JP2006072316A - Optical multiplexer/demultiplexer, optical communication system, and method of manufacturing the optical multiplexer/demultiplexer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical multiplexer/demultiplexer capable of possessing superior characteristics as well as reducing loss. <P>SOLUTION: An optical multiplexer/demultiplexer 100 is provided with a first member 110, a second member 120 and an optical filter 130. The first member 110 is a planar waveguide and is formed with an optical waveguide 111 and another optical waveguide 112. The second member 120 is a planar waveguide and is formed with an optical waveguide 121 and another optical waveguide 122. The optical filter 130 is a dielectric multi-layered filter and is sandwiched between the end face 110a of the first member 110 and the end face 120a of the second member 120. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical transmission system that transmits signal light having a plurality of wavelengths, an optical multiplexer / demultiplexer used in such an optical transmission system, and a method of manufacturing the optical multiplexer / demultiplexer.

In an optical transmission system that transmits signal light of a plurality of wavelengths, an optical multiplexer / demultiplexer that combines or demultiplexes the signal lights of a plurality of wavelengths is used. Particularly, in an optical transmission system (FTTH: fiber to the home) between a terminal station and a subscriber's home, an optical multiplexer / demultiplexer is required to be small and inexpensive. For example, in an optical multiplexer / demultiplexer described in Non-Patent Document 1, two optical waveguides are formed so as to cross each other on a substrate, and a V-groove is formed so as to pass through the crossing portion. An optical filter is inserted and fixed with an adhesive. In this optical multiplexer / demultiplexer, light having a certain wavelength out of the light that has been guided through one optical waveguide and reached the V-groove passes through the optical filter and is further guided through the optical waveguide. The light having the wavelength is reflected by the optical filter and guided through the other optical waveguide.
M. Yanagisawa, et al., "Low-loss and compact TFF-embedded silica-waveguide WDM filter for video distribution services in FTTH systems", OFC2004, TuI4

  In the optical multiplexer / demultiplexer described in Non-Patent Document 1, the width of the V-groove formed on the substrate needs to be larger than the width of the optical filter, and the cross-sectional shape of the groove is V-shaped. Therefore, a gap is generated between the V-groove side end face of the optical waveguide and the optical filter. Usually, this gap is filled with an adhesive having a refractive index substantially equal to the refractive index of the optical waveguide. However, there is a possibility that the position and posture of the optical filter may be deviated from the optimum state, and since the structure of the adhesive is different from the structure of the optical waveguide, loss during optical multiplexing / demultiplexing tends to increase. Furthermore, since the optical properties (refractive index, etc.) of the adhesive have temperature dependence and the adhesive becomes thicker, the temperature dependence and reliability of the multiplexing / demultiplexing characteristics of the optical multiplexer / demultiplexer There is also a problem in terms.

  The present invention has been made to solve the above-described problems, and is an optical multiplexer / demultiplexer capable of reducing loss and having excellent characteristics, and optical transmission including such an optical multiplexer / demultiplexer. It is an object of the present invention to provide a system and a method capable of manufacturing such an optical multiplexer / demultiplexer.

  An optical multiplexer / demultiplexer according to the present invention includes a first member provided until the first optical waveguide and the second optical waveguide reach the end surface, a second member provided until the third optical waveguide reaches the end surface, An optical filter provided between the end face of the first member and the end face of the second member, and the optical filter transmits light from the end face of the first member after propagating through the first optical waveguide. The light transmitted through the second member is incident on the third optical waveguide from the end surface of the second member, and the light reflected by the optical filter is incident on the second optical waveguide from the end surface of the first member, or has propagated through the third optical waveguide. Of the light emitted from the end face of the second member, the light transmitted through the optical filter is incident on the first optical waveguide from the end face of the first member, propagates through the second optical waveguide, and is emitted from the end face of the first member. Of the light, the light reflected by the optical filter is reflected from the end face of the first member Characterized in that to be incident on the optical waveguide.

  This optical multiplexer / demultiplexer is configured such that an optical filter is sandwiched between a first member and a second member prepared separately. Therefore, in this optical multiplexer / demultiplexer, the distance between the end face of the first member and the optical filter and the distance between the end face of the second member and the optical filter can be reduced, respectively. The position and orientation can be optimized, and the loss during optical multiplexing / demultiplexing can be reduced. Furthermore, when the optical filter is fixed with an adhesive, the adhesive can be thinned, which is excellent in terms of temperature dependence and reliability of the multiplexing / demultiplexing characteristics of the optical multiplexer / demultiplexer.

  In the optical multiplexer / demultiplexer according to the present invention, the first member is preferably a planar waveguide, the second member is preferably a planar waveguide, or the second member is an optical fiber or an optical fiber. A fiber array is preferred. Here, the mode field diameter of the planar waveguide is preferably enlarged at the end face, and the mode field diameter of each optical fiber included in the optical fiber or the optical fiber array as the second member is at the end face. It is preferred that it is enlarged. The optical filter is preferably a dielectric multilayer filter.

  In the optical multiplexer / demultiplexer according to the present invention, it is preferable that the optical axis of the first optical waveguide at the end face of the first member and the optical axis of the third optical waveguide at the end face of the second member are not on the same straight line. is there. That is, each optical waveguide is formed so that the optical coupling between the first optical waveguide on the first member and the third optical waveguide on the second member is optimal. Since the first member and the second member constituting the optical multiplexer / demultiplexer are prepared separately, it is easy to optimize the optical axis of each optical waveguide in this way.

  In the optical multiplexer / demultiplexer according to the present invention, the optical filter is preferably formed by vapor deposition on the end face of the first member or the end face of the second member, or the end face of the first member or the second member. It is preferable that it is fixed to the end face of the substrate with an adhesive.

  In the optical multiplexer / demultiplexer according to the present invention, it is preferable that the first optical waveguide, the second optical waveguide, the third optical waveguide, and the optical filter are provided as a set, and a plurality of these sets are provided. At this time, it is preferable that the optical waveguide on the same side with respect to the optical filter is provided on the common member. Moreover, it is preferable that the optical filter is integrated with respect to a plurality of sets. In addition, it is preferable that the optical axes of the respective optical waveguides on the same side with respect to the optical filter are parallel to each other in the vicinity of the member end surface different from the member end surface facing the optical filter.

