JP2002319731A - Optical circuit and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical circuit which has a constitution for improving the product yield. SOLUTION: This wavelength-selecting light source optical circuit 30 comprises four DFB lasers 32A to 32D, having different oscillation wavelengths λ1 , λ2 , λ3 and λ4 , a first redundant circuit 34 connected to the DFB laser 32, a second redundant circuit 35 connected to the first redundant circuit, and a third redundant circuit 38 connected to the second redundant circuit. The first redundant circuit constituted of four first optical element circuits 44A to 44D, each having one of four first MMI couplers 40A to 40D, and an optical waveguide 42 for connecting adjacent two DFB lasers of the DFB lasers to one first MMI coupler. The second and third redundant circuits are similar. The two first optical element circuits 44B, 44D are selected from the first circuit 34, the two second optical element circuits 50B, 50C are selected from the second circuit 36, and further the one third optical element circuit 56C is selected from the third circuit 38.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of first optical elements and two or more second optical elements having different functions.
An optical circuit having a first optical element and two or more types of second optical elements sequentially optically connected by an optical waveguide, for example, a multi-wavelength light source optical circuit. The present invention relates to an optical circuit having a configuration with a high product yield.

[0002]

2. Description of the Related Art In recent years, as a backup light source for a WDM system, a multi-wavelength light source optical circuit used as a light source capable of wavelength selection by integrating a DFB laser having different wavelengths and an MMI coupler (Multi Model Interference) coupler on the same substrate. Is attracting attention. The multi-wavelength light source optical circuit generally connects a plurality of DFB lasers having different oscillation wavelengths to one MMI coupler to perform optical multiplexing. MM
An I-coupler is an optical multiplexing element that multiplexes a plurality of lights into one light, or an optical multiplexing element that multiplexes one light into a plurality of lights. For example, in the case of an optical multiplexing element, a plurality of input optical waveguides, an optical multiplexing unit (multi-wave interference unit) integrating the input optical waveguides, And a plurality of output optical waveguides branched from the optical multiplexing section.

Here, a conventional optical circuit used as a multi-wavelength selection light source capable of wavelength selection and a method of manufacturing the same will be described with reference to FIGS. A conventional multi-wavelength light source optical circuit (hereinafter, referred to as an optical circuit) 10 is, as shown in FIG.
A plurality of semiconductor laser elements having mutually different emission wavelengths formed in the substrate 12, for example, four DFB lasers 14 having oscillation wavelengths of λ ₁ , λ ₂ , λ ₃ and λ ₄ respectively.
A to D, one MMI coupler 18 optically connected to the DFB lasers 14A to 14D via four optical waveguides 16A to 16D, and one MMI coupler 1 via one optical waveguide 20.
8, one semiconductor optical amplifier optically connected to the
22 (referred to as SOA).

Referring to FIG. 5, a method of manufacturing the optical circuit 10 will be described below. First, a number of Ds arranged in parallel
FB laser 14, multiple MMI couplers 18 arranged in parallel corresponding to DFB laser 14, and multiple MMI couplers 18
Many SOAs 2 arranged in parallel corresponding to the coupler 18
2 are formed on the substrate 24. Next, the DFB laser 12, the MMI
Optical waveguide 1 for sequentially connecting coupler 18 and SOA 22
6A to 6D, the optical waveguide 20 is formed, and as shown in FIG. 5, an optical circuit body 25 before cleavage is manufactured. Then, by cleaving along the cleavage lines 26, individual optical circuits 10 can be manufactured.

[0005]

However, the conventional optical circuit has a problem in that the yield is extremely low when fabricating the optical circuit, as described below. The required accuracy of the oscillation wavelength of the DFB laser is required to be strictly less than 0.1 nm, and all the DFB laser chips in one laser bar 28 are manufactured so as to oscillate at the oscillation wavelength within the required accuracy. It is difficult. For this reason, in a wavelength selection light source that integrates a plurality of DFB lasers, if even one of the integrated DFB lasers has a defect, the optical circuit 10 itself becomes defective. However, although the product yield is relatively high and the production cost is low, there is a problem that the product yield of the optical circuit is low.

