Phase adjuster

Abstract

To provide a phase adjuster with which it is possible to reduce phase errors due to manufacturing errors while keeping the difference in a change amount of an effective refractive index to a waveguide width and the element length in two waveguides at a prescribed level or below.SOLUTION: The phase adjuster comprises: a first phase adjustment unit 4 located in a first optical path L1 and a second phase adjustment unit 5 located in a second optical path L2, with light in the optical paths L1, L2 given a prescribed phase difference. The phase adjustment units 4, 5 include a clad layer 2 composed of a clad material, and a core layer 3 composed of a high refractive index material whose refractive index is higher than that of the clad material. The first phase adjustment unit 4 includes, in a phase adjustment region, a waveguide where the intensity of propagated light becomes maximum inside. The second phase adjustment unit 5 includes, in the phase adjustment region, two patterns arranged in parallel adjacent to each other, and a section of the clad layer 2 located in a space between the two patterns propagates light and the intensity of the light becomes maximum in the interior of the section or at a boundary with the pattern.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a phase adjuster. [Background technology]

[0002] Conventionally, a passive phase adjuster has two waveguides through which two incident lights propagate, and adjusts the phases of the two incident lights depending on the difference in shape of the two waveguides. For example, the phase adjuster described in Patent Document 1 adjusts the phase difference between the two lights propagating through the two waveguides.

[0003] In this phase adjuster, the direction in which light propagates in the waveguide is defined as the propagation direction, and the width of the waveguide in a direction perpendicular to the propagation direction is defined as the waveguide width W, and the waveguide width W has different values ​​for the two waveguides. In this phase adjuster, the effective refractive index n eff By utilizing the change in the phase angle .DELTA..phi., a predetermined phase difference .DELTA..phi. is imparted to the two light beams propagating through the waveguide by adjusting the waveguide width W. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-163825 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the phase shifter having the structure described in Patent Document 1, when the waveguide width W in the phase adjustment region for generating the phase difference Δφ deviates from the design value due to manufacturing errors, the effective refractive index n eff This causes a deviation in the phase difference Δφ from the set value. error In order to reduce the effective refractive index n eff The change in dneff It is conceivable to design it so that the difference in / dW is small.

[0006] For the sake of simplicity, the phase error φ caused by the manufacturing error of the waveguide width W is error is simply expressed as "phase error φ error " and the effective refractive index n eff The change in dn eff / dW is simply "change amount dn eff In this case, the length in the propagation direction of the portion of the phase shifter that adjusts the waveguide width W is defined as element length L, and in order to obtain a predetermined phase difference Δφ, it is necessary to increase element length L.

[0007] Here, the phase difference Δφ is the function of the element length L and the effective refractive index n eff Therefore, when the element length L is increased, the phase error φ error Since the value of φ also becomes large, the phase error error The effect of reducing the

[0008] On the other hand, if the element length L is reduced, the difference between the two waveguide widths W must be increased to obtain a predetermined phase difference Δφ. However, in this case, the amount of change dn eff The difference between / dW becomes large, and the phase error φ error In other words, the above phase shifter is designed to reduce the change in the two waveguides, dn eff Since the difference between / dW and the element length L is in a trade-off relationship, the phase error φ error It is difficult to reduce

[0009] In view of the above, the present disclosure provides a method for determining the dn eff While keeping the difference between the phase error and the phase error φ error It is an object of the present invention to provide a phase adjuster having a structure capable of reducing [Means for solving the problem]

[0010] According to one aspect of the present disclosure, a phase adjuster is a phase adjuster that imparts a predetermined phase difference between light in a first optical path (L1) and light in a second optical path (L2), and includes a first phase adjuster (4) arranged in the first optical path and a second phase adjuster (5) arranged in the second optical path, and the first phase adjuster and the second phase adjuster each include a clad layer (2) made of a clad material and a core layer (3) made of a high refractive index material having a refractive index higher than that of the clad material, and the first phase adjuster has a first phase adjustment region (42) made of a high refractive index material and equipped with a waveguide pattern (33) in which the intensity of propagating light is maximum inside the high refractive index material, and a second phase adjustment region (52) equipped with two pattern portions (36) in which high refractive index material is arranged adjacent to each other in parallel, and a propagation portion (21) located in the gap between the two pattern portions in the cladding layer and propagating light, and the intensity of the propagating light in the propagation portion is maximum inside or at the boundary with the pattern portions.

