A temperature compensation structure based on arrayed waveguide grating

Abstract

The present invention discloses a temperature compensation structure based on an arrayed waveguide grating. The temperature compensation structure based on an arrayed waveguide grating comprises: a bottom plate; an arrayed waveguide grating chip, which is cut into a first sub-section and a second sub-section along a slit; a secondary temperature compensation structure, comprising a first compensation rod, a second compensation rod, a third compensation rod, a fourth compensation rod and a fifth compensation rod, which are fixedly connected in sequence in a bow shape, the first compensation rod is fixedly connected to the first sub-section, and the fifth compensation rod is fixedly connected to the bottom plate; the thermal expansion coefficients of the first compensation rod and the third compensation rod are greater than the thermal expansion coefficients of the fourth compensation rod, and the thermal expansion coefficients of the fourth compensation rod are greater than the thermal expansion coefficients of the second compensation rod and the fifth compensation rod. The technical solution provided by the embodiment of the present invention can make the movement rate of the first sub-section in the arrayed waveguide grating chip increase with the increase of temperature, thereby effectively improving the wavelength drift of each temperature section and realizing effective secondary compensation.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of optical communications, and in particular to a temperature compensation structure based on an arrayed waveguide grating. Background Art

[0002] Arrayed Waveguide Grating (AWG) is an important optical device based on planar optical waveguide integration technology. With the changes in market demand and the advancement of technology, AWG has begun to transition from the first generation of heated type to the second generation of athermal type, that is, AWG does not need to be heated when working. The advantages are: eliminating complex temperature control circuits and heaters, reducing costs and enhancing the stability of the device. It is a purely passive device, saving energy consumption in the communication system, and has a wider range of applications.

[0003] The usual athermal AWG uses temperature compensation technology to maintain wavelength stability, such as connecting the input waveguide with a metal compensation rod, and moving the input waveguide under the drive of the rod's thermal expansion and contraction to compensate for the wavelength drift with temperature. These compensation methods are all linear compensation for the temperature characteristics of the wavelength. However, the actual AWG wavelength offset curve with temperature is not linear, such as Figure 1 As shown. Therefore, these compensation methods can only maintain the stability of the wavelength within a limited temperature range, and are difficult to meet the requirements for applications with a larger temperature change range such as outdoors. To solve the above problems, the patent application document with publication number CN101576637B proposes a temperature compensation structure capable of secondary compensation, but the compensation of this structure is symmetrical, that is, when it contracts due to cold, the lower the temperature, the smaller the movement change, and when it expands due to heat, the higher the temperature, the smaller the movement change, which is inconsistent with the temperature characteristic curve of the arrayed waveguide grating chip, so effective secondary compensation cannot be performed. Summary of the invention

[0004] The present invention provides a temperature compensation structure based on an array waveguide grating, which can effectively perform secondary compensation on wavelength drift caused by temperature change.

[0005] An embodiment of the present invention provides a temperature compensation structure based on an arrayed waveguide grating, comprising:

[0006] Base plate;

[0007] An arrayed waveguide grating chip, comprising an incident slab waveguide, an arrayed waveguide and an exit slab waveguide, wherein one end of the arrayed waveguide is connected to the incident slab waveguide, and the other end is connected to the exit slab waveguide, the arrayed waveguide grating chip is cut into a first sub-portion and a second sub-portion along a slit, the slit runs through the incident slab waveguide and is perpendicular to the extension direction of the incident light in the incident slab waveguide, the first sub-portion comprises a partial structure of the incident slab waveguide, and the second sub-portion comprises another partial structure of the incident slab waveguide, the arrayed waveguide and the exit slab waveguide; the second sub-portion is fixed to the bottom plate;

[0008] The secondary temperature compensation structure includes a first compensation rod, a second compensation rod, a third compensation rod, a fourth compensation rod and a fifth compensation rod which are fixedly connected in sequence in a bow shape, wherein the second compensation rod, the third compensation rod and the fourth compensation rod are all L-shaped, and under normal temperature, the second compensation rod is in stress-free contact with the fourth compensation rod, the first compensation rod is fixedly connected to the first sub-portion, and the fifth compensation rod is fixedly connected to the bottom plate; the thermal expansion coefficients of the first compensation rod and the third compensation rod are greater than the thermal expansion coefficient of the fourth compensation rod, and the thermal expansion coefficient of the fourth compensation rod is greater than the thermal expansion coefficient of the second compensation rod and the fifth compensation rod.

