the single-mode optical waveguide opposite to the first end face coupled to the multi-mode optical waveguide. A single-mode optical fiber having at least a coupled single-mode fiber, and the length of the single-mode optical waveguide is an interference period between the zero-order intrinsic mode of the single-mode waveguide and the higher-order radiative mode. n times (n = 0, 1, 2,...) within ± 40 μm (however, a positive number).
(4) The length of the single-mode waveguide optically coupled to the second end face of the multimode waveguide is such that the zero-order intrinsic mode of the single-mode waveguide and the higher-order radiation The optical waveguide according to (4), wherein n times the interference period with the mode (where n = 0, 1, 2,...) Is within ± 20 μm (however, a positive number). It is a waveguide member.
(5) a multimode optical waveguide, a plurality of single mode optical waveguides optically coupled to the first end face of the multimode optical waveguide, and the opposite side of the first end face of the multimode optical waveguide A single-mode optical waveguide optically coupled to a second end face; and an optically coupled second end face of the single-mode optical waveguide opposite to the first end face coupled to the multi-mode optical waveguide. Propagation between the zero-order eigenmode of the single-mode waveguide and the radiative higher-order mode having at least a coupled single-mode fiber and the length of the single-mode optical waveguide It is characterized by being in the range (where n = 0, 1, 2,...) (Where n = 0, 1, 2,...) That is a value obtained by dividing π by a constant difference. It is an optical waveguide member.
(6) The length of the single-mode waveguide optically coupled to the second end face of the multimode waveguide is such that the zero-order intrinsic mode of the single-mode waveguide and the higher-order radiation A range of n-1 / 10 to n + 1/10 times (where n = 0, 1, 2,...) Obtained by dividing π by the propagation constant difference with the mode (a positive number) The optical waveguide member according to (5), which is characterized in that:
(7) a multimode optical waveguide, a plurality of single mode optical waveguides optically coupled to the first end face of the multimode optical waveguide, and the opposite side of the first end face of the multimode optical waveguide A single mode optical waveguide optically coupled to the second end face, and a second mode of the single mode optical waveguide opposite to the first end face coupled to the multimode optical waveguide. The end face can be optically coupled to a single mode fiber, and the length of the single mode optical waveguide is between the zeroth order intrinsic mode and the radiative higher order mode of the single mode waveguide. The optical waveguide member is characterized in that it is within ± 40 μm (positive number) from the value obtained by dividing π by the propagation constant difference.
(8) The length of the single-mode waveguide optically coupled to the second end face of the multimode waveguide is such that the zero-order intrinsic mode of the single-mode waveguide and the higher-order radiation The optical waveguide member is characterized in that it is within ± 20 μm (however, a positive number) from the value obtained by dividing π by the propagation constant difference with the mode.
(9) a multimode optical waveguide, a plurality of single mode optical waveguides optically coupled to the first end face of the multimode optical waveguide, and the opposite side of the first end face of the multimode optical waveguide A single mode optical waveguide optically coupled to the second end face, and a second mode of the single mode optical waveguide opposite to the first end face coupled to the multimode optical waveguide. The end face can be optically coupled to a single mode fiber, and the length of the single mode optical waveguide is between the zeroth order intrinsic mode and the radiative higher order mode of the single mode waveguide. In the range (n = 0, 1, 2,...) (Where n = 0, 1, 2,...) Of the value obtained by dividing 2π by the propagation constant difference of. The optical waveguide member.
(10) The length of the single-mode waveguide optically coupled to the second end face of the multimode waveguide is such that the zero-order intrinsic mode of the single-mode waveguide and the higher-order radiation N-1 / 10 to n + 1/10 times (where n = 0, 1, 2,...) Of the value obtained by dividing 2π by the propagation constant difference from the mode (where n is a positive number) And an optical waveguide member.
(11) A multi-mode optical waveguide, a plurality of single-mode optical waveguides optically coupled to the first end face of the multi-mode optical waveguide, and the opposite side of the first end face of the multi-mode optical waveguide A single mode optical waveguide optically coupled to the second end face, and a second mode of the single mode optical waveguide opposite to the first end face coupled to the multimode optical waveguide. The end face can be optically coupled to a single mode fiber, and the length of the single mode optical waveguide is between the zeroth order intrinsic mode and the radiative higher order mode of the single mode waveguide. The optical waveguide member is characterized in that it is within ± 40 μm (however, a positive number) from the value obtained by dividing 2π by the propagation constant difference.
(12) The length of the single-mode waveguide optically coupled to the second end face of the multimode waveguide is such that the zero-order eigenmode of the single-mode waveguide and the higher-order radiation The optical waveguide member according to (11), wherein the optical waveguide member is within ± 20 μm (however, a positive number) from a value obtained by dividing 2π by a propagation constant difference from the mode.

  The practical forms of the optical waveguide member of the present invention are listed and listed below.

  The first feature is that at least one of a multimode waveguide or a single mode waveguide of the optical waveguide member of the present invention is made of a polymer material.

