JPH1114846A - Single-mode optical waveguide and its manufacture, and optical module using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the single-mode optical waveguide which has high position precision as to a positioning index, a thin groove for filter insertion, etc., and small-sized constitution and can prevent a clad mode from leaking to a reflection port, and its manufacture and the optical module using it. SOLUTION: A bench 25 for mounting a light emitting element 22 and a light receiving element 19 is formed on a substrate 11, a buffer layer 27 is formed except at benches 25 and 46 on the substrate 11, and a height adjustment layer 28 for optical axis alignment with both the elements 22 and 19 is formed on the buffer layer 27; and a waveguide core 12 is formed on the height adjustment layer 28, the alignment index for both the elements 19 and 22 is formed on the bench 25, and a clad layer 13 is formed on the substrate 11 where the index is formed. Then a deep groove for exposing the benches 25, 42a, and 46 is formed on the clad layer 13, and electrodes 39 to 41 for supplying a current to the light emitting element 22 and leading a current out of the photodetecting element 19 are formed on the bench 25 to obtain the single-mode optical waveguide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single mode optical waveguide, a method for manufacturing the same, and an optical module using the same.

[0002]

2. Description of the Related Art For the spread of optical fiber communication, particularly for the spread of optical subscriber systems, it is important to reduce the size and cost of optical modules. In order to solve this problem, an optical module in which a waveguide is formed on a Si substrate and a chip-level LD (laser diode), PD (photodiode) and MPD (monitoring photodiode) are surface-mounted has been studied. I have.

FIG. 8 is a diagram showing a platform structure of an optical module on which an LD is surface-mounted.

In this surface-mount type optical module 1, a buffer layer 3 is formed on a Si substrate 2 having a terrace structure, and a buried quartz-based waveguide comprising a waveguide core 4 and a cladding layer 5 is formed on the buffer layer 3. Waveguide element 6 is formed, and LD 8 is arranged on Si bench 7. The Si bench 7 of the optical module 1 is expected to function not only as a substrate for mounting semiconductor elements but also as a heat sink.

[0005] The structure of the optical circuit formed in the optical module 1 includes a video signal (wavelength λ1) and a communication signal (wavelength λ2, λ2).
合 λ1), the wavelength λ is added to the waveguide.
A method of inserting a filter having a characteristic of transmitting the light of No. 2 and reflecting the light of the wavelength λ1 is being studied.

FIG. 9 is an external perspective view of a conventional optical module.

In the optical module 10 shown in FIG. 1, a Y-shaped quartz glass single-mode optical waveguide element 14 comprising a waveguide core 12 and a cladding layer 13 is formed on a Si substrate 11, and a Y-shaped branch is formed. The unit is provided with a filter 15 that transmits light of wavelength λ2 and reflects light of wavelength λ1 (λ2 ≠ λ1).

The light propagating through the waveguide core 12 of the optical module 10 will be described in order.

First, the light of wavelength λ2 incident from the common port 16 passes through the waveguide core 12, passes through the filter 15, and is branched by the Y branch optical tap 17 at a desired distribution ratio.
It reaches the PD 19 through the D port 18.

The light of wavelength λ1 incident from the common port 16 passes through the waveguide core 12, is reflected by the filter 15, is guided to the reflection port 20, and propagates through the optical fiber 21.

The light of wavelength λ2 emitted from LD 22 is
The light passes through the LD port 23, the Y-branch optical tap 17, and the filter 15 and is guided to the common port 16 and the optical fiber 21.

Conventionally, PD19, LD22 and MPD24
In the method of adjusting the optical axis between the device and the waveguide core 12, the optical axis is adjusted while monitoring the optical output. However, the PD19, the LD22, and the MP22 are accurately adjusted.
A passive alignment mounting method for positioning D24 has been studied. In this method, the device is positioned and mounted by recognizing a marker (not shown) provided on the Si substrate 11 on which the PD 19, the LD 22 and the MPD 24 are mounted, and is expected to be mass-produced and reduced in cost. .