  In the optical multiplexer / demultiplexer according to the present invention, it is preferable that the first optical waveguide or the second optical waveguide is provided linearly in the first member. At this time, the planar shape of the first member is a rectangle having a first side facing the optical filter, a second side opposite to the first side, and a third side and a fourth side parallel to each other. It is preferable that the third side and the fourth side are parallel and the second side is perpendicular to the linearly provided optical waveguide of the first optical waveguide and the second optical waveguide. It is. Alternatively, the planar shape of the first member is a rectangle having a first side facing the optical filter, a second side opposite to the first side, and a third side and a fourth side parallel to each other. The third side and the fourth side are parallel to the linearly provided optical waveguide of the first optical waveguide and the second optical waveguide, and the second side is parallel to the first side. Preferably there is.

  In the optical multiplexer / demultiplexer according to the present invention, it is preferable that each of the end surface of the first member and the end surface of the second member is a polished surface. It is preferable that the end surface of the first member and the end surface of the second member are each perpendicular to the plane including the first waveguide, the second waveguide, and the third waveguide. Each of the end surface of the first member and the end surface of the second member is preferably perpendicular to a straight line that bisects the angle formed by the first waveguide and the second waveguide. Further, it is preferable that the end face of the first member and the end face of the second member are in close contact with the optical filter.

  An optical transmission system according to the present invention is an optical transmission system that transmits signal light having a plurality of wavelengths, and includes the above-described optical multiplexer / demultiplexer according to the present invention, and the signal light having a plurality of wavelengths is multiplexed by the optical multiplexer / demultiplexer. Alternatively, it is characterized by demultiplexing. When an optical multiplexer / demultiplexer in which the first optical waveguide or the second optical waveguide is linearly provided in the first member is used, the first wavelength of the plurality of wavelengths is provided in the linearly provided optical waveguide. It is preferable to guide the signal light having the second wavelength shorter than the first wavelength among the plurality of wavelengths to the other optical waveguide.

  An optical multiplexer / demultiplexer manufacturing method according to the present invention is a method for manufacturing the above-described optical multiplexer / demultiplexer according to the present invention, wherein the first member is provided until the first optical waveguide and the second optical waveguide reach the end faces. And a second member provided until the third optical waveguide reaches the end surface, an optical filter is formed on the end surface of the first member or the end surface of the second member by vapor deposition, and the end surface of the first member Both end faces of the two members are opposed to each other, and both are fixed. Alternatively, the optical filter is bonded and fixed to the end face of the first member or the end face of the second member, and the end face of the first member and the end face of the second member are opposed to each other, and both are fixed. Further, before forming the optical filter on the end surface of the first member or the end surface of the second member by vapor deposition, or before adhering and fixing the optical filter to the end surface of the first member or the end surface of the second member, the first member It is preferable to polish each of the end surface of the second member and the end surface of the second member. Further, when each of the end surface of the first member and the end surface of the second member is polished, each of the polishing surfaces is perpendicular to the plane including the first waveguide, the second waveguide, and the third waveguide. It is preferable to polish the end face. Further, it is preferable that after polishing the end surface of the first member and the end surface of the second member, an optical filter is sandwiched between the end surface of the first member and the end surface of the second member, and the periphery thereof is fixed with an adhesive. It is.

  The optical multiplexer / demultiplexer according to the present invention can reduce loss and have excellent characteristics.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  (First embodiment of optical multiplexer / demultiplexer)

  First, a first embodiment of an optical multiplexer / demultiplexer according to the present invention will be described. FIG. 1 is a perspective view of an optical multiplexer / demultiplexer 100 according to the first embodiment. FIG. 2 is a plan view of the optical multiplexer / demultiplexer 100 according to the first embodiment. The optical multiplexer / demultiplexer 100 shown in these drawings includes a first member 110, a second member 120, and an optical filter 130.

The first member 110 is a planar waveguide, and an optical waveguide 111 and an optical waveguide 112 are formed. The second member 120 is a planar waveguide, and an optical waveguide 121 and an optical waveguide 122 are formed. For example, each of the first member 110 and the second member 120 is formed by forming a clad made of quartz glass and a core made of quartz glass doped with GeO ₂ on a substrate made of quartz glass or silicon. . This core becomes an optical waveguide. The optical filter 130 is a dielectric multilayer filter, and is sandwiched between the end surface 110 a of the first member 110 and the end surface 120 a of the second member 120.

  Each of the optical waveguides 111 and 112 on the first member 110 is provided until reaching the end face 110a of the first member 110 on the optical filter 130 side, and guides light between the end face 110a and the opposite end face 110b. It is formed to be able to. Each of the optical waveguides 121 and 122 on the second member 120 is provided until reaching the end surface 120a of the second member 120 on the optical filter 130 side, and guides light between the end surface 120a and the opposite end surface 120b. It is formed to be able to. Each optical waveguide is preferably optically connected to an optical fiber or an optical fiber array on each of the end surface 110b of the first member 110 and the end surface 120b of the second member 120.

The optical filter 130 is preferably formed by vapor deposition on the end surface 110a of the first member 110 or the end surface 120a of the second member 120, or is formed separately and fixed with an adhesive. It is also suitable. The optical filter 130, while transmitting light of a certain wavelength lambda _T, to reflect light of other wavelengths lambda _R. For example, the transmission wavelength λ _T is 1.55 μm and the reflection wavelength λ _R is 1.31 μm and 1.49 μm, but is not limited thereto.

Then, for example, the optical filter 130 is introduced into the optical waveguide 111 of the first member 110 from the end surface 110b, and the wavelength λ _T transmitted through the optical filter 130 out of the light guided through the optical waveguide 111 and emitted from the end surface 110a. the light is guided to the optical waveguide 122 from the end surface 120a of the second member 120, thereby guiding the light of the wavelength lambda _R reflected by the optical filter 130 from the end surface 110a of the first member 110 to the optical waveguide 112. Namely, in this case, the optical demultiplexer 100 may demultiplex the light of the light and the wavelength lambda _R of the wavelength lambda _T.

