JP3699919B2 - Optical integrated circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical integrated circuit and an optical propagation device. In particular, the present invention relates to an optical integrated circuit and an optical propagation device that can arrange optical waveguides at a narrow interval.
[0002]
[Prior art]
As a conventional optical integrated circuit that detects light propagating through an optical waveguide formed on a dielectric substrate, the end of the optical waveguide is arranged by arranging the light receiving surface of the photodiode perpendicular to the longitudinal direction of the optical waveguide. There is an optical integrated circuit that receives light emitted from a light source.
[Problems to be solved by the invention]
The present invention solves the problem of arranging optical waveguides at narrow intervals in an optical integrated circuit.
[0003]
Therefore, an object of the present invention is to provide an optical integrated circuit and an optical propagation device that can solve the above-described problems. This object is achieved by a combination of features described in the independent claims. The dependent claims define further advantageous specific examples of the present invention.
[0004]
[Means for Solving the Problems]
In other words, according to the first aspect of the present invention, there is provided an optical integrated circuit for detecting light, the first and second optical waveguides for propagating the light formed on the first dielectric substrate, The second optical waveguide and the third optical waveguide formed so as to be able to deliver the light to and from the first optical waveguide; and the second optical waveguide and the light on the second dielectric substrate. An optical fiber provided so as to be able to deliver, an optical path conversion unit that changes a propagation direction of the light propagating through the third optical waveguide in a thickness direction of the second dielectric substrate, and an optical path conversion unit An optical integrated circuit comprising: a light receiving unit that receives the light whose propagation direction has changed and generates an electrical signal.
[0005]
It is desirable that the optical path conversion unit is a tip surface of the third optical waveguide. The third optical waveguide may be embedded in the second dielectric substrate, and the optical path changing unit may be a notch formed in the second dielectric substrate.
[0006]
The optical fiber is preferably provided so as to cross the cut, and more preferably, the cut is formed perpendicular to the third optical waveguide. Moreover, it is preferable that the second dielectric substrate has an accommodation groove that is formed orthogonal to the notch and that accommodates the optical fiber. In this case, the optical fiber may be bonded to the receiving groove.
[0007]
The optical fiber may be provided substantially parallel to the third optical waveguide. The second dielectric substrate may be formed of the same material as the first dielectric substrate.
[0008]
The optical path changing unit may change the propagation direction of the light in a direction away from the dielectric substrate. In this case, it is preferable that the light receiving portion is provided to face a surface of the second dielectric substrate on which the third optical waveguide is formed.
[0009]
The optical path changing unit may change the propagation direction of the light to a direction that transmits the dielectric substrate. In this case, it is preferable that the light receiving portion is provided to face the back surface of the surface on which the third optical waveguide is formed in the second dielectric substrate.
[0010]
According to a second aspect of the present invention, there is provided a light propagation device for propagating light, the first and second optical waveguides for propagating the light, formed on a first dielectric substrate, and second The first optical waveguide and the third optical waveguide formed so as to be able to deliver the light to the dielectric substrate, and the second optical waveguide and the light are delivered to the second dielectric substrate. An optical fiber provided in a possible manner, and an optical path changing unit that changes a propagation direction of the light propagating through the third optical waveguide in a thickness direction of the second dielectric substrate, An optical propagation device is provided.
[0011]
The above summary of the invention does not enumerate all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the claimed invention, and all combinations of features described in the embodiments are the solution of the invention. It is not always essential to the means.
[0013]
FIG. 1 shows an optical integrated circuit 100 according to an embodiment of the present invention. 1A to 1D are a plan view, an AA ′ cross-sectional view, a BB ′ cross-sectional view, and a bottom view of the optical integrated circuit 100, respectively. FIG. 1E shows the optical integrated circuit 100 viewed from the direction C in FIG. The optical integrated circuit 100 includes a light propagation device 101 that propagates light and a light receiving device 102 that receives light propagated through the light propagation device 101.
[0014]
The light propagation device 101 includes a first dielectric substrate 72, a first optical waveguide 70 and a second optical waveguide 74 formed on the first dielectric substrate 72, a second dielectric substrate 22, The third optical waveguide 20 on which the second dielectric substrate 22 is formed, and an optical path conversion unit that changes the propagation direction of light propagating through the third optical waveguide 20 in the thickness direction of the second dielectric substrate 22 And an incision 30 as an example.