[0013]

However, an optical module 1 having an optical waveguide element 14 formed on a Si substrate 11
0 indicates that the alignment of the photomask in each step is accurately performed, and the Si bench 25 formed in each step is
It is necessary to accurately perform relative positioning of the waveguide core 12, the PD 19, the index for positioning of the LD 22, and the like, and the relative positioning of the narrow groove 26 for inserting a filter and the like.

In the single-mode optical waveguide element 14 formed on the Si substrate 11, light emitted from the LD 22 generates a radiation mode at a coupling portion with the waveguide core 12 and at the optical waveguide element 14, and the radiation mode is generated. The mode is confined in the cladding layer 13 and becomes a cladding mode and leaks into the reflection port 20 facing the LD 22.

Further, for further mass production and cost reduction, it is necessary to reduce the size of the optical waveguide element 14.

As a method for achieving this, the optical waveguide element 14
Waveguide core 12 (refractive index nco) and cladding layer 13
(Refractive index ncl) relative refractive index difference Δ (Δ = (nco−nc
1) / nco × 100%) may be considered to be larger than the relative refractive index difference Δ = 0.3% of the single mode optical fiber. However, when the relative refractive index difference Δ of the optical waveguide element 14 is increased,
Due to the mode field mismatch with the optical fiber 21, the connection loss increases, and the optical module 10
There is a problem that the loss as a whole increases.

Accordingly, an object of the present invention is to solve any or all of the above-mentioned problems, and to provide an index for positioning,
A single mode optical waveguide capable of realizing any or all of the improvement of the positional accuracy of a filter insertion narrow groove and the like, miniaturization, and prevention of leakage of a clad mode into a reflection port, a method of manufacturing the same, and an optical module using the same. To provide.

[0018]

In order to achieve the above object, a single mode optical waveguide according to the present invention comprises a single mode optical waveguide having a single mode optical waveguide element formed on a substrate. A bench for mounting the element is formed on the surface of the substrate, a buffer layer is formed on a portion other than the bench on the substrate, and a height adjustment layer for aligning an optical axis with the light emitting element and the light receiving element is formed on the buffer layer. Is formed,
A waveguide core is formed on the height adjustment layer, an index for alignment of the light emitting element and the light receiving element is formed on the bench, a cladding layer is formed on the height adjustment layer and the waveguide core, and the light emitting element is formed on the bench. An electrode for supplying a current to the device and extracting a current from the light receiving element is formed.

In addition to the above configuration, the single mode optical waveguide of the present invention has a y-shaped waveguide formed on the height adjusting layer, a narrow groove formed at the y-branch portion, and a wavelength λ1 in the narrow groove. A filter that reflects light of wavelength λ2 and transmits light of wavelength λ2 (λ1 ≠ λ2) is provided, and a Y-branch light tap that divides light of wavelength λ2 into an arbitrary branching ratio is formed between the y-shaped waveguide and the bench. It is preferred that

In addition to the above configuration, in the single mode optical waveguide of the present invention, a filter index for forming a narrow groove and inserting a filter is preferably formed on a substrate.

In addition to the above configuration, in the single mode optical waveguide of the present invention, it is preferable to form a groove around the waveguide core and insert a light-shielding member in the groove.

In addition to the above configuration, in the single mode optical waveguide of the present invention, it is preferable that at least one groove into which a light-shielding member is inserted is formed between the filter and the end face of the waveguide.

In addition to the above configuration, in the single mode optical waveguide of the present invention, it is preferable that the end face of the waveguide is obliquely polished.

According to the single mode optical waveguide of the present invention, in a single mode optical waveguide having a single mode optical waveguide element formed on a substrate, a bench for mounting a light emitting element and a light receiving element is formed on the surface of the substrate. A buffer layer is formed on a portion other than the bench on the substrate, a height adjustment layer for optical axis alignment with the light emitting element and the light receiving element is formed on the buffer layer, and a y-shape is formed on the height adjustment layer. Is formed in the Y-branch, and a filter that reflects light of wavelength λ1 and transmits light of wavelength λ2 (λ1 ≠ λ2) is disposed in the narrow groove. The radius of curvature of the curved portion of the filter is different before and after the filter, a cladding layer is formed on the height adjustment layer and on the waveguide core so as to cover the waveguide core,
An electrode for supplying current to the light emitting element and extracting current from the light receiving element is formed on the bench.