[0011] As a result, by having the first phase adjustment unit and the second phase adjustment unit, which are waveguides with different structures, the amount of change dn eff This phase adjuster has a structure in which the difference between dn / dW and the element length is not in a trade-off relationship. eff While keeping the difference in / dW below a certain level, the element length is kept small and the phase error φ error It is now possible to reduce

[0012] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and specific components described in the embodiments described below. [Brief description of the drawings]

[0013] [Figure 1] 3 is a schematic diagram showing an application example of the phase adjuster of the first embodiment. FIG. [Diagram 2] 4 is a top view showing a configuration example of a first phase adjustment unit. FIG. [Diagram 3] 11 is a top view showing a configuration example of a second phase adjustment unit. FIG. [Figure 4] FIG. 13 is a top view showing a phase adjuster of a comparative example. [Diagram 5] 11 is a graph showing the relationship between the amount of manufacturing error in the waveguide width and the phase difference in the phase shifter of the comparative example, and the phase error. [Figure 6] 13 is a graph showing the relationship between the waveguide width and the effective refractive index in a phase shifter of a comparative example. [Figure 7] 13 is a graph showing a relationship between a waveguide width and an amount of change in effective refractive index relative to an amount of change in the waveguide width in a phase shifter of a comparative example. [Figure 8] 11 is a graph showing an example of a relationship between a waveguide width of a first phase adjustment unit and an amount of change in effective refractive index relative to an amount of change in the waveguide width. [Figure 9] 13 is a graph showing an example of a relationship between a waveguide width of a second phase adjustment unit and an amount of change in effective refractive index relative to an amount of change in the waveguide width. [Figure 10] 4 is a graph showing the relationship between the amount of manufacturing error in the waveguide width and the phase difference in the phase adjuster of the first embodiment, and the phase error. [Figure 11] FIG. 11 is a top view illustrating a first phase adjustment unit in a phase adjustment device according to a second embodiment. [Figure 12] FIG. 13 is a top view illustrating a first phase adjustment unit in a phase adjustment device according to a third embodiment. [Figure 13] FIG. 13 is a top view illustrating a second phase adjustment unit in the phase adjustment device of the third embodiment. [Figure 14] FIG. 13 is a top view showing a first phase adjustment unit in a phase adjustment device according to a fourth embodiment. [Figure 15] FIG. 13 is a top view showing a second phase adjustment unit in a phase adjustment device according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals.

[0015] (First embodiment) A phase shifter 1 of the first embodiment will be described with reference to the drawings.

[0016] For ease of viewing, Fig. 1 shows a simplified first phase adjustment unit 4 and a second phase adjustment unit 5, which will be described later. Figs. 1 to 3 show the phase adjustment device 1 or the phase adjustment units 4 and 5 as viewed from a normal direction relative to a plane on which a core layer 3, which will be described later, is formed, and this state may be referred to as a "top view."

[0017] [Basic configuration] The phase adjustment device 1 of this embodiment is disposed between the input side multiplexer / demultiplexer Mi and the output side multiplexer / demultiplexer Mo, as shown in FIG. 1, for example. The phase adjustment device 1 is used to adjust the phases of two lights incident from the input side multiplexer / demultiplexer Mi to the phase adjustment device 1, and output the two lights after adjustment to the output side multiplexer / demultiplexer Mo. For example, the phase adjustment device 1 imparts a predetermined phase difference to two lights incident from the input side multiplexer / demultiplexer Mi in a phase-aligned state, and outputs two lights in a phase-shifted state to the output side multiplexer / demultiplexer Mo. The phase adjustment device 1 can also change the phases of two lights incident from the input side multiplexer / demultiplexer Mi in a phase-shifted state, adjust the phases of the two lights so that they are aligned, and output them to the output side multiplexer / demultiplexer Mo.

[0018] The phase shifter 1 is formed by, for example, laminating a cladding layer 2 made of a cladding material on a silicon substrate (not shown), and a core layer 3 made of a high refractive index material having a higher refractive index than the cladding material. The term "high refractive index" here means that the refractive index is relatively higher than that of the cladding material, and does not necessarily mean that the absolute value is equal to or higher than a predetermined value. The phase shifter 1 is manufactured, for example, by forming a part of the cladding layer 2 on a silicon substrate (not shown), laminating a film made of a high refractive index material thereon, and forming the core layer 3 by patterning, and then laminating the remaining part of the cladding layer 2. The cladding material is, for example, silicon oxide, an insulator, i.e., SiO 2 The high refractive index material may be, but is not limited to, a material with a higher refractive index than the cladding material, such as, but not limited to, silicon nitride, or SiN.

[0019] The phase shifter 1 includes a first optical path L1 and a second optical path L2 into which light is incident from the input-side multiplexer / demultiplexer Mi. The optical paths L1 and L2 are formed of a cladding layer 2 and a core layer 3, and a part of the core layer 3 serves as a waveguide for propagating light. The waveguide is provided with a phase adjustment unit for adjusting the phase of light propagating between the input-side multiplexer / demultiplexer Mi and the output-side multiplexer / demultiplexer Mo. The phase shifter 1 adjusts the phase of light incident on the first optical path L1 with the first phase adjustment unit 4 and adjusts the phase of light incident on the second optical path L2 with the second phase adjustment unit 5, thereby imparting a predetermined phase difference to these lights. The first phase adjustment unit 4 and the second phase adjustment unit 5 are both formed of a part of the cladding layer 2 and the core layer 3, but have different structures.

