JP2015203789A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module having a core part hardly being peeled off by arranging the shape of cladding to thereby improve the yield rate.SOLUTION: The optical module includes: an internal waveguide 16 formed in a waveguide forming groove 1a on the surface of a base plate 1; and a mirror part 15 formed on the front end face of the groove 1a. The optical module also includes: optical elements 15a and 15b which are mounted on the surface of the base plate 1 facing the mirror part 15 to emit an optical signal into the core part 17 of the internal waveguide 16 via a mirror part 15 or to receive an optical signal from the core part 17 of the internal waveguide 16 via the mirror part 15. The internal waveguide 16 is constituted of the core part 17 and the cladding 18. A front end 18a of the cladding 18 is disposed at least at a position of a front end 1c of the waveguide forming groove 1a.

Description

  The present invention relates to an optical module including an optical element.

  Conventionally, as shown in FIG. 12A, the optical module includes an internal waveguide 16 provided in a first groove (waveguide forming groove) 1a formed on the surface of the substrate 1, and the first groove 1a. And an optical path converting mirror portion 15 formed on the front end surface of the optical path. Further, the optical element 12 is provided that emits an optical signal to the core portion 17 of the internal waveguide 16 via the mirror portion 15 or receives an optical signal from the core portion 17 of the internal waveguide 16 via the mirror portion 15. ing.

  Furthermore, an optical fiber (external waveguide) 2 having a fiber core portion 21 provided in the second groove 1b formed on the surface of the substrate 1 and optically coupled to the core portion 17 of the internal waveguide 16 is provided. (See Patent Document 1).

  By the way, when the optical module is operating, the mirror portion 15 and the synthetic resin internal waveguide 16 may generate heat due to light absorption. In particular, when the optical element 12 is a light-emitting element, the vicinity of the mirror portion 15 near this is before the light spreads, and thus the heat density tends to increase because the light power density is high.

  In such an optical module, if the transmission distance is short or low, the power density of the light from the optical element 12 is low, so that the heat generation temperature of the mirror portion 15 and the internal waveguide 16 in the vicinity thereof is so high as to be a problem. Don't be. However, in the case of long distance and high-speed transmission, higher light output is required to ensure transmission reliability, and the heat generation temperature of the mirror unit 15 and the internal waveguide 16 in the vicinity thereof is increased accordingly.

  Therefore, the core portion 17 may be peeled off due to the stress caused by the temperature rise of the mirror portion 15 and the internal waveguide 16 in the vicinity thereof.

  Therefore, as shown in FIG. 12B, a device has been proposed in which the front end 17 a of the core portion 17 is retracted from the mirror portion 15 to suppress the temperature rise so that peeling does not easily occur.

JP 2013-3549 A

  However, by retreating the front end 17a of the core part 17 from the mirror part 15, the adhesion force of the core part 17 whose contact area with the substrate 1 is reduced is reduced. In addition, the front end 18 a of the clad portion 18 that covers the core portion 17 is also retracted from the front end 17 a of the core portion 17, whereby stress is easily applied to the core portion 17 exposed from the clad portion 18.

  For these reasons, there is a problem that the core portion 17 is easily peeled off and the yield rate of the optical module is lowered.

  Here, the reason why the front end 18a of the clad portion 18 is retracted from the front end 17a of the core portion 17 is as follows. That is, if the front end 18 a of the cladding portion 18 protrudes forward from the front end 17 a of the core portion 17 and covers the front end surface of the core portion 17, light loss occurs. For this reason, conventionally, it has been usual that the tolerance is greatly anticipated from the accuracy of the manufacturing apparatus, and it is usually retracted by about 50 μm. As a result, the front end 18a of the clad portion 18 is located behind the front end 1c of the first groove 1a.

  The present invention has been made to solve the above problems, and provides an optical module that makes it difficult to peel off the core portion by improving the shape of the cladding portion and can improve the yield rate. It is intended.

  In order to solve the above-mentioned problems, the present invention provides an internal waveguide provided in a waveguide forming groove formed on the surface of a substrate, and an optical path converting mirror portion formed on the front end face of the groove. It has. Also, it is mounted on the surface of the substrate so as to face this mirror part, and emits an optical signal to the core part of the internal waveguide through the mirror part, or light from the core part of the internal waveguide through the mirror part. The optical module includes at least an optical element that receives a signal. The internal waveguide includes a core part and a clad part covering the core part, and the front end of the clad part is set at least at the position of the front end of the waveguide forming groove. It is what.