  Second, at least one of a multimode waveguide or a single mode waveguide of the optical waveguide member of the present invention is manufactured on a silicon substrate.

  Third, the end surface of the single mode waveguide that is optically coupled to the second end surface of the multimode waveguide is optically coupled to the single mode fiber at the end surface that is not coupled to the multimode waveguide. It is characterized by being.

  Fourth, the single-mode fiber is fixed by a groove having a V-shape or other cross-sectional shape formed on the same substrate as the multi-mode waveguide or single-mode waveguide. is there.

  Fifth, the optical waveguide member characterized in that the end face of the single-mode fiber on the side not optically coupled to the single-mode waveguide or the multi-mode waveguide is optically coupled to the multi-mode fiber. It is. A mode in which the present technical idea is applied to the third and fourth modes is preferable.

  Examples of the optical module of the present application are listed below.

  The first embodiment has at least one optical multiplexer or optical demultiplexer according to the present invention, and optically forms a first end face of a multimode waveguide of the optical multiplexer or optical demultiplexer. At least one of the coupled single-mode waveguides is optically coupled to an optical element, an optical waveguide, a single-mode fiber, or a multi-mode fiber at the end face that is not optically coupled to the multi-mode waveguide. This is an optical module characterized by

  Second, a single mode fiber or multimode fiber that is optically coupled to a single mode waveguide that is optically coupled to the first end face of the multimode waveguide is a multimode waveguide or The optical module according to the first embodiment, wherein the optical module is fixed by a groove having a V-shape or other cross-sectional shape formed on the same substrate as the single-mode waveguide.

  Third, in the optical module of the first embodiment, each of the plurality of single mode waveguides optically coupled to the first end face of the multimode waveguide in the optical multiplexer has an oscillation wavelength. The optical module is characterized in that different distributed feedback or distributed reflection type semiconductor lasers are optically coupled.

  Fourth, in the optical module of the first embodiment, a plurality of single mode waveguides optically coupled to the first end face of the multimode waveguide in the optical demultiplexer are waveguide types. This is an optical module characterized in that a photodiode is optically coupled.

  A feature of the present invention is that it has a multimode optical waveguide and a plurality of first single-mode optical waveguides optically coupled to the first end face of the multimode optical waveguide. The second end surface opposite to the first end surface is an optical waveguide member characterized in that it can be optically coupled to a single mode fiber, and has a large mounting position deviation tolerance, such as an optical coupling member. A duplexer can be provided.

FIG. 1 is a plan view showing a first embodiment according to the present invention. FIG. 2 is a plan view showing a second embodiment according to the present invention. FIG. 3 is a perspective view showing one form of a second embodiment according to the present invention. FIG. 4 is a partial cross-sectional view showing the manufacturing process of the polymer optical waveguide portion of the second embodiment according to the present invention. FIG. 5 is a plan view showing a third embodiment according to the present invention. FIG. 6 is a plan view showing a fourth embodiment according to the present invention. FIG. 7 is a plan view showing a fifth embodiment according to the present invention. FIG. 8 is a plan view showing a sixth embodiment according to the present invention. FIG. 9 is a plan view showing a seventh embodiment according to the present invention. FIG. 10 is a plan view showing an eighth embodiment according to the present invention. FIG. 11 is a plan view showing a ninth embodiment according to the present invention. FIG. 12 is a plan view showing a tenth embodiment according to the present invention. FIG. 13 is a plan view showing a conventional example. FIG. 14 is a plan view showing a state of light propagation in the conventional configuration. FIG. 15 is a diagram showing an example of the relationship between the single-core single-mode waveguide length and the insertion loss.

Explanation of symbols

1: substrate, 2: multimode waveguide, 3: single mode waveguide array, 4: single mode fiber, 4 ′: single mode fiber, 5: DFB type semiconductor laser, 6: V groove, 7: dicing groove, 8 : V-groove, 10: single mode waveguide, 13: 0 order mode, 14: radioactive higher order mode, 20: Si substrate, 21: silicon dioxide film, 22: cladding layer, 23: core layer, 24: cladding layer , 231, 232, 233, 234: single mode waveguide, 51, 52, 53, 54: DFB semiconductor laser, 30: multimode fiber, 40: transmission LSI, 41: wiring.