[0006] For example, in FIG.
Is a non-defective product, and the matte DFB laser 14 is a defective product.
Both optical circuits 10A and 10B are defective. Moreover, the manufacturing cost of the DFB laser is different from that of other MMIs.
It is significantly higher than the cost of manufacturing couplers and SOAs. Therefore, even a good DFB laser is treated as a defective product,
It is extremely unreasonable.

In the above description, an optical circuit in which a plurality of optical elements are integrated has been described by taking a multi-wavelength light source optical circuit as an example. However, this is not limited to the multi-wavelength light source optical circuit. This is a problem universally applicable to an optical circuit in which elements are integrated.
Accordingly, an object of the present invention is to provide an optical circuit having a configuration for improving the product yield and a method for manufacturing the same.

[0008]

In order to achieve the above object, an optical circuit according to the present invention comprises a plurality of first optical elements and a plurality of first optical elements.
An optical circuit having at least two types of second optical elements, wherein the first optical element and two or more types of second optical elements are sequentially optically connected by an optical waveguide; Are connected to optical element circuits selected from a redundant circuit composed of a plurality of optical element circuits, each optical element circuit has a second optical element, and a first optical element and a second optical element. Or an optical waveguide for optically connecting the second optical element and the first optical element via another second optical element.

In the present invention, the types of the first optical element and the second optical element are not limited. Further, the second optical element may be an optical element having a different function from that of the first optical element. For example, the first optical element is a semiconductor laser element, and the second optical element is MM.
It is an I coupler.

For example, a multi-wavelength light source optical circuit according to the present invention, to which the optical circuit of the present invention is applied, has a plurality of first optical elements and two or more types of second optical elements. Optical element and 2
A multi-wavelength light source optical circuit in which at least two types of second optical elements are optically connected in order by an optical waveguide, wherein the first optical element is a plurality of semiconductor laser elements having mutually different oscillation wavelengths. , The second optical element has an MMI coupler, and further includes one of a semiconductor optical amplifier and an optical waveguide output unit, and the redundant circuit is connected to the first redundant circuit and the second redundant circuit connected to the first redundant circuit. And the first redundant circuit is a MM.
A plurality of first optical element circuits each having an optical waveguide connecting the I-coupler and the MMI coupler to the semiconductor laser element, wherein the second redundant circuit includes a semiconductor optical amplifier, and the semiconductor optical amplifier and the MMI coupler; The semiconductor laser device is configured as a plurality of second optical element circuits having optical waveguides for connecting the first and second redundant circuits via the first optical element circuit selected from the first redundant circuit. It is characterized by being optically connected to the selected second optical element circuit.

A method for manufacturing an optical circuit according to the present invention includes a plurality of first optical elements and two or more second optical elements having functions different from those of the first optical element. An optical circuit manufacturing method in which an optical element and two or more types of second optical elements are sequentially optically connected by an optical waveguide, wherein a plurality of first optical elements are provided on a substrate.
Of the first optical element and the first optical element in addition to the second optical element.
A plurality of optical elements having an optical waveguide for optically connecting the second optical element and the first optical element via the second optical element or the second optical element. Forming a redundant circuit composed of a circuit on a substrate; inspecting a plurality of first optical elements to identify a first optical element having predetermined performance; and identifying the identified first optical element. It is characterized by comprising a step of selecting an optical element circuit to be connected to the element from a redundant circuit to configure an optical circuit, and a step of separating the configured optical circuit from a substrate.