[0009] The arrayed waveguide grating-based temperature compensation structure provided by the embodiment of the present invention includes a bottom plate, an arrayed waveguide grating chip, including an incident slab waveguide, an arrayed waveguide and an exit slab waveguide, one end of the arrayed waveguide is connected to the incident slab waveguide, and the other end is connected to the exit slab waveguide, the arrayed waveguide grating chip is cut into a first sub-portion and a second sub-portion along a slit, the slit runs through the incident slab waveguide and is perpendicular to the extension direction of the incident light in the incident slab waveguide, the first sub-portion includes a partial structure of the incident slab waveguide, the second sub-portion includes another partial structure of the incident slab waveguide, the arrayed waveguide and the exit slab waveguide, The second sub-section is fixed on the bottom plate, and the secondary temperature compensation structure includes a first compensation rod, a second compensation rod, a third compensation rod, a fourth compensation rod and a fifth compensation rod which are fixedly connected in sequence in a bow shape, the second compensation rod, the third compensation rod and the fourth compensation rod are all L-shaped, under normal temperature, the second compensation rod and the fourth compensation rod are in stress-free contact, the first compensation rod is fixedly connected to the first sub-section, the fifth compensation rod is fixedly connected to the bottom plate, the thermal expansion coefficients of the first compensation rod and the third compensation rod are greater than the thermal expansion coefficients of the fourth compensation rod, and the thermal expansion coefficients of the fourth compensation rod are greater than the thermal expansion coefficients of the second compensation rod and the fifth compensation rod. The above-mentioned secondary temperature compensation structure can make the movement rate of the first sub-section in the arrayed waveguide grating chip increase with the increase of temperature, thereby effectively improving the wavelength drift of each temperature section and realizing effective secondary compensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required to describe the embodiments. Obviously, the drawings introduced are only drawings of a part of the embodiments to be described in the present invention, rather than all the drawings. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0011] Figure 1 is a graph showing the variation of the wavelength offset of the arrayed waveguide grating with temperature;

[0012] Figure 2 is a schematic structural diagram of a temperature compensation structure based on an arrayed waveguide grating provided by an embodiment of the present invention;

[0013] Figure 3 It is a schematic diagram of a top view of a two-stage temperature compensation structure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0014] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all of the contents, are shown in the accompanying drawings. It should be mentioned before discussing the exemplary embodiments in more detail that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow charts describe each operation (or step) as sequential processes, many of the operations therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of each operation can be rearranged. The process can be terminated when its operation is completed, but can also have additional steps not included in the accompanying drawings. The process can correspond to methods, functions, procedures, subroutines, subprograms, etc.

