JP4777382B2 - Optical module - Google Patents

Description

  The present invention relates to an optical module, and more particularly to an optical module that suppresses stress applied to a PLC chip due to thermal deformation of a substrate or a mount and prevents optical characteristic deterioration.

  In recent years, the demand for large-capacity optical communication systems using wavelength division multiplexing is increasing due to an increase in traffic volume centered on the Internet. As a component for optical communication that realizes a large-capacity optical communication system, a high-performance optical module that is produced by a planar lightwave circuit (PLC) technology and combines optical functional elements having a plurality of functions is attracting expectations. Wavelength multiplexer / demultiplexer arrayed waveguide diffraction grating (AWG), variable optical attenuator (VOA) array and monitor PD array integrated optical multiplexer / demultiplexer with variable optical attenuator (V-AWG) Yes. These high-performance optical modules have recently been particularly applied to metro networks in large-capacity optical communication systems, and thus there is a strong demand for miniaturization, high density, and high functionality. In order to meet these requirements, single-chip integrated high-performance optical modules in which optical functional elements having a plurality of functions are integrated on a single substrate have been developed. However, since a single-chip integrated high-performance optical module integrates a plurality of optical functional elements having different functions on a single substrate, the manufacturing process becomes complicated, and individual optical functional elements are Since there is a problem that it cannot be manufactured with a waveguide structure, an optical functional element is mainly formed by forming optical functional elements on a plurality of PLC substrates with respective optimum manufacturing processes and waveguide structures, and connecting them so as to optically couple them. It is manufactured.

  FIG. 3 shows a configuration example of an optical module in which optical waveguide end faces of a plurality of PLC chips are butted and optically connected. 3A is a top view and FIG. 3B is a side view. The PLC chip 2 and the PLC chip 3 are connected so that the output optical waveguide array 5b of the PLC chip 2 and the input optical waveguide array 7a of the PLC chip 3 are optically coupled. The input optical waveguide array 5a of the PLC chip 2 is connected to be optically coupled to the optical fiber array 4a, and the output optical waveguide 7b of the PLC chip 3 is connected to be optically coupled to the optical fiber 4b. The input optical waveguide array 5a and the output optical waveguide array 5b are connected via the VOA array 6, and the input optical waveguide array 7a and the output optical waveguide 7b are connected via the AWG 8. A convex portion is formed on the substrate 1, the PLC chip 2 is directly fixed to the convex portion of the substrate 1, and the PLC connection portion and the substrate 1 are connected to the PLC chip 3, which is arranged to float from the mount 1. It is held by the elastic adhesives 9a and 9b stacked on top.

  In this method, since the PLC chips are not connected by optical fibers, the number of fiber connection processes is reduced, and no fiber member is required, so that the cost can be reduced. It becomes possible. Further, since one PLC chip 2 is directly fixed on the convex portion of the substrate 1 and the other PLC chip 3 is arranged in a floating state on the mount 1, the connection loss between the PLC chips is stable. It has been improved. In other words, due to thermal deformation of the mount, force applied from the outside of the mount, etc., an excessive load is applied to the connection part between the PLC chips, and an axis shift occurs between the waveguides on the two PLC chips, and the loss varies. Is suppressed. Furthermore, since the floated PLC chip 3 is held at both ends by the elastic adhesives 9a and 9b stacked on the substrate 1, the vibration / impact resistance is improved. Furthermore, the vibration / impact strength can be further improved by filling a filler between the PLC chip 3 and the substrate 1. (See Patent Document 1).

  It is desirable that the substrate 1 to which the PLC chip is fixed has the same thermal expansion coefficient as that of the PLC chip so as not to deteriorate the optical characteristics of the PLC chip by applying stress to the PLC chip by thermal deformation. A PLC chip is generally formed on a substrate made of an inorganic material having a smaller thermal expansion coefficient than that of a general metal material such as aluminum such as silicon or quartz, but has a low thermal expansion coefficient equivalent to those of silicon or quartz. Generally, a metal material having is expensive. Therefore, if the entire substrate is simply made of a material having a low thermal expansion coefficient in order to make the thermal expansion coefficient coincide with that of the PLC chip, the manufacturing cost is increased. Therefore, as shown in FIG. 4, the convex portion is deleted from the substrate 1, the mount A10 is manufactured with a material having a low thermal expansion coefficient different from the substrate material, and fixed on the substrate 1 to form the convex portion. A mounting method for fixing the PLC chip 2 on top is used. 4A is a top view, and FIG. 4B is a side view. Other than the above, the configuration is the same as the configuration example of the optical module in FIG. In this mounting method, only the mount A10 needs to be manufactured with a material having a low thermal expansion coefficient, and the amount of the material having a low thermal expansion coefficient is reduced compared to the case where the entire substrate 1 is manufactured with a material having a low thermal expansion coefficient. Manufacturing costs can be kept low.

JP 2006-243391 A

  However, in the case of the structure shown in FIGS. 3 and 4, when the substrate 1 for fixing the PLC chip 2 or the mount A10 is changed to a material having a low thermal expansion coefficient, the thermal expansion coefficient of the elastic adhesive is generally the substrate 1 or Since the coefficient of thermal expansion of the metal material composing the mount A10 is larger, when a temperature change occurs, the difference in thermal deformation in the vertical direction between the substrate 1 or the mount A10 and the elastic adhesives 9a and 9b There was a problem that the vertical positions of the PLC chip 2 and the PLC chip 3 were not matched. That is, there is a problem in that the vertical optical axis shift occurs in the output optical waveguide array 5b of the PLC chip 2 and the input optical waveguide array 7a of the PLC chip 3, and the loss stability deteriorates.