[0020] For ease of explanation, the direction along which a portion of the core layer 3 located in a phase adjustment region 42 described later extends on the plane on which the core layer 3 is formed as shown in Fig. 2 will be referred to as the "first direction D1," and the direction perpendicular to the first direction D1 will be referred to as the "second direction D2." Note that the directions D1 and D2 indicated by arrows in Fig. 3 and subsequent figures correspond to the above-mentioned first direction D1 and second direction D2, respectively.

[0021] 2, the first phase adjustment unit 4 includes a conversion region 41 that functions as a converter, and a phase adjustment region 42 that adjusts the phase of incident light. The first phase adjustment unit 4 is disposed in the first optical path L1 between the first core layer 31 into which the light from the input-side multiplexer / demultiplexer Mi is incident, and the third core layer 34 that outputs light to the output-side multiplexer / demultiplexer Mo.

[0022] The conversion region 41 is disposed closer to the input-side multiplexer / demultiplexer Mi than the phase adjustment region 42. The conversion region 41 includes, for example, a part of the first core layer 31, two substantially diamond-shaped pattern portions 32 disposed in parallel and spaced apart from each other, and a part of the second core layer 33 when viewed from above.

[0023] The first core layer 31 has an end opposite to the input-side multiplexer / demultiplexer Mi that is a narrow portion whose width gradually narrows toward the output-side multiplexer / demultiplexer Mo. The two pattern portions 32 are disposed adjacent to the narrow portion of the first core layer 31 with a gap between them. The second core layer 33 has an end opposite to the input-side multiplexer / demultiplexer Mi that is a narrow portion whose width gradually narrows toward the input-side multiplexer / demultiplexer Mi, and is disposed so that the narrow portion is inserted into the gap between the two pattern portions 32.

[0024] The conversion region 41 propagates the light propagating through the first core layer 31 to a portion of the cladding layer 2 located in the gap between the two pattern portions 32, and propagates the propagated light to the second core layer 33 of the phase adjustment region 42. The conversion region 41 is provided such that the element length L3 and the element length L4 are approximately the same, where the length of the phase adjustment region 42 in the first direction D1 is the "element length L3" and the length of the phase adjustment region 52 of the second phase adjustment unit 5 in the same direction is the "element length L4". "Approximately the same" means not only the case where they are completely the same, but also the case where they are not completely the same due to unavoidable factors such as dimensional tolerances, but can be considered to be almost the same.

[0025] The phase adjustment region 42 is composed of a substantially linear second core layer 33 adjacent to the conversion region 41. The phase adjustment region 42 adjusts the effective refractive index n eff1 , and imparts a predetermined phase difference Δφ between the light and the light incident on the second phase adjustment section 5. The phase adjustment region 42 is a waveguide in which the intensity of the propagating light is maximized inside the second core layer 33. In the phase adjustment region 42, the waveguide width W1 of the second core layer 33 is adjusted, and the effective refractive index n eff1 The change in dn eff1 / dW1 is set to a desired value. Design examples of the waveguide width W1 and the element length L3 will be described later.

[0026] For ease of explanation, a waveguide that is made of a material with a higher refractive index than the cladding material and has a structure in which the intensity of propagating light is maximized inside, such as the above-mentioned second core layer 33, will be referred to as a "normal waveguide" below. The first core layer 31, the second core layer 33, the third core layer 34, the fourth core layer 35 and the fifth core layer 37 are all normal waveguides.

[0027] 3, the second phase adjustment section 5 has a first conversion region 51, a phase adjustment region 52, and a second conversion region 53. The second phase adjustment section 5 is disposed in the second optical path L2 between a fourth core layer 35 into which light from the input-side multiplexer / demultiplexer Mi is incident, and a fifth core layer 37 from which light is emitted to the output-side multiplexer / demultiplexer Mo. The second phase adjustment section 5 has a part of the fourth core layer 35, two pattern sections 36 extending along the first direction D1 and disposed in parallel, and a part of the fifth core layer 37.

[0028] The fourth core layer 35, like the first core layer 31, has a narrow width portion at an end opposite to the input-side multiplexer / demultiplexer Mi that gradually narrows toward the output-side multiplexer / demultiplexer Mo. The two pattern portions 36 are, for example, linear in top view, and have a linear portion with a width W2 in the second direction D2 and narrow width portions located at both ends in the first direction D1 that sandwich the linear portion. The two pattern portions 36 are, for example, configured such that the width of the narrow width portions at both ends in the second direction D2 narrows as they move away from the linear portion. The fourth core layer 35 is arranged such that the narrow width portion is inserted into the gap between the narrow width portions of the two pattern portions 36 on the input-side multiplexer / demultiplexer Mi side. The fifth core layer 37 has a narrow portion whose width gradually narrows as the end on the input side multiplexer / demultiplexer Mi approaches the input side multiplexer / demultiplexer Mi, and this narrow portion is positioned so as to be inserted into the gap between the narrow portions of the two pattern portions 36 on the output side multiplexer / demultiplexer Mo side.

[0029] Hereinafter, the distance between the two pattern portions 36 in the second direction D2 will be referred to as "gap G1," and the width of the straight line portion of the pattern portion 36 in the second direction D2 will be referred to as "pattern width W2."