Further, for example, the optical filter 130 transmits the light having the wavelength λ _T that has been guided through the optical waveguide 122 on the second member 120 and emitted from the end face 120 a, and transmits the light having the wavelength λ _T of the first member 110. The light is guided from the end face 110a to the optical waveguide 111. Further, the optical filter 130, the light of the wavelength lambda _R in which the optical waveguide 112 on the first member 110 come into guided emitted from the end surface 110a is reflected, the end face 110a of the light having the wavelength lambda _R first member 110 To the optical waveguide 111. That is, the optical multiplexer 100 may multiplex the light of the light and the wavelength lambda _R of the wavelength lambda _T.

  In this optical multiplexer / demultiplexer 100, since two optical waveguides are formed in each of the first member 110 and the second member 120, there are various usage modes. However, only one optical waveguide is formed in one member. May be.

  In this optical multiplexer / demultiplexer 100, as described in Non-Patent Document 1, a V-groove is formed on one substrate on which two optical waveguides are formed so as to cross each other, and an optical filter is provided in the V-groove. The optical filter 130 is sandwiched between the first member 110 and the second member 120 which are not inserted but are prepared separately. Therefore, in this optical multiplexer / demultiplexer 100, the distance between the end face 110a of the first member 110 and the optical filter 130 and the distance between the end face 120a of the second member 120 and the optical filter 130 are reduced. Therefore, the position and posture of the optical filter 130 can be optimized, and loss during optical multiplexing / demultiplexing can be reduced. Furthermore, when the optical filter 130 is fixed with an adhesive, the adhesive can be thinned, which is excellent in terms of temperature dependence and reliability of the multiplexing / demultiplexing characteristics of the optical multiplexer / demultiplexer 100.

  The distance between the end surface 110a of the first member 110 and the optical filter 130 is preferably 3 μm or less, and the distance between the end surface 210a of the second member 210 and the optical filter 130 is 3 μm or less. Is preferred. By doing in this way, the loss in the case of optical multiplexing / demultiplexing is reduced.

  The mode field diameter of each of the optical waveguides 111 and 112 on the end face 110a and the mode field diameter of each of the optical waveguides 121 and 122 on the end face 120a are preferably larger than the mode field diameter of a normal single mode optical fiber, for example, 20 μm or more. Is preferred. Thus, by increasing the mode field diameter of the optical waveguide at the end faces 110a and 120a facing the optical filter 130, it is possible to suppress the influence of diffraction in the optical filter 130, and to reduce the loss during multiplexing / demultiplexing. Can be suppressed. Actually, beam propagation analysis or the like is performed to consider the incident angle of light to the optical filter 130, the loss in the optical waveguide, the influence of higher-order modes, and the like. It is necessary to select an optimum value for the field diameter.

FIG. 3 is a partially enlarged view of the optical multiplexer / demultiplexer 100 according to the first embodiment. In FIG. 3, the light guiding direction and propagation direction are indicated by a one-dot chain line. As shown in this figure, the optical axis of the optical waveguide 111 on the end surface 110a of the first member 110 and the optical axis of the optical waveguide 122 on the end surface 120a of the second member 120 are parallel to each other, but are collinear. Not. Further, the optical axis of the optical waveguide 112 on the end surface 110a of the first member 110 and the optical axis of the optical waveguide 121 on the end surface 120a of the second member 120 are parallel to each other, but are not on the same straight line. More specifically, in consideration of the refractive indexes of the optical waveguides 111, 112, 121, 122 and the optical filter 130, the coupling of light having a transmission wavelength λ _T between the optical waveguide 111 and the optical waveguide 122, and Each optical waveguide is formed so as to optimize the coupling of light having a transmission wavelength λ _T between the optical waveguide 112 and the optical waveguide 121. Since the first member 110 and the second member 120 constituting the optical multiplexer / demultiplexer 100 are prepared separately, it is easy to optimize the optical axis of each optical waveguide in this way.

  Next, a method for manufacturing the optical multiplexer / demultiplexer 100 will be described. FIG. 4 is a diagram for explaining a method of manufacturing the optical multiplexer / demultiplexer 100 according to the first embodiment. First, the 1st member 110 and the 2nd member 120 are prepared (the figure (a)). It is preferable that the end surfaces 110a and 110b of the first member 110 are polished and the end surfaces 120a and 120b of the second member 120 are polished. Subsequently, the optical filter 130 is formed by vapor deposition on the end surface 110a of the first member 110 or the end surface 120a of the second member 120, or the separately created optical filter 130 is fixed with an adhesive (FIG. 5B). . And the end surface 110a of the 1st member 110 and the end surface 120a of the 2nd member 120 are made to oppose, and after aligning, both are fixed (the figure (c), (d)).

  As a method for preparing the first member 110 and the second member 120, a part of the member on which the optical waveguide is previously formed is cut so that the optical waveguide reaches the end surface, and further, the end surface of the cut member Or an optical waveguide that has been formed in advance but does not reach the end face of the member, and then the end face is polished until the optical waveguide reaches the end face.

  The polished surface is preferably perpendicular to the surface including the optical waveguide, and is preferably perpendicular to a straight line that bisects the angle formed by the first optical waveguide and the second optical waveguide. In the configuration shown in FIG. 3, it is preferable that the angle formed by the perpendicular of the end face 110 a and the optical axis of the optical waveguide 111 and the angle formed by the perpendicular of the end face 110 a and the optical axis of the optical waveguide 112 are equal to each other. Moreover, it is preferable that the angle formed by the perpendicular of the end surface 120a and the optical axis of the optical waveguide 121 is equal to the angle formed by the normal of the end surface 120a and the optical axis of the optical waveguide 122. This angle is usually a design incident angle to the optical filter 130. When only one optical waveguide is formed on one of the first member 110 and the second member 120, the normal of the end surface and the optical waveguide An angle formed by the optical axis is a design incident angle to the optical filter 130. Note that the roughness of the polished surface is desirably sufficiently smaller than the wavelength. For example, the center line average roughness Ra is desirably 10 nm or less. Thereby, the diffraction and scattering of the light at the end face are reduced, and the return loss can be increased.

  At the time of fixing, the end surfaces 110a and 120b and the surface of the optical filter 130 may be fixed by thinly applying an adhesive (FIG. 5C), or the end surfaces 110a and 120b and the optical filter 130 are brought into contact with each other. Later, the periphery may be hardened with an adhesive 140 ((d) in the figure). Further, the first member 110, the second member 120, and the optical filter 130 may be fixed using an outer box or a fixing jig, for example.