  In addition, since the substrate 1 and the mount A10 having different thermal expansion coefficients are fixed, the substrate 1 and the mount A10 fixed by the bimetal effect are warped when the temperature changes, and accordingly, the substrate 1 and the mount A10 are fixed on the mount A10. Further, the PLC chip 2 is warped. Accordingly, there is a problem that stress is applied to the PLC chip 2 and the characteristics of the PLC chip deteriorate. Further, the PLC chip 3 of the PLC chip 2 and the vicinity of the connection part are inclined due to warpage, and the PLC 3 also tends to incline, and the PLC chip 3 is held on the substrate 1 by the elastic adhesives 9a and 9b. In this case, a force is applied to the connecting portion between the PLC chip 2 and the PLC chip 3 without being able to tilt freely, so that the output optical waveguide array 5b of the PLC chip 2 and the input optical waveguide array 7a of the PLC chip 3 have a vertical axis. There was a problem that a shift occurred and the loss stability deteriorated.

  In addition, when a material having a low thermal expansion coefficient equivalent to that of the PLC chips 2 and 3 is not used for the substrate 1, the horizontal expansion of the substrate 1 and the horizontal direction of the PLC chip 2 and the PLC chip 3 when a temperature change occurs. Since the thermal expansion in the direction is different, a force in the direction of peeling the PLC chip 2 and the PLC chip 3 is applied to the connection surface between the PLC chip 2 and the PLC chip 3, and the output optical waveguide array 5b of the PLC chip 2 and the PLC chip 3 There has been a problem that the input optical waveguide array 7a is displaced in the vertical direction and delaminated, resulting in deterioration of loss stability.

  The present invention has been made in view of such problems. The object of the present invention is to reduce the force applied to the connection portion of the PLC chip or the PLC chip by thermal deformation of the substrate or the mount, and to reduce the loss and characteristics. Is to provide a low-cost optical module with high stability.

In order to achieve such an object, the invention described in claim 1 is an optical module, and includes a first planar lightwave circuit (PLC) chip, a second PLC chip, a first mount, and a substrate. The first PLC chip is fixed to the first mount, the end surface of the second PLC chip is abutted against the end surface of the first PLC chip, and is connected so as to be optically coupled . The first mount is fixed to the substrate at one end of the first mount on the connection surface side of the first PLC chip and the second PLC chip, and is fixed to the substrate movably in a horizontal plane at the other end. And an end of the second PLC chip opposite to the end face to which the first PLC chip is connected is fixed to the second mount by an elastic adhesive, and the second mount is 2 Mau The first mount is fixed to the substrate at one end of the first and the other end is fixed to the substrate movably in a horizontal plane, and the first mount is connected to the first PLC chip and the second PLC chip from the connection surface. the length l _e of up to the first fixed position closest to the connection surface among the fixed position fixed to the substrate, the thermal expansion coefficient of the first PLC chip k _e, from the connecting surface to the elastic adhesive A length l _f , a thermal expansion coefficient k _f of the second PLC chip, a length l _c from a second fixing position where the second mount is fixed to the substrate to the connection surface, and a thermal expansion of the substrate coefficient k _c, the thermal expansion coefficient k _b of the second mount, the length l _b from the second fixed position to the elastic adhesive is characterized by satisfying the relationship of formula (B).
(For l _f ≧ l _c) (Formula _{B) l e · k e +} l f · k f = (l e + l c) · k c + l b · k b
_{l e · k e + l f} · k f = ( the case of _{l f <l c) (l} e + l c) · k c -l b · k b

  In another aspect, the optical module according to claim 1 is characterized in that the first PLC chip and the first mount have the same thermal expansion integer.

The invention according to claim 2 is an optical module, which includes a first planar lightwave circuit (PLC) chip, a second PLC chip, a first mount, and a substrate, wherein the first PLC chip is the optical module. The first mount is fixed to the first mount, and the end face of the second PLC chip is abutted with the end face of the first PLC chip so as to be optically coupled. The first mount is connected to the first mount of the first mount. The first PLC chip and the second PLC chip are fixed to the substrate at one end on the connection surface side, and are fixed to the substrate at the other end so as to be movable in a horizontal plane. The end opposite to the end face to which the first PLC chip is connected is fixed to the second mount by an elastic adhesive, and the thickness d _a of the first mount, the thickness of the second mount d _b, the second The distance d _d between opposite faces of the PLC chip and the second mount, the thermal expansion of the first mount of the thermal expansion coefficient k _a, the thermal expansion coefficient of the second mount k _b, and the elastic adhesive The coefficient k _d satisfies the relationship of the formula (A).
(Formula A) d _a · k _a = d _b · k _b + d _d · k _d
.

