JP2014182224A - Optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To feed light to a PD provided for each wavelength while maintaining sufficient light intensity for high-speed communication.SOLUTION: An optical element includes first to Nth photosensitive elements 4-4for receiving first to N-th light components λ-λof different wavelengths contained in an incoming first optical signal IN, a grating 3G for outputting a second optical signal OUT along a same light path as that of the first optical signal, and a wavelength filter block 6 with a reflective member 11 provided above the grating, all provided on a common substrate 1. The wavelength filter block has a wavelength filter film 7 having zeroth to N-th regions for transmitting the second optical signal and the first to N-th light components, respectively, where the second optical signal transmits through the zeroth region, and the first to N-th light components reflected by the zeroth region propagates through while being reflected between the reflective member and the first to N-th regions, during which the i-th light component transmits through the i-th region (i is an integer from 1 to N) and is received by the i-th photosensitive element 4.

Description

  The present invention relates to an optical element used for multiplexing / demultiplexing component light having different wavelengths in wavelength division multiplexing (WDM) communication.

  An optical subscriber communication system (hereinafter referred to as a subscriber) that performs optical transmission (uplink communication) from the subscriber side to the station side and optical transmission (downlink communication) from the station side to the subscriber side using a single optical fiber. In some cases, light of different wavelengths may be used for upstream communication and downstream communication. The most popular subscriber system is GE-PON (Gigabit Ethernet (registered trademark) -Passive Optical Network) capable of bidirectional communication at a speed of 1 Gbps or more. In recent years, as a next-generation technology that replaces GE-PON, WDM-PON with increased multiplicity of wavelengths used for communication has been studied. In WDM-PON, in principle, a communication speed exceeding 10 Gbps can be obtained in both directions.

  In WDM-PON, a station-side terminator (OLT: Optical Line Terminal) and a subscriber-side terminator (ONU: Optical Network Unit) are provided at the ends of the optical fiber used for communication at the station side and the subscriber side, respectively. It is done. These terminators include a light emitting element, a light receiving element, and a wavelength multiplexing / demultiplexing element that multiplexes / demultiplexes light of a plurality of wavelengths. Hereinafter, a case where a laser diode (hereinafter also referred to as LD) is used as an example of a light emitting element and a photo diode (hereinafter also referred to as PD) is used as an example of a light receiving element will be described.

Generally, an optical chip is configured by integrating optical elements such as LD, PD, and wavelength multiplexing / demultiplexing elements on a common substrate having an optical waveguide (for example, Non-Patent Document 1 and Patent Documents 1 to 18). reference). In recent years, in one optical chip, between optical elements, Si using a core made of silicon (Si) and a clad made of silicon oxide (SiO ₂ ) having a large refractive index difference from Si are used. In many cases, they are connected by optical waveguides. Since the refractive index of the core of the Si optical waveguide is much larger than the refractive index of the clad, light confinement is strong, and a curved optical waveguide that bends light with a small curvature radius of about 1 μm can be formed. In addition, since it can be manufactured using the processing technology of the Si electronic device, an extremely fine submicron cross-sectional structure can be realized. For these reasons, the optical chip can be reduced in size by using the Si optical waveguide.

Optics Express vol. 18, p. 23891,8 November 2010

JP 2003-029093 A JP 2010-286683 A Japanese Patent Laid-Open No. 06-075137 Japanese Patent Laid-Open No. 08-190026 JP 11-218651 A Japanese Patent Laid-Open No. 11-248977 JP 2003-322739 A JP 2004-157192 A JP 2008-209904 A JP 2010-204387 A JP 2005-309370 A JP 2007-243121 A JP 2010-014831 A International Publication No. 2009/081539 JP 2002-169054 A Japanese Patent Laid-Open No. 2003-241006 JP 2004-085860 A JP 2004-058661 A

  By the way, a light receiving element used in WDM-PON is required to have a capability of receiving a wavelength-multiplexed high-speed signal. For this purpose, an optical signal having a good extinction ratio needs to be input to the PD from the station side. Here, the “extinction ratio” is an intensity ratio between “1” code and “0” code constituting an optical signal.

  In general, since the light intensity of the “0” code is determined by the noise level, the light intensity of the “1” code, that is, the intensity of the optical signal may be increased in order to improve the extinction ratio. In the optical chip using the Si optical waveguide, the received optical signal is sent to the PD through the Si optical waveguide. However, the optical coupling efficiency is low (−3 to −4 dB) due to the large difference in size between the beam diameter of several hundred nm of the optical signal output from the Si optical waveguide and the light receiving unit of about 10 μmφ of PD. The strength required for receiving high-speed signals could not be obtained.

  The present invention has been made with such a technical background. Accordingly, an object of the present invention is to obtain an optical element that inputs a wavelength-multiplexed optical signal to a PD provided for each wavelength while maintaining sufficient light intensity for high-speed communication without using a Si optical waveguide. It is in.

  As a result of intensive studies, the inventor has come up with the idea that the above-described object can be achieved by using a wavelength filter block whose propagation path can be designed geometrically and a wavelength filter film whose transmission wavelength is changed depending on the location.

  Therefore, the optical element of the present invention includes first to Nth light receiving elements, a grating, a wavelength filter block, and a reflecting member provided on a common substrate.

  Here, the first to Nth light receiving elements respectively receive the first to Nth component lights (N is an integer of 1 or more) having different wavelengths included in the incident first optical signal. The grating changes the path of the second optical signal having a wavelength different from that of the first to N-th component lights to the same path as the first optical signal and emits the same. The wavelength filter block is provided on the upper side of the grating.

  The wavelength filter block includes a parallel plate main body and a wavelength filter film provided on one surface of the main body, and the wavelength filter film transmits the second optical signal and the first to N-th component lights, respectively. 0th to Nth regions are provided. Here, the 0th region transmits the second optical signal and reflects the first to Nth component light. The reflected first to N-th component lights propagate in the i-th region (i is an integer from 1 to N) in the process of propagating while reflecting between the reflecting member and the first to N-th regions. Is transmitted and received by the i-th light receiving element.

  The optical element of the present invention can propagate the wavelength-multiplexed downstream signal to each PD while wavelength-separating without depending on the Si optical waveguide. As a result, it is possible to receive a signal having sufficient strength for high-speed communication required by WDM-PON.

1 is a plan view showing a schematic structure of an optical element according to Embodiment 1. FIG. FIG. 2 is a cut end view taken along line II of FIG. 1. (A) And (B) is a top view which shows the schematic structure of the optical element of Embodiment 2 and 3. FIG. 6 is an end view showing a schematic structure of an optical element according to Embodiment 4. FIG. 10 is an end view showing a schematic structure of an optical element according to Embodiment 5. FIG. FIG. 10 is an end view showing a schematic structure of an optical element according to a sixth embodiment. FIG. 10 is an end view showing a schematic structure of an optical element according to a seventh embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. In each figure, the shape, size, and arrangement relationship of the components are schematically shown to such an extent that the present invention can be understood. Each of the following embodiments is a preferred example of the present invention, and the material and numerical conditions of each component are merely examples of preferred cases. Accordingly, the present invention is not limited to the following embodiments. Moreover, in each figure, the same code | symbol is attached | subjected to a common component and the description may be abbreviate | omitted.