[0030] In the first conversion region 51 of the second phase adjustment unit 5, incident light from the fourth core layer 35 propagates to the propagation portion 21 located in the gap of the pattern portion 36 of the cladding layer 2. The second phase adjustment unit 5 is a slot waveguide in which the intensity of the light propagated from the fourth core layer 35 is maximum inside the propagation portion 21 or at the boundary with the pattern portion 36. In other words, the first conversion region 51 functions as a converter that propagates light from the fourth core layer 35 of the normal waveguide to the phase adjustment region 52 of the slot waveguide.

[0031] The second phase adjustment section 5 has a gap G1 of a predetermined width or less so that the second phase adjustment section 5 functions as a slot waveguide. The second phase adjustment section 5 has a pattern width W2 of the phase adjustment region 52 adjusted, and the effective refractive index n eff2 In addition, the second phase adjustment unit 5 changes the effective refractive index n eff2 The change in dn eff2 / dW2 is the above dn eff1 / dW1 is designed to be equal to or smaller than a predetermined value. That is, if the phase adjustment region 42 of the first phase adjustment unit 4 is the first phase adjustment region, the phase adjustment region 52 of the second phase adjustment unit 5 has a second phase adjustment region corresponding to the phase adjustment region 42. Design examples of the pattern width W2 and the gap G1 will be described later. The light propagating through the propagation unit 21 is propagated to the fifth core layer 37 in the second conversion region 53. That is, the second conversion region 53 functions as a converter that propagates light from the phase adjustment region 52 of the slot waveguide to the fifth core layer 37 of the normal waveguide.

[0032] The above is the basic configuration of the phase adjuster 1. In the above, the first optical path L1 and the second optical path L2 are arranged substantially parallel to each other, and the entire area of ​​the portion that becomes the waveguide is formed linearly along the first direction D1. However, the present invention is not limited to this. For example, the phase adjuster 1 may have a configuration including the first phase adjuster 4 of a normal waveguide and the second phase adjuster 5 of a slot waveguide, and the core layers 31, 34, 35, and 37 may have a partially curved shape. In this way, the shape of a part of the configuration of the phase adjuster 1 may be changed to another known shape as appropriate.

[0033] [Reduction of phase error] Next, a description will be given of reduction in phase error caused by manufacturing errors in phase shifter 1 of the present embodiment.

[0034] First, a phase error in the phase adjuster of the comparative example will be described. The phase adjuster 100 of the comparative example includes a first optical path 110 and a second optical path 120, as shown in FIG. 4, for example. The phase adjuster 100 includes a cladding layer made of a cladding material and a core layer made of a material having a higher refractive index than the cladding material, and the optical paths 110 and 120 are formed of a part of the core layer. Both of the optical paths 110 and 120 are normal waveguides. The first optical path 110 includes a first phase adjuster 111 extending along a first direction D1, and the waveguide width of the first phase adjuster 111 in the second direction D2 is Wa. The second optical path 120 includes a second phase adjuster 121 extending along the first direction D1, and the waveguide width of the second phase adjuster 121 in the second direction D2 is Wb, which is different from Wa.

[0035] In phase adjuster 100, phase adjusters 111 and 121 have different waveguide widths Wa and Wb, and impart a predetermined phase difference Δφ to light incident on two optical paths 110 and 120. In phase adjuster 100, phase adjusters 111 and 121 have the same width along second direction D2, i.e., element length Lr. Phase adjuster 100 sets the effective refractive index in first phase adjuster 111 to n eff (Wa), and the effective refractive index in the second phase adjustment unit 121 is n effAssuming that the phase difference is Wb, the phase difference Δφ is expressed by the following equation (1).

[0036]

number

[0037] When the above-mentioned design values ​​are used, and a manufacturing error in the range of -50 nm to +50 nm occurs in the waveguide widths Wa and Wb, the phase difference Δφ deviates from the design value as shown in Fig. 5. In this case, in phase adjuster 100, when the manufacturing error amount is -50 nm, the phase difference Δφ is about 96.6°, and when the manufacturing error amount is +50 nm, the phase difference Δφ is about 83.1°. In other words, the amount of deviation from the set value of phase difference Δφ=90° is expressed as the phase error φ error As a result, the phase error φ error The range was about 13.5° when the manufacturing error was within the range of ±50 nm.

[0038] With the above design values, phase shifter 100 has an effective refractive index n eff is about 1.6, and the effective refractive index n eff 7, the phase shifter 100 has an effective refractive index n eff The change in dn eff / dW is different between the phase adjustment units 111 and 121. Specifically, the amount of change dn eff / dW is about 5.6×10 -5 and in the second phase adjustment unit 121, it is about 2.8×10 -5 The difference between these is about 2.8 × 10 -5 It is.