[0015] Figure 2 It is a structural schematic diagram of a temperature compensation structure based on an arrayed waveguide grating provided in an embodiment of the present invention. Figure 3 Schematic diagram of a top view of a secondary temperature compensation structure provided by an embodiment of the present invention. Figure 2As shown, the temperature compensation structure based on the arrayed waveguide grating includes a base plate 100, an arrayed waveguide grating chip, including an incident slab waveguide, an arrayed waveguide 222 and an output slab waveguide 223, one end of the arrayed waveguide 222 is connected to the incident slab waveguide, and the other end is connected to the output slab waveguide 223, the arrayed waveguide grating chip is cut into a first sub-section 210 and a second sub-section 220 along a slit 400, the slit 400 passes through the incident slab waveguide and is perpendicular to the extension direction of the incident light in the incident slab waveguide, the first sub-section 210 includes a partial structure of the incident slab waveguide, the second sub-section 220 includes another partial structure 221 of the incident slab waveguide, the arrayed waveguide 222 and the output slab waveguide 223, and the second sub-section 220 is fixed on the base plate 100. The secondary temperature compensation structure 300, specifically, as shown in FIG. Figure 2 and Figure 3 As shown, it includes a first compensation rod 310, a second compensation rod 320, a third compensation rod 330, a fourth compensation rod 340 and a fifth compensation rod 350 which are fixedly connected in sequence in a bow shape. The second compensation rod 320, the third compensation rod 330 and the fourth compensation rod 340 are all L-shaped. At room temperature, the second compensation rod 320 and the fourth compensation rod 340 are in stress-free contact. The first compensation rod 310 is fixedly connected to the first sub-section 210, and the fifth compensation rod 350 is fixedly connected to the bottom plate 100. The thermal expansion coefficients of the first compensation rod 310 and the third compensation rod 330 are greater than the thermal expansion coefficients of the fourth compensation rod 340, and the thermal expansion coefficients of the fourth compensation rod 340 are greater than the thermal expansion coefficients of the second compensation rod 320 and the fifth compensation rod 350.

[0016] It should be noted that if Figure 1 As shown, the wavelength offset of the arrayed waveguide grating per degree Celsius increases with increasing temperature. Normally, within a smaller temperature range, such as -5°C to 65°C, it can be approximated as a linear change, and the wavelength offset can be compensated using conventional compensation methods. However, when the temperature extends to -40°C to 85°C, at two extreme temperatures, the wavelength offset changes nonlinearly with temperature, and the conventional compensation method can no longer be used to compensate for the wavelength offset.

[0017] The temperature compensation structure provided in this embodiment can effectively compensate for the wavelength offset within a larger temperature range. The specific principle is as follows:

[0018] 1. The wavelength offset can be compensated by the displacement at the incident end

[0019] Specifically, according to the basic principle of arrayed waveguide grating, there is the following formula 1:

[0020] n s dsinθ i +n c Δl+n s dsinθo =mλ ------Formula 1

[0021] Among them, n s is the effective refractive index of the slab waveguide in the arrayed waveguide grating, n c is the effective refractive index of the arrayed waveguide 222 in the arrayed waveguide grating, Δl is the length difference of the arrayed waveguide 222, d is the spacing of the arrayed waveguide 222, and m is the diffraction order;

[0022] Under the small angle approximation, the derivatives of both sides of the equation 1 with respect to wavelength are taken, and the relationship between the central wavelength is used to obtain the following equation 2:

[0023]

[0024] At small angles, the following formula 3 exists:

[0025] x=Rθ o ------Formula 3

[0026] Where R is the focal length of the slab waveguide.

[0027] According to the above formula 2 and formula 3, we can get:

[0028]

[0029]

[0030] Among them, x is the displacement compensation amount at the incident end of the waveguide array grating, and T is the temperature.

[0031] It can be seen that in order to obtain the most accurate compensation, the change in the displacement compensation amount at the incident end of the waveguide array grating needs to be synchronized with the wavelength change of the array waveguide grating. The displacement compensation amount at the incident end of the waveguide array grating increases with the increase of the wavelength change, and decreases with the decrease of the wavelength change, that is, there is a corresponding relationship between the displacement compensation amount at the incident end of the waveguide array grating and the wavelength change.