According to a third aspect of the invention, in the optical module according to claim 1, wherein said thickness d _a of the first mount, the thickness d _b of the second mount, the second PLC chip first the distance d _d between opposite faces of the second mount, the thermal expansion coefficient of the first mount k _a, the thermal expansion coefficient of the second mount k _b, and the thermal expansion coefficient k _d of the elastic adhesive, The relationship of the formula (A) is satisfied.
(Formula A) d _a · k _a = d _b · k _b + d _d · k _d

According to a fourth aspect of the present invention, in the optical module according to the third aspect , the thermal expansion coefficients k _a , k _b , k _c , k _e and k _f satisfy the relationship of the formula (C). And
(Formula C) k _c > k _a , k _b , k _e , k _f

The invention according to claim 5 is an optical module, which includes a first PLC chip, a second PLC chip, a mount, and a substrate, and an end face of the first PLC chip is provided with the second PLC chip . End faces are connected to be optically coupled to each other, the substrate has a convex portion, the first PLC chip is fixed to the convex portion, and the first PLC chip of the second PLC chip is An end opposite to the connected end face is fixed to the second mount by an elastic adhesive, the mount is fixed to the substrate at one end of the mount, and is movably movable in a horizontal plane at the other end. A first fixing that is fixed to the substrate and is closest to the connection surface among the fixed positions where the first PLC chip is fixed to the substrate from the connection surface of the first PLC chip and the second PLC chip. position The length l _e in the thermal expansion coefficient of the first PLC chip k _e, the length l _f from the connecting surface to the elastic adhesive, the thermal expansion coefficient of the second PLC chip k _f, the mounting the length l _c of the second fixed position fixed to said substrate to said connecting surface, the thermal expansion coefficient k _c of the substrate, the thermal expansion coefficient k _b of the mounting, from the second fixed position elastic adhesive the length l _b of up agent, and satisfies a relationship of formula (B).
(For l _f ≧ l _c) (Formula _{B) l e · k e +} l f · k f = (l e + l c) · k c + l b · k b
_{l e · k e + l f} · k f = ( the case of _{l f <l c) (l} e + l c) · k c -l b · k b

The invention according to claim 6 is an optical module, which includes a first PLC chip, a second PLC chip, a first mount, a second mount, and a substrate. The end face of the second PLC chip is abutted to the end face and connected so as to be optically coupled, the first PLC chip is fixed to the first mount, the first mount is fixed to the substrate, An end of the second PLC chip opposite to the end face to which the first PLC chip is connected is fixed to the second mount by an elastic adhesive, and the second mount is the second mount. One end of the first PLC chip is fixed to the substrate, and the other end is fixed to the substrate movably in a horizontal plane. The first mount is connected to the substrate from the connection surface of the first PLC chip and the second PLC chip. In The length of the boss was length l _e of up to the first fixed position closest to the connecting surface within the fixed position, the thermal expansion coefficient k _e of the first PLC chip, from the connecting surface to the elastic adhesive l _f , the thermal expansion coefficient k _f of the second PLC chip, the length l _c from the second fixed position where the second mount is fixed to the substrate to the connection surface, the thermal expansion coefficient k of the substrate _c, the thermal expansion coefficient k _b of the second mount, the length l _b from the second fixed position to the elastic adhesive is characterized by satisfying the relationship of formula (B).
(For l _f ≧ l _c) (Formula _{B) l e · k e +} l f · k f = (l e + l c) · k c + l b · k b
_{l e · k e + l f} · k f = ( the case of _{l f <l c) (l} e + l c) · k c -l b · k b

  In another aspect, the optical module according to claim 8 is characterized in that the first PLC chip and the first mount have the same thermal expansion integer.

The invention according to claim 7 is an optical module, which includes a first PLC chip, a second PLC chip, a mount, and a substrate, and an end face of the second PLC chip on an end face of the first PLC chip . Are connected so as to be optically coupled, the substrate has a convex portion, the first PLC chip is fixed to the convex portion, and the first PLC chip of the second PLC chip is connected An end opposite to the formed end surface is fixed to the mount with an elastic adhesive, and the mount is fixed to the substrate. The thickness d _{a of} the convex portion, the thickness d _{b of the} mount, the second A distance d _d between the PLC chip and the facing surface of the mount, a thermal expansion coefficient ka of the convex part, a thermal expansion coefficient k _{b of} the mount, and a thermal expansion coefficient k _d of the elastic adhesive are _expressed by the formula (A ) Is satisfied.
(Formula A) d _a · k _a = d _b · k _b + d _d · k _d

The invention according to claim 8 is an optical module, comprising a first PLC chip, a second PLC chip, a first mount, a second mount, and a substrate, wherein the first PLC chip The end face of the second PLC chip is abutted to the end face and connected so as to be optically coupled, the first PLC chip is fixed to the first mount, the first mount is fixed to the substrate, An end portion of the second PLC chip opposite to the end face to which the first PLC chip is connected is fixed to the second mount by an elastic adhesive, the second mount is fixed to the substrate, The thickness d _a of the first mount, the thickness d _{b of} the second mount, the distance d _d between the second PLC chip and the opposing surface of the second mount, the heat of the first mount expansion coefficient k _a, the second mount Thermal expansion coefficient k _b, and the thermal expansion coefficient k _d of the elastic adhesive is characterized by satisfying the relationship of formula (A).
(Formula A) d _a · k _a = d _b · k _b + d _d · k _d

  In another aspect, the optical module according to claim 10 is characterized in that the first PLC chip and the first mount have the same thermal expansion integer.