[0039] Here, the phase difference Δφ is calculated by the above formula (1) using the element length Lr and the effective refractive index n eff Therefore, the phase error φ error In order to reduce eff For example, in phase shifter 100, the waveguide widths Wa and Wb of phase adjustment units 111 and 121 are set to 1.9 μm and 2.0 μm, respectively, to reduce the difference in the waveguide width, and the amount of change dn eff / dW = 0.4 × 10 -5 In this case, in order to obtain a phase difference Δφ=90° according to equation (1), the element length Lr must be increased, and the element length Lr becomes 130.9 μm. In such a design, the phase error φ error The value of was in the range of 11.2° when the manufacturing error was within the range of ±50 nm. eff This structure has a trade-off relationship between the difference in / dW and the element length Lr, and the phase error φ error It is difficult to reduce

[0040] In contrast, in the phase shifter 1 of the present embodiment, the first phase shifter 4 is configured with a normal waveguide, and the second phase shifter 5 is configured with a slot waveguide. eff (W1), and the effective refractive index in the second phase adjustment unit 5 is n eff If (W2) and the element lengths L3 and L4 are equal, the phase difference Δφ is calculated by the following equation (2).

[0041]

number

[0042] The graph shown in Fig. 8 is a calculation result when the thickness of the core layer 3 is 0.3 µm, and the element length L3 of the phase adjustment region 42 of the second core layer 33 is 5.68 µm. The graph shown in Fig. 9 is a calculation result when the thickness of the core layer 3 is 0.3 µm, the element length L4 of the phase adjustment region 52 of the two pattern portions 36 is 5.68 µm, and the gap G1 is 0.15 µm.

[0043] Here, if the waveguide width W1 in the first phase adjustment unit 4 is 0.78 μm and the pattern width W2 in the second phase adjustment unit 5 is 1.08 μm, the amount of change dn eff 10. In this case, the element lengths L3 and L4 of the phase adjustment regions 42 and 52 are 5.68 μm as described above, and the phase shifter 1 has a phase difference Δφ as shown in FIG. 10 when the manufacturing error of the widths W1 and W2 is within the range of ±50 nm. Specifically, the phase difference Δφ is a maximum of approximately 91.3° when the manufacturing error is +50 nm, and the phase error φ error In the above design example, the phase shifter 1 has an effective refractive index n eff The difference between the effective refractive index n eff The difference between them can be ensured to be greater than 0.04.

[0044] In summary, in the design example of the phase shifter 1, the change amount dn eff / dW is 0.4 to 2.8×10 -510, which is at least one order of magnitude smaller than -14 The element lengths of the two phase adjustment units in phase adjuster 1 were 5.68 μm, which was one order of magnitude smaller than the 19.6 μm to 130.9 μm in phase adjuster 100 of the comparative example. error However, the change in the amount of change in the phase shifter 100 was 1.3°, which is less than 1 / 10 of the 11.2° to 13.5° in the phase shifter 100 of the comparative example. eff The difference between the widths W1 and W2 and the lengths L3 and L4 of the elements can be designed to be equal to or smaller than a predetermined value. error This shows that it is possible to reduce

[0045] In the above, a case where phase shifter 1 is designed to have a phase difference Δφ=90° has been described as a representative example, but the present invention is not limited to this representative example, and the phase difference Δφ can be changed as appropriate. Furthermore, in phase shifter 1, the waveguide width W1, the pattern width W2, the element lengths L3 and L4 in the phase adjustment regions of two phase adjustment units 4 and 5, the gap G1 of the slot waveguide, the thickness of core layer 3, and the like can be changed as appropriate according to the design of the phase difference Δφ.

[0046] For example, the change amount dn eff / dW to dn eff1 / dW, and the amount of change in the second phase adjustment unit 5 is dn eff / dW to dn eff2 At this time, the phase shifter 1 changes the amount of change dn eff The difference in absolute value of / dW, that is, dn eff The above parameters may be appropriately designed so that the difference between / dW is minimized.

[0047] dn eff / dW difference = ||dn eff1 / dW|-|dn eff2 / dW||···(3) Here, dn effThe difference between the phase shifts dn eff The present invention is not limited to the case where the difference in / dW is zero, but may be any case where the difference is one order of magnitude smaller than that of the comparative example. -7 or less, including cases where it can be considered nearly zero.

[0048] According to this embodiment, there are two optical paths L1 and L2, and the two optical paths L1 and L2 are provided with phase adjustment units 4 and 5 having different structures, so that the change amount dn eff It is possible to keep the difference between the amount of change dn eff The difference between the width W1 and the width W2 of the waveguide and the element length L is not in a trade-off relationship, and the phase error φ error is reduced compared to the conventional case.

[0049] In addition, in phase adjuster 1, the two phase adjusters 4 and 5 are configured with the common cladding layer 2 and core layer 3, so no difference in processing error due to material differences occurs in the optical paths L1 and L2. Therefore, in phase adjuster 1, the difference in processing error between the waveguide width W1 of first phase adjuster 4 and the pattern width W2 of second phase adjuster 5 is reduced compared to a case in which the constituent materials of cladding layer 2 and core layer 3 are different in optical paths L1 and L2, and an effect of reducing manufacturing costs is also obtained.