[0032] 2. Specific principles

[0033] a. Temperature drop

[0034] According to the principle of thermal expansion and contraction, when the temperature drops, the fourth compensation rod 340 contracts. Since the fifth compensation rod 350 is fixed on the bottom plate 100, the contraction direction of the fourth compensation rod 340 points to the fifth compensation rod 350 along the extension direction of the first compensation rod 310. The third compensation rod 330 contracts. Since the third compensation rod 330 is fixedly connected to the fourth compensation rod 340, the contraction direction of the third compensation rod 330 deviates from the fifth compensation rod 350 along the extension direction of the first compensation rod 310. Similarly, when the first compensation rod 310 contracts, the contraction direction deviates from the fifth compensation rod 350 along the extension direction of the first compensation rod 310. Since the contraction directions of the third compensation rod 330 and the fourth compensation rod 340 are opposite, the third compensation rod 330 pushes the second compensation rod 320 to approach the fourth compensation rod 340. When the temperature continues to drop, since the second compensation rod 320 and the fourth compensation rod 340 are already pressed tightly, the displacement of the first sub-section 210 is the sum of the displacements of the first compensation rod 310 and the fourth compensation rod 340, and the displacement directions of the first compensation rod 310 and the fourth compensation rod 340 are opposite, and the displacement formula of the first sub-section 210 can be obtained as follows:

[0035]

[0036] Wherein, ΔL1(T) is the displacement of the first sub-section 210, L4(T) is the length of the first compensation rod 310 before the temperature change, is the thermal expansion coefficient of the first compensation rod 310, ΔT is the temperature change, L6(T) is the length of the fourth compensation rod 340 before the temperature change, is the thermal expansion coefficient of the fourth compensation rod 340 .

[0037] It can be seen that compared with the temperature compensation structure that only includes the first compensation rod 310, the displacement change rate of the first sub-section 210 corresponding to the temperature compensation structure in this embodiment is smaller, thereby reducing the displacement change rate of the first sub-section 210 in the low-temperature section, so that the change rate in the low-temperature section and the wavelength drift of the arrayed waveguide grating are roughly consistent, thereby realizing secondary compensation in the low-temperature section.

[0038] b. Temperature rise

[0039] Similarly, according to the principle of thermal expansion and contraction, as the temperature rises, the third compensation rod 330 expands, so that the third compensation rod 330 drives the second compensation rod 320 to move along the extension direction of the first compensation rod 310 toward the side of the fifth compensation rod 350, and the second compensation rod 320 and the fourth compensation rod 340 are no longer in contact. The fourth compensation rod 340 expands. Since the fifth compensation rod 350 is fixedly connected to the bottom plate 100, the expansion direction of the fourth compensation rod 340 is away from the fifth compensation rod 350 along the extension direction of the first compensation rod 310. Similarly, the first compensation rod 310 expands in the same direction as the expansion direction of the third compensation rod 330. At this time, the displacement of the first sub-section 210 is the sum of the displacements of the first compensation rod 310, the third compensation rod 330 and the fourth compensation rod 340. According to the expansion directions of the above three compensation rods, the following displacement formula of the first sub-section 210 can be obtained:

[0040]

[0041] Wherein, ΔL1(T) is the displacement of the first sub-section 210, L4(T) is the length of the first compensation rod 310 before the temperature change, is the thermal expansion coefficient of the first compensation rod 310, ΔT is the temperature change, L6(T) is the length of the fourth compensation rod 340 before the temperature change, is the thermal expansion coefficient of the fourth compensation rod 340, L7(T) is the length of the third compensation rod 330 before the temperature changes, is the thermal expansion coefficient of the third compensation rod 330 .

[0042] It can be seen that a reasonable selection of the lengths of the first compensation rod 310, the third compensation rod 330 and the fourth compensation rod 340 can make the displacement change rate of the first sub-section 210 greater than the displacement change rate corresponding to the temperature compensation structure including only the first compensation rod 310, thereby accelerating the displacement change rate of the first sub-section 210 in the high temperature section, so that the change rate in the high temperature section is roughly consistent with the wavelength drift of the arrayed waveguide grating, thereby realizing secondary compensation in the high temperature section.