[0015]
The first optical waveguide 70 and the second optical waveguide 74 are preferably embedded in the first dielectric substrate 72. The third optical waveguide 20 is preferably embedded in the second dielectric substrate 22. In this example, the first dielectric substrate 72 and the second dielectric substrate 22 are LiNbO 3 substrates. In addition, the first optical waveguide 70, the second optical waveguide 74, and the third optical waveguide 20 are made of, for example, titanium on the first dielectric substrate 72 and the second dielectric substrate 22 which are LiNbO 3 substrates, respectively. It is formed by thermal diffusion.
[0016]
The first optical waveguide 70 and the second optical waveguide 74 propagate light such as an optical signal in wavelength division multiplexing optical communication, for example. The third optical waveguide 20 is formed on the second dielectric substrate 22 so as to be able to exchange light with the first optical waveguide 70. The third optical waveguide 20 is desirably formed so that the optical axis of the first optical waveguide 70 substantially coincides.
[0017]
The third optical waveguide 20 is formed so that one end can pass light to the first optical waveguide 70 at the end of the second dielectric substrate 22, and the tip surface 32 at the other end is the third end surface 32. The optical waveguide 20 is formed obliquely with respect to the longitudinal direction. In this example, the tip surface 32 of the third optical waveguide 20 is a part of the notch 30 as shown in FIG. 1B, and the second dielectric substrate 22 and the third optical waveguide 20 are For example, it is formed by cutting using a dicing saw. It is desirable that the cut 30 has a V-shaped cross section in a direction substantially perpendicular to the longitudinal direction of the third optical waveguide 20. More preferably, the notch 30 is formed so that the distal end surface 32 of the third optical waveguide 20 totally reflects light, for example, an angle of about 45 degrees with respect to the longitudinal direction of the third optical waveguide 20. The In this case, the notch 30 is preferably formed by cutting the second dielectric substrate 22 and the third optical waveguide 20 using a V-shaped blade. In another example, the cut 30 may be formed by a micromachine such as etching or a semiconductor process.
[0018]
As shown in FIG. 1E, the optical fiber 78 includes a core 86 that propagates light, and a clad 88 that surrounds the core 86 and reflects light propagating through the core 86. The optical fiber 78 is provided on the second dielectric substrate 22 so as to be able to exchange light with the second optical waveguide 74. Specifically, as shown in FIG. 1C, the center of the cross section of the optical fiber 78 is substantially coincident with the center of the cross section of the second optical waveguide 74 formed on the first dielectric substrate 72. In addition, the optical fiber 78 is preferably provided on the second dielectric substrate 22.
[0019]
In the present example, the second dielectric substrate 22 has an accommodation groove 76 for accommodating the optical fiber 78. The accommodation groove 76 is formed to a depth such that the optical axis of the optical fiber 78 to be accommodated substantially coincides with the optical axis of the second optical waveguide 74 formed on the first dielectric substrate 72. Specifically, the accommodation groove 76 may be formed to a depth such that the center of the cross section of the optical fiber 78 is located near the surface of the second dielectric substrate 22. For example, when the center of the cross section of the second optical waveguide 74 is formed at a depth of about 1 to 3 μm from the surface of the first dielectric substrate 72, the center of the cross section of the optical fiber 78 is the second dielectric. The accommodation groove 76 is formed at a predetermined depth so as to substantially coincide with the depth from the surface of the substrate 22.
[0020]
The housing groove 76 is formed by precision machining such as a dicing saw or a precision grinding apparatus. Further, in this example, as shown in FIG. 1E, the accommodation groove 76 has a V-shaped cross section, and the second dielectric substrate 22 is cut using a V-shaped blade. It is formed by. In another example, the receiving groove 76 may be formed by a micromachine such as etching or a semiconductor process. Further, as shown in FIG. 1C, the accommodation groove 76 may be formed shallower than the notch 30 in the second dielectric substrate 22 or may be formed deeper.
[0021]
The accommodation groove 76 is formed in the second dielectric substrate 22 from the contact surface with the first dielectric substrate 72 to a surface facing the contact surface, substantially parallel to the third optical waveguide 20. It is preferable. In this case, the optical fiber 78 may be provided so as to protrude from the second dielectric substrate 22 on the facing surface.
[0022]
The accommodation groove 76 is formed so as to cross the notch 30 in the second dielectric substrate 22. In this example, the cut 30 is formed substantially perpendicular to the third optical waveguide 20, and the receiving groove 76 is formed substantially perpendicular to the cut 30.