[Embodiment 1]
With reference to FIGS. 1 and 2, the optical element of Embodiment 1 (hereinafter, also referred to as a first optical element) will be described. FIG. 1 is a plan view showing a schematic structure of the first optical element. 2 is a cut end view taken along the line II of FIG. In FIG. 1, the grating, PD, and the like cannot be directly seen because they are covered with the wavelength filter block, but are shown by solid lines for emphasis.

  First, referring to FIG. 1, directions and dimensions used in the following description are defined. Considering a right-handed orthogonal coordinate system as shown in FIG. 1, the X direction is the direction from the left to the right of the paper on which the figure is drawn, and is also referred to as the length direction. In addition, the Z direction is a direction from the back surface to the front surface of the paper on which the drawing is drawn, and is also referred to as a height direction or a thickness direction. The Y direction is the direction from the bottom to the top of the paper on which the drawing is drawn, and is also referred to as the width direction. The geometric length measured along the X direction is also referred to as “length”, the geometric length measured along the Y direction is also referred to as “width”, and the geometric length measured along the Z direction. The target length is also referred to as “height” or “thickness”. Further, the direction along the direction in which the propagation light IN and OUT propagate is defined as the light propagation direction. A section perpendicular to the light propagation direction of a predetermined structure is referred to as a “cross section”. In this example, the main surface of the substrate extends parallel to the XY plane (paper surface).

(Construction)
First, the structure of the first optical element 10 will be described with reference to FIGS. 1 and 2. Here, a case where the first optical element 10 is used in an ONU of a subscriber system is illustrated. As shown in FIG. 1, the first optical element 10 includes first to Nth light receiving elements 4 ₁ to 4 _N (N is an integer of 1 or more), a grating 3G, and a wavelength filter block 6 (hereinafter simply referred to as a block 6). And a total reflection film 11 as a reflection member. These components are all integrated on a common substrate 1. The first to Nth light receiving elements 4 ₁ to 4 _N are also simply referred to as “light receiving element 4”. Furthermore, the 1st optical element 10 is equipped with the light emitting element 5 integrated on the main surface 1a side of the board | substrate 1 as an arbitrary structure.

A first optical signal IN transmitted from the station side is input to the first optical element 10 through the optical fiber 12 as a downstream signal including first to N-th component lights having different wavelengths (λ _{1 to} λ _N ). Is done. Also, the second optical signal OUT, which is an upstream signal emitted from the light emitting element 5, propagates from the first optical element 10 in the reverse direction along the same path as the first to Nth component light, and passes through the optical fiber 12. Is output to the station side.

The wavelength lambda ₀ of the second optical signal OUT, and the first to N component light of the wavelength lambda ₁ to [lambda] _N constituting the first optical signal IN, are different. Thereafter, the second optical signal and the first to N-th component lights are converted into “second optical signal λ ₀ ” and “i-th component light λ _i ” (where i is 1 to 1) using the respective wavelengths λ _{0 to} λ _N. (Integer of N).

Referring to FIG. 1, the first to Nth light receiving elements 4 ₁ to 4 _N are arranged on the main surface 1a at equal intervals on a straight line along the incident direction D _IN of the first optical signal IN. First to N light receiving element ₄ 1 to 4 _N is provided in a position for receiving the first to N component light lambda ₁ to [lambda] _N, which is wavelength-multiplexed respectively. For example, when the substrate 1 is silicon, the light receiving element 4 is formed by crystal growth of Ge (germanium) on the main surface 1a. The region for receiving light in the light receiving element 4 is a circle having a diameter of about 10 μm. Incidentally, on the main surface 1a, a propagation direction _{D IN} of the first optical signal IN, propagation direction _{D OUT} of the second optical signal OUT to be described later nonparallel, i.e., intersect.

  The grating 3G is a planar diffraction grating, and is capable of coupling the second optical signal OUT emitted parallel to the main surface 1a from the light emitting element 5 to the optical fiber 12, and is inclined with respect to the main surface 1a. Change to the same path as the signal IN. Further, in order to match the spot size of the second optical signal OUT emitted from the light emitting element 5 to the spot size of the optical waveguide 14, a spot size converter 31 is provided at the input end of the second optical signal OUT. Yes. Since the spot size converter 31 is well known and is not directly related to the gist of the present invention, further explanation is omitted. Further, a tapered portion 3 is provided between the spot size converter 31 and the grating 3G.

  The grating 3G, the spot size converter 31, and the tapered portion 3 are all configured as an optical waveguide 14 in which the core 14a is surrounded by a clad 14b having a refractive index smaller than that of the core 14a.

In this example, the clad 14b is a film body having a uniform film thickness of about 3 μm formed on the main surface 1a, and SiO ₂ having a refractive index of about 1.45 is a material. The core 14a is made of Si having a refractive index of about 3.47 and has a thickness of about 200 to 300 nm. Thus, by making the refractive index of the clad 14b less than 71.4% of the refractive index of the core 14a, the light confinement ability to the core 14a is improved, and a curved optical waveguide having a small curvature radius can be formed. it can.

  In order to prevent undesired coupling of light propagating through the optical waveguide 14 to the substrate 1, it is preferable to interpose a cladding 14 b having a thickness of 1 μm or more between the core 14 a and the substrate 1. In this example, a clad 14b of about 1.5 μm is interposed between the main surface 1a and the lower surface of the core 14a. In this example, the material of the substrate 1 is Si.

Block 6 is mainly the first through N component light lambda ₁ to [lambda] _N included in the first optical signal IN and wavelength separation, respectively, is input to the first to N light receiving element ₄ 1 to 4 _N It has a function. The block 6 includes a block main body 6a having a parallel plate and a wavelength filter film 7 having different transmission wavelengths depending on the location on a lower surface 6c which is one surface of the block main body 6a.

Here, the configuration of the block 6 and the total reflection film 11 will be described in detail with reference to FIG. The block main body 6a is made of an optically transparent substance. In this example, a glass substrate having a thickness of about 1 mm is used. Thus, since the thickness of the block main body 6a is sufficiently large with respect to the wavelength of the propagating light, the behavior of the light propagating through the block main body 6a can be handled geometrically. The wavelength filter film 7 is a planar film body formed on the lower surface 6c. The wavelength filter film 7 has _{0th to} Nth regions 7 _{0 to} 7 _N configured to change the transmission wavelength according to the distance from the grating 3G. More specifically, the zeroth region _{7 0} is configured to transmit the second optical signal OUT of the wavelength lambda _0, the first to N region ₇ 1 to _7-N, respectively, the wavelength lambda ₁ to [lambda] _N It is comprised so that the 1st-Nth component light may be permeate | transmitted.