[0043] The temperature compensation structure based on arrayed waveguide grating provided in this embodiment includes a base plate 100, an arrayed waveguide grating chip, including an incident slab waveguide, an arrayed waveguide 222 and an output slab waveguide 223, one end of the arrayed waveguide 222 is connected to the incident slab waveguide, and the other end is connected to the output slab waveguide 223, the arrayed waveguide grating chip is cut into a first sub-section 210 and a second sub-section 220 along a slit 400, the slit 400 passes through the incident slab waveguide and is perpendicular to the extension direction of the incident light in the incident slab waveguide, the first sub-section 210 includes a partial structure of the incident slab waveguide, the second sub-section 220 includes another part 221 structure of the incident slab waveguide, the arrayed waveguide 222 and the output slab waveguide 223, and the second sub-section 220 is fixed to the base plate 100. The secondary temperature compensation structure 300 includes a first compensation rod 310, a second compensation rod 320, a third compensation rod 330, a fourth compensation rod 340 and a fifth compensation rod 350 which are fixedly connected in sequence in a bow shape. The second compensation rod 320, the third compensation rod 330 and the fourth compensation rod 340 are all L-shaped. At room temperature, the second compensation rod 320 and the fourth compensation rod 340 are in stress-free contact. The first compensation rod 310 is fixedly connected to the first sub-section 210, and the fifth compensation rod 350 is fixedly connected to the bottom plate 100. The thermal expansion coefficients of the first compensation rod 310 and the third compensation rod 330 are greater than the thermal expansion coefficients of the fourth compensation rod 340, and the thermal expansion coefficients of the fourth compensation rod 340 are greater than the thermal expansion coefficients of the second compensation rod 320 and the fifth compensation rod 350. The secondary temperature compensation structure 300 can make the movement rate of the first sub-section 210 in the arrayed waveguide grating chip increase with the increase of temperature, thereby effectively improving the wavelength drift of each temperature section and realizing effective secondary compensation.

[0044] See also Figure 2 and Figure 3 The third compensation rod 330 further includes an elastic terminal 331 , the extendable direction of the elastic terminal 331 is the same as the extending direction of the first compensation rod 310 , and the third compensation rod 330 is connected to the second compensation rod 320 via the elastic terminal 331 .

[0045] It should be noted that the elastic terminal 331 can realize the elastic connection between the second compensation rod 320 and the third compensation rod 330, so as to avoid the second compensation rod 320 or the third compensation rod 330 from being deformed in an unchangeable manner due to compression of the low temperature section.

[0046] For example, Figure 2 As shown, the elastic terminal 331 may be a Z-shaped hollow structure. It is understandable that any structure that can achieve the beneficial effects of the elastic terminal 331 is within the protection scope of this embodiment, and this embodiment does not make any specific limitation.

[0047] Continue to see Figure 2 and Figure 3The second compensation rod 320 may include a first side 321 and a second side 322 extending in directions perpendicular to each other.

[0048] Optionally, the first compensation rod 310 and the third compensation rod 330 may be made of the same material.

[0049] It should be noted that such a design is conducive to simplifying the manufacturing process of the temperature compensation structure. Exemplarily, the thermal expansion coefficient of the material of the first compensation rod 310 and the third compensation rod 330 can be about 20 ppm.

[0050] Exemplarily, the material of the first compensation rod 310 and the third compensation rod 330 may be aluminum alloy.

[0051] It can be understood that in the present embodiment, the materials of the first compensation rod 310 and the third compensation rod 330 can also be other materials. In addition, the materials of the first compensation rod 310 and the third compensation rod 330 can also be different. Any material that can satisfy the relative relationship between the expansion coefficients of each compensation rod in the temperature compensation structure is within the protection scope of this embodiment.

[0052] Exemplarily, the material of the fourth compensation rod 340 may be iron or stainless steel.

[0053] Similarly, in other implementations of this embodiment, the material of the fourth compensation rod 340 may also be other materials. Any material that can satisfy the relative relationship between the expansion coefficients of the compensation rods in the temperature compensation structure is within the protection scope of this embodiment.

[0054] Exemplarily, the thermal expansion coefficient of the material of the fourth compensation rod 340 may be between 10 ppm and 15 ppm.

[0055] Optionally, the second compensation rod 320 and the fifth compensation rod 350 may be made of the same material.