In addition to the above configuration, the single mode optical waveguide of the present invention has a relative refractive index difference Δ of the single mode optical waveguide of 0.42.
~ 0.47%, the size of the waveguide core is 6.8 × 6.8 μm
^It is preferable that the thickness be ² to 7.2 × 7.2 μm ² .

In addition to the above configuration, in the single mode optical waveguide of the present invention, the radius of curvature of the curved portion of the waveguide core is preferably 10 to 15 mm before the filter and 6 to 9 mm after the filter.

In addition to the above configuration, the single mode optical waveguide of the present invention preferably has an inflection point at the inflection point of the curved portion of the core.

In addition to the above configuration, in the single mode optical waveguide of the present invention, it is preferable that the offset amount of the offset structure of the waveguide core is changed before and after the filter.

In the optical waveguide module of the present invention, a bench for mounting a light emitting element and a light receiving element is formed on a surface of a substrate, a buffer layer is formed on a portion other than the bench on the substrate, and the light emitting element is formed on the buffer layer. And a height adjustment layer for optical axis alignment with the light receiving element is formed, a waveguide core is formed on the height adjustment layer, an alignment index for the light emitting element and the light receiving element is formed on the bench, and height adjustment is performed. A cladding layer is formed on the layer and the waveguide core, electrodes for supplying current to the light emitting element and extracting current from the light receiving element are formed on the bench, and the light emitting element and the light receiving element are mounted on the bench. Is what it is.

In addition to the above configuration, the optical waveguide module of the present invention preferably has an optical fiber connected to the end face of the waveguide.

The method for manufacturing a single mode optical waveguide according to the present invention comprises:
In a method for manufacturing a single-mode optical waveguide in which a single-mode optical waveguide element is formed on a substrate, a substrate for mounting a light-emitting element and a light-receiving element and a bench for forming an index for inserting a filter are left on the substrate. An etching step of etching the surface, a buffer layer forming step of forming a buffer layer on a portion other than the bench on the substrate, and a height adjustment layer for aligning an optical axis with the light emitting element and the light receiving element on the buffer layer. Forming a height adjusting layer, forming a waveguide core on the height adjusting layer, and simultaneously forming an index for aligning a light emitting element and a light receiving element and an index for inserting a filter on a bench. An index forming step, a clad layer forming step of forming a clad layer on the substrate on which the index is formed, and a bench. A deep groove etching step of performing deep grooves etched in cladding layer for out, in which an electrode forming step of forming an electrode for taking out current from the light receiving element current supply to the light emitting element on the bench.

In addition to the above configuration, in the method of manufacturing a single mode optical waveguide of the present invention, it is preferable that a mark is formed at the same time as forming a bench on a substrate, and alignment is performed in each step using the mark as a mark.

In addition to the above configuration, the method for manufacturing a single mode optical waveguide of the present invention comprises the steps of: exposing a waveguide core on a height adjusting layer by photolithography and exposing an index on a bench. It is preferable that the alignment is performed simultaneously using one photomask, and the relative alignment between the waveguide core and the index for aligning the light emitting element and the light receiving element and the index for inserting the filter is performed.

With the above configuration, the first step, Si
A mark that serves as a mark for mask alignment is formed during the bench formation process, and by aligning this mark with the mark printed on the photomask, the alignment of the photomask is accurate, easy, and short. Done on time.

[0035]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an external perspective view showing an embodiment of an optical module using a single mode optical waveguide according to the present invention. FIG. 2A is a plan view of FIG. 1, and FIG.
FIG. 2A is a cross-sectional view taken along line AA, and FIG.
FIG. 2D is a sectional view taken along line CC of FIG. 2A. Note that the same members as those of the conventional example shown in FIG.

As shown in FIG.
The buffer layer 2 is formed on the Si substrate 11 on which the bench 25 is formed.
7 are formed. A height adjustment layer 28 is formed on the buffer layer 27, and the waveguide core 12 is formed on the height adjustment layer 28.
In addition, a single-mode optical waveguide element 14 including the cladding layer 13 is formed.