[0023]
The optical fiber 78 is preferably fixed by being bonded to the second dielectric substrate 22. The optical fiber 78 may be fixed to the dielectric substrate 22 using, for example, an ultraviolet curable resin that is cured by irradiation with ultraviolet light as an adhesive member. In this example, as shown in FIG. 1E, the optical fiber is fixed to the second dielectric substrate 22 in the accommodation groove 76 by an adhesive member 87 such as an ultraviolet curable resin.
[0024]
In the present embodiment, by providing an optical fiber adjacent to the optical waveguide in which the propagation direction of the light propagating by the optical path changing unit is changed at one end, the degree of freedom in arranging the optical waveguide can be increased.
[0025]
The light propagation device 101 has a first dielectric substrate 72 on the surface where the first optical waveguide 70 and the second optical waveguide 74 are formed. The polishing member 80 is provided. Similarly, the light propagation device 101 has a second polishing member 82 at the end where the third optical waveguide 20 is formed on the second dielectric substrate 22 at the end where it is joined to the first dielectric substrate 72. Have Further, in this example, the second polishing member 82 has a groove for sandwiching the optical fiber 78 corresponding to the region where the accommodation groove 76 is formed in the second dielectric substrate 22.
[0026]
The first dielectric substrate 72 and the second dielectric substrate 22 are preferably bonded after the surfaces to be bonded are polished. In this example, first, a first polishing member 80 and a second polishing member 82 are bonded to the first dielectric substrate 72 and the second dielectric substrate 20, respectively. The surface where the first dielectric substrate 72 and the second dielectric substrate are bonded to each other, and the surface where the first polishing member 80 and the second polishing member 82 are bonded to each other are predetermined. It grind | polishes so that it may have the flatness of. In this case, the first optical waveguide 70, the second optical waveguide 74, and the third optical waveguide 20 are polished so that the bonding surface 90 has a predetermined angle.
[0027]
In this example, the first polishing member 80 and the second polishing member 82 are formed of the same material as the first dielectric substrate 72 and the second dielectric substrate 22. The first dielectric substrate 72 and the second dielectric substrate 22 have a bonding surface 90 that is approximately equal to the first optical waveguide 70, the second optical waveguide 74, and the third optical waveguide 20, respectively. Polished to have an angle of 3 to 7 degrees. The first dielectric substrate 72 and the second dielectric substrate 22 are bonded using a bonding member that transmits light, such as an ultraviolet curable resin.
[0028]
In this embodiment, by polishing the dielectric substrate using the polishing member, the bonding surface is polished without cutting the corner formed by the bonding surface where the dielectric substrate is bonded and the surface where the optical waveguide is formed. can do.
[0029]
The light receiving device 102 receives the light whose propagation direction has been changed by the notch 30 of the light propagation device 101 and generates an electrical signal. The photodiode 10 is an example of a light receiving unit that generates an electrical signal, and the transmission path 40 that propagates the generated electrical signal. With. In this example, the light receiving device 102 further includes an amplification circuit board 50 that amplifies the electric signal propagated through the transmission path 40.
[0030]
As shown in FIGS. 1B and 1D, the photodiode 10 is provided on a surface of the second dielectric substrate 22 that faces the surface on which the third optical waveguide 20 is provided. In this example, the photodiode 10 is fixed to the second dielectric substrate 22 by solder bumps 60.
[0031]
The transmission path 40 transmits the electrical signal generated by the photodiode 10. The transmission path 40 includes an anode transmission path 44 that is electrically connected to the anode electrode of the photodiode 10 and a plurality of cathodes that are electrically connected to the cathode electrode of the photodiode 10 and sandwiching the anode transmission path 44. A transmission line 42. The transmission line 40 is formed by a coplanar structure, a microstrip structure, or the like so as to have a predetermined impedance of 50Ω, for example, according to the dielectric constant of the material forming the second dielectric substrate 22. The amplifying circuit board 50 may be provided on a surface of the second dielectric substrate 22 substantially parallel to the third optical waveguide 20 and has an amplifying circuit that amplifies the electric signal transmitted through the transmission path 40.
[0032]
The operation of the optical integrated circuit 100 will be described.
The light propagated through the first optical waveguide 70 passes through the bonding surface 90 between the first dielectric substrate 72 and the second dielectric substrate 22 and propagates through the third optical waveguide 20. Then, the light propagated through the third optical waveguide 20 is caused by the distal end surface 32 of the third optical waveguide 20 formed in the notch 30 which is an example of the optical path conversion unit at the end of the third optical waveguide 20. The optical path is converted in the thickness direction of the second dielectric substrate 22.