  In the fixing shown in FIG. 4D, the members 110 and 120 and the optical filter 130 can be completely adhered. In the fixing shown in FIG. 5C, even if the flatness of the members 110 and 120 is poor, the adhesive acts as a cushion, so that the optical filter 130 can be prevented from being damaged. Further, in the fixing shown in FIG. 5C, the adhesive can be applied with a thickness of several μm or less, and the end faces 110a and 120a and the optical filter 130 are substantially in close contact with each other, and are generated here. This loss can be negligible.

  As shown in FIG. 5C, when an adhesive is inserted between each of the first member 110 and the second member 120 and the optical filter 130, the refractive index of the adhesive and the refractive index of the optical waveguide are Preferably they are equal to each other. When the difference between the refractive index of the adhesive and the refractive index of the optical waveguide is large, the reflection at the interface deteriorates the characteristics, so that the first member 110 and the second member 120 are respectively shown in FIG. And the optical filter 130 are preferably in close contact with each other.

  The optical multiplexer / demultiplexer 100 according to the first embodiment described above can be variously modified. Below, other embodiment which is the modification is described.

  (Second embodiment of optical multiplexer / demultiplexer)

  Next, a second embodiment of the optical multiplexer / demultiplexer according to the present invention will be described. FIG. 5 is a diagram illustrating a plane and a side surface of the optical multiplexer / demultiplexer 200 according to the second embodiment. The figure (a) is a top view, The figure (b) is a side view. The optical multiplexer / demultiplexer 200 shown in this figure has a configuration in which four sets of optical multiplexer / demultiplexers 100 (FIGS. 1 and 2) are arranged in parallel. The optical multiplexer / demultiplexer 200 includes a first member 210, a second member 220, and an optical filter 230.

The first member 210 is a planar waveguide, and optical waveguides 211 _{1 to} 211 ₄ and optical waveguides 212 _{1 to} 212 ₄ are formed. The second member 220 is a planar waveguide, and optical waveguides 221 _{1 to} 221 ₄ and optical waveguides 222 _{1 to} 222 ₄ are formed. For example, each of the first member 210 and the second member 220 is formed by forming a clad made of quartz glass and a core made of quartz glass to which GeO ₂ is added on a substrate made of quartz glass or silicon. . This core becomes an optical waveguide. The optical filter 230 is a dielectric multilayer filter, and is sandwiched between the end surface 210 a of the first member 210 and the end surface 220 a of the second member 220.

The optical waveguides 211 _n and 212 _n on the first member 210 are provided until reaching the end surface 210a of the first member 210 on the optical filter 230 side, and guide light between the end surface 210a and the opposite end surface 210b. It is formed so that it can wave. The optical waveguides 221 _n and 222 _n on the second member 220 are provided until reaching the end surface 220a of the second member 220 on the optical filter 230 side, and guide light between the end surface 220a and the opposite end surface 220b. It is formed so that it can wave. Here, the subscript n is an arbitrary integer from 1 to 4.

Each optical waveguide is optically connected to the optical fiber array 250 on the end surface 220 b of the second member 220. That is, at the end face 220 b, the optical waveguide 221 _n of the second member 220 is optically coupled to the optical fiber core 251 _n of the optical fiber array 250, and the optical waveguide 222 _n of the second member 220 is the optical fiber of the optical fiber array 250. core 252 _n and are optically coupled.

The optical filter 230 is preferably formed by vapor deposition on the end surface 210a of the first member 210 or the end surface 220a of the second member 220. Alternatively, the optical filter 230 is separately formed and fixed with an adhesive. It is also suitable. The optical filter 230, while transmitting light of a certain wavelength lambda _T, to reflect light of other wavelengths lambda _R.

In this optical multiplexer / demultiplexer 200, each set of optical waveguides 211 _n , 212 _n , 221 _n , 222 _n and the optical filter 230 have the same configuration as that of the optical multiplexer / demultiplexer 100 (FIGS. 1 and 2). To work.

Eight optical waveguides 211 _{1 to} 211 ₄ , 212 _{1 to} 212 ₄ are formed on one first member 210, and eight optical waveguides 221 _{1 to} 221 ₄ , 222 are formed on one second member 220. _{1-222 4} is formed. From this, the manufacturing cost per channel in each of the first member 210 and the second member 220 can be reduced. Further, the optical filter 130 may be provided separately for each group, but it is preferable to provide the optical filter 130 integrated for the four groups. In the latter case, the optical multiplexer / demultiplexer 200 is provided. It can be manufactured at low cost.

The first member 210 onto the eight optical waveguides ₂₁₁ 1-211 _{4, 212} 1 to 212 ₄ is preferred that a constant spacing be parallel to one another in each of the optical axes end face 210 b, also a second member It is preferable that the optical axes of the eight optical waveguides 221 _{1 to} 221 ₄ and 222 _{1 to} 222 ₄ are parallel to each other on the end face 220b and have a constant interval. In this case, the first member 210, the second member 220 and the optical fiber array can be aligned and joined together.

  (Third embodiment of optical multiplexer / demultiplexer)

  Next, a third embodiment of the optical multiplexer / demultiplexer according to the present invention will be described. FIG. 6 is a plan view of an optical multiplexer / demultiplexer 300 according to the third embodiment. The optical multiplexer / demultiplexer 300 shown in this figure includes a first member 310, a second member 320, and an optical filter 330.

The first member 310 is a planar waveguide, and an optical waveguide 311 and an optical waveguide 312 are formed. The second member 320 is a planar waveguide, and an optical waveguide 321 and an optical waveguide 322 are formed. For example, each of the first member 310 and the second member 320 is formed by forming a clad made of quartz glass and a core made of quartz glass doped with GeO ₂ on a substrate made of quartz glass or silicon. . This core becomes an optical waveguide. The optical filter 330 is a dielectric multilayer filter, and is sandwiched between the end surface 310 a of the first member 310 and the end surface 320 a of the second member 320.