The refractive index n ₁ of the buffer layer 27, the height adjusting layer 28, and the cladding layer 13 is set to 1.458, and the refractive index n ₂ of the waveguide core 12 is set to the relative refractive index difference (Δ
= 46% (relative refractive index difference Δ =
0.5%), the size of the optical waveguide element 14 is reduced. The core size is wavelength λ2 (1.3 μm
The band was set to 6 × 6 μm in order to make a single mode.

An optical fiber 21 is connected to the core end face of the optical waveguide element 14, and PDs 19, L
D22 and MPD24 are mounted. A groove 29 having a width of about 300 μm is formed near the waveguide core 12 in a direction crossing the waveguide core 12, and a light-shielding member (for example, a black resin) 30 is inserted in the groove 29. A narrow groove 26 intersecting with the waveguide core 12 is formed in the Y branch portion 31, and the filter 15 is inserted in the narrow groove 26. Si
An electrode 32 is formed on the cladding layer 13 on the bench 25 side, and an optical module 33 is formed. Since the width w of the cladding layer 13 is as small as about 60 μm,
The cross section of 0 is actually as shown by the broken line L (FIG. 2C), but the effect of the blocking remains unchanged.

In the mount portions of the PD 19, the LD 22, and the MPD 24, the Si substrate 11 is exposed by glass etching, so that the heat emission efficiency of the LD 22 during light emission is improved. The current supply to the LD 22 is performed by the electrode 32 and the wire 3
4 and the extraction of the signal current from the PD 19 is performed by the wires 35 and 36. Extraction of the signal current from the MPD 24 is performed by wires 37 and 38, and the electrodes 32 and the wires 34 to 38 are bonded to external electrode pins (not shown) such as an IC board. As described above, the electrode 32 on the cladding layer 13 plays a role of relaying the wire, and particularly when the distance between the electrode 39, 40, 41 on the Si bench 25 and the external electrode pin is long, the length of the wire is suppressed. Can be useful.

The end face of the optical waveguide element 14 is
As a countermeasure for reducing the connection loss with 1 and a countermeasure for reflected return light at the end face, it is polished at an angle of 8 ° with respect to the vertical face.

As shown in FIG. 2, the pattern of the waveguide core 12 is composed of a Y-shaped optical waveguide having a branch angle of 20 ° and a Y-branch optical tap 17. The filter 15 provided in the Y branch portion 31 has a short-wavelength band pass type dielectric multilayer film structure that transmits light of wavelength λ2 (1.3 μm band) and reflects light of wavelength λ1 (1.55 μm band). Filter. The Y-branch optical tap 17 has a structure in which the rate of increase of the core width from the branch point of the Y-branch optical tap 17 is changed, and the branching ratio can be arbitrarily changed.

Here, the light of wavelength λ1 (1.55 μm) incident from the common port 16 is reflected by the filter 15 and guided to the reflection port 20. In this pass,
If the position of the filter 15 is shifted by several μm, a loss due to the shift occurs. Therefore, an index 42 for processing the narrow groove 26 for inserting a filter is formed, and the index 42 is used as a mark to recognize an image, whereby the narrow groove 2 is formed.
The processing accuracy of No. 6 is improved. In order to further improve the relative positional accuracy between the index 42 and the waveguide core 12, it is preferable to form the index 42 and the waveguide core 12 using the same mask. As a result, ±
The processing of the narrow groove 26 with an accuracy of 1 μm became possible.

In the optical module shown in FIG. 1, a waveguide is provided from the common port 16 or the reflection port 20 to the filter 15, from the filter 15 to the Y branch optical tap 17, from the Y branch optical tap 17 to the LD port 23 or the PD port 18. The core 12 is routed with a single curvature.

When the waveguide core 12 is routed with a single curvature, bending loss is involved. The bending loss depends on the radius of curvature and the waveguide core 12.
And increases as the radius of curvature decreases.

On the other hand, the bending loss decreases as the wavelength of the light propagating in the waveguide core 12 decreases. In the waveguide structure of the optical module shown in FIG. 1, light having a wavelength λ1 (1.55 μm) is reflected by the filter 15.
Only the light of m) is guided.