[0033]
The light whose optical path has been converted passes through the second dielectric substrate 22 and is irradiated to the photodiode 10. The photodiode 10 detects the irradiated light and generates an electrical signal based on the intensity of the irradiated light. The transmission path 40 transmits the electric signal and supplies the electric signal to the amplification circuit board 50. The amplification circuit board 50 amplifies the electrical signal and supplies the amplified electrical signal to another external device or the like.
[0034]
FIG. 2 shows another example of the optical integrated circuit 100. The optical integrated circuit 100 includes a third dielectric substrate 94 bonded at one end of the first dielectric substrate 72, a fourth optical waveguide 92 formed on the third dielectric substrate 94, A light emitting element 11 that is an example of a light emitting unit that generates light propagating through the optical waveguide 92, and a cut 31 and a tip surface that are an example of an optical path changing unit that guides the light generated in the light emitting element 11 to the fourth optical waveguide 92 33 is further provided. The third dielectric substrate 94 may be bonded to the first dielectric substrate 72 via the bonding surface 91 in the same manner as the second dielectric substrate 22.
[0035]
The cut 31 is formed in the third dielectric substrate 94. The fourth optical waveguide 92 is formed so as to be able to exchange light with the first optical waveguide 70. That is, the fourth optical waveguide 92 may be formed in the same manner as the third optical waveguide 20 with respect to the first optical waveguide 70. The optical integrated circuit 100 may further include an optical fiber provided on the third dielectric substrate 94. In this case, the optical fiber may be provided on the third dielectric substrate 94 in the same manner as the optical fiber 78 provided on the second dielectric substrate 22.
[0036]
The light emitting element 11 is arranged so that emitted light travels in the thickness direction of the third dielectric substrate 94. In the present example, the light emitting element 11 is disposed so as to face the back surface of the third dielectric substrate 94 on which the fourth optical waveguide 92 is formed. Specifically, the light-emitting element 11 transmits the third light through the third dielectric substrate 94 and irradiates the front end surface 33 which is an example of the optical path conversion unit via the solder ball 60. 3 is fixed to the dielectric substrate 94.
[0037]
The light emitting element 11 may be a surface light emitting element. In this case, the optical integrated circuit 100 may include a lens that focuses the light emitted from the light emitting element 11 between the light emitting element 11 and the distal end surface 33.
[0038]
FIG. 3 shows an enlarged view of the vicinity of the notch 30 in still another example of the optical integrated circuit 100. In this example, the photodiode 10 is provided on the second dielectric substrate 22 so as to face the optical waveguide forming surface on which the third optical waveguide 20 is formed. The photodiode 10 is provided between the bonding pad 12 provided on the photodiode 10, the bonding pad 24 provided on the second dielectric substrate 22, and the bonding pads 12 and 24. The solder ball 60 is fixed to the second dielectric substrate 22.
[0039]
The bonding pads 12 and 24 are, for example, a laminated film of titanium, chromium, and gold. In the second dielectric substrate 24, the bonding pad 24 is desirably provided in a region other than the region where the third optical waveguide 20 is formed.
[0040]
In this example, the front end surface 32 which is an example of the optical path changing unit is such that the light propagating through the third optical waveguide 20 is in the thickness direction of the second dielectric substrate 22, and from the second dielectric substrate 22. The optical path is changed in the direction of leaving. The notch 30 forming the distal end surface 32 is preferably formed so that the second dielectric substrate 22 and the third optical waveguide 20 have a bowl shape. Further, the optical integrated circuit 100 may include an antireflection film 34 provided so as to cover the vicinity of the front end surface 32 on the surface of the second dielectric substrate 22 on which the third optical waveguide 20 is formed. The antireflection film 34 is an example of an antireflection means for preventing light from being reflected on the surface of the third optical waveguide 20 due to a mismatch in refractive index when light is emitted from the third optical waveguide 20 to the outside. is there.
[0041]
The light that has propagated through the third optical waveguide 20 is reflected by the distal end surface 32 that functions as a reflection mirror. In this example, the front end surface 32 is formed at about 45 degrees with respect to the optical waveguide forming surface on which the third optical waveguide 20 is formed on the second dielectric substrate 22, and the light reflected by the front end surface 32 is The optical path is changed at an angle of about 90 degrees with respect to the optical waveguide forming surface. Then, the light passing through the antireflection film 34 is irradiated onto the light receiving surface of the photodiode 10, whereby information contained in the irradiated light can be converted into an electrical signal.