  Each of the optical waveguides 311 and 312 on the first member 310 is provided until reaching the end surface 310a of the first member 310 on the optical filter 330 side, and guides light between the end surface 310a and the opposite end surface 310b. It is formed to be able to. Each of the optical waveguides 321 and 322 on the second member 320 is provided until reaching the end face 320a of the second member 320 on the optical filter 330 side, and guides light between the end face 320a and the opposite end face 320b. It is formed to be able to. Each optical waveguide is preferably optically connected to an optical fiber or an optical fiber array on each of the end surface 310b of the first member 310 and the end surface 320b of the second member 320.

The optical filter 330 is preferably formed by vapor deposition on the end surface 310a of the first member 310 or the end surface 320a of the second member 320, or is formed separately and fixed with an adhesive. It is also suitable. The optical filter 330, while transmitting light of a certain wavelength lambda _T, to reflect light of other wavelengths lambda _R. For example, the transmission wavelength λ _T is 1.55 μm and the reflection wavelength λ _R is 1.31 μm and 1.49 μm, but is not limited thereto.

  The optical multiplexer / demultiplexer 300 has the same configuration as the optical multiplexer / demultiplexer 100 (FIGS. 1 and 2) and operates in the same manner.

  In general, when the optical waveguide is curved, the longer the wavelength of the guided light, the greater the propagation loss of the guided light. However, in this optical multiplexer / demultiplexer 300, the optical waveguide 311 on the first member 310 is linearly formed between the end surface 310a and the end surface 310b. Similarly, the optical waveguide 322 on the second member 320 is linearly formed between the end surface 320a and the end surface 320b. Therefore, when this optical multiplexer / demultiplexer 300 is used, long-wavelength light is guided in the linear optical waveguides 311 and 322, while short-wavelength light is guided in the optical waveguides 312 and 321 having curved portions. It is preferable to guide the light, and by doing so, it is possible to suppress loss during optical multiplexing / demultiplexing.

  The planar shape of the first member 310 includes a first side (side on the end surface 310a side) facing the optical filter 330, a second side (side on the end surface 310b side) opposite to the first side, A rectangular shape having a third side and a fourth side parallel to each other, and each of the third side and the fourth side is parallel to the optical waveguide 311 provided in a straight line, and the second side is vertical. It is. Further, the first side is not parallel to the second side. In this case, since the linear optical waveguide 311 is vertical on the end face 310b, it is convenient for coupling the optical fiber and the optical waveguide 311, for example. The same applies to the planar shape of the second member 320.

  (Fourth embodiment of optical multiplexer / demultiplexer)

  Next, a fourth embodiment of the optical multiplexer / demultiplexer according to the present invention will be described. FIG. 7 is a plan view of an optical multiplexer / demultiplexer 400 according to the fourth embodiment. The optical multiplexer / demultiplexer 400 shown in this figure has a configuration in which four sets of optical multiplexer / demultiplexers are arranged in parallel. The optical multiplexer / demultiplexer 400 includes a first member 410, a second member 420, and an optical filter 430.

The first member 410 is a planar waveguide, and optical waveguides 411 _{1 to} 411 ₄ and optical waveguides 412 _{1 to} 412 ₄ are formed. The second member 420 is a planar waveguide, and optical waveguides 421 _{1 to} 421 ₄ and optical waveguides 422 _{1 to} 422 ₄ are formed. Each of the first member 410 and the second member 420 is formed by, for example, forming a clad made of quartz glass and a core made of quartz glass doped with GeO ₂ on a substrate made of quartz glass or silicon. . This core becomes an optical waveguide. The optical filter 430 is a dielectric multilayer filter, and is sandwiched between the end surface 410 a of the first member 410 and the end surface 420 a of the second member 420.

The optical waveguides 411 _n and 412 _n on the first member 410 are provided until reaching the end surface 410a of the first member 410 on the optical filter 430 side, and guide light between the end surface 410a and the opposite end surface 410b. It is formed so that it can wave. The optical waveguides 421 _n and 422 _n on the second member 420 are provided until reaching the end surface 420a of the second member 420 on the optical filter 430 side, and guide light between the end surface 420a and the opposite end surface 420b. It is formed so that it can wave. Here, the subscript n is an arbitrary integer from 1 to 4.

  In the end face 410b of the first member 410, each optical waveguide is preferably optically connected to the optical fiber array. Moreover, it is preferable that each optical waveguide is optically connected to the optical fiber array on the end surface 420b of the second member 420.

The optical filter 430 is preferably formed by vapor deposition on the end surface 410a of the first member 410 or the end surface 420a of the second member 420. Alternatively, the optical filter 430 is separately formed and fixed with an adhesive. It is also suitable. The optical filter 430, while transmitting light of a certain wavelength lambda _T, to reflect light of other wavelengths lambda _R.

In this optical multiplexer / demultiplexer 400, each set of optical waveguides 411 _n , 412 _n , 421 _n , 422 _n and the optical filter 430 have substantially the same configuration as the optical multiplexer / demultiplexer 300 and operate in substantially the same manner.

The planar shape of the first member 410 includes a first side facing the optical filter 430 (side on the end surface 410a side), a second side opposite to the first side (side on the end surface 410b side), A rectangular shape having a third side and a fourth side parallel to each other, each of the third side and the fourth side being parallel to the linearly provided optical waveguide 411, and to the first side The second side is parallel. In this case, the waveguide lengths of the optical waveguides 411 _{1 to} 411 ₄ can be set to a constant value, and the waveguide lengths of the optical waveguides 412 _{1 to} 412 ₄ can also be set to a constant value. The same applies to the planar shape of the second member 420. Therefore, the loss at the time of multiplexing / demultiplexing in each of the four sets of optical multiplexer / demultiplexers can be made constant.

  (Fifth embodiment of optical multiplexer / demultiplexer)

  Next, a fifth embodiment of the optical multiplexer / demultiplexer according to the present invention will be described. FIG. 8 is a plan view of an optical multiplexer / demultiplexer 500 according to the fifth embodiment. The optical multiplexer / demultiplexer 500 shown in this figure has a configuration in which four sets of optical multiplexer / demultiplexers are arranged in parallel. The optical multiplexer / demultiplexer 500 includes a first member 510, an optical fiber array 520 as a second member, and an optical filter 530.