  According to the present invention, it is possible to reduce the force applied to the PLC chip or the connection part of the PLC chip due to thermal deformation of the substrate or the mount, and to realize a low-cost optical module with high loss and stability of characteristics. become.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1A shows a top view of an optical module according to an embodiment of the present invention, and FIG. 1B shows a side view of the optical module of FIG. The PLC chip 2 and the PLC chip 3 are connected so that the output optical waveguide array 5b of the PLC chip 2 and the input optical waveguide array 7a of the PLC chip 3 are optically coupled. The input optical waveguide array 5a of the PLC chip 2 is connected to be optically coupled to the optical fiber array 4a, and the output optical waveguide 7b of the PLC chip 3 is connected to be optically coupled to the optical fiber 4b. The input optical waveguide array 5a and the output optical waveguide array 5b are connected via the VOA array 6, and the input optical waveguide array 7a and the output optical waveguide 7b are connected via the AWG 8.

  Mount A10 and mount B11 are fixed to the upper surface of substrate 1, and PLC chip 2 is fixed to the upper surface of mount A10. The thickness of the mount A10 is smaller than the thickness of the mount B11, and the PLC chips 3 connected to the PLC chip 2 and arranged so as to float from the mount B11 are elastic adhesives 9a and 9b stacked on the mount B11. Is held by. The mount A10 is completely fixed to the substrate 1 with a fixing screw 12a, and is fixed to the substrate 1 with a fixing screw 12b so that it can freely move within a plane parallel to the top surface of the mount A10. The mount B11 is completely fixed to the substrate 1 with a fixing screw 13a, and is fixed to the substrate 1 with a fixing screw 13b so as to be freely movable in a plane parallel to the upper surface of the mount B11.

The effects obtained in this embodiment will be described in detail. Hereinafter, a case where the temperature changes from T ₀ to T ₀ + ΔT will be considered.

First, a method for suppressing the vertical axis misalignment at the PLC connecting portions of the PLC chips 2 and 3 caused by different thermal deformations of the substrate 1 and the mount A10 will be described. Substrate 1 and the mount A10 at the temperature T is, the fixing screws 12a, when it is completely fixed at 12b, and the coefficient of thermal expansion of the substrate 1 and the mount A10 as k _1, k ₂ respectively, the fixing screws substrate 1 at a temperature T If the length from the hole for 12a to the hole for fixing screw 12b is l ₁ , the length from the hole for fixing screw 12a of substrate 1 and mount A10 to the hole for fixing screw 12b at temperature T ₀ + ΔT Respectively extend by l ₁ · k ₁ · ΔT and l ₁ · k ₂ · ΔT. Here, if k ₁ > k ₂ and ΔT> 0, the length from the hole for the fixing screw 12a of the substrate 1 to the hole for the fixing screw 12b is from the hole for the fixing screw 12a of the mount A10 to the fixing screw 12b. Thus, the substrate 1 and the mount A10 both warp downward in a convex manner, extending by l ₁ · (k ₁ −k ₂ ) · ΔT rather than the length to the hole. In this case, the PLC chip 2 is inclined in a direction in which the PLC chip 3 side is upward at the connection surface with the PLC chip 3, and the PLC chip 3 also tries to incline, and the PLC chip 3 is elastic adhesives 9a and 9b. Therefore, the strain cannot be freely tilted, and the distortion is applied to the connecting portion between the PLC chip 2 and the PLC chip 3, and the output optical waveguide array 5 b of the PLC chip 2 and the input optical waveguide array 7 a of the PLC chip 3. Axis misalignment is generated during this period to vary the connection loss.

  On the other hand, as in this embodiment, the mount A10 is completely fixed to the substrate 1 with the fixing screw 12a, and is fixed to the substrate 1 with the fixing screw 12b so as to be freely movable in a plane parallel to the upper surface of the mount A10. In this case, even if the thermal deformations of the substrate 1 and the mount A10 are different, the substrate 1 and the mount A10 are not warped. Therefore, the output optical waveguide array 5b of the PLC chip 2 and the input optical waveguide array 7a of the PLC chip 3 There is no axis misalignment between them, and connection loss does not fluctuate.

Here, the effect of suppressing the vertical axis misalignment at the PLC connecting portions of the PLC chips 2 and 3 caused by different thermal deformations of the substrate 1 and the mount A10 obtained by the present invention will be described using specific numerical values. To do. The material of the substrate 1 is aluminum, and its thermal expansion coefficient is 23 × 10 ⁻⁶ [1 / ° C.]. The material of the mount A10 is Si—SiC, and its thermal expansion coefficient is 3 × 10 ⁻⁶ [1 / ° C.], which is the same as the silicon used as the substrate of the PLC chip. The length l ₁ from the hole for the fixing screw 12a of the substrate 1 to the hole for the fixing screw 12b at a temperature of 20 ° C. is 50 mm. When the temperature is changed to 70 ° C. from this state, the substrate 1 extends from 50 mm to 50.0575 mm, and the mount A10 extends from 50 mm to 50.0075 mm. When the mount A10 is fixed to the substrate 1 with the fixing screw 12b so that the mount A10 can freely move within a plane parallel to the upper surface of the mount A10, the substrate 1 and the mount can be mounted even if the elongation of the substrate 1 and the mount A10 is different. A10 does not warp. For this reason, the inclination of the PLC chip 3 connected to the PLC chip 2 does not change, and no force is applied to the connecting portion between the PLC chip 2 and the PLC chip 3 so as to cause an axis shift. On the other hand, when the mount A10 is completely fixed to the substrate 1 even at the position of the fixing screw 12b, the substrate 1 and the mount A10 are warped, and the mount at the center position of the distance from the fixing screw 12a to the fixing screw 12b. The height of the upper surface of A10 is lower than the height of the upper surface of the mount A10 at the positions of the fixing screws 12a and 12b. Since the PLC chip 2 fixed to the mount A10 is warped in the same manner as the mount A10, the connection portion with the PLC chip 3 is inclined upward. Therefore, the PLC chip 3 connected to the PLC chip 2 also tends to incline in the direction in which the side connected to the PLC chip 2 is lowered, but the PLC chip 3 is held on the mount B11 by the elastic adhesives 9a and 9b and is free. Therefore, a force that generates an axial deviation is applied to the connecting portion between the PLC chip 2 and the PLC chip 3 due to the distortion.