  According to the present invention, the tolerance is greatly reviewed from the viewpoint of improving the accuracy of the manufacturing apparatus, and the front end of the clad portion is set at least at the position of the front end of the waveguide forming groove, so that the waveguide is formed in the clad portion. The core part can be pressed down to the front end position of the groove. In other words, it is possible to press down a portion corresponding to the neck of the mirror bottom portion of the core portion where peeling is likely to occur. This makes it difficult for the core part to be peeled between the front end position of the waveguide forming groove and the mirror part, thereby improving the yield rate of the optical module.

  The front end of the cladding part may be configured to extend to the vicinity of the upper end of the mirror part.

  According to this configuration, the core part can be pressed to the vicinity of the upper end of the mirror part by the clad part. As a result, the core part is more difficult to peel off, and the yield rate of the optical module is improved.

  The front end of the core part is set at a position retracted from the mirror part, and the front end of the clad part extends to the vicinity of the front end of the retracted core part.

  According to this configuration, by setting the front end of the core portion to a position retracted from the mirror portion, the temperature rise of the core portion is suppressed and peeling is less likely to occur. In addition, since the front end of the clad portion extends to the vicinity of the front end of the core portion, the core portion is hardly exposed from the clad portion, so that the pressing force of the core portion is increased. This makes it difficult for the core part that has been retracted from the mirror part to peel off, and the yield rate is improved.

  In addition, since the amount of underfill filled in the waveguide forming groove between the mirror part and the front end of the core part is reduced after mounting the optical element, the stress due to the underfill is also reduced. It becomes difficult to peel off and the yield is improved.

  The front end of the clad part may be configured to extend only near the top of the core part to the vicinity of the front end of the core part.

  According to this configuration, since only the portion directly above the core portion is covered with the clad portion, the UV light at the time of hardening of the core portion is reflected on the inclined surface around the mirror bottom, and an unnecessary portion outside the pattern Until it is cured. Therefore, the yield is further improved.

  The front end of the cladding portion may be configured such that only both side portions near the core portion extend to the vicinity of the upper end of the mirror portion.

  According to this configuration, the adhesion area between the clad portion and the surface of the substrate is increased, so that the adhesion force of the core portion is increased. Further, since the filling amount of the underfill filled in the waveguide forming groove between the mirror portion and the front end of the core portion is reduced, the stress due to the underfill is also reduced. For this reason, the core part is difficult to peel off, and the yield is improved. Furthermore, it is easy to fill the underfill, and voids (bubbles) at the time of filling the underfill are reduced, so that the yield is improved.

  The inner edge portions of both side portions of the clad portion extending to the vicinity of the upper end of the mirror portion may be narrowly set so as to cover the corners of both side portions of the core portion.

  According to this configuration, the close contact strength of the corner of the core portion, which is likely to be a starting point of the core portion peeling, is further increased. Further, since the filling amount of the underfill filled in the waveguide forming groove between the mirror portion and the front end of the core portion is reduced, the stress due to the underfill is also reduced. For this reason, the core part is difficult to peel off, and the yield is improved. Furthermore, it is easy to fill underfill and voids are reduced, so that the yield is improved.

  The waveguide forming groove may have a substantially trapezoidal or V-shaped cross-sectional shape.

  According to this configuration, the cross-sectional shape of the waveguide forming groove is not particularly limited. However, although the manufacturing cost is lower than that of the substantially trapezoidal shape, the core portion has poor adhesion, and the core at the corner of the mirror bottom or the V groove bottom. In the case of a substantially V shape in which stress tends to concentrate on the part, a better effect can be obtained by preventing peeling.

  According to the present invention, it is difficult for the core part to be peeled at least between the position of the front end of the waveguide forming groove and the mirror part, and the yield rate of the optical module is improved.