Here, the jth region (j is an integer of 0 to N) of the wavelength filter film 7 is configured such that the transmission wavelength changes to the longer wavelength side with the distance from the grating 3G. For example, the second optical signal λ ₀ (upstream signal) has a wavelength of 1.31 μm, the first component light λ _{1 of} the first optical signal (downstream signal) has a wavelength of 1.49 μm, and the second component light λ ₂ is Consider the case of a wavelength of 1.55 μm. In this case, ₀ zeroth region ₇ existing overlapping with grating 3G is configured to transmit the second optical signal lambda ₀ (1.31 .mu.m). The first region _{7 1} adjacent to the zeroth region _{7 0,} then configured to allow transmission of the first component light lambda ₁ having a longer wavelength 1.49μm wavelength. The second region _{7 2} adjacent to the first region _{7 1,} then configured as a second component light lambda ₂ long 1.55μm wavelength can be transmitted.

In order to change the transmission wavelength in each of the regions 7 _{1 to} 7 _N of the wavelength filter film 7, for example, the wavelength λ _j of each component light of the second optical signal and the first optical signal is increased with j. Correspondingly, the transmission wavelength of the j-th region 7 _j may be changed. That is, the k-th region ₇ k (k is 0 to N-1 integer), the distance from the grating 3G adjacent to the k region _{7 k} thinking and a distant first k + 1 regions _{7 k + 1,} k-th region _{7 k} is The wavelength λ _k is transmitted, and the light of other wavelengths (≠ λ _k ) is reflected. Similarly, in the k + 1 regions 7 _{k + 1,} is transmitted through the wavelength of lambda _{k + 1,} is configured to reflect light of a different wavelength from the lambda _{k + 1.}

For the wavelength filter 7, a conventionally known dielectric multilayer film can be used. That is, a low refractive index film and a high refractive index film having a refractive index larger than that of the low refractive index film are alternately stacked in a plurality of stages. In each region 7 _{0 to} 7 _N , in order to change the transmission wavelength range, either the film thickness or the refractive index of the low refractive index film, or the film thickness or the refractive index of the high refractive index film Are different from each other.

The total reflection film 11 is formed on the upper surface 6b which is the other surface facing the wavelength filter film 7 across the thickness direction of the main body 6a. The total reflection film 11 is configured as, for example, a metal thin film that reflects light of all wavelengths. The wavelength filter film 7, the block body 6a, and the total reflection film 11 combine to perform wavelength separation of the input first to N-th component light λ _{1 to} λ _N.

(Operation)
Hereinafter, the wavelength separation operation of the block 6 will be described with reference to FIG.

As shown in FIG. 2, the first optical signal IN is incident on the block 6 from the optical fiber 12 from the direction inclined with respect to the main surface 1 a of the substrate 1, and the second optical signal OUT is transmitted in the reverse direction on the same path. Is emitted. Wavelength filter membrane 7 has a zeroth region _{7 0} which is transmitted through the second optical signal lambda ₀ as described above, the first to N region and ₇ 1 - for transmitting a first to N component light lambda ₁ to [lambda] _N 7 Divided into _{N. 0} zeroth region 7 is provided so as to overlap with the grating 3G.

First, the second optical signal OUT having the wavelength λ ₀ emitted from the first optical element 10 will be described. The second optical signal OUT emitted parallel to the main surface 1a from the light emitting element 5 is diffracted by the grating 3G, the propagation path is changed obliquely with respect to the main surface 1a, and the 0th of the wavelength filter film 7 is changed. incident on the region _{7 0.} However, the zeroth region 7 ₀ is configured to transmit light of wavelength lambda _0, reflecting the lambda ₀ other wavelengths of light (λ ₁ ~λ _N). Therefore, the second optical signal OUT of the wavelength lambda ₀ is the zeroth region 7 ₀ and the block body 6a is transmitted through the reverse of the first optical signal IN and the path from the area of the upper surface 6b of the total reflection film 11 is not provided Emitted in the direction and coupled to the optical fiber 12.

Next, the first optical signal IN incident on the first optical element 10 will be described. First optical signal IN including first to N component light lambda ₁ to [lambda] _N emitted from the optical fiber 12 propagates through the second optical signal OUT in the same path in the reverse direction, the through block body 6a and it enters the 0 region _{7 0.} Zeroth region 7 ₀ Since the reflection light other than the wavelength lambda _0, the first optical signal IN, along its incident direction, so to speak the block body 6a between the wavelength filter layer 7 and the total reflection film 11 Propagating in a zigzag manner, each component light λ _{1 to} λ _N is successively wavelength-separated in the process.

More specifically, the first optical signal IN is incident on the zeroth region 7 ₀ for reflecting light of a wavelength other than lambda _0, all component light lambda ₁ to [lambda] _N is reflected to the total reflection film 11 direction The Then, by the total reflection film 11, it is reflected back to the wavelength filter membrane 7 direction, and enters the first region 7 _1. Meanwhile, the first region 7 ₁ is configured so as to transmit light of wavelength lambda _1, reflecting the lambda ₁ other than the wavelengths of light (λ ₂ ~λ _N).

Thus, the first component beam with a wavelength lambda ₁ is transmitted through the first region 7 _1, received by the first light receiving element 4 ₁ provided on the lower side of the first region 7 _1. Meanwhile, the second to N component light lambda ₂ to [lambda] _N, in the first region 7 ₁ is reflected toward the total reflection film 11, it is reflected back to the wavelength filter membrane 7 direction reaches the total reflection film 11 , and it enters the second region _{7 2.}

The same applies hereinafter, and the first optical signal IN including the component lights λ _{i to} λ _N is reflected again by the total reflection film 11 in the direction of the wavelength filter film 7 and enters the _i- th region 7 _i . Incidentally, the i region 7 _i is configured to not transmit light of the wavelength lambda _i, reflects light having a wavelength other than _{λ i (λ i + 1 ~λ} N). Therefore, the i-th component light of the wavelength lambda _i is transmitted through the i-th region 7 _i, is received by the i-th light receiving element 4 _i provided on the lower side of the i region 7 _i. On the other hand, the (i + 1) -th to _{N- th} component lights λ _{i + 1 to} λ _N are reflected toward the total reflection film 11 in the i-th region 7 _i and are reflected again toward the wavelength filter film 7 when reaching the total reflection film 11. Then, the light enters the i + 1th region 7 _{i + 1} .

In this manner, first to N component light lambda ₁ to [lambda] _N included in the first optical signal is demultiplexed for each component light are respectively received by the light receiving element 4 ₁ to 4 _N.