Next, a method for suppressing the force that peels off the PLC chip 2 and the PLC chip 3 caused by different thermal deformations of the substrate 1, the mount B11, and the PLC chips 2 and 3 will be described. The lengths from the connecting surface of the PLC chip 2 and the PLC chip 3 at the temperature T to the fixing screw 12a of the mount A10, the fixing screw 13a of the mount B11, and the elastic adhesives 9a and 9b are respectively l ₂ , l ₃ , and l _4, to the fixing screw 13a of the mount B11 elastic adhesive 9a, until 9b a length of l _5. The thermal expansion coefficients of the substrate 1, the PLC chip 2, the PLC chip 3, and the mount B11 are k ₁ , k ₂ , k ₃ , and k ₁₁ , respectively.

When the temperature changes to T + ΔT and the PLC chip 2 and the PLC chip 3 are thermally deformed without stress, the length from the fixing screw 12a of the mount A10 to the elastic adhesives 9a, 9b is
l ₂ · k ₂ · ΔT + l ₄ · k ₃ · ΔT (a)
Only changes. On the other hand, when the substrate 1 and the mount B11 are thermally deformed without stress, the length from the fixing screw 12a of the mount A10 to the elastic adhesives 9a and 9b is l ₄ ≧ l ₃ , that is, the PLC chip 2 When the length to the elastic adhesives 9a and 9b is larger than the length to the fixing screw 13a of the mount B11 when viewed from the connection surface of the PLC chip 3,
(L ₂ + l ₃ ) · k ₁ · ΔT + l ₅ · k ₁₁ · ΔT (b1)
Only changes. When l ₄ <l ₃ , that is, when the length to the elastic adhesives 9a and 9b is smaller than the length to the fixing screw 13a of the mount B11 when viewed from the connection surface of the PLC chip 2 and the PLC chip 3,
(L ₂ + l ₃ ) · k ₁ · ΔT-l ₅ · k ₁₁ · ΔT (b2)
Only changes. In order to prevent a force from being applied to the connection surfaces of the PLC chips 2 and 3 and the PLC chip 2 and the PLC chip 3, the amount of change (a) between the PLC chip 2 and the PLC chip 3, and the substrate 1 and the mount The amount of change (b1) or (b2) in the length from the fixing screw 12a of the mount A10 to the elastic adhesives 9a, 9b when B11 is thermally deformed without stress may be made equal. That is,
l ₂ · k ₂ · ΔT + l ₄ · k ₃ · ΔT
= (L ₂ + l ₃ ) · k ₁ · ΔT + l ₅ · k ₁₁ · ΔT (when l ₄ ≧ l ₃ )
= (L ₂ + l ₃ ) · k ₁ · ΔT−l ₅ · k ₁₁ · ΔT (when l ₄ <l ₃ ) (1)
It should be designed to satisfy the relationship.

Here, a specific numerical value is used to suppress the effect of peeling the PLC chip 2 and the PLC chip 3 caused by different thermal deformations of the substrate 1, the mount B11, and the PLC chips 2 and 3 obtained by the present invention. explain. The material of the substrate 1 is aluminum, and its thermal expansion coefficient k ₁ is 23 × 10 ⁻⁶ [1 / ° C.]. The material of the mount B11 is zirconium tungstate (ZrW ₂ O ₃ ), and its thermal expansion coefficient k ₁₁ is −9 × 10 ⁻⁶ [1 / ° C.]. The PLC chips 2 and 3 use silicon as a substrate material, and their thermal expansion coefficients k ₂ and k ₃ are set to 3 × 10 ⁻⁶ [1 / ° C.] equivalent to the thermal expansion coefficient of silicon. The length l ₂ from the connecting surface of the PLC chip 2 and the PLC chip 3 at a temperature of 20 ° C. to the fixing screw 12a of the mount A10 and the length l ₃ to the fixing screw 13a of the mount B11 are 5 mm, The length from the fixing screw 13a of the mount B11 to the elastic adhesives 9a and 9b is l ₅ . In the formula (1) (when l ₄ ≧ l ₃ ),
l ₄ = l ₃ + l ₅ (c)
Substituting and rearranging for l ₅ ,
l ₅ = {(l ₂ + l ₃ ) · k ₁ − (l ₂ · k ₂ + l ₃ · k ₃ )} / (k ₃ −k ₁₁ ) (d)
When the coefficient of thermal expansion and dimensions of each member described above are substituted into the formula (d),
l ₅ = 25 [mm] (e)
Is obtained. When the temperature changes to 70 ° C. in this state, when the PLC chip 2 and the PLC chip 3 are thermally deformed without stress, the length of the mount A10 from the fixing screw 12a to the elastic adhesives 9a and 9b is increased. When the substrate 1 and the mount B11 are thermally deformed in a stress-free state, the length of the mount A10 from the fixing screw 12a to the elastic adhesives 9a and 9b is expressed by the equation (a ) And formula (b1) are both calculated to be 0.006 mm. Therefore, a force for peeling the PLC chip 2 and the PLC chip 3 is not generated.