That is, after the filter 15, the wavelength λ2
The bending loss of only (1.31 μm) light may be considered.

Therefore, before the filter 15 (left side in the figure)
Compared to the radius of curvature R1 of the waveguide core 12 of FIG.
The radius of curvature R2 after is reduced.

FIG. 3A is a plan view of the optical module showing a case where the radius of curvature of the waveguide core is equal before and after the filter. FIG. 3B is a diagram showing the radius of curvature of the waveguide core before and after the filter. FIG. 3 is a plan view of an optical module showing a case;
FIG. 3C is an enlarged view of the inside of a circle D in FIG.

The radius of curvature of the waveguide core 12 is
3 (a), the optical module is different when the radius of curvature of the waveguide core 12 is different before and after the filter 15 (R1> R2, FIG. 3 (b)). It can be seen that the size can be reduced.

Specific refractive index difference Δ = 0.43%, core size =
FIG. 4 shows the relationship between the radius of curvature and the bending loss in the case of an optical waveguide structure of 7.2 × 7.2 μm ² . In the present optical waveguide device, since the leading portion with a single curvature is short, the radius of curvature R1 in front of the filter 15 is 13 mm, and
After that, the radius of curvature R2 was set to 8 mm. Note that an offset structure is used at the inflection point 43 of the curved portion of the waveguide core 12 in order to reduce transition loss. Filter 15
Since the radius of curvature before and after is different, the offset amount is changed.

Conventional examples of waveguide parameters used for miniaturization of a waveguide element are: a relative refractive index difference Δ = 0.5%, a core size = 6 × 6 μm ^2, and a single mode in a wavelength 1.3 μm band. The method is general. However, in this structure, the connection loss due to the mismatch with the single mode optical fiber is about 0.3 dB / point. Therefore, Δ = 0.4
2 to 0.47%, core size 6.8 × 6.8 μm ^{2 to} 7.
By setting it to 2 × 7.2 μm ² , the connection loss with the fiber can be reduced to about 0.1 dB / point. However, in the present waveguide structure parameters, the cutoff wavelength is 1.4 to 1.
5 μm, and does not become a single mode in the wavelength band of 1.3 μm. Therefore, a higher-order mode can be intentionally radiated by reducing the radius of curvature in the routing portion of the waveguide core. If the radius of curvature is too small,
In order to increase the bending loss, the radius of curvature of the present structure is set to 10 in front of the filter portion where the wavelength of 1.5 μm propagates.
The optimum value is 6 to 9 mm after the filter portion where the wavelength band of 1.5 to 15 mm does not propagate.

The wavelength λ2 (1.31) emitted from the LD 22
μm) passes through the LD port 23, the Y-branch optical tap 17 and the filter 15, and is guided to the common port 16 and the optical fiber 21. At this time, the LD 22 and the waveguide core 1
2, a clad mode occurs at the junction with the Y-branch 2, the Y-branch optical tap 17, and the branch 31 of the y-shaped optical waveguide. This cladding mode is confined and propagated between the Si substrate 11 and the air layer above the cladding layer 13, but is blocked by the light shielding member 30 inserted in the groove 29 and the Si bench 46. Therefore, it is possible to suppress the cladding mode from leaking into the optical fiber 21 of the reflection port 20.

In the optical module shown in FIG.
Of light having a wavelength λ2 (1.31 μm) emitted from the optical fiber 21 on the reflection port 20 side is 55 dB, which is 15 dB as compared with the conventional example (leakage 40 dB) without the groove 29 and the light shielding member 30. I could improve it.

FIG. 5 is an external perspective view showing another embodiment of the optical module of the present invention.

The difference from the embodiment shown in FIG. 1 is that when the optical waveguide element 14 and the optical fiber 21 are connected, the reinforcing plate 44 and the fiber block 45 as shown in FIG. This is the point that the bonding surface is widened using.

Even with such a structure, the same effects as those of the optical module shown in FIG. 1 can be obtained.

Next, a method for manufacturing a single mode optical waveguide according to the present invention will be described.