Claims (20)

  A multimode optical waveguide and at least a plurality of first single-mode optical waveguides optically coupled to a first end face of the multimode optical waveguide, wherein the first of the multimode optical waveguide An optical waveguide member characterized in that a second end surface opposite to the end surface can be optically coupled to a single mode fiber.   2. The optical waveguide member according to claim 1, further comprising at least a single mode fiber optically coupled to a second end surface opposite to the first end surface of the multimode optical waveguide.   The groove structure for holding the optical fiber optically coupled to the second end face is disposed adjacent to the second end face of the multimode optical waveguide. The optical waveguide member as described.   A groove structure for holding an optical fiber optically coupled to the second end face is disposed adjacent to the second end face of the multimode optical waveguide, and the second end face of the multimode optical waveguide is disposed. The optical waveguide member according to claim 2, further comprising a single mode fiber optically coupled to the groove structure, wherein the single mode fiber is held in the groove structure.   2. The optical waveguide member according to claim 1, wherein at least one of the multimode optical waveguide and the first single-mode optical waveguide is made of a polymer resin material.   3. The optical waveguide member according to claim 2, wherein at least one of the multimode optical waveguide and the first single mode optical waveguide is made of a polymer resin material.   The optical waveguide member according to claim 1, wherein at least one of the multimode optical waveguide and the first single mode optical waveguide is mounted on a silicon substrate.   The optical waveguide member according to claim 2, wherein at least one of the multimode optical waveguide and the first single mode optical waveguide is mounted on a silicon substrate. Having at least one of the optical waveguide members according to claim 2,
At least one of a plurality of first single-mode optical waveguides optically coupled to the first end face of the multimode optical waveguide of the optical waveguide member;
An optical element optically coupled to the second end face, an optical waveguide, a single mode fiber, a second end face of the multimode optical waveguide on a side not optically coupled to the multimode optical waveguide, An optical module comprising at least one member selected from the group of a multimode fiber and a groove structure for holding the optical fiber.   A multi-mode optical waveguide, a plurality of first single-mode optical waveguides optically coupled to the first end face of the multi-mode optical waveguide, and a side opposite to the first end face of the multi-mode optical waveguide At least one second single-mode optical waveguide optically coupled to the second end face, and the length of the second single-mode optical waveguide is 40 μm or less. Optical waveguide member.   The at least one second single mode optical waveguide has third and fourth end faces, and the third end face of the second single mode optical waveguide is optically coupled to the second end face of the multimode optical waveguide. And a single-mode fiber optically coupled to a fourth end surface opposite to the third end surface coupled to the multimode optical waveguide. Optical waveguide member.   The at least one second single-mode optical waveguide has third and fourth end faces, and the third end face of the second single-mode optical waveguide is optically connected to the second end face of the multi-mode optical waveguide. The optical waveguide member according to claim 10, wherein the at least one second single-mode optical waveguide has a length of 20 μm or less.   The optical waveguide member according to claim 12, further comprising a single mode fiber optically coupled to the fourth end face of the at least one second single mode optical waveguide.   The at least one second single mode optical waveguide has a third end surface and a fourth end surface, and the third end surface of the second single mode optical waveguide is a second end surface of the multimode optical waveguide. And a groove structure for holding an optical fiber optically coupled to the fourth end face of the second single-mode optical waveguide is disposed adjacent to the fourth end face. The optical waveguide member according to claim 10.   A groove structure for holding an optical fiber optically coupled to the fourth end face of the second single mode optical waveguide is disposed adjacent to the fourth end face, and the fourth mode of the multimode optical waveguide is arranged. 12. The optical waveguide member according to claim 11, further comprising a single mode fiber optically coupled to an end face of the optical fiber, wherein the single mode fiber is held in the groove structure.   The groove structure for holding the optical fiber optically coupled to the fourth end face of the second single mode optical waveguide is disposed adjacent to the fourth end face. 13. An optical waveguide member according to 12. 11. The optical waveguide member according to claim 10, wherein at least one of the multimode optical waveguide and the first and second single mode optical waveguides is made of a polymer resin material. The optical waveguide member according to claim 10, wherein at least one of the multimode optical waveguide and the first and second single mode optical waveguides is mounted on a silicon substrate.   A multi-mode optical waveguide, a plurality of first single-mode optical waveguides optically coupled to the first end face of the multi-mode optical waveguide, and a side opposite to the first end face of the multi-mode optical waveguide At least one second single-mode optical waveguide optically coupled to a second end face, and the length of the at least one second single-mode optical waveguide is equal to the second single-mode optical waveguide. N-1 / 5 to n + 1/5 times the interference period between the waveguide zero-order intrinsic mode and the radioactive higher-order mode (where n = 0, 1, 2,...). Or a value obtained by dividing π by the propagation constant difference between the zeroth-order intrinsic mode and the radioactive higher-order mode of the second single-mode waveguide. -1/5 times to n + 1/5 times (where n = 0, 1, 2,...) Or n + 1/5 times the value obtained by dividing 2π by the propagation constant difference between the zeroth-order intrinsic mode and the radioactive higher-order mode of the second single-mode waveguide. An optical waveguide member having a range represented by at least one of a range (where n = 0, 1, 2,...) (Here, a positive number). The at least one second single-mode optical waveguide has third and fourth end faces, and the third end face of the second single-mode optical waveguide is optically connected to the second end face of the multi-mode optical waveguide. And
The single mode fiber according to claim 19, further comprising a single mode fiber optically coupled to a fourth end surface opposite to the second end surface coupled to the multimode optical waveguide of the single mode optical waveguide. Optical waveguide member.

Images