The first member 510 is a planar waveguide, and optical waveguides 511 _{1 to} 511 ₄ and optical waveguides 512 _{1 to} 512 ₄ are formed. For example, the first member 510 is formed by forming a clad made of quartz glass and a core made of quartz glass doped with GeO ₂ on a substrate made of quartz glass or silicon. This core becomes an optical waveguide. The optical fiber array 520 as the second member is one in which optical fiber cores 522 _{1 to} 522 ₄ are arranged in parallel. The optical filter 530 is a dielectric multilayer filter, and is sandwiched between the end surface 510a of the first member 510 and the end surface 520a of the optical fiber array 520.

The optical waveguides 511 _n and 512 _n on the first member 510 are provided until reaching the end surface 510a of the first member 510 on the optical filter 530 side, and guide light between the end surface 510a and the opposite end surface 510b. It is formed so that it can wave. The optical fiber core 522 _n of the optical fiber array 520 guides the light that has been guided through the optical waveguide 511 _n on the first member 510 and transmitted through the optical filter 530 to the end face. Here, the subscript n is an arbitrary integer from 1 to 4.

  Each optical waveguide is preferably optically connected to the optical fiber array at the end face 510b of the first member 510.

The optical filter 530 is preferably formed by vapor deposition on the end surface 510a of the first member 510. Alternatively, the optical filter 530 is preferably formed separately and fixed with an adhesive. The optical filter 530, while transmitting light of a certain wavelength lambda _T, to reflect light of other wavelengths lambda _R.

The planar shape of the first member 510 in the optical multiplexer / demultiplexer 500 is the same as the planar shape of the first member 410 in the optical multiplexer / demultiplexer 400. In this optical multiplexer / demultiplexer 500, each set of optical waveguides 511 _n , 512 _n , 522 _n and optical filter 530 operate in substantially the same manner as the optical multiplexer / demultiplexer 400.

Further, in the vicinity of the end face 520a, and the addition of each optical fiber core 522 _n included in the optical fiber array 520 is diffused, it is preferable that the mode field diameter of the optical fibers is enlarged. By doing in this way, the loss in the case of optical multiplexing / demultiplexing is suppressed.

  (First Embodiment of Optical Transmission System)

  Next, a first embodiment of the optical transmission system according to the present invention will be described. FIG. 9 is a configuration diagram of the optical transmission system 1 according to the first embodiment. The optical transmission system 1 shown in this figure is an FTTH (fiber to the home) system that transmits and receives signal light bidirectionally between a station 10 and subscriber homes 21 to 23.

In the station 10, data transmission devices 11 _{1 to} 11 ₃ , video signal transmitters 12 _{1 to} 12 ₃ and an optical multiplexer / demultiplexer 13 are provided. Each of the data transmission devices 11 _{1 to} 11 ₃ is connected to the Internet and transmits / receives digital data to / from the subscriber homes 21 to 23. Each of the video signal transmitters 12 _{1 to} 12 ₃ transmits a video signal (analog data) to the subscriber homes 21 to 23. The wavelength of the signal light transmitted from the subscriber's home 21 to 23 to the data transmission device ₁₁ 1 to 11 ₃ is 1.31 .mu.m, the signal sent from the data transmission device ₁₁ 1 to 11 ₃ to the subscriber's home 21 to 23 The wavelength of the light is 1.49 μm, and the wavelength of the signal light transmitted from the video signal transmitters 12 _{1 to} 12 ₃ to the subscriber homes 21 to 23 is 1.55 μm.

The optical multiplexer / demultiplexer 13 provided in the station 10 multiplexes / demultiplexes signal light of three wavelengths transmitted / received by the data transmission apparatuses 11 _{1 to} 11 ₃ and the video signal transmitters 12 _{1 to} 12 ₃ . As the optical multiplexer / demultiplexer 13, the optical multiplexer / demultiplexer of each embodiment described above is used, and among them, the optical multiplexer / demultiplexers 200, 400, 500 in which a plurality of sets of optical multiplexer / demultiplexers are arranged in parallel are particularly preferable. Can be used.

  An optical receiver 41 is provided in the subscriber's home 21, and an optical multiplexer / demultiplexer 51 is provided in the optical receiver 41. Other subscriber homes 22 and 23 are also provided with optical receivers. Further, a star coupler 30 is provided in the vicinity of the subscriber homes 21 to 23. This star coupler 30 branches the signal light (wavelength 1.49 μm, 1.55 μm) transmitted from the station 10, sends each branched signal light to the subscriber homes 21 to 23, and joins it. Signal light (wavelength: 1.33 μm) transmitted from the side of the user's homes 21 to 23 is sent to the station 10. The optical multiplexer / demultiplexer 51 multiplexes / demultiplexes signal light of three wavelengths, and the optical multiplexer / demultiplexer of each embodiment described above is used.

In this optical transmission system 1, the signal light (wavelength 1.49 μm, 1.55 μm) output from the data transmission device 11 _n and the video signal transmitter 12 _n in the station 10 is combined by the optical multiplexer / demultiplexer 13. Waved and sent out. The signal light transmitted from the station 10 is branched by the star coupler 30, the branched signal light is demultiplexed by the optical multiplexer / demultiplexer 51 in the optical receiver 41, and one of the demultiplexed signal lights (wavelength) 1.49 μm) is transmitted to the personal computer in the subscriber's house 21, and the other signal light (wavelength 1.55 μm) is transmitted to the television receiver in the subscriber's house 21. The signal light (wavelength 1.33 μm) transmitted from the personal computer in the subscriber's home 21 passes through the optical multiplexer / demultiplexer 51 in the optical receiver 41, the star coupler 30, and the optical multiplexer / demultiplexer 13 in the station 10. Received by the transmission device 11 _n .

  In the present embodiment, since the optical multiplexer / demultiplexer of each of the embodiments described above is used as the optical multiplexer / demultiplexers 13 and 52, loss during the multiplexing / demultiplexing is small, and high-quality signal light transmission is possible. is there.

  (Second Embodiment of Optical Transmission System)

  Next, a second embodiment of the optical transmission system according to the present invention will be described. FIG. 10 is a configuration diagram of the optical transmission system 2 according to the second embodiment. The optical transmission system 2 shown in this figure is an FTTH system that transmits and receives signal light bidirectionally between the station 10 and the subscriber homes 21 and 22 in the apartment 20. Compared with the optical transmission system 1 according to the first embodiment (FIG. 9), the optical transmission system 2 according to the second embodiment is such that the subscriber homes 21 and 22 are apartment houses in the apartment 20, and The difference is that one optical receiver 40 is provided for the apartment 20.