FIGS. 6A to 6J are process diagrams showing one embodiment of a method for manufacturing a single-mode optical waveguide according to the present invention.

The PD 19, the LD 22 and the M
The periphery of the Si substrate 11 is etched so that the Si bench 25 for mounting the PD 24, the Si bench 46 for removing the cladding mode, and the Si bench 42a for forming the index 42 for inserting the filter remain (FIG. 6). (A), (b)).

The buffer layer 27 is formed on the Si substrate 11 (FIG. 6C).

The buffer layer 27 is polished and flattened to expose the Si benches 25, 42a and 46 (FIG. 6).
(D)).

The PD 19 and LD 22 are formed on the buffer layer 27.
Then, a height adjustment layer 28 for optical axis alignment is formed (FIG. 6E).

The waveguide core 12 is formed on the height adjustment layer 28, and the mask 47 for forming the index 43 for mounting the PD 19, the LD 22 and the MPD 24 and the index 42 for inserting the filter is formed on the Si bench 2.
5, 42a (FIG. 6 (f)).

An index 43 for mounting the PD 19, the LD 22, and the MPD 24 is formed on the Si bench 25, and an index 42 for inserting a filter is formed on the Si bench 42a (FIG. 6 (g)).

The waveguide core 12, the height adjusting layer 28 and the Si
The clad layer 13 is formed on the benches 25, 42a, 46 (FIG. 6 (h)).

The deep groove etching is performed on the clad layer 13 so that the surfaces of the Si benches 25, 42a and 46 are exposed (FIG. 6 (i)).

The electrodes 32, 39, 40 and 41 are formed on the cladding layer 13 and the Si bench 25 (FIG. 6 (j)).

In the above manufacturing process, exposure by photolithography is performed several times. Therefore, if the respective photomasks are not accurately aligned, misalignment occurs in each step, and an optical waveguide or optical module with good performance cannot be manufactured.

Therefore, in the present embodiment, the first step is the formation of Si benches 25, 42a, 46 (FIG. 6).
In (b)), a mark serving as a mark for alignment of the photomask is provided.

FIG. 7 shows a top view of the Si wafer 11a after the Si benches 25, 42a, 46 and the mark 48 have been formed. Although only four elements are shown for the sake of simplicity of explanation, in actuality, about 100
An element is arranged.

FIG. 7A is a plan view of the Si wafer 11a for forming the substrate of the optical module shown in FIG. 1, and FIG. 7B is a sectional view taken along line EE of FIG. It is.

By aligning the mark 48 on the Si wafer 11a with the mark printed on the photomask (not shown), the photomask can be accurately, easily and quickly adjusted in the subsequent steps. . Electrode 32,
After the formation of 39 to 40, the Si wafer 11a is diced to form the Si on which the optical waveguide element 14 is formed.
The substrate 11 is obtained.

The waveguide core 12, PD 19, LD2
2 and the MPD 24 and the waveguide core 12 and the filter 15 are aligned by the index alignment method, so that the relative positions of the waveguide core 12 and the index 42 are adjusted with submicron accuracy. There is a need.

Therefore, the exposure for forming the index may be performed simultaneously with the exposure for forming the waveguide core, that is, using the same mask. This allows index 4
Not only is the relative position between the waveguide core 12 and the waveguide core 12 accurate, but also the photomask alignment is not required, and the number of steps can be reduced.

As described above, according to the present invention, it is possible to form the Si bench, the waveguide core, the LD and PD alignment index, the filter insertion narrow groove, and the like with high relative positional accuracy. In addition, it is possible to suppress the clad mode from leaking into the reflection port and to realize the miniaturization of the optical waveguide.

[0077]

In summary, according to the present invention, the following excellent effects are exhibited.

In the first step of forming the Si bench, a mark serving as a mark for positioning the mask is formed, and this mark is aligned with the mark printed on the photomask to provide a positioning mark. The positioning accuracy of the index, filter insertion groove, etc. is high and compact.
It is possible to realize a single-mode optical waveguide, a method of manufacturing the same, and an optical module using the same that can prevent the clad mode from leaking into the reflection port.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing an embodiment of an optical module using a single mode optical waveguide according to the present invention.