(Method for Manufacturing First Optical Element 10)
Since the first optical element 10 can be manufactured by using a normal Si semiconductor manufacturing process technique, the description of the overall element manufacturing method is omitted, and a method for manufacturing the wavelength filter film 7 and the optical waveguide 14 is described below. I will explain only.

  An example of a method for manufacturing the wavelength filter film 7 having different transmission wavelengths depending on the location will be described. As described above, the wavelength filter film 7 is formed by alternately laminating low refractive index films and high refractive index films. Therefore, in order to change the transmission wavelength depending on the location, the film thickness of the low refractive index film and the high refractive index film may be changed continuously.

  As a method capable of forming such a film, a vacuum deposition method or a sputtering film formation method can be given. For example, in the case of the sputtering film forming method, a first sputtering target made of the same material as the low refractive index film and a second sputtering target made of the same material as the high refractive index film are prepared. Then, the lower surface 6c of the block 6 which is a film formation surface is disposed at a position shifted from the center axis of these targets and is inclined with respect to the targets.

Then, sputtering film formation is performed while alternately switching the first and second sputtering targets. Thereby, the film thickness of the high refractive index film and the low refractive index film becomes thin on the lower surface 6c located far from the target, and conversely, the high refractive index film and the low refractive index film on the lower surface 6c located near the target. The film thickness increases. That is, along with the distance from the target, the transmission wavelength of the wavelength filter film 7 formed on the lower surface 6c gradually decreases. Here, as a material for the low refractive index film and the high refractive index film, a known dielectric material such as SiO ₂ having a refractive index of 1.47 or Ta ₂ O ₅ having a refractive index of 2.15 is used. Can do.

The optical waveguides 14 such as the grating 3G, the tapered portion 3 and the spot size converter 31 are formed using an SOI (Si On Insulator) substrate in which a SiO ₂ layer and a Si layer are stacked in this order on a Si substrate. The That is, using the uppermost Si layer, the above-described grating 3G, taper portion 3, and core 14a of the spot size converter 31 are formed by dry etching or the like. At this time, a SiO ₂ layer, which is a BOX (Buried-OXide) layer, is used as the lower layer of the cladding 14b. Then, a SiO ₂ layer corresponding to the upper layer of the clad 14b is formed by a CVD (Chemical Vapor Deposition) method or the like so as to embed the core 14a. Thereby, the optical waveguide 14 is formed.

(effect)
In the first optical element 10, the block 6 and the total reflection film 11 receive the first optical signal IN emitted from the optical fiber 12 without using the Si optical waveguide for each of the component lights λ _{1 to} λ _N. It propagates to 4 ₁ to 4 _N and receives light. That is, in the first optical element 10, the light receiving element 4 having the light receiving part of the same size can receive light without changing the spot size (about 10 μmφ) of the first optical signal IN emitted from the optical fiber 12. it can.

  As a result, it is possible to avoid an intensity loss as much as 1/2 to 1/3 when light is coupled from the Si optical waveguide to the light receiving element 4. Thereby, the light intensity of the first optical signal IN received by the light receiving element 4 can be increased by 2 to 3 times compared to the conventional example in which the Si optical waveguide and the light receiving element 4 are connected. The S / N ratio of IN is greatly improved. As a result, the communication speed that can be received by the first optical element 10 can be increased to 10 to 40 Gbps, which is about 10 to 40 times that of the conventional one.

Further, as shown in FIG. 1, light receiving elements 4 ₁ to 4 _N are provided non-parallel to the propagation path of the stray light OUTx derived from the second optical signal that travels straight without being diffracted because it exceeds the diffraction efficiency of the grating 3G. . Thereby, deterioration of the extinction ratio derived from the stray light OUTx can be prevented.

(Modification)
In this example, the case where the light emitting element 5 is integrated on the common substrate 1 together with other members has been described. However, the light emitting element 5 may be provided separately from the substrate 1 as long as it emits light parallel to the main surface 1 a of the substrate 1.

  In this example, the case where a glass substrate is used as the block 6 has been described. However, as long as the block 6 is transparent to the first and second optical signals IN and OUT, there are no particular restrictions on the material, refractive index, and the like. For example, an optical resin such as an acrylic resin may be used.

  In this example, the thickness of the block 6 is about 1 mm. However, the thickness of the block 6 is sufficiently large with respect to the wavelengths of the first and second optical signals IN and OUT, and these optical signals are geometrically optical. Any thickness that can be handled easily. In other words, the block 6 is not particularly limited as long as the thickness allows the diffraction phenomenon of the first and second optical signals IN and OUT to be ignored.

  In addition, the block 6 may be configured by stacking sub-blocks having different refractive indexes in the Z direction or combining them in the XY plane if the loss of light reflection or diffraction that occurs at the boundary between adjacent sub-blocks can be allowed. May be.

  In this example, the case where the grating 3G is used to change the propagation direction of the second optical signal OUT from the direction parallel to the main surface 1a to the direction toward the optical fiber 12 has been described. However, for changing the propagation direction of the second optical signal OUT, a mirror having a reflecting surface inclined at a predetermined angle with respect to the main surface 1a may be used.

[Embodiment 2]
Subsequently, an optical element according to Embodiment 2 (hereinafter, also referred to as a second optical element) will be described with reference to FIG. FIG. 3A is a plan view showing a schematic structure of the second optical element.

  The second optical element 30 is except that an optical circuit 35 is provided between the light emitting element 5 and the grating 3G, and a light shielding region 32 is provided between the grating 3G and the light receiving element 4. Thus, the configuration is the same as that of the first optical element 10. Therefore, these differences will be mainly described.

  The second optical element 30 processes the laser light emitted from the light emitting element 5 by the optical circuit 35 and then outputs it as the second optical signal OUT. That is, the second optical element 30 is provided with a spot size converter 31 facing the emission end of the second optical signal OUT of the light emitting element 5, and the spot size of the second optical signal OUT is changed to a channel type. In order to propagate through the optical waveguide 36, it is converted to an appropriate diameter.

  An optical circuit 35 is provided between the spot size converter 31 and the grating 3G. The optical circuit 35 includes a ring resonator 33 as an external resonator, an external modulator 34, and a channel type optical waveguide 36 that connects each component.

  The ring resonator 33 is for changing the wavelength of the laser beam output from the light emitting element 5. The external modulator 34 performs high-speed modulation with the second optical signal OUT, which is an upstream signal, to increase the communication speed.

The light shielding region 32 is provided on the main surface 1a of the substrate 1, and is made of a metal film such as Ge having a thickness equal to the thickness of the clad 14b. The light shielding region 32 has a function of shielding stray light (for example, OUTx) derived from the second optical signal OUT from the light receiving elements 4 ₁ to 4 _N. By providing the light shielding area 32, the stray light from the light emitting element 5 can be further reduced, further enhancing that the extinction ratio of the first to N component light lambda ₁ to [lambda] _N of the respective light receiving elements 4 ₁ to 4 _N is received Can do.