[0042]
As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.
[0043]
【The invention's effect】
As is apparent from the above description, according to the present invention, it is possible to provide an optical integrated circuit and an optical propagation device capable of arranging optical waveguides at a narrow interval.
[Brief description of the drawings]
FIG. 1 shows an optical integrated circuit 100 according to an embodiment of the present invention.
2 shows another example of the optical integrated circuit 100. FIG.
FIG. 3 is an enlarged view of the vicinity of the notch 30 in another example of the optical integrated circuit 100. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Photodiode, 11 ... Light emitting element, 12 ... Bonding pad, 20 ... 3rd optical waveguide, 22 ... 2nd dielectric substrate, 24 ... Bonding pad , 30, 31 ... notches, 32, 33 ... tip surface, 34 ... antireflection film, 40 ... transmission path, 42 ... cathode transmission path, 44 ... anode transmission path, 50 ... Amplification circuit board, 60 ... solder ball, 70 ... first optical waveguide, 72 ... first dielectric substrate, 74 ... second optical waveguide, 76 ... accommodating Groove, 78 ... optical fiber, 80 ... first polishing member, 82 ... second polishing member, 86 ... core, 87 ... adhesive member, 88 ... clad, 90, 91 ... bonding surface, 92 ... fourth optical waveguide, 94 ... third dielectric substrate, 100 ... optical integration Road, 101 ... optical transmitting device, 102 ... receiving device

Claims (13)

An optical integrated circuit for receiving light propagating through first and second optical waveguides formed on a first dielectric substrate ,
A third optical waveguide formed on the surface of the second dielectric substrate so as to be able to receive the light from the first optical waveguide;
A direction of propagation of the light propagating through the third optical waveguide, which is formed on the surface of the second dielectric substrate and includes a tip surface of the third optical waveguide as a part, is defined as the second dielectric. Incision to change in the thickness direction of the body substrate,
An optical fiber provided on the surface of the second dielectric substrate so as to cross the notch and capable of receiving the light from the second optical waveguide;
An optical integrated circuit comprising: a light receiving unit that receives the light whose propagation direction has been changed by the cut and generates an electrical signal. The optical integrated circuit according to claim 1, wherein the third optical waveguide is embedded in the second dielectric substrate. Optical integrated circuit according to claim 1, wherein the notch is vertically formed in the third optical waveguide.   The optical integrated circuit according to claim 1, wherein the optical fiber is provided substantially parallel to the third optical waveguide. 5. The optical integrated circuit according to claim 4 , further comprising an accommodation groove that is formed orthogonal to the notch and accommodates the optical fiber on the surface of the second dielectric substrate. The optical integrated circuit according to claim 5 , wherein the optical fiber is bonded to the receiving groove. The optical integrated circuit according to claim 1, wherein the second dielectric substrate is formed of the same material as the first dielectric substrate. The optical integrated circuit according to claim 1 , wherein the cutting changes a propagation direction of the light in a direction away from the second dielectric substrate . The optical integrated circuit according to claim 8 , wherein the light receiving portion is provided to face a surface of the second dielectric substrate on which the third optical waveguide is formed. 8. The optical integrated circuit according to claim 1 , wherein the cutting changes a propagation direction of the light to a direction that transmits the second dielectric substrate . 9. The optical integrated circuit according to claim 10 , wherein the light receiving portion is provided to face a back surface of a surface of the second dielectric substrate on which the third optical waveguide is formed. An optical integrated circuit for delivering light to first and second optical waveguides formed on a first dielectric substrate,
  A third optical waveguide formed on the surface of the second dielectric substrate so as to be able to deliver the first optical waveguide and the light;
  A light emitting unit that emits light traveling in the thickness direction of the second dielectric substrate;
  A notch that is formed on the surface of the second dielectric substrate, includes a tip surface of the third optical waveguide as a part, and guides the light emitted from the light emitting unit to the third optical waveguide;
  An optical fiber provided on the surface of the second dielectric substrate so as to cross the cut and provided so as to be able to deliver the light to the second optical waveguide;
An optical integrated circuit comprising: The optical integrated circuit according to claim 12 , wherein the third optical waveguide is embedded in the second dielectric substrate.

Images