1 is a schematic side view of an optical module according to the present invention. It is an internal waveguide of 1st Embodiment, (a) is a top view, (b) is the II sectional view taken on the line of (a), (c) is the II-II sectional view taken on the line (a). It is an internal waveguide of 2nd Embodiment, (a) is a top view, (b) is the II sectional view taken on the line of (a). It is an internal waveguide of 3rd Embodiment, (a) is a top view, (b) is the II sectional view taken on the line of (a). (A) is a top view of the internal waveguide of 4th Embodiment, (b) is a top view of the internal waveguide of 5th Embodiment, (c) is a top view of the internal waveguide of 6th Embodiment. It is an internal waveguide of the modification of 1st Embodiment, (a) is a top view, (b) is II sectional view taken on the line of (a), (c) is II-II sectional view taken on the line of (a). It is. It is an internal waveguide of the modification of 2nd Embodiment, (a) is a top view, (b) is the II sectional view taken on the line of (a). It is an internal waveguide of the modification of 3rd Embodiment, (a) is a top view, (b) is the II sectional view taken on the line of (a). (A) is a top view of the internal waveguide of the modification of 4th Embodiment, (b) is a top view of the internal waveguide of the modification of 5th Embodiment, (c) is the internal waveguide of 6th Embodiment. It is a top view of the modified example. It is embodiment of the internal waveguide extended until the front end of the core part contacted the mirror part, (a) is a top view, (b) is the II sectional view taken on the line of (a). It is sectional drawing of embodiment which made the front end of a core part retreat rather than the front end of a 1st groove | channel. It is an internal waveguide of the optical module of background art, (a) is side surface sectional drawing, (b) is side surface sectional drawing which made the front end of a core part retreat.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. Note that portions having the same configuration and operation as those of the background art are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 1 is a schematic side view of an optical module according to the present invention. In FIG. 1, the optical module includes a first substrate (mount substrate) 1 on the light emitting side, a first substrate (mount substrate) 3 on the light receiving side, and an optical fiber 2 that optically couples the first substrates 1 and 3. It has.

  The first substrates 1 and 3 need to have rigidity in order to avoid the influence of heat during mounting and the influence of stress due to the use environment. In the case of optical transmission, since optical coupling efficiency from the light emitting element 12a to the light receiving element 12b is required, the optical elements (the light emitting element 12a and the light receiving element 12b) 12 can be mounted with high accuracy and the position in use. It is necessary to suppress fluctuations as much as possible. For this reason, a silicon (Si) substrate is employed as the first substrates 1 and 3 in this embodiment.

  In particular, in the case of a silicon substrate, it is possible to process a highly accurate etching groove on the surface by utilizing the crystal orientation of silicon [a highly accurate mirror portion 15 (described later) using this groove, and an internal waveguide 16 ( (To be described later). ]. In addition, the silicon substrate has good flatness.

  The first substrates 1 and 3 are respectively installed on the surface (upper surface) of a second substrate (interposer substrate) 6 having a larger size. Connectors 7 for electrically connecting to other circuit devices are respectively attached to the back surface (lower surface) of each second substrate 6.

  On the surface (upper surface) of the first substrate 1, a light emitting element 12a for converting an electrical signal into an optical signal is flip-chip mounted with bumps 12c (see FIG. 12B) with the light emitting surface facing downward. An IC substrate (signal processing unit) 4a on which an IC circuit for transmitting an electrical signal to the light emitting element 12a is formed is mounted on the surface of the second substrate 6.

  In the present embodiment, a surface emitting laser (VCSEL (Vertical Cavity Surface Emitting Laser)) that is a semiconductor laser is employed as the light emitting element 12a. The light emitting element 12a may be an LED or the like.

  The IC substrate 4a is a driver IC that drives the VCSEL, and is disposed in the vicinity of the light emitting element 12a. The light emitting element 12a and the IC substrate 4a are connected to a metal circuit (patterning circuit by copper or gold sputtering) formed on the surface of the first substrate 1.

  A substantially V-shaped first groove (waveguide forming groove) 1a as shown in FIG. 2 and a substantially V-shaped second groove 1b deeper than the first groove 1a are provided on the front surface of the first substrate 1. It is formed continuously in the direction.

  On the front end face of the first groove 1a, an optical path changing mirror portion 15 for bending the optical path by 90 degrees is formed at a position directly below the light emitting element 12a. The mirror portion 15 is subjected to gold plating for improving the reflectance.

  In the first groove 1a of the first substrate 1, an internal waveguide 16 that is optically coupled to the light emitting element 12a of the first substrate 1 is provided.

  Referring to FIG. 2, the internal waveguide 16 includes a core part 17 having a high refractive index through which light propagates and a clad part 18 having a refractive index lower than that. Both left and right sides of the core portion 17 are covered with a clad portion 18. The upper portion of the core portion 17 is substantially the same height as the surface of the first substrate 1, and the upper portion of the cladding portion 18 is slightly raised from the surface of the first substrate 1. The upper portion of the clad portion 18 is in close contact with the surface of the substrate 1 on both sides of the first groove 1a.

  Returning to FIG. 1, a light emitting element 12 a is mounted at a predetermined position on the surface of the first substrate 1 on which the internal waveguide 16 is provided. Between the light emitting element 12 a and the surface of the first substrate 1, Underfill is filled.