The above-described method for producing an optical circuit can be applied to the production of a multi-wavelength light source optical circuit. In other words, the method of manufacturing an optical circuit according to the present invention is a method of manufacturing a multi-wavelength light source optical circuit having a semiconductor laser device, an MMI coupler, and a semiconductor optical amplifier having different oscillation wavelengths, which are sequentially arranged in parallel, A plurality of semiconductor laser devices having different oscillation wavelengths are formed on a substrate, and an MMI coupler and an MM
A first redundant circuit including a plurality of first optical element circuits each having an optical waveguide connecting the I-coupler and the semiconductor laser element; a semiconductor optical amplifier; and a semiconductor optical amplifier and the first optical element circuit. Forming a second redundant circuit comprising a plurality of second optical element circuits having optical waveguides to be connected on a substrate, and inspecting the semiconductor laser element to identify a semiconductor laser element having predetermined laser characteristics The process of
A first optical element circuit connected to the specified semiconductor laser element is selected from the first redundant circuit, and a second optical element circuit connected to the selected first optical element circuit is selected from the second redundant circuit. And a step of configuring the multi-wavelength light source optical circuit and a step of separating the configured multi-wavelength light source optical circuit from the substrate.

In this embodiment, a redundant design is performed for the MMI coupler, the optical waveguide, and the semiconductor optical amplifier, so that a semiconductor laser device having a high manufacturing cost is used as a reference.
A wavelength-selective light source circuit comprising a non-defective semiconductor laser element and an optical element circuit selected from a redundant circuit can be configured, thereby improving the product yield.

[0014]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, the film type, film thickness,
The film forming method, other dimensions, and the like are examples for facilitating the understanding of the present invention, and the present invention is not limited to these examples. Embodiment 1 of Optical Circuit This embodiment is an example of an embodiment in which the optical circuit according to the present invention is applied to a wavelength selection light source circuit, and FIG. 1 is a schematic plan view of the optical circuit of this embodiment. 2 and FIG. 2 are plan views at the stage of manufacturing the optical circuit of this embodiment. The multi-wavelength light source optical circuit (hereinafter, referred to as an optical circuit) 30 of the present embodiment includes:
As shown in FIG. 1, λ ₁ , whose oscillation wavelengths are different from each other,
four DFB lasers 32A-D of λ ₂ , λ ₃ , λ ₄ ;
A first redundant circuit 34 connected to the DFB laser 32;
Second redundant circuit 36 connected to first redundant circuit 34
And the third redundant circuit 3 connected to the second redundant circuit 36
8 are provided on a substrate 39.

Each of the first redundant circuits 34 includes one of the four first MMI couplers 40A to 40D,
Optical waveguide 4 connecting two adjacent DFB lasers 32 of lasers 32A to 32D and one first MMI coupler 40
2 and four first optical element circuits 44A to 44D. The second redundant circuit 36 includes one of the four second MMI couplers 46A to 46D and two adjacent first MMI couplers 40A to 40D.
, And four second optical element circuits 50 </ b> A to 50 </ b> D each having an optical waveguide 48 that connects one MMI coupler 40 to one second MMI coupler 46. Third redundant circuit 3
8 is one of the four SOAs 52A-D and two adjacent ones of the four second MMI couplers 46A-D, respectively.
It is composed of four third optical element circuits 56A to 56D each having an optical waveguide 54 connecting the second MMI coupler 46 and one SOA 52.

In the optical circuit 30 of the present embodiment, as shown in FIG. 1, two first optical element circuits 44B and 44D are selected from the first redundant circuit 34, and the second redundant circuit 36
, Two second optical element circuits 50B and 50C are selected. Further, one third optical element circuit 5 is output from the third redundant circuit 38.
6C is selected. When two second optical element circuits 50B and 50C are selected from the second redundant circuit 36,
One of the two optical waveguides 48 connected to the adjacent first MMI couplers 40 by the MMI couplers 46B and 46C is selected. In FIG. 1, a solid line indicates a selected optical waveguide, and a broken line indicates an unselected optical waveguide.

Embodiment of an Optical Circuit Fabrication Method This embodiment is an example of an embodiment in which the optical circuit fabrication method according to the present invention is applied to the fabrication of the above-described multi-wavelength light source optical circuit 30. FIG. 2 is a plan view showing a state before cleavage of the optical circuit 30 manufactured by the method of the present embodiment. Although not shown, first, an n-InP lower cladding layer was formed on an n-InP substrate by metal organic chemical vapor deposition (MOCVD).
An InGaAs PMQW active layer and a p-InP upper cladding layer are grown in this order to form a stacked structure of a DFB laser unit, a first MMI coupler unit, a second MMI coupler unit, and an SOA unit. Next, the DFB laser portion and the SO
P-InP cladding layer and InGaAsPM other than part A
The QW active layer is removed.