Next, a method of suppressing vertical axis misalignment at the PLC connecting portions of the PLC chips 2 and 3 due to different thermal deformations of the mount A10, the mount B11, and the elastic adhesives 9a and 9b will be described. FIG. 1C shows the height of each member according to the embodiment of the present invention. The heights of the mount A10 and the mount B11 are d ₁₀ and d ₁₁ , the thermal expansion coefficients are k ₁₀ and k ₁₁ , and the height from the top surface of the mount B11 of the elastic adhesives 9a and 9b to the bottom surface of the PLC chip 3 is d ₉ When the expansion coefficient and k _9,
d ₁₀ = d ₁₁ + d ₉ (2)
d ₁₀ '= d ₁₀ + d ₁₀ · k ₁₀ · ΔT (3)
d ₁₁ '+ d ₉ ' = d ₁₁ + d ₉ + (d ₁₁ · k ₁₁ + d ₉ · k ₉ ) · ΔT (4)
Holds. Expression (3) represents the change in height accompanying the temperature change ΔT of the height of the mount A10, and Expression (4) represents the height from the top surface of the mount B11 and the elastic adhesives 9a and 9b to the bottom surface of the PLC chip 3. This represents a change in height accompanying the temperature change ΔT. Since these PLC chips 2 and 3 should be designed so that their heights match even after thermal deformation,
d ₁₀ ′ = d ₁₁ ′ + d ₉ ′ (5)
The relationship between the height and the thermal expansion coefficient is d ₁₀ · k ₁₀ = d ₁₁ · k ₁₁ + d ₉ · k ₉ (6)
Design to be

  Thus, the mount A10 and the mount B11 are fixed on the substrate 1, the PLC chip 3 is held by the elastic adhesives 9a and 9b accumulated on the upper surface of the mount B11, and the mount A10, the mount B11, and the elastic adhesive 9a By adjusting the height of 9b and the coefficient of thermal expansion as described above, it is possible to suppress loss fluctuation due to the axis misalignment of the PLC connecting portions of the PLC chips 2 and 3 at low cost.

Here, the effect of suppressing the vertical axis misalignment in the PLC connecting portions of the PLC chips 2 and 3 due to different thermal deformations of the mount A10, the mount B11, and the elastic adhesives 9a and 9b, obtained by the present invention, is specifically described. This will be described using numerical values. The material of the mount A10 is Si—SiC, the height d ₁₀ at a temperature of 20 ° C. is 3 mm, and the thermal expansion coefficient k ₁₀ is 3 × 10 ⁻⁶ [1 / ° C.]. The material of the mount B11 is zirconium tungstate (ZrW ₂ O ₃ ), the height d ₁₁ at a temperature of 20 ° C. is 2 mm, and the thermal expansion coefficient k ₁₁ is −9 × 10 ⁻⁶ [1 / ° C.]. Elastic adhesive 9a, 9b is, 1 mm a height from the upper surface of the mount B11 at temperature 20 ° C. until the bottom surface of the PLC chip 3, and the thermal expansion coefficient k _9. If the expression (6) to organize for k _{9,
k 9 = (d 10 · k} 10 -d 11 · k 11) / d 9 ··· (f)
When the coefficient of thermal expansion and dimensions of each member described above are substituted into the formula (f),
k ₉ = 27 × 10 ⁻⁶ [1 / ° C.] (e)
Is obtained. In this state, when the temperature changes to 70 ° C., the height from the upper surface of the substrate 1 to the lower surfaces of the PLC chip 2 and the PLC chip 3, and the thermal expansion coefficient and dimensions of each member described above are expressed by Equation (3) and When calculated by substituting into the equation (4), the heights of the lower surfaces of the PLC chip 2 and the PLC chip 3 are both 3.00045 mm, and the force that causes the vertical axis misalignment in the PLC connecting portions of the PLC chips 2 and 3 is obtained. Does not occur.

  On the other hand, without using the mount B11, the PLC chip 3 is held by the elastic adhesives 9a and 9b accumulated on the upper surface of the substrate 1, and from the upper surface of the substrate 1 of the elastic adhesives 9a and 9b at a temperature of 20 ° C. Consider a case where the height to the bottom surface of the PLC chip 3 is 3 mm, and other than that is equal to the above. In this case, when the temperature is changed to 70 ° C., the height from the upper surface of the substrate 1 to the lower surface of the PLC chip 3 becomes 3.00405 mm, and the height from the upper surface of the substrate 1 to the lower surface of the PLC chip 2 becomes 0. A difference of 0036 mm is generated, and a force that causes a vertical axis shift in the PLC connecting portions of the PLC chips 2 and 3 is generated.