  In this example, the channel type optical waveguide 36 is a Si optical waveguide that can form a curved portion having a small radius of curvature.

As described above, the second optical element 30 having the light shielding region 32 has an extinction ratio higher than that of the first optical element 10, and therefore can receive each of the component lights λ _{1 to} λ _N modulated at higher speed.

  In addition, since the optical circuit 35 is provided between the light emitting element 5 and the grating 3G, various processes can be performed on the second optical signal OUT output from the second optical element 30.

[Embodiment 3]
With reference to FIG. 3B, an optical element of the third embodiment (hereinafter also referred to as a third optical element) will be described. FIG. 3B is a plan view showing a schematic structure of the third optical element.

  The third optical element 40 is configured in substantially the same manner as the first optical element 10 except that the propagation directions of the first and second optical signals IN and OUT on the main surface 1a are parallel. Therefore, these differences will be mainly described.

As shown in FIG. 3 (B), the third optical element 40 adjusts the extending direction of the grating grooves of the grating 3G so that the light emitting element 5, the grating 3G, and the light receiving elements 4 ₁ to 4 _N are linearly formed. Is arranged. A light shielding region 32 is provided to shield the stray light OUTx that could not be diffracted by the grating 3G.

  The third optical element 40 can be further downsized as compared with the first optical element 10 because all the constituent elements are arranged in a straight line.

[Embodiment 4]
With reference to FIG. 4, the optical element of Embodiment 4 (hereinafter also referred to as a fourth optical element) will be described. FIG. 4 is an end view showing a schematic structure of the fourth optical element, and is an end view taken along the same line as the line II of FIG.

  The fourth optical element 50 is different from the first optical element 10 in the following points.

(1) a point on the upper surface 6b of the block 6 has a second wavelength filter layer 7b (2) is the reflection mirror ₈ 1 to 8 _N as a reflecting member for reflecting the light component, the upper surface 6b side of the block 6 Points provided These points will be mainly described below.

The second wavelength filter film 7b provided on the upper surface 6b of the block 6 is configured in the same manner as the wavelength filter film 7 of the first optical element 10 except that it does not have the 0th region 7 ₀ b. That is, the second wavelength filter layer 7b is partitioned each component light lambda ₁ to [lambda] _N to the first to N region ₇ 1 _{b~7 N} b which transmits respectively. In this embodiment, the wavelength filter film 7 provided on the lower surface 6c of the block is referred to as a first wavelength filter film 7a for convenience.

The second wavelength filter film 7b does not include the 0th region 7 ₀ b that reflects the _first to N-th component lights λ _{1 to} λ _N. That is, the upper surface 6b of the block 6 is exposed at the portion of the upper surface 6b where the first and second optical signals IN and OUT enter and exit. This is because, if this portion providing the zeroth region 7 _{0 b,} first through N component light lambda ₁ to [lambda] _N is will be reflected, since not input in the block 6.

Further, on the upper surface 6b side of the block 6, MEMS including a reflective mirror _{8 i} for reflecting the respective component beam lambda _i which has passed through the i-th region _{7 i} b of the second wavelength filter layer 7b (Micro Electro Mechanical Systems) A mirror device 8 is provided. Hereinafter, the MEMS mirror device 8 will be described in detail.

MEMS mirror device 8, a reflecting mirror ₈ 1 to 8 _N provided corresponding to each component light lambda ₁ to [lambda] _N, control driver for controlling the inclination angle of the reflection mirror ₈ 1 to 8 _N respectively 8a.

Reflecting mirror 8 _i is provided on the upper side of the i region 7 _{i b} of the second wavelength filter membrane 7b, under the control of the control drive unit 8a, about a rotational axis extending in the Y-axis direction, The tilt angle can be changed.

  Next, the operation of the fourth optical element 50 will be described with reference to FIG. Since the behavior of the second optical signal OUT emitted from the light emitting element 5 is the same as that of the first optical element 10, the description thereof is omitted.

The first optical signal IN output from the optical fiber 12 enters the block 6 from the upper surface 6b on which the second wavelength filter film 7b is not provided, propagates through the block 6, and passes through the first wavelength filter film 7a. The 0th region 7 ₀ a is reached.

The first optical signal IN is reflected by the 0th region 7 ₀ a, enters the first region 7 ₁ b of the second wavelength filter film 7 b across the block body 6 a. Since the first region 7 ₁ b transmits the first component light having the wavelength λ ₁ , the first component light λ ₁ transmits the first region 7 ₁ b and is a reflection provided above the upper surface 6 b. incident on the mirror _{8 1.}

On the other hand, the second to N component light lambda ₂ to [lambda] _N of the first non-component light lambda ₁ is reflected by the first region _{7 1} b, across the block body 6a, the first color filter layer 7a first It is incident on one region 7 ₁ a. Then, it is re-reflected by the first region 7 ₁ a and enters the second region 7 ₂ b of the second wavelength filter film 7 b. Since the second region 7 ₂ b transmits the second component light having the wavelength λ ₂ , the second component light λ ₂ transmits the second region 7 ₂ b and is a reflection provided above the upper surface 6 b. incident on the mirror _82.

On the other hand, the _{third to} N-th component lights having wavelengths λ ₃ to λ _N are blocked in the second region 7 ₂ b of the second wavelength filter film 7 b and the second region 7 ₂ a of the first wavelength filter film 7 a. 6a is reflected so as to cross zigzag and enters the third region 7 ₃ b of the second wavelength filter film 7b. Then, in the same manner as described above, the third component light of the wavelength lambda ₃ is withdrawn in the third region 7 _{3 b} passes through the reflection mirror 8 _3, component light of other wavelengths, the first and second wavelengths In the process of reciprocating reflection between the filter films 7a and 7b, one wavelength is extracted and incident on the corresponding reflecting mirror.

Next, the behavior of the _i- th component light λ _i incident on the reflecting mirror 8 _i will be described by taking the first component light λ ₁ as an example. The first component light lambda ₁ is the reflecting mirror _81, it is reflected toward the light receiving element 4 ₁ located on the lower side of the block 6. Since the first and second wavelength filter films 7a and 7b provided in the path from the reflecting mirror 8 ₁ to the light receiving element 4 ₁ are both the first regions 7 ₁ a and 7 ₁ b, the first component light λ ₁ It includes a block 6 is transmitted through the first and second wavelength filter films 7a and 7b, is received by the light receiving element 4 _1.

  The fourth optical element 50 has the following two effects in addition to the same effects as those of the first and second optical elements 10 and 30.