Next, an optical waveguide structure layer having a wavelength of 1.3 μm is regrown, and the optical waveguide and the first MMI are formed in a butted joint structure with a DFB laser and an SOA part.
Form a coupler and a second MMI coupler. Then, D
The mesa formation is performed by etching the laminated structure of the FB laser region, the optical waveguide region, the first MMI coupler region, the optical waveguide region, the second MMI coupler region, the optical waveguide region, and the SOA region by a dry etching method. After the pn current blocking layer was regrown, p-
Regrow the InP cladding layer. Next, passivation and electrode formation are performed to complete the multi-wavelength light source optical circuit shown in FIG.

That is, as shown in FIG. 2, a laser area 58 in which four DFB lasers 32A to 32D of λ ₁ , λ ₂ , λ ₃ , and λ ₄ having different oscillation wavelengths are sequentially arranged in parallel.
A region of a plurality of first redundant circuits connected to each DFB laser 32, a region of a plurality of second redundant circuits connected to the first redundant circuit, and a second redundant circuit
An optical circuit body 61 having a plurality of third redundant circuits 38 connected thereto on a substrate 60 is formed.

Each of the first redundant circuits 34 includes a first MMI coupler 40 and two adjacent DFB lasers 32.
And a plurality of first optical element circuits 44 each having an optical waveguide 42 connecting the first MMI coupler 40 and the first MMI coupler 40. Each of the second redundant circuits 36 has a second MMI
A coupler 46 and two adjacent first MMI couplers 40
And a second optical element circuit 50 having an optical waveguide 48 connecting the second MMI coupler 46 to the second optical element circuit 50. Each of the third redundant circuits 38 includes an SOA 52 and a third optical element circuit 56 having an optical waveguide 54 that connects two adjacent second MMI couplers 46 and the SOA 52.

Next, the DFB laser 32 is inspected to specify a DFB laser 32 having predetermined laser characteristics.
For example, it is assumed that the inspection result of the DFB laser 32 as shown in FIG. 3 is obtained. In FIG. 3, black and matte areas indicate a good DFB laser 32 and a defective DFB laser 32 having predetermined laser characteristics, respectively. DFB laser 32 specified
Based on D, A, B, and C (shown as 62 in FIG. 3), two first optical element circuits 44 are selected from the first redundant circuit 34 as shown in FIG. The two second optical element circuits 50 are selected from the redundant circuit 36, and one third optical element circuit 56 is further selected from the third redundant circuit 38. The optical circuit 30 having the above performance is determined. Subsequently, as shown in FIG.
By cleaving the optical circuit 30 along 4, the optical circuit 30 shown in FIG. 1 can be manufactured. However, the order of the DFB lasers 32A to 32D of the optical circuit 30 in FIG. 1 is different from the order of the DFB lasers 32D to 32C of the optical circuit 30 in FIG. The redundant SOA portion can also be used as a monitor PD.

When the yield of the MMI coupler alone and the SOA alone is set to 100% and the yield of the DFB laser alone is set to 77%, the products of the conventional multi-wavelength light source optical circuit 10 and the multi-wavelength light source optical circuit 30 of the present embodiment are obtained. The yield is 2
2% and 68%. That is, in this embodiment,
It can be seen that the product yield of the multi-wavelength light source optical circuit is greatly improved. Further, in the present embodiment, the present invention is described by taking the optical circuit 30 in which four elements are integrated as an example. However, even if the number of elements increases, the same effect can be obtained by increasing the number of stages of the MMI coupler. This is apparent from FIG.