  On the other hand, the basic configuration of the first substrate 3 on the light receiving side is the same as that of the first substrate 1 on the light emitting side. However, a light receiving element 12b for converting an optical signal into an electrical signal is flip-chip mounted on the surface (upper surface) of the first substrate 3 on the light receiving side with the light receiving surface facing downward. In addition, on the surface of the second substrate 6, an IC substrate (signal processing unit) 4b on which an IC circuit for transmitting an electric signal to the light receiving element 12b is formed is mounted. Different from 1. As this light receiving element 12b, PD (Photo Diode) is adopted, and the IC substrate 4b is an element such as a TIA (Trans-impedance Amplifier) that performs current / voltage conversion.

  The first substrate 1 on the light emitting side, the first substrate 3 on the light receiving side, and the IC substrates 4 a and 4 b are shielded by a shield case 8 attached to the surface of the second substrate 6, respectively. The through hole 8a is penetrated.

  The optical fiber 2 includes a fiber core portion 21 that can optically couple the core portion 17 of the internal waveguide 16 of the first substrate 1 on the light emitting side and the core portion 17 of the internal waveguide 16 of the first substrate 3 on the light receiving side. Inside. And it is a cord type comprised by the fiber cladding part 22 surrounding the outer periphery of this fiber core part 21, and the coating | coated part 23 which coat | covers the outer periphery of this fiber cladding part 22. FIG. The fiber core portion 21, the fiber clad portion 22, and the covering portion 23 are circular.

  The optical fiber 2 penetrates the through hole 8a of the shield case 8 and the covering portion 23 is peeled off in the vicinity of the second groove 1b of the first substrate 1 to expose the fiber clad portion 22.

  And the fiber clad part 22 of the optical fiber 2 is installed in the 2nd groove | channel 1b of the 1st board | substrate 1, and the fiber clad part 22 is positioned in the rising inclination part of the boundary part with the 1st groove | channel 1a. At this time, it is optically coupled with the optical axis of the core part 17 of the internal waveguide 16 of the first substrate 1 and the fiber core part 21 of the optical fiber 2 being aligned.

  At the position of the surface of the first substrate 1, a press block 24 is disposed above the fiber cladding portion 22 of the optical fiber 2, and the space between the press block 24 and the second groove 1b is filled with an adhesive. ing.

  In this way, the tip side of the fiber clad portion 22 of the optical fiber 2 is pressed and fixed to the first substrate 1 together with the presser block 24 while being pressed against the second groove 1b by the presser block 24. Become.

  2A and 2B show the internal waveguide 16 of the first embodiment, where FIG. 2A is a plan view, FIG. 2B is a cross-sectional view taken along line II of FIG. 2A, and FIG. 2C is a line II-II of FIG. It is sectional drawing.

  The cross-sectional shape of the first groove 1a of the substrate 1 is substantially V-shaped. Further, the width of the upper portion of the clad portion 18 is set wider than the maximum width W of the mirror bottom 15a, but it may be set narrower.

  The front end 17 a of the core portion 17 is retracted to the vicinity of the lower end 15 b of the mirror portion 15. The front end 18a of the clad portion 18 is set at least at the position of the front end 1c of the first groove 1a. It is important that the front end 18a of the clad portion 18 is set at least at the position of the front end 1c of the first groove 1a. Therefore, as illustrated in FIG. 11, even if the front end 17a of the core portion 17 is set at a position retracted from the front end 1c of the first groove 1a, the front end 18a of the cladding portion 18 is at least of the first groove 1a. If it is set to the position of the front end 1c, there is no problem. This is the same in the embodiment in which the cross-sectional shape of the first groove 1a is substantially trapezoidal as will be described later.

  If it is the structure of 1st Embodiment, a tolerance will be reexamined significantly from a viewpoint of the precision improvement of a manufacturing apparatus, and the front end 18a of the clad part 18 will be set to the position of the front end 1c of the 1st groove | channel 1a at least. Therefore, the core part 17 can be pressed down by the clad part 18 to the position of the front end 1c of the first groove 1a. In other words, a portion corresponding to the neck of the part of the mirror bottom 15a of the core portion 17 that easily peels can be pressed. Thereby, the core part 17 becomes difficult to peel between the position of the front end 1c of the 1st groove | channel 1a, and the mirror part 15, and the yield rate of an optical module comes to improve.