[0050] Second embodiment The phase adjuster 1 of the second embodiment will be described with reference to FIG.

[0051] 11, phase adjuster 1 of the present embodiment differs from that of the first embodiment in that first phase adjuster 4 includes two dummy patterns 6. This difference will be mainly described in this embodiment.

[0052] In the present embodiment, the first phase adjustment section 4 has two dummy patterns 6 formed in the vicinity of the second core layer 33 .

[0053] The two dummy patterns 6 are formed, for example, on both sides of the phase adjustment region 42 sandwiching the second core layer 33. The two dummy patterns 6, for example, have a width in the first direction D1 that is the same as the element length L3 of the second core layer 33, and are arranged parallel to the second core layer 33 with the extension direction aligned. The width of the two dummy patterns 6 in the second direction D2 may be the same as the waveguide width W1 of the second core layer 33, or may be different. The distance between the dummy pattern 6 and the second core layer 33 in the second direction D2 may be the same as the gap G1 between the two pattern portions 36, or may be different. The two dummy patterns 6 are, for example, made of the same material as the core layer 3, and are formed in the same process as the core layer 3. The two dummy patterns 6 are, for example, linear pattern shapes with a constant width in the second direction D2, the same as the second core layer 33, but are not limited to this pattern shape and may be other shapes.

[0054] The two dummy patterns 6 are provided to bring the pattern density of the phase adjustment region 42 of the first phase adjustment unit 4 closer to the pattern density of the phase adjustment region 52 of the second phase adjustment unit 5, thereby matching the fill factor. As a result, in the phase adjuster 1 of this embodiment, the difference in manufacturing error between the waveguide width W1 and the pattern width W2 is reduced, and the phase error φ caused by the manufacturing error in the width of the core layer 3 is reduced. error It is possible to further reduce the

[0055] For example, when the core layer 3 does not have two dummy patterns 6, the phase adjustment region 42 has one second core layer 33, and the phase adjustment region 52 has two pattern portions 36. In this case, for example, when the waveguide width W1 is designed to be 0.78 μm and the pattern width W2 is designed to be 1.08 μm, the manufacturing error of the waveguide width W1 is ±30 nm, and the manufacturing error of the pattern width W2 is ±20 nm, and the manufacturing error value is different. This manufacturing error difference is caused by the difference in density of the pattern of the core layer 3, and is reduced by making the pattern density closer. The "density of the pattern" here means the ratio of the area occupied by the pattern of the core layer 3 in a predetermined area of ​​the phase adjustment region when viewed from above. In this embodiment, the phase adjuster 1 forms two dummy patterns 6, and the phase adjustment region 42 has a pattern shape having three straight line portions made of a high refractive index material, which is close to the pattern density of the phase adjustment region 52 having two pattern portions 36. Therefore, for example, in the above design example, the manufacturing error of the waveguide width W1 is smaller than ±30 nm, and is close to the manufacturing error of the pattern width W2.

[0056] According to this embodiment, the phase adjuster 1 can obtain the same effect as that of the first embodiment. Moreover, in the phase adjuster 1, the first phase adjustment unit 4 has two dummy patterns 6, and the density difference of the patterns in the phase adjustment regions 42 and 52 is reduced. Therefore, the difference in the manufacturing error between the waveguide width W1 and the pattern width W2 is reduced, and the phase error φ error In addition, the effect of further reducing the

[0057] Third embodiment The phase adjuster 1 of the third embodiment will be described with reference to FIGS.

[0058] 12 and 13, the phase shifter 1 of this embodiment differs from the first embodiment in that the first phase shifter 4 has three dummy patterns 6 and the second phase shifter 5 has two dummy patterns 7. This difference will be mainly described in this embodiment. Also, the dummy patterns 6 are basically the same as those in the second embodiment, so the difference from the second embodiment will be mainly described.

[0059] For the sake of distinction, dummy pattern 6 will be referred to as "first dummy pattern 6" and dummy pattern 7 will be referred to as "second dummy pattern 7" below.

[0060] In the present embodiment, the first phase adjustment section 4 has three first dummy patterns 6 arranged in parallel with the second core layer 33 in the phase adjustment region 42, as shown in FIG. 12. The first dummy patterns 6 are, for example, linear pattern shapes similar to the second core layer 33, and are arranged in parallel apart from each other with the same extension direction. The first dummy patterns 6 are, for example, arranged one on one side of the second core layer 33 and two on the other side. The distance between the first dummy patterns 6 in the second direction D2 and the distance between the first dummy patterns 6 and the second core layer 33 in the second direction D2 may be the same as the gap G1 between the two pattern sections 36, or may be different. Moreover, these distances may all be the same, or may be partially or entirely different. The first dummy patterns 6 are formed to make the pattern densities of the phase adjustment regions 42 and 52 approximately the same.

[0061] In the present embodiment, as shown in FIG. 13, for example, in the phase adjustment region 52, the second phase adjustment section 5 has second dummy patterns 7 formed on both sides of the two pattern sections 36 therebetween.