2A is a plan view of FIG. 1, and FIG. 2B is a plan view of FIG.
A sectional view taken along line A, (c) is a sectional view taken along line BB of (a), (d)
FIG. 3 is a cross-sectional view taken along line CC of FIG.

FIG. 3A is a plan view of the optical module showing a case where the radius of curvature of the waveguide core is equal before and after the filter, and FIG.
Is a plan view of the optical module showing a case where the radius of curvature of the waveguide core is different before and after the filter, and (c) is a circle D in (b).
It is an enlarged view inside.

FIG. 4 is a characteristic diagram showing a relationship between a radius of curvature and a bending loss.

FIG. 5 is an external perspective view showing another embodiment of the optical module of the present invention.

FIGS. 6A to 6J are process diagrams showing one embodiment of a method for manufacturing a single-mode optical waveguide according to the present invention.

7A is a plan view of a Si wafer for forming the substrate of the optical module shown in FIG. 1, and FIG. 7B is a cross-sectional view taken along line EE of FIG.

FIG. 8 is a diagram showing a platform structure of an optical module on which an LD is surface-mounted.

FIG. 9 is an external perspective view of a conventional optical module.

[Explanation of symbols]

 Reference Signs List 11 substrate (Si substrate) 12 waveguide core 13 clad layer 19 light receiving element (PD) 22 light emitting element (LD) 25, 46 bench (Si bench) 27 buffer layer 28 height adjustment layer 32, 39 to 41 electrode

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Yoshinori Hibino, Inventor 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Yasufumi Yamada 3-192, Nishi-Shinjuku, Shinjuku-ku, Tokyo No. Within Nippon Telegraph and Telephone Corporation (72) Inventor Masahiro Okawa 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture Within Opto-Systems Research Laboratory, Hitachi Cable, Ltd. (72) Inventor Naoto Uezuka Hidaka, Hitachi City, Ibaraki Prefecture 5-1-1, Machi-cho, Hitachi Cable, Ltd. Opto-System Research Laboratory (72) Inventor Hiroaki Okano 5-1-1, Hidaka-cho, Hitachi, Ibaraki Prefecture, Hitachi Cable, Opto-System Research Laboratory (72) Inventor Tatsuo Teraoka 5-1-1, Hidakacho, Hitachi City, Ibaraki Pref. Hitachi Cable, Ltd. Optosystem Research Laboratory (72) Inventor Tomoyuki Nishio Hitachi Cable, Ltd. Opto-Systems Research Laboratories 5-1-1, Hidaka-cho, Hitachi City, Ibaraki Prefecture (72) Inventor Yasunori Iwato 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture, Hitachi, Ltd. ) Inventor Tatsunori Kanaya 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Information and Communication Division of Hitachi, Ltd.

Claims (16)