The reflection behavior of the i-th component light λ _{i in} the block 6 may slightly change due to the dimensional error of the block 6, the error of the reflection wavelength of the wavelength filter films 7a and 7b, the wavelength shift of the first optical signal IN, or the like. is there. When the reflection behavior changes in this way, the beam spot (about 10 μmφ) of the i-th component light λ _i may be displaced from the light receiving part (about 10 μmφ) of the light receiving element 4 _i , and the received light intensity may be reduced. However, if the reflecting mirror 8 _i is provided as in the fourth optical element 50, the incident angle of the _i- th component light λ _i can be accurately matched with the light receiving portion of the light receiving element 4 _i , and the received light intensity can be increased. Can be increased. For example, when the positional deviation between the beam spot and the light receiving part is large, the light receiving intensity in the light receiving element 4 _i can be improved by about 2 to 3 dB by adjusting the propagation direction of the i-th component light λ _i by the reflecting mirror 8 _i .

  Furthermore, in the WDM-PON, the first optical signal IN including a plurality of component lights having different distances between the station and the subscriber may be included in one optical fiber 12. In this case, the component light transmitted from a station close to the subscriber has a very high intensity. When such strong component light is received, the light receiving capability of the light receiving element 4 is saturated, and the optical signal cannot be received accurately. In such a case, the beam spot of the component light is intentionally shifted from the light receiving portion by the reflecting mirror 8, thereby reducing the intensity of the component light to be within the range of the light receiving capability of the light receiving element 4, and an accurate optical signal. Can be received.

In this example, the case where the light shielding region 32 is not provided in the fourth optical element 50 has been described. However, the light shielding region 32 may be provided between the grating 3G and the light receiving elements 4 ₁ to 4 _N. By doing so, it is possible to prevent stray light derived from the second optical signal OUT from entering the light receiving elements 4 ₁ to 4 _N and becoming noise.

In this example, the i-th component light λ _i passes through the _i- th region 7 _i b of the second wavelength filter film 7 b twice before being received by the light receiving element 4 _i , and further, the first wavelength filter It passes through the _i- th region 7 ia of the membrane 7a once. That is, the i-th component light λ _i is subjected to wavelength selection by the wavelength filter films 7a and 7b three times in total. Therefore, the wavelength selectivity can be improved as compared with the first optical element 10 in which the number of times of transmission through the wavelength filter film 7 is one. Specifically, the half-value width with respect to the wavelength axis of the i-th component light λ _i can be made narrower than that of the first optical element 10, and noise derived from light of unnecessary wavelengths can be reduced.

  Similarly to the case of the second optical element 30, an optical circuit such as an external modulator or an external resonator may be provided between the light emitting element 5 and the grating 3G.

[Embodiment 5]
With reference to FIG. 5, the optical element of Embodiment 5 (hereinafter also referred to as a fifth optical element) will be described. FIG. 5 is an end view showing a schematic structure of the fifth optical element, and is an end view taken along the same line as the line II in FIG.

The fifth optical element 60 is different from the first optical element 10 in that the reflecting member is composed of the total reflection film 11 and the reflecting mirrors 8 ₁ to 8 _N. Hereinafter, these points will be mainly described.

In other words, the fifth optical element 60 has a structure in which the reflecting mirrors 8 ₁ to 8 _N are provided in the clad 14 b of the first optical element 10. The total reflection film 11, which is one member constituting the reflection member, is provided on the upper surface 6 b of the block 6 similarly to the first optical element 10. Further, the reflecting mirrors 8 ₁ to 8 _N which are other members constituting the reflecting member are provided in the clad 14b. More specifically, the reflecting mirror ₈₁ includes a grating 3G is provided between the light-receiving element 4 _1, reflecting mirror ₈₂ is provided between the light-receiving element 4 ₁ and 4 _2. Similarly, the reflecting mirror 8 _i is provided between the light receiving elements 4 _i-1 and 4 _i .

These reflecting mirrors 8 ₁ to 8 _N are configured such that individual inclination angles can be changed by a control driving device (not shown).

  Next, the operation of the fifth optical element 60 will be described with reference to FIG. Since the behavior of the second optical signal OUT emitted from the light emitting element 5 is the same as that of the first optical element 10, the description thereof is omitted.

The first optical signal IN emitted from the optical fiber 12 enters the block 6 from the upper surface 6 b where the total reflection film 11 is not provided, propagates through the block 6, and enters the 0th region 7 of the wavelength filter film 7. Reach ₀ .

The first optical signal IN is again reflected by the total reflection film 11 of the top surface 6b after being reflected by the zeroth region 7 _0, enters the block body 6a in the first region 7 ₁ across the zigzag. The first region 7 _1, since the transmission of the first component beam with a wavelength lambda _1, a first component light lambda ₁ is transmitted through the first region 7 _1, reflectors provided on the lower side of the bottom surface 6c 8 Incident on ₁ .

On the other hand, the second to N component light lambda ₂ to [lambda] _N of the first non-component light lambda ₁ is re-reflected by the total reflection film 11 of the top surface 6b after being reflected by the first region 7 _1, the block body 6a It enters the second area 7 ₂ across the zigzag. The second region 7 _2, since transmitted through the second light component of the wavelength lambda _2, the second component light lambda ₂ is transmitted through the second region 7 _2, reflectors provided on the lower side of the bottom surface 6c incident on the 8 _2.

Hereinafter, the same applies, and the ( _{i + 1)} -th to _{N- th} component light λ _{i + 1 to} λ N other than the _i- th component light λ _i that has not passed through the i-th region 7 _i are i + 1 to N-th regions 7 _{i + 1 to} 7 _N. , between the total reflection film 11 in the process of propagating in a zigzag, the corresponding wavelength lambda _{m (m} is an integer of i + 1 to N) transmitted through the m-th region 7 _m that transmits, incident on the reflecting mirror 8 _m .

Next, the behavior of the _{i- th} component light λ _i incident on the reflecting mirror 8 _i will be described by taking the first component light λ ₁ as an example. The first component light lambda ₁ is led to the total reflection film 11 is reflected by the reflecting mirror _81, and is received is further reflected by the total reflection film 11 and the light receiving element 4 _1. Wavelength filter film 7 existing in the path to the light receiving element 4 ₁ from the reflection mirror _81, so is the first region 7 ₁ passing through the first component light lambda _1, a first component light lambda _1, wavelength filter membrane without being reflected at 7, it is received by the light receiving element 4 _1.

  The fifth optical element 60 has the same effects as the fourth optical element 50 in addition to the same effects as the first and second optical elements 10 and 30.

  In this example, the light shielding region 32 may be provided also in the fifth optical element 60 for the same reason as the fourth optical element 50.

In this example, the i-th component light λ _i passes through the _i- th region 7 _i of the wavelength filter film 7 three times before being received by the light receiving element 4 _i . That is, the i-th component light λ _i is subjected to wavelength selection three times. Therefore, for the same reason as the fourth optical element 50, it is possible to reduce noise derived from light having an unnecessary wavelength.