In this embodiment, when the mount A10 and the mount B11 are fixed to the substrate 1 with the fixing screws 12b and 13b, a screw hole is formed in the substrate 1, and the mount A10 and the mount B11 have a screw diameter larger than the screw diameter. A large through hole is formed. The mount A10 and the mount B11 can move freely with respect to a plane parallel to the top surfaces of the mount A10 and the mount B11, and cannot move in a direction perpendicular to the top surfaces of the mount A10 and the mount B11. The screw is fixed using a torque screwdriver while adjusting the screw tightening amount. However, the present invention is not limited to this fixing method, for example, a through hole may be formed in the substrate, a screw hole may be formed in the mount, and the mount is sandwiched between a flat plate and a substrate prepared separately, Similar effects can be obtained by another fixing method such as a method of fixing the flat plate and the substrate with screws. Further, in the present embodiment, the case where l ₄ ≧ l ₃ is shown, but the present invention is not limited to this, and the case where l ₄ <l ₃ is satisfied so as to satisfy the above formula (1). As a result, the same effects as those of the present embodiment can be obtained. In this embodiment, both the mount A10 and the mount B11 are completely fixed to the substrate 1 with a part of fixing screws, and can be moved in a plane parallel to the top surfaces of the mount A10 and the mount B11 with other fixing screws. Although the case where the substrate 1 is fixed to the substrate 1 has been shown, the present invention is not limited to this, and only one of the mount A10 and the mount B11 is used as shown in FIGS. 2 (a) and 2 (b). Even when fixed to the substrate 1 with the other fixing screws, and fixed to the substrate 1 so as to be movable in a plane parallel to the top surfaces of the mount A10 and the mount B11 with the other fixing screws, The same effect is produced. In the present embodiment, only the case where the coefficient of thermal expansion and the dimension of each member are set to the specific values described above is shown, but the present invention is not limited to this, and the formula ( If the coefficient of thermal expansion and the dimension of each member are set so as to satisfy 1) and Expression (6), the same effects as those of the present embodiment can be obtained.

(A) is a top view of the optical module which concerns on embodiment of this invention, (b) is a side view of the optical module of (a), (c) is a figure which shows the height of each member. It is. It is a top view of the optical module which concerns on embodiment of this invention, (a) is a figure which shows the case where the mount A10 is fixed so that the one part can move in the plane parallel to the upper surface of mount A10, (B) is a figure which shows the case where mount B11 is fixed so that the one part can move in the plane parallel to the upper surface of mount B11. (A) is a top view of the optical module which fixed one conventional PLC chip with the elastic adhesive agent, (b) is a side view of the optical module shown to (a). (A) is a top view of the optical module which used the conventional one mount as a member of a different thermal expansion coefficient, (b) is a side view of the optical module shown to (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2, 3 PLC chip 4a Optical fiber array 4b Optical fiber 5a, 7a Input optical waveguide array 5b Output optical waveguide array 6 VOA array 7b Output optical waveguide 8 AWG (array waveguide diffraction grating)
9a, 9b Elastic adhesive 10 Mount A
11 Mount B
12a, 12b, 13a, 13b Fixing screw

Claims (8)