[0056] It should be noted that such a design can also achieve the beneficial effect of simplifying the preparation process of the temperature compensation structure.

[0057] Exemplarily, the material of the second compensation rod 320 and the fifth compensation rod 350 may be Invar.

[0058] In other implementations of this embodiment, the materials of the second compensation rod 320 and the fifth compensation rod 350 can also be other materials. In addition, the materials of the second compensation rod 320 and the fifth compensation rod 350 can also be different. Any material that can meet the relative relationship between the expansion coefficients of each compensation rod in the temperature compensation structure is within the protection scope of this embodiment.

[0059] Exemplarily, the operating temperature range of the temperature compensation structure may be -40° to 85°.

[0060] It should be noted that, within a relatively large temperature range of -40° to 85°, the temperature compensation structure provided in this embodiment can achieve effective secondary compensation and improve the wavelength drift phenomenon.

[0061] Optionally, the first compensation rod 310 and the fifth compensation rod 350 are both connected to the bottom plate 100 by epoxy resin glue.

[0062] It should be noted that in other implementations of this embodiment, other structures can also be used to achieve the connection between the first compensation rod 310 and the fifth compensation rod 350 and the base plate 100, as long as it can be ensured that no relative movement occurs between the two connected components after the connection. This embodiment does not make specific limitations on this.

[0063] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A temperature compensation structure based on an arrayed waveguide grating, characterized in that: include: Base plate; An arrayed waveguide grating chip, comprising an incident slab waveguide, an arrayed waveguide and an exit slab waveguide, wherein one end of the arrayed waveguide is connected to the incident slab waveguide, and the other end is connected to the exit slab waveguide, the arrayed waveguide grating chip is cut into a first sub-portion and a second sub-portion along a slit, the slit runs through the incident slab waveguide and is perpendicular to the extension direction of the incident light in the incident slab waveguide, the first sub-portion comprises a partial structure of the incident slab waveguide, and the second sub-portion comprises another partial structure of the incident slab waveguide, the arrayed waveguide and the exit slab waveguide; the second sub-portion is fixed to the bottom plate; The secondary temperature compensation structure comprises a first compensation rod, a second compensation rod, a third compensation rod, a fourth compensation rod and a fifth compensation rod which are fixedly connected in sequence in a bow shape, wherein the second compensation rod, the third compensation rod and the fourth compensation rod are all L-shaped, and under normal temperature, the second compensation rod is in stress-free contact with the fourth compensation rod, the first compensation rod is fixedly connected to the first sub-portion, and the fifth compensation rod is fixedly connected to the bottom plate; the thermal expansion coefficients of the first compensation rod and the third compensation rod are greater than the thermal expansion coefficient of the fourth compensation rod, and the thermal expansion coefficient of the fourth compensation rod is greater than the thermal expansion coefficients of the second compensation rod and the fifth compensation rod; The third compensation rod further includes an elastic terminal, the extendable direction of the elastic terminal is the same as the extending direction of the first compensation rod, and the third compensation rod is connected to the second compensation rod via the elastic terminal; The first compensation rod and the third compensation rod are made of the same material; The second compensating rod and the fifth compensating rod are made of the same material.

2. The temperature compensation structure according to claim 1, characterized in that: The second compensation rod includes a first side and a second side extending in directions perpendicular to each other.

3. The temperature compensation structure according to claim 1, characterized in that: The first compensation rod and the third compensation rod are made of aluminum alloy.

4. The temperature compensation structure according to claim 1, characterized in that: The fourth compensation rod is made of iron or stainless steel.

5. The temperature compensation structure according to claim 1, characterized in that: The second compensation rod and the fifth compensation rod are made of Invar.

6. The temperature compensation structure according to claim 1, characterized in that: The operating temperature range of the temperature compensation structure is -40° to 85°.

7. The temperature compensation structure according to claim 1, characterized in that: The first compensation rod and the fifth compensation rod are both connected to the bottom plate by epoxy resin glue.

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