[Claims] In a single mode optical waveguide in which a single mode optical waveguide element is formed on a substrate, a bench for mounting a light emitting element and a light receiving element is formed on a surface of the substrate, and a bench other than the bench on the substrate is provided. A buffer layer is formed in the portion, a height adjustment layer for optical axis alignment with the light emitting element and the light receiving element is formed on the buffer layer, and a waveguide core is formed on the height adjustment layer. An alignment index for the light emitting element and the light receiving element is formed on the bench, a cladding layer is formed on the height adjustment layer and the waveguide core, and current supply to the light emitting element is performed on the bench. A single mode optical waveguide, wherein an electrode for extracting a current from a light receiving element is formed. 2. A y-shaped waveguide is formed on the height adjusting layer, a narrow groove is formed in the y-branch, and light having a wavelength of λ1 is reflected on the narrow groove and a wavelength of λ2 (λ1 ≠). 2. The filter according to claim 1, further comprising a filter that transmits light of λ2), and a Y-branch light tap for dividing the light of wavelength λ2 into an arbitrary branch ratio between the y-shaped waveguide and the bench. Single mode optical waveguide. 3. The single mode optical waveguide according to claim 2, wherein a filter index for forming the narrow groove and inserting the filter is formed on the substrate. 4. The single mode optical waveguide according to claim 2, wherein a groove is formed around the waveguide core, and a light blocking member is inserted in the groove. 5. The single mode optical waveguide according to claim 4, wherein at least one groove in which a light-shielding member is inserted is formed between the filter and the end face of the waveguide. 6. The single mode optical waveguide according to claim 1, wherein an end face of the waveguide is obliquely polished. 7. In a single-mode optical waveguide having a single-mode optical waveguide element formed on a substrate, a bench for mounting a light-emitting element and a light-receiving element is formed on a surface of the substrate. A height adjustment layer for optical axis alignment with the light emitting element and the light receiving element is formed on the buffer layer, and a y-shaped waveguide is formed on the height adjustment layer. A core is formed, a narrow groove is formed in the Y branch portion, and a filter that reflects light of wavelength λ1 and transmits light of wavelength λ2 (λ1 ≠ λ2) is disposed in the fine groove. The radius of curvature of the curved portion is different before and after the filter, a cladding layer is formed on the height adjustment layer and on the waveguide core so as to cover the waveguide core, and the light emitting element on the bench is formed on the bench. Supply current and extract current from the photo detector Single mode optical waveguide, wherein the electrode for are formed. 8. The relative refractive index difference Δ of the single mode optical waveguide.
Is 0.42 to 0.47%, and the dimension of the waveguide core is 6.
Single mode optical waveguide according to claim 7 8 a × 6.8μm ² ~7.2 × 7.2μm ^2. 9. A radius of curvature of a curved portion of the waveguide core is:
10-15 mm before the filter, 6-9 after the filter
The single mode optical waveguide according to claim 7 or 8, wherein 10. The single mode optical waveguide according to claim 7, wherein an inflection point of the curved portion of the waveguide core has an offset structure. 11. The single mode optical waveguide according to claim 10, wherein an offset amount of the offset structure of the waveguide core is changed before and after the filter. 12. A bench for mounting a light emitting element and a light receiving element is formed on a surface of a substrate, a buffer layer is formed on a portion other than the bench on the substrate, and the light emitting element and the light receiving element are formed on the buffer layer. A height adjustment layer for optical axis alignment with the element is formed, a waveguide core is formed on the height adjustment layer, an alignment index for the light emitting element and the light receiving element is formed on the bench, A cladding layer is formed on the height adjustment layer and on the waveguide core, electrodes for supplying current to the light emitting element and extracting current from the light receiving element are formed on the bench, and the light emitting element is formed on the bench. And an optical waveguide module on which a light receiving element is mounted. 13. The optical waveguide module according to claim 12, wherein an optical fiber is connected to an end face of the waveguide. 14. A method for manufacturing a single mode optical waveguide in which a single mode optical waveguide element is formed on a substrate, wherein a bench for mounting a light emitting element and a light receiving element and a bench for forming an index for inserting a filter are provided. An etching step of etching the surface of the substrate so as to remain; a buffer layer forming step of forming a buffer layer on a portion other than the bench on the substrate; and an optical axis of the light emitting element and the light receiving element on the buffer layer. A height adjustment layer forming step of forming a height adjustment layer for alignment, a waveguide core forming step of forming a waveguide core on the height adjustment layer, and alignment of the light emitting element and the light receiving element on the bench Forming an index for inserting a filter and an index for inserting a filter simultaneously, and forming a cladding layer on the substrate on which the index is formed. Forming a clad layer, forming a deep groove on the clad layer to expose the bench, and forming a deep groove on the bench, supplying an electric current to the light emitting element and extracting an electric current from the light receiving element on the bench. Forming a single mode optical waveguide. 15. The method for manufacturing a single mode optical waveguide according to claim 14, wherein a mark is formed at the same time as the bench is formed on the substrate, and alignment is performed using the mark as a mark in each step. 16. An exposure for forming a waveguide core by photolithography on the height adjustment layer and an exposure for forming an index on the bench are simultaneously performed using a single photomask. 16. The method for manufacturing a single-mode optical waveguide according to claim 14, wherein relative alignment between the waveguide core and the index for alignment of the light emitting element and the light receiving element and the index for inserting the filter is performed.