  An optical multiplexer / demultiplexer 50 is provided in the optical receiver 40 provided in the apartment 20. This optical multiplexer / demultiplexer 50 multiplexes / demultiplexes signal light of three wavelengths, and the optical multiplexer / demultiplexer of each embodiment described above is used. Among them, a plurality of sets of optical multiplexer / demultiplexers are arranged in parallel. The optical multiplexer / demultiplexers 200, 400, and 500 can be particularly preferably used. The star coupler 30 may be provided in the optical receiver 40.

In the optical transmission system 2, signal light (wavelengths 1.49 μm and 1.55 μm) output from the data transmission device 11 _n and the video signal transmitter 12 _n in the station 10 is combined by the optical multiplexer / demultiplexer 13. Waved and sent out. The signal light transmitted from the station 10 is branched by the star coupler 30, and the branched signal light is demultiplexed by the optical multiplexer / demultiplexer 50 in the optical receiver 40, and one of the demultiplexed signal lights (wavelength). 1.49 μm) is transmitted to a personal computer in each subscriber's house, and the other signal light (wavelength 1.55 μm) is transmitted to a television receiver in each subscriber's house. The signal light (wavelength 1.33 μm) transmitted from the personal computer in each subscriber's home passes through the optical multiplexer / demultiplexer 50 in the optical receiver 40, the star coupler 30, and the optical multiplexer / demultiplexer 13 in the station 10 to transmit data. Received by device _11n .

  (Third embodiment of optical transmission system)

  Next, a third embodiment of the optical transmission system according to the present invention will be described. FIG. 11 is a configuration diagram of the optical transmission system 3 according to the third embodiment. The optical transmission system 3 shown in this figure is an FTTH system that transmits and receives signal light bidirectionally between the station 10 and the subscriber homes 21 and 22 in the apartment 20. Compared with the optical transmission system 2 (FIG. 10) according to the second embodiment, the optical transmission system 3 according to the third embodiment includes the star couplers 31 and 32 and the optical multiplexer / demultiplexer 50 in the optical receiver 40. Is different.

In this optical transmission system 3, signal light (wavelength 1.49 μm, 1.55 μm) output from each of the data transmission device 11 _n and the video signal transmitter 12 _n in the station 10 is combined by the optical multiplexer / demultiplexer 13. Waved and sent out. The signal light transmitted from the station 10 is demultiplexed by the optical multiplexer / demultiplexer 50 in the optical receiver 40. One signal light (wavelength 1.49 μm) demultiplexed by the optical multiplexer / demultiplexer 50 is branched by the star coupler 31 and transmitted to a personal computer in each subscriber's home, and the other signal light (wavelength 1.55 μm) is star-coupled. The data is branched by the coupler 32 and transmitted to the television receiver in each subscriber's house. The signal light (wavelength 1.33 μm) transmitted from the personal computer in each subscriber's house passes through the star coupler 31 and the optical multiplexer / demultiplexer 50 in the optical receiver 40 and the optical multiplexer / demultiplexer 13 in the station 10 for data transmission. Received by device _11n .

1 is a perspective view of an optical multiplexer / demultiplexer 100 according to a first embodiment. 1 is a plan view of an optical multiplexer / demultiplexer 100 according to a first embodiment. 1 is a partially enlarged view of an optical multiplexer / demultiplexer 100 according to a first embodiment. It is a figure explaining the method to manufacture the optical multiplexer / demultiplexer 100 which concerns on 1st Embodiment. It is a figure which shows the plane and side surface of the optical multiplexer / demultiplexer 200 which concern on 2nd Embodiment. It is a top view of the optical multiplexer / demultiplexer 300 which concerns on 3rd Embodiment. It is a top view of the optical multiplexer / demultiplexer 400 which concerns on 4th Embodiment. It is a top view of the optical multiplexer / demultiplexer 500 which concerns on 5th Embodiment. 1 is a configuration diagram of an optical transmission system 1 according to a first embodiment. FIG. It is a block diagram of the optical transmission system 2 which concerns on 2nd Embodiment. It is a block diagram of the optical transmission system 3 which concerns on 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1-3 ... Optical transmission system, 10 ... Station, 11 ... Data transmission apparatus, 12 ... Video signal transmitter, 13 ... Optical multiplexer / demultiplexer, 20 ... Condominium, 21-23 ... Subscriber's house, 30-32 ... Star coupler , 40, 41 ... optical receiver, 50, 51 ... optical multiplexer / demultiplexer, 100 ... optical multiplexer / demultiplexer, 110 ... first member, 111, 112 ... optical waveguide, 120 ... second member, 121, 122 ... optical waveguide , 130 ... optical filter, 140 ... adhesive, 200 ... optical multiplexer / demultiplexer, 210 ... first member, 211, 212 ... optical waveguide, 220 ... second member, 221, 222 ... optical waveguide, 230 ... optical filter, 250 ... Optical fiber array, 251, 252 ... Optical fiber core, 300 ... Optical multiplexer / demultiplexer, 310 ... First member, 311, 312 ... Optical waveguide, 320 ... Second member, 321, 322 ... Optical waveguide, 330 ... Optical filter , DESCRIPTION OF SYMBOLS 00 ... Optical multiplexer / demultiplexer, 410 ... 1st member, 411, 412 ... Optical waveguide, 420 ... 2nd member, 421, 422 ... Optical waveguide, 430 ... Optical filter, 500 ... Optical multiplexer / demultiplexer, 510 ... 1st member 511, 512 ... Optical waveguide, 520 ... Optical fiber array, 522 ... Optical fiber core, 530 ... Optical filter.