  In particular, if the cross-sectional shape of the first groove 1a is substantially V-shaped, the adhesion of the core part 17 at the mirror bottom 15a is poor, and the core part 17 of the corner part 1e of the mirror bottom 15a or the V bottom of the first groove 1a. Stress concentrates on the part and is easy to peel off. Therefore, as described above, by pressing a portion corresponding to the neck of the portion where peeling is likely to occur, a better effect can be obtained for preventing peeling.

  In addition, by setting the front end 17a of the core portion 17 to a position retracted from the mirror portion 15, the temperature rise of the core portion 17 is suppressed and peeling is less likely to occur.

  3A and 3B show the internal waveguide 16 according to the second embodiment. FIG. 3A is a plan view, and FIG. 3B is a cross-sectional view taken along the line II of FIG. The difference from the first embodiment is that the front end 18 a of the cladding portion 18 extends (advances) to the vicinity of the upper end 15 c of the mirror portion 15 and is in close contact with the surface of the substrate 1.

  If it is the structure of 2nd Embodiment, the core part 17 can be pressed down to the vicinity of the upper end 15c of the mirror part 15 with the clad part 18. FIG. Thereby, although optical loss occurs compared with the first embodiment, the core portion 17 becomes more difficult to peel off, and the yield rate of the optical module is improved.

  4A and 4B show the internal waveguide 16 according to the third embodiment. FIG. 4A is a plan view and FIG. 4B is a cross-sectional view taken along the line II of FIG. The difference from the first embodiment is that the front end 18a of the clad portion 18 extends (advances) to the vicinity of the front end 17a of the retracted core portion 17.

  Here, the vicinity of the front end 17a of the core portion 17 means a position flush with the front end 17a of the core portion 17 in addition to the position slightly retracted (for example, about 5 μm) from the front end 17a of the core portion 17 (as shown in the figure). (See symbol b). Further, a position (see symbol c) slightly extending from the front end 17a of the core portion 17 (for example, about 5 μm) is also included. The position slightly extending from the front end 17a of the core portion 17 includes not only the position covering the entire front end surface of the front end 17a of the core portion 17 but also the position covering only the periphery of the front end surface.

  In the configuration of the third embodiment, since the front end 18a of the cladding portion 18 extends to the vicinity of the front end 17a of the core portion 17, the core portion 17 is hardly exposed from the cladding portion 18. The holding force increases. This makes it difficult for the core portion 17 retracted from the mirror portion 15 to be peeled off, thereby improving the yield rate.

  In addition, since the amount of underfill filled in the first groove 1a between the mirror portion 15 and the front end 17a of the core portion 17 after mounting the optical element (light emitting element 12a or light receiving element 12b) 12 is reduced, Since stress due to underfill is also reduced, the core portion 17 is difficult to peel off and the yield is improved.

  FIG. 5A is a plan view of the internal waveguide 16 of the fourth embodiment. The difference from the first embodiment is that the front end 18a of the clad portion 18 is extended (advanced) further to the vicinity of the front end 17a of the core portion 17 only in the vicinity immediately above the core portion 17.

  In the case of the configuration of the fourth embodiment, since only the vicinity directly above the core portion 17 is covered with the clad portion 18, the UV light at the time of curing the core portion 17 is reflected by the inclined surface around the mirror bottom 15a. In this case, it is possible to prevent the unnecessary portion outside the pattern from being cured, and the yield is further improved.

  FIG. 5B is a plan view of the internal waveguide 16 of the fifth embodiment. The difference from the first embodiment is that the front end 18a of the clad portion 18 is further extended (advanced) only to both side portions near the top of the core portion 17 to the vicinity of the upper end 15c of the mirror portion 15. It is.

  In the case of the internal waveguide 16 of the fifth embodiment, the contact area between the clad portion 18 and the surface of the substrate 1 is increased, so that the adhesion force of the core section 17 is increased.

  Further, since the filling amount of the underfill filling the first groove 1a between the mirror portion 15 and the front end 17a of the core portion 17 is reduced, the stress due to the underfill is also reduced. Therefore, the core part 17 becomes difficult to peel and the yield is improved. Furthermore, it is easy to fill the underfill, and voids (bubbles) at the time of filling the underfill are reduced, so that the yield is improved.

  FIG. 5C is a plan view of the internal waveguide 16 of the sixth embodiment. The difference from the fifth embodiment is that inner edge portions 18c of both side portions of the cladding portion extended (advanced) to the vicinity of the upper end 15c of the mirror portion 15 cover corners 17b of both side portions of the core portion 17. This is a narrow point.