A first planar lightwave circuit (PLC) chip, a second PLC chip, a first mount and a substrate;
The first PLC chip is fixed to the first mount;
The end face of the second PLC chip is abutted against the end face of the first PLC chip and connected so as to be optically coupled;
The first mount is fixed to the substrate at one end on the connection surface side of the first PLC chip and the second PLC chip of the first mount, and movably in a horizontal plane at the other end. Fixed to the board ,
An end of the second PLC chip opposite to the end face to which the first PLC chip is connected is fixed to the second mount by an elastic adhesive,
The second mount is fixed to the substrate at one end of the second mount, and is fixed to the substrate movably in a horizontal plane at the other end.
The length l from the connection surface of the first PLC chip and the second PLC chip to the first fixed position closest to the connection surface among the fixed positions where the first mount is fixed to the substrate. _e , the thermal expansion coefficient k _e of the first PLC chip, the length l _f from the connection surface to the elastic adhesive, the thermal expansion coefficient k _f of the second PLC chip , and the second mount Length l _c from the second fixed position fixed to the substrate to the connection surface , coefficient of thermal expansion k _{c of} the substrate, coefficient of thermal expansion k _b of the second mount, elasticity from the second fixed position optical module length l _b until the adhesive is characterized by satisfying the relationship of formula (B).
(For l _f ≧ l _c) (Formula _{B) l e · k e +} l f · k f = (l e + l c) · k c + l b · k b
_{l e · k e + l f} · k f = ( the case of _{l f <l c) (l} e + l c) · k c -l b · k b A first planar lightwave circuit (PLC) chip, a second PLC chip, a first mount and a substrate;
  The first PLC chip is fixed to the first mount;
  The end face of the second PLC chip is abutted against the end face of the first PLC chip and connected so as to be optically coupled;
  The first mount is fixed to the substrate at one end on the connection surface side of the first PLC chip and the second PLC chip of the first mount, and movably in a horizontal plane at the other end. Fixed to the board,
  An end of the second PLC chip opposite to the end face to which the first PLC chip is connected is fixed to the second mount by an elastic adhesive,
  The thickness d of the first mount _a The thickness d of the second mount _b , Distance d between the opposing surfaces of the second PLC chip and the second mount _d , Coefficient of thermal expansion k of the first mount _a , Coefficient of thermal expansion k of the second mount _b And the thermal expansion coefficient k of the elastic adhesive _d Satisfy | fills the relationship of Formula (A), The optical module characterized by the above-mentioned.
  (Formula A) d _a ・ K _a = D _b ・ K _b + D _d ・ K _d The thickness d of the first mount _a The thickness d of the second mount _b , Distance d between the opposing surfaces of the second PLC chip and the second mount _d , Coefficient of thermal expansion k of the first mount _a , Coefficient of thermal expansion k of the second mount _b And the thermal expansion coefficient k of the elastic adhesive _d Satisfies the relationship of the formula (A), the optical module according to claim 1.
  (Formula A) d _a ・ K _a = D _b ・ K _b + D _d ・ K _d Coefficient of thermal expansion k _a , K _b , K _c , K _e And k _f Satisfies the relationship of the formula (C), the optical module according to claim 3.
  (Formula C) k _c > K _a , K _b , K _e , K _f A first PLC chip, a second PLC chip, a mount and a substrate;
  The end face of the second PLC chip is abutted against the end face of the first PLC chip and connected so as to be optically coupled;
  The substrate has a convex portion, and the first PLC chip is fixed to the convex portion;
  An end of the second PLC chip opposite to the end face to which the first PLC chip is connected is fixed to the mount by an elastic adhesive,
  The mount is fixed to the substrate at one end of the mount, and is fixed to the substrate movably in a horizontal plane at the other end,
  Length from the connection surface of the first PLC chip and the second PLC chip to the first fixed position closest to the connection surface among the fixed positions where the first PLC chip is fixed to the substrate l _e , Coefficient of thermal expansion k of the first PLC chip _e , Length l from the connecting surface to the elastic adhesive _f , Coefficient of thermal expansion k of the second PLC chip _f , Length l from the second fixed position where the mount is fixed to the substrate to the connection surface _c , Thermal expansion coefficient k of the substrate _c , Thermal expansion coefficient k of the mount _b , Length l from the second fixed position to the elastic adhesive _b Satisfy | fills the relationship of Formula (B), The optical module characterized by the above-mentioned.
  (Formula B) l _e ・ K _e + L _f ・ K _f = (L _e + L _c ) ・ K _c + L _b ・ K _b (L _f ≧ l _c in the case of)
          l _e ・ K _e + L _f ・ K _f = (L _e + L _c ) ・ K _c -L _b ・ K _b (L _f <L _c in the case of) A first PLC chip, a second PLC chip, a first mount, a second mount, and a substrate;
  The end face of the second PLC chip is abutted against the end face of the first PLC chip and connected so as to be optically coupled;
  The first PLC chip is fixed to the first mount;
  The first mount is fixed to a substrate;
  An end of the second PLC chip opposite to the end face to which the first PLC chip is connected is fixed to the second mount by an elastic adhesive,
  The second mount is fixed to the substrate at one end of the second mount, and is fixed to the substrate movably in a horizontal plane at the other end.
  The length l from the connection surface of the first PLC chip and the second PLC chip to the first fixed position closest to the connection surface among the fixed positions where the first mount is fixed to the substrate. _e , Coefficient of thermal expansion k of the first PLC chip _e , Length l from the connecting surface to the elastic adhesive _f , Coefficient of thermal expansion k of the second PLC chip _f , Length l from the second fixed position where the second mount is fixed to the substrate to the connection surface _c , Thermal expansion coefficient k of the substrate _c , Coefficient of thermal expansion k of the second mount _b , Length l from the second fixed position to the elastic adhesive _b Satisfy | fills the relationship of Formula (B), The optical module characterized by the above-mentioned.
  (Formula B) l _e ・ K _e + L _f ・ K _f = (L _e + L _c ) ・ K _c + L _b ・ K _b (L _f ≧ l _c in the case of)
          l _e ・ K _e + L _f ・ K _f = (L _e + L _c ) ・ K _c -L _b ・ K _b (L _f <L _c in the case of) A first PLC chip, a second PLC chip, a mount and a substrate;
  The end face of the second PLC chip is abutted against the end face of the first PLC chip and connected so as to be optically coupled;
  The substrate has a convex portion, and the first PLC chip is fixed to the convex portion;
  An end of the second PLC chip opposite to the end face to which the first PLC chip is connected is fixed to the mount with an elastic adhesive,
  The mount is fixed to the substrate;
  Thickness d of the convex part _a , The thickness d of the mount _b A distance d between the second PLC chip and the opposing surface of the mount; _d , Coefficient of thermal expansion k _a , Thermal expansion coefficient k of the mount _b And the thermal expansion coefficient k of the elastic adhesive _d Satisfy | fills the relationship of Formula (A), The optical module characterized by the above-mentioned.
  (Formula A) d _a ・ K _a = D _b ・ K _b + D _d ・ K _d A first PLC chip, a second PLC chip, a first mount, a second mount, and a substrate;
  The end face of the second PLC chip is abutted against the end face of the first PLC chip and connected so as to be optically coupled;
  The first PLC chip is fixed to the first mount;
  The first mount is fixed to a substrate;
  The end of the second PLC chip opposite to the end face to which the first PLC chip is connected is fixed to the second mount by an elastic adhesive,
  The second mount is fixed to the substrate;
  The thickness d of the first mount _a The thickness d of the second mount _b , Distance d between the opposing surfaces of the second PLC chip and the second mount _d , Coefficient of thermal expansion k of the first mount _a , Coefficient of thermal expansion k of the second mount _b And the thermal expansion coefficient k of the elastic adhesive _d Satisfy | fills the relationship of Formula (A), The optical module characterized by the above-mentioned.
  (Formula A) d _a ・ K _a = D _b ・ K _b + D _d ・ K _d

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