  Similarly to the case of the second optical element 30, an optical circuit such as an external modulator or an external resonator may be provided between the light emitting element 5 and the grating 3G.

[Embodiment 6]
With reference to FIG. 6, the optical element of Embodiment 6 (hereinafter also referred to as a sixth optical element) will be described. FIG. 6 is an end view showing a schematic structure of the sixth optical element, and is an end view taken along the same line as the line II of FIG.

  The sixth optical element 70 is different from the fifth optical element 60 in the following points.

(1) Points where the light receiving elements 4 ₁ to 4 _N are provided on the upper surface 6 b side of the block 6 (2) The second wavelength filter film 7 b is provided on the upper surface 6 b of the block 6 instead of the total reflection film 11. The following points are mainly described.

The second wavelength filter film 7b provided on the upper surface 6b of the block main body 6a is the same as the first wavelength filter film 7a except for the areas where the first and second optical signals IN and OUT are input and output. To Nth regions 7 ₀ b to 7 _N b. Result of providing the input and output regions of the first and second optical signals IN and OUT on the upper surface 6b, the first and second wavelength filter films 7a and 7b, the corresponding respective areas ₇ to _j a and _{7 j} b is, X direction Are provided at positions shifted from each other.

In the sixth optical element 70, the light receiving elements 4 ₁ to 4 _N are provided not on the main surface 1a of the substrate 1 but on the upper surface 6b side of the block body 6a.

  Next, the operation of the sixth optical element 70 will be described with reference to FIG. Since the behavior of the second optical signal OUT emitted from the light emitting element 5 is the same as that of the first optical element 10, the description thereof is omitted.

The first optical signal IN output from the optical fiber 12 enters the block 6 from the upper surface 6b where the second wavelength filter 7b is not provided, propagates through the block 6, and passes through the first wavelength filter film 7a. 0 region 7 ₀ a is reached.

The first optical signal IN is reflected by the 0th region 7 ₀ a, crosses the block body 6a, is reflected again by the 0th region 7 ₀ b of the second wavelength filter film 7b, and crosses the block body 6a again. Thus, it reaches the first region 7 ₁ a of the first wavelength filter film 7a.

Since the first region 7 ₁ a transmits the first component light having the wavelength λ ₁ , the first component light λ ₁ transmits the first region 7 ₁ a and is reflected below the lower surface 6 c. incident on the mirror _{8 1.}

Meanwhile, the second to N component light lambda ₂ to [lambda] _N, a first region _{7 1} a of the first color filter layer 7a, between the first region _{7 1} b of the second wavelength filter layer 7b zigzag After two reciprocations, it reaches the second region 7 ₂ a of the first wavelength filter film 7 a. Since the second region 7 ₂ a transmits the second component light of the wavelength λ ₂ , the second component light λ ₂ is transmitted through the second region 7 ₂ a and is reflected below the lower surface 6 c. incident on the mirror _82.

On the other hand, the third to N-th component light λ _{3 to} λ _N zigzags between the first region 7 ₂ a of the first wavelength filter film 7 a and the second region 7 ₂ b of the second wavelength filter film 7 b. After two reciprocations, the third region 7 ₃ a of the first wavelength filter film 7 a is reached. Then, in the same manner as described above, the third component light of the wavelength lambda ₃ is withdrawn in the third region 7 ₃ passes through the _a reflecting mirror 8 _3, component light of other wavelengths, the first and second wavelengths In the process of reciprocating reflection between the filter films 7a and 7b, one wavelength is extracted and incident on the corresponding reflecting mirror.

Next, the behavior of the _i- th component light λ _i incident on the reflecting mirror 8 _i will be described by taking the first component light λ ₁ as an example. The first component light lambda ₁ is the reflecting mirror _81, it is reflected toward the light receiving element 4 ₁ located on the upper side of the block 6. Since the first and second wavelength filter films 7a and 7b provided in the path from the reflecting mirror 8 ₁ to the light receiving element 4 ₁ are both the first regions 7 ₁ a and 7 ₁ b, the first component light λ ₁ It passes through the block 6 and is received by the light receiving element 4 _1.

  In addition to the same effect as that of the fifth optical element 60, the sixth optical element 70 can further form the light receiving element 4 at the end of the manufacturing process of the sixth optical element 70. The sixth optical element 70 can be easily created. For example, the sixth optical element 70 can be manufactured by attaching a commercially available light receiving element 4 to the upper surface 6 b of the block 6.

[Embodiment 7]
With reference to FIG. 7, the optical element of Embodiment 7 (hereinafter also referred to as a seventh optical element) will be described. FIG. 7 is an end view showing a schematic structure of the seventh optical element, and is an end view taken along the same line as the line II of FIG.

In the seventh optical element 80, the wavelength filter films 9 _{1 to} 9 _N having different transmission wavelengths are stacked in the Z direction, and regions 7 _{1 to} 7 _N having different transmission wavelengths are provided on _one wavelength filter film 7. This is different from the one-light element 10 (FIG. 2). Hereinafter, this difference will be mainly described.

In the seventh optical element 80, wavelength filter blocks 6 _{1 to} 6 _N corresponding to the number (N) of component lights to be separated are laminated in this order on the upper surface of the clad 14b. Then, the wavelength filters that reflect the component lights λ ₁ to λ _N and transmit light having wavelengths exceeding λ ₁ to λ _N on the upper surfaces 6 ₁ b to 6 _N b of the blocks 6 _{1 to} 6 _N , respectively. Films 9 _{1 to} 9 _N are provided. Hereinafter, when the blocks 6 _{1 to} 6 _N are collectively referred to, they are also simply referred to as “block 6”. Similarly, when the wavelength filter films 9 _{1 to} 9 _N are generically referred to, they are also simply referred to as “wavelength filter films 9”.

Each of the blocks 6 _{1 to} 6 _N has a thickness on the order of mm, which is sufficiently large with respect to the wavelength of each of the component lights λ _{1 to} λ _N so that the light propagating therethrough can be handled geometrically. On the upper surface of each block 6 _i, reflect light of each component light lambda _i, wavelength filter film 9 made of engineered dielectric multilayer film so as to transmit light of wavelengths greater than lambda _{i i} Is formed.

A wavelength filter film 13 is provided on the upper surface of the clad 14b in a region where the first and second optical signals IN and OUT are incident. The wavelength filter film 13 is configured to transmit only the second optical signal OUT having the wavelength λ ₀ emitted from the light emitting element 5 and reflect the component lights λ _{1 to} λ _N included in the first optical signal IN. ing.

On the upper surface of the cladding 14b, the lens ₁₅ 1-15 for entering the light receiving element ₄ 1 to 4 _N each wavelength filter film ₉ 1 to 9 _N in the reflected component light lambda ₁ to [lambda] _N collimates _N is provided.