[0062] The second dummy pattern 7 is, for example, a linear pattern shape with a constant width in the second direction D2, similar to the linear portion of the pattern portion 36, and is arranged in parallel with the two pattern portions 36 with the extension direction aligned. The width of the second dummy pattern 7 in the second direction D2 may be the same as the pattern width W2, for example, or may be different. The second dummy pattern 7 is made of, for example, the same high refractive index material as the pattern portion 36, and is formed in the same process as the process of the core layer 3. The distance in the second direction D2 between the adjacent second dummy pattern 7 and the pattern portion 36 may be the same as the gap G1, or may be different.

[0063] The second dummy pattern 7 is adjusted so that, for example, the density of the pattern made of the high refractive index material in the phase adjustment region 42 is substantially the same as the density of the pattern made of the same material in the phase adjustment region 52. That is, in the phase adjuster 1 of this embodiment, the total number of the second core layers 33 and the first dummy patterns 6 in the phase adjustment region 42 is the same as the total number of the pattern portions 36 and the second dummy patterns 7 in the phase adjustment region 52. As a result, the densities of the patterns made of the high refractive index material in the phase adjustment regions 42 and 52 are the same, and the difference in manufacturing error between the waveguide width W1 and the pattern width W2 is further reduced than in the second embodiment.

[0064] According to this embodiment, the phase adjuster 1 can obtain the same effect as that of the first embodiment. In addition, in the phase adjuster 1, the phase adjustment units 4 and 5 each have a dummy pattern, and the pattern densities in the phase adjustment regions 42 and 52 are substantially the same, so that the difference in manufacturing error between the waveguide width W1 and the pattern width W2 is further reduced, and the phase error φ error The reduction effect is further improved.

[0065] (Fourth embodiment) The phase adjuster 1 of the fourth embodiment will be described with reference to FIGS.

[0066] 14 and 15, the phase shifter 1 of this embodiment differs from the first embodiment in that the widths of the dummy patterns 6 and 7 in the second direction D2, the gap width between the first dummy pattern 6 and the second core layer 33, and the gap width between the first dummy patterns 6 are adjusted. In this embodiment, this difference will be mainly described.

[0067] For the sake of convenience, the first dummy pattern 6 adjacent to the second core layer 33 will be referred to as the "first dummy pattern 61", and the first dummy pattern 61 adjacent to the second core layer 33 will be referred to as the "first dummy pattern 62". The width of the first dummy pattern 61 in the second direction D2 will be referred to as the "dummy width W3", and the width of the first dummy pattern 62 in the second direction D2 will be referred to as the "dummy width W4". The gap width between the first dummy pattern 61 and the second core layer 33 in the second direction D2 will be referred to as the "gap G2", and the gap width between adjacent first dummy patterns 6 in the second direction D2 will be referred to as the "gap G3". The width of the second dummy pattern 7 in the second direction D2 will be referred to as the "dummy width W5", and the gap width between the second dummy pattern 7 and the pattern portion 36 in the second direction D2 will be referred to as the "gap G4".

[0068] In the present embodiment, the first phase adjustment section 4 is designed so that the dummy widths W3 and W4 of the first dummy pattern 6 are different from the widths of other adjacent patterns, as shown in FIG. 14, for example. For example, when the second core layer 33 is designed with a waveguide width W1=0.78 μm, a pattern width W2=1.08 μm of the pattern section 36, and a gap G1=0.15 μm, the dummy width W3 of the first dummy pattern 61 is designed to have a value different from 0.78 μm. In addition, the dummy width W4 of the first dummy pattern 62 is designed to have a value different from the dummy width W3 of the first dummy pattern 6. As a result, the effective refractive index of the second core layer 33, which is a normal waveguide, is different from the effective refractive index of the adjacent first dummy pattern 61, and the light propagating through the second core layer 33 is suppressed from propagating to the first dummy pattern 61, thereby reducing the loss of light.

[0069] In this embodiment, the second phase adjustment section 5 is designed so that the dummy width W5 of the second dummy pattern 7 is different from the pattern width W2 of the adjacent pattern section 36, as shown in FIG.

[0070] In the above design example, it is more preferable to set the dummy width W3 to 1.08 μm, the dummy width W4 to 0.78 μm, the dummy width W5 to 0.78 μm, and the gaps G2, G3, and G4 to 0.15 μm. This makes the pattern density of the phase adjustment region 42 of the first phase adjustment unit 4 and the phase adjustment region 52 of the second phase adjustment unit 5 match, the manufacturing errors of the normal waveguide and the slot waveguide become the same, and the phase error φ error It is possible to further reduce the

[0071] According to this embodiment, the phase adjuster 1 can obtain the same effect as the first embodiment. In addition, in the phase adjuster 1, the phase adjustment units 4 and 5 each have a dummy pattern, and the pattern densities in the phase adjustment regions 42 and 52 are the same, so that the manufacturing errors of the waveguide width W1 and the pattern width W2 are the same, and the phase error φ error In addition, by making the waveguide width W1 of the second core layer 33 different from the dummy width W3 of the adjacent first dummy pattern 61, the propagation of light from the normal waveguide to the dummy pattern is suppressed, and the loss of light is reduced.