Claims (29)

A first member provided until the first optical waveguide and the second optical waveguide reach the end surface, a second member provided until the third optical waveguide reaches the end surface, the end surface of the first member, and the second member An optical filter provided between the end face of the member,
The optical filter is
Of the light propagating through the first optical waveguide and emitted from the end face of the first member, the light transmitted through the optical filter is incident on the third optical waveguide from the end face of the second member, and The light reflected by the optical filter is incident on the second optical waveguide from the end face of the first member;
Or, the light that has propagated through the third optical waveguide and has been transmitted through the optical filter out of the light emitted from the end surface of the second member is incident on the first optical waveguide from the end surface of the first member, The light that has propagated through the second optical waveguide and is reflected by the optical filter out of the light emitted from the end surface of the first member is incident on the first optical waveguide from the end surface of the first member.
An optical multiplexer / demultiplexer characterized by that.   The optical multiplexer / demultiplexer according to claim 1, wherein the first member is a planar waveguide.   The optical multiplexer / demultiplexer according to claim 1, wherein the second member is a planar waveguide.   2. The optical multiplexer / demultiplexer according to claim 1, wherein the second member is an optical fiber or an optical fiber array.   4. The optical multiplexer / demultiplexer according to claim 2, wherein a mode field diameter of the planar waveguide is enlarged at the end face.   The optical multiplexer / demultiplexer according to claim 4, wherein a mode field diameter of each optical fiber included in the optical fiber or the optical fiber array is enlarged at the end face.   2. The optical multiplexer / demultiplexer according to claim 1, wherein the optical filter is a dielectric multilayer filter.   The optical axis of the first optical waveguide at the end face of the first member and the optical axis of the third optical waveguide at the end face of the second member are not collinear. The optical multiplexer / demultiplexer according to 1.   The optical multiplexer / demultiplexer according to claim 1, wherein the optical filter is formed by vapor deposition on the end surface of the first member or the end surface of the second member.   The optical multiplexer / demultiplexer according to claim 1, wherein the optical filter is fixed to the end face of the first member or the end face of the second member with an adhesive.   2. The optical multiplexer / demultiplexer according to claim 1, wherein a plurality of sets of the first optical waveguide, the second optical waveguide, the third optical waveguide, and the optical filter are provided.   12. The optical multiplexer / demultiplexer according to claim 11, wherein an optical waveguide on the same side with respect to the optical filter is provided on a common member.   The optical multiplexer / demultiplexer according to claim 11, wherein the optical filter is integrated with the plurality of sets.   12. The optical joint according to claim 11, wherein the optical axes of the respective optical waveguides on the same side with respect to the optical filter are parallel to each other in the vicinity of a member end surface different from the member end surface facing the optical filter. Waver.   2. The optical multiplexer / demultiplexer according to claim 1, wherein the first optical waveguide or the second optical waveguide is linearly provided in the first member. The planar shape of the first member is a rectangle having a first side facing the optical filter, a second side opposite to the first side, and a third side and a fourth side parallel to each other. There,
The third side and the fourth side are each parallel to the linearly provided optical waveguide of the first optical waveguide and the second optical waveguide, and the second side is vertical.
16. The optical multiplexer / demultiplexer according to claim 15, wherein The planar shape of the first member is a rectangle having a first side facing the optical filter, a second side opposite to the first side, and a third side and a fourth side parallel to each other. There,
Each of the third side and the fourth side is parallel to the linearly provided optical waveguide of the first optical waveguide and the second optical waveguide, and the second side with respect to the first side Are parallel,
16. The optical multiplexer / demultiplexer according to claim 15, wherein   2. The optical multiplexer / demultiplexer according to claim 1, wherein each of the end surface of the first member and the end surface of the second member is a polished surface.   Each of the end surface of the first member and the end surface of the second member is perpendicular to a plane including the first waveguide, the second waveguide, and the third waveguide. The optical multiplexer / demultiplexer according to claim 18.   Each of the end surface of the first member and the end surface of the second member is perpendicular to a straight line that bisects an angle formed by the first waveguide and the second waveguide. The optical multiplexer / demultiplexer according to claim 19.   The optical multiplexer / demultiplexer according to claim 1, wherein the end face of the first member and the end face of the second member are in close contact with the optical filter.   An optical transmission system for transmitting signal light of a plurality of wavelengths, comprising the optical multiplexer / demultiplexer according to any one of claims 1 to 21, wherein the signal light of the plurality of wavelengths is multiplexed by the optical multiplexer / demultiplexer. An optical transmission system characterized by demultiplexing.   An optical transmission system for transmitting signal light having a plurality of wavelengths, comprising the optical multiplexer / demultiplexer according to any one of claims 15 to 17, wherein the first optical waveguide and the second optical waveguide are linear. Of the plurality of wavelengths is guided to one optical waveguide provided in the optical waveguide, and a signal light having a second wavelength shorter than the first wavelength of the plurality of wavelengths is guided to the other optical waveguide. An optical transmission system characterized by causing waves. A method of manufacturing the optical multiplexer / demultiplexer according to claim 1,
Preparing a first member provided until the first optical waveguide and the second optical waveguide reach the end surface, and a second member provided until the third optical waveguide reaches the end surface;
Forming an optical filter on the end surface of the first member or the end surface of the second member by vapor deposition;
Fixing the both by facing the end surface of the first member and the end surface of the second member;
An optical multiplexer / demultiplexer manufacturing method. A method of manufacturing the optical multiplexer / demultiplexer according to claim 1,
Preparing a first member provided until the first optical waveguide and the second optical waveguide reach the end surface, and a second member provided until the third optical waveguide reaches the end surface;
An optical filter is bonded and fixed to the end face of the first member or the end face of the second member;
Fixing the both by facing the end surface of the first member and the end surface of the second member;
An optical multiplexer / demultiplexer manufacturing method.   Before forming the optical filter on the end face of the first member or the end face of the second member by vapor deposition, the end face of the first member and the end face of the second member are polished. An optical multiplexer / demultiplexer manufacturing method according to claim 24.   Each of the end surface of the first member and the end surface of the second member is polished before the optical filter is bonded and fixed to the end surface of the first member or the end surface of the second member. An optical multiplexer / demultiplexer manufacturing method according to claim 25.   When each of the end surface of the first member and the end surface of the second member is polished, the polishing surface is perpendicular to a plane including the first waveguide, the second waveguide, and the third waveguide. 28. The method of manufacturing an optical multiplexer / demultiplexer according to claim 27, wherein each end face is polished so that   After polishing the end surface of the first member and the end surface of the second member, the optical filter is sandwiched between the end surface of the first member and the end surface of the second member, and the periphery thereof is bonded. 29. The method of manufacturing an optical multiplexer / demultiplexer according to claim 28, wherein the optical multiplexer / demultiplexer is fixed with an agent.

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