Next, the operation of the seventh optical element 80 will be described with reference to FIG. The second optical signal OUT having the wavelength λ ₀ emitted from the light emitting element 5 is changed by the grating 3G so that the propagation direction is inclined with respect to the main surface 1a, passes through the wavelength filter film 13, and enters the optical fiber 12. Combined.

On the other hand, the first optical signal IN having wavelengths λ _{1 to} λ _N output from the optical fiber 12 propagates through the blocks 6 _{1 to} 6 _N and is reflected by the wavelength filter film 13. Among the first optical signal IN that is reflected, the first light component of the wavelength lambda ₁ is the wavelength filter film 9 ₁ block _61, is reflected to the light receiving element 4 _{in one} direction. The other second to N component light lambda ₂ to [lambda] _N is transmitted through the wavelength filter film _{9 1} and enters the next block _{6 2.}

Of the second to N component light lambda ₂ to [lambda] _N, a second component light having a wavelength of lambda ₂ is a wavelength filter film _{9 2} blocks _{6 2,} are reflected to the light receiving element _{4 in two} directions. Third to N component light lambda ₃ to [lambda] _N having a wavelength greater than the wavelength lambda ₂ is transmitted through the wavelength filter film 9 ₂ and enters the next block 6 _3. Similarly, the i-th component light is reflected in the direction of the light receiving element 4 _{i by} the wavelength filter film 9 _i of each block 6 _i .

Next, the behavior of the _i- th component light λ _i incident on the wavelength filter film 9 _i will be described by taking the second component light λ ₂ as an example. The second component light lambda ₂ is a wavelength filter film 9 _2, it is reflected toward the light receiving element 4 _2. The first wavelength filter film 9 ₁ provided on the path from the wavelength filter film 9 ₂ to the light receiving element 4 _2, so is transmitted through the second component light lambda ₂ wavelength exceeding the wavelength lambda _1, the second component light lambda ₂ is collimated by the lens 15 _2, it is received by the light receiving element _{4 2.}

The seventh optical element 80 has the same effect as the first optical element 10, but unlike the first optical element 10, there is no need to change the transmission wavelength inside one wavelength filter film 7, and the wavelength filter The film 9 _i can be easily formed.

10, 30, 40, 50, 60, 70, 80 Optical element 1 Substrate 1a Main surface 3 Tapered portion 3G Grating 4, 4 ₁ to 4 _N Light receiving element 5 Light emitting element 6, 6 _{1 to} 6 _N wavelength filter block 6a Block body 6b top 6c lower surface _{7, 9} 1 _{to 9} N, 13 a wavelength filter film 7a first wavelength filter layer 7b second wavelength filter film _{7 0 ~7 N, 7 0 a~7} N a, 7 0 b~7 N b the 0 to Nth region 8 MEMS mirror device 8a Control drive device 8 ₁ to 8 _N reflecting mirror 11 Total reflection film 12 Optical fiber 14 Optical waveguide 14a Core 14b Cladding 15 ₁ to 15 _N lens 31 Spot size converter 32 Light shielding region 33 External Resonator 34 External modulator 35 Optical circuit 36 Channel type optical waveguide

Claims (16)

Provided on the board,
First to Nth light receiving elements that receive first to Nth component lights (N is an integer equal to or greater than 1), each having a different wavelength, included in the incident first optical signal;
A grating that emits the second optical signal having a wavelength different from that of the first to N-th component lights by changing the path to the same path as the first optical signal;
A wavelength filter block provided on the upper side of the grating;
A reflective member,
The wavelength filter block includes a parallel plate main body, and a wavelength filter film provided on one surface of the main body,
The wavelength filter film includes 0th to Nth regions that transmit the second optical signal and the first to Nth component light, respectively.
The zeroth region transmits the second optical signal and reflects the first to Nth component light;
The reflected first to N-th component lights propagate through the i-th region (i is an integer from 1 to N) in the process of propagating while reflecting between the reflecting member and the first to N-th regions. An optical element, wherein i-component light is transmitted and received by an i-th light receiving element.   2. The optical element according to claim 1, wherein the 0th to Nth regions are configured such that a transmission wavelength changes to a long wavelength side along with a distance from the grating. In the j-th region (j is an integer of 0 to N), a low refractive index film and a high refractive index film having a refractive index larger than that of the low refractive index film are alternately laminated in a plurality of stages,
3. The film thickness and refractive index of the low refractive index film differ from either the film thickness and refractive index of the high refractive index film for each j. An optical element according to 1.   The said 1st-Nth light receiving element is arrange | positioned on the main surface of the said board | substrate along the incident direction of the said 1st optical signal, The Claim 1 characterized by the above-mentioned. Optical element.   5. The propagation direction of the second optical signal on the main surface of the substrate with respect to the grating and the propagation direction of the first optical signal on the main surface are non-parallel. The optical element as described in any one.   The propagation direction of the second optical signal with respect to the grating on the principal surface of the substrate and the propagation direction of the first optical signal on the principal surface are parallel to each other. An optical element according to claim 1.   The optical element according to claim 1, wherein the reflection member is a reflection film provided on the other surface of the main body facing the one surface. The second wavelength filter film having the first to N-th regions is provided on the other surface of the main body opposite to the one surface except that the zeroth region is not included,
The reflecting member is a reflecting mirror that reflects the first to N-th component light transmitted through the second wavelength filter film toward the wavelength filter film, and the reflecting mirror is provided on the other surface side. The optical element according to claim 1, wherein the optical element is an optical element. The reflective member is provided on the other surface side of the main body facing the one surface on which the wavelength filter film is provided; and
A reflecting mirror that reflects each of the first to N-th component lights that pass through the wavelength filter film;
The optical element according to claim 1, wherein the reflecting mirror is provided on the one surface side. A second wavelength filter film configured to be equal to the wavelength filter film is provided on the other surface of the main body facing the one surface,
The reflecting member is a reflecting mirror that reflects the first to N-th component light transmitted through the wavelength filter film toward the second wavelength filter film, and the reflecting mirror is provided on the one surface side. ,
The optical element according to claim 1, wherein the first to Nth light receiving elements are provided on the other surface side.   The spot size converter for changing the spot size of the said 2nd optical signal is provided in the input terminal into which the said 2nd optical signal is input, The Claim 1 characterized by the above-mentioned. Optical element.   The optical element according to claim 1, wherein an optical circuit is provided between the spot size converter and the grating.   The optical device according to claim 12, wherein the optical circuit is an external modulator.   14. The optical element according to claim 12, wherein the optical circuit is an external resonator.   The optical element according to claim 1, wherein a light shielding region is provided between the grating and the first to Nth light receiving elements.   The optical element according to claim 1, wherein a light emitting element is provided on the substrate, and the second optical signal is output in parallel to a main surface of the substrate.

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