[0072] (Other embodiments) Although the present disclosure has been described based on the embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, and other combinations and forms including only one element, more than one, or less than one, are also within the scope and concept of the present disclosure.

[0073] In each of the above embodiments, it goes without saying that the elements constituting the embodiment are not necessarily essential, except when it is specifically stated that they are essential or when it is clearly considered essential in principle. In addition, in each of the above embodiments, when the numbers, values, amounts, ranges, etc. of the components of the embodiment are mentioned, they are not limited to the specific numbers, except when it is specifically stated that they are essential or when it is clearly limited to a specific number in principle. In addition, in each of the above embodiments, when the shapes, positional relationships, etc. of the components are mentioned, they are not limited to the shapes, positional relationships, etc., except when it is specifically stated that they are essential or when it is clearly limited to a specific shape, positional relationship, etc. in principle. [Explanation of symbols]

[0074] 2...cladding layer, 21...propagation portion, 3...core layer, 33...second core layer, 36...pattern portion, 4...first phase adjustment portion, 42...first phase adjustment region, 5...second phase adjustment portion, 52...first phase adjustment region, D1...first direction, D2...second direction, L1...first optical path, L2...second optical path, W1...waveguide width, W2...pattern width

Claims

1. A phase adjuster that imparts a predetermined phase difference between light in a first optical path (L1) and light in a second optical path (L2), A first phase adjustment unit (4) disposed in the first optical path; A second phase adjustment unit (5) disposed in the second optical path, The first phase adjustment section and the second phase adjustment section each include a clad layer (2) made of a clad material and a core layer (3) made of a high refractive index material having a refractive index higher than that of the clad material, The first phase adjustment section has a first phase adjustment region (42) made of the high refractive index material and equipped with a waveguide (33) in which the intensity of propagating light is maximized inside the high refractive index material, the second phase adjustment section has a second phase adjustment region (52) including two pattern sections (36) in which the high refractive index material is arranged adjacent to each other in parallel, and a propagation section (21) located in a gap between the two pattern sections of the cladding layer and propagating light; The propagation portion is a phase adjuster in which the intensity of the propagating light is maximized inside or at the boundary with the pattern portion.

2. A direction along a direction in which the waveguide extends on a plane on which the core layer is formed is defined as a first direction (D1), and a direction perpendicular to the first direction on the plane is defined as a second direction (D2), A width of the waveguide in the second direction is defined as a waveguide width (W1), and a width of the pattern portion in the second direction is defined as a pattern width (W2), The effective refractive index n of the waveguide with respect to the change in the waveguide width ｅｆｆ１ The change in ｅｆｆ１ / dW1, and the effective refractive index n ｅｆｆ２ The change in ｅｆｆ２ / dW2, The first phase adjustment unit and the second phase adjustment unit ｅｆｆ１ / dW1|-|dn ｅｆｆ２ 2. The phase adjuster according to claim 1, wherein a value of / dW2∥ is equal to or smaller than a predetermined value.

3. the first phase adjustment unit has a first dummy pattern (6) arranged adjacent to the waveguide and made of the high refractive index material; 2. The phase adjuster according to claim 1, wherein the second phase adjustment portion has a second dummy pattern (7) arranged adjacent to the pattern portion and made of the high refractive index material.

4. 4. The phase adjuster according to claim 3, wherein a total number of the waveguides and the first dummy patterns in the first phase adjustment section is the same as a total number of the pattern sections and the second dummy patterns in the second phase adjustment section.

5. On a plane on which the core layer is formed, a direction along a direction in which the waveguide is extended is defined as a first direction (D1), and a direction perpendicular to the first direction on the plane is defined as a second direction (D2), a width (W3) in the second direction of the first dummy pattern adjacent to the waveguide is equal to a pattern width (W2) which is a width of the pattern portion in the second direction, 5. The phase adjuster according to claim 3, wherein a width (W5) of the second dummy pattern in the second direction is equal to a waveguide width (W1) that is a width of the waveguide in the second direction.

6. a width (W3) in the second direction of the first dummy pattern adjacent to the waveguide is different from a width of the waveguide; 6. The phase adjuster according to claim 5, wherein a width (W5) of the second dummy pattern in the second direction is different from the pattern width.

7. The first phase adjustment unit has a conversion region (41) that is formed on a side where external light is incident on the first optical path relative to the first phase adjustment region and functions as a converter, 2. The phase adjuster according to claim 1, wherein the second phase adjustment section has two conversion regions (51, 53) formed on both sides of the second phase adjustment region.

8. 8. The phase adjuster of claim 7, wherein on a plane on which the core layer is formed, a direction along which the waveguide extends is defined as a first direction (D1), and a width (L3) of the first phase adjustment region in the first direction is equal to a width (L4) of the two pattern portions in the first direction.

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