  If it is the internal waveguide 16 of 6th Embodiment, the contact | adhesion power of the corner | angular 17b of the core part 17 which becomes a starting point of peeling of the core part 17 will become larger. Further, since the filling amount of the underfill filling the first groove 1a between the mirror portion 15 and the front end 17a of the core portion 17 is reduced, the stress due to the underfill is also reduced. Therefore, the core part 17 becomes difficult to peel and the yield is improved. Furthermore, it is easy to fill underfill and voids are reduced, so that the yield is improved.

  In the first to sixth embodiments, the cross-sectional shape of the first groove 1a of the first substrate 1 is substantially V-shaped, but the cross-sectional shape of the first groove 1a may be substantially trapezoidal.

  FIG. 6 is a diagram corresponding to the first embodiment of FIG. FIG. 7 is a diagram corresponding to the second embodiment of FIG. FIG. 8 is a diagram corresponding to the third embodiment of FIG. FIGS. 9A to 9C are views corresponding to the fourth to sixth embodiments of FIGS. 5A to 5C.

  In addition, when the cross-sectional shape of the 1st groove | channel 1a is a substantially trapezoid, as shown in FIG. 6 and FIG. 7, the mirror bottom 15a and the front end 1c of the 1st groove | channel 1a correspond. Therefore, the front end 18a of the clad portion 18 is also set at the position of at least the mirror bottom 15a and the front end 1c of the first groove 1a.

  Thus, even if the cross-sectional shape of the 1st groove | channel 1a is made into a substantially trapezoid, there can exist an effect similar to 1st-6th embodiment.

  In each of the above embodiments, it is assumed that the front end 17a of the core portion 17 is retracted to the vicinity of the lower end 15b of the mirror portion 15.

  However, as shown in FIG. 10, the front end 17 a of the core portion 17 may be extended (advanced) until it contacts the mirror portion 15.

  In FIG. 10, as in the second embodiment of FIG. 3, the front end 18 a of the cladding portion 18 extends (advances) to the vicinity of the upper end 15 c of the mirror portion 15 and is in close contact with the surface of the substrate 1. It is. However, the front end 18a of the clad portion 18 is located at the position of the first embodiment of FIG. 2, the position of the third embodiment of FIG. 4, and the positions of the fourth to sixth embodiments of FIGS. Can be set.

  Similarly to FIGS. 6 to 8 and FIGS. 9A to 9C, the first groove 1a has the same trapezoidal cross section.

  Each of the embodiments deals with heat generation when the optical element 12 is the light emitting element 12a, and the heat generation when the optical element 12 is the light receiving element 12b is less problematic. Therefore, when the optical element 12 is the light receiving element 12b, the type shown in FIG. 10 can be suitably employed.

1 1st board | substrate 1a 1st groove | channel (groove for waveguide formation)
1c Front end 12a Light emitting element 12b Light receiving element 15 Mirror part 15a Mirror bottom 15b Lower end 15c Upper end 16 Internal waveguide 17 Core part 17a Front end 17b Corner 18 Cladding part 18a Front end 18c Inner edge

Claims (7)

An internal waveguide provided in a waveguide forming groove formed on the surface of the substrate, an optical path converting mirror formed on the front end surface of the groove, and the surface of the substrate so as to face the mirror And an optical module that includes at least an optical element that emits an optical signal to the core portion of the internal waveguide via the mirror portion or receives an optical signal from the core portion of the internal waveguide via the mirror portion. In
The internal waveguide is composed of a core part and a clad part covering the core part,
The optical module according to claim 1, wherein a front end of the clad portion is set at least at a position of a front end of the waveguide forming groove.   The optical module according to claim 1, wherein a front end of the cladding portion extends to a vicinity of an upper end of the mirror portion.   The front end of the core part is set at a position retracted from the mirror part, and the front end of the clad part extends to the vicinity of the front end of the retracted core part. The optical module as described.   4. The optical module according to claim 3, wherein the front end of the clad part extends only to the vicinity immediately above the core part to the vicinity of the front end of the core part.   4. The optical module according to claim 3, wherein the front end of the clad part extends only to both sides near the upper part of the core part to the vicinity of the upper end of the mirror part.   6. The light according to claim 5, wherein inner edges of both side portions of the clad portion extending to near the upper end of the mirror portion are narrowly set so as to cover corners of both side portions of the core portion. module.   The optical module according to claim 1, wherein the waveguide forming groove has a substantially trapezoidal shape or a substantially V-shaped cross-sectional shape.

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