Second Embodiment of Optical Circuit This embodiment is another example of the embodiment of the optical circuit according to the present invention, and FIG. 7 is a schematic plan view of the optical circuit of this embodiment. . As shown in FIG. 7, the optical circuit 70 of the present embodiment includes three semiconductor optical amplifiers 72A for amplifying three optical inputs λ ₁ , λ ₂ , and λ ₃ having different wavelengths, respectively.
B, C, two MMI couplers 74A, B, one semiconductor optical amplifier 76 for outputting an amplified optical output, and a first redundant circuit 78 connecting the semiconductor optical amplifier 72 and the MMI coupler 74. , MMI coupler 74 and semiconductor optical amplifier 78
And a second redundant circuit 80 for connecting the same.

The first redundant circuit 78 includes the semiconductor optical amplifier 7
2A, two optical waveguides selectively connected to B,
First redundant circuit 76A connected to MMI coupler 74A
And 2 selectively connected to the semiconductor optical amplifiers 72B and 72C.
It is configured so as to be connected to the MMI coupler 74A. The second redundant circuit 80 has two optical waveguides selectively connected to the MMI couplers 74A and 74B, and is configured to be connected to the semiconductor optical amplifier 78.

Third Embodiment of Optical Circuit This embodiment is still another example of the embodiment of the optical circuit according to the present invention. FIG. 8 is a schematic plan view of the optical circuit according to the present embodiment. is there. 8, parts that are the same as those in FIG. 1 are given the same reference numerals. Optical circuit 82 of this embodiment
Is a wavelength-selective optical passive circuit, and has the same configuration as the multi-wavelength light source optical circuit 30 except that a photodetector 84 is provided instead of the DFB laser 32 of the multi-wavelength light source optical circuit 30 of the first embodiment. It has.

The photodetectors 84A to 84D have diffraction gratings 86A to 86D having different wavelengths on the input side, respectively, and have wavelengths λ ₁ , λ ₂ , λ ₃ , λ determined by the diffraction grating 86.
₄ is input to the photodetector 84. In the optical circuit 82 of the present embodiment, λ ₁ , λ ₂ ,
By simultaneously receiving light including light having wavelengths of λ ₃ and λ ₄ and monitoring the output signal of the photodetector 84,
Non-defective photodetectors can be specified. In this inspection process, four non-defective photodetectors 84 adjacent to each other are selected, and element isolation is performed in the same manner as in the production of the optical circuit 30 to produce a wavelength-selective optical passive circuit 82 with good yield. Can be. In the wavelength selective optical passive circuit 82 of the present embodiment, the optical circuit 30 of the first embodiment is used.
Unlike the case where the SOA 52 receives light,
Light may be received by an MMI coupler instead of OA.

[0027]

According to the present invention, the first optical element and the second
By forming an optical circuit from an optical element circuit and an optical element circuit selected from a redundant circuit, the optical circuit, for example, a multi-wavelength light source optical circuit can significantly improve the product yield and reduce the cost. realizable. Further, the method of the present invention realizes an economical method for manufacturing the optical circuit according to the present invention.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of an optical circuit according to a first embodiment.

FIG. 2 is a schematic plan view of an optical circuit intermediate, which is the final stage when fabricating an optical circuit according to the method of the embodiment.

FIG. 3 is a schematic plan view of an optical circuit intermediate showing a result of inspecting a DFB laser.

FIG. 4 is a schematic plan view showing a configuration of a conventional multi-wavelength light source optical circuit.

FIG. 5 is a schematic plan view of an optical circuit intermediate, which is the final stage when fabricating a multi-wavelength light source optical circuit according to a conventional method.

FIG. 6 is a schematic plan view of an optical circuit intermediate showing a problem of a conventional multi-wavelength light source optical circuit and a method of manufacturing the same.

FIG. 7 is a schematic plan view of an optical circuit according to a second embodiment.

FIG. 8 is a schematic plan view of an optical circuit according to a third embodiment.

[Explanation of symbols]

 Reference Signs List 10 Conventional multi-wavelength light source optical circuit 12 Substrate 14 DFB laser 16 Optical waveguide 18 MMI coupler 20 Optical waveguide 22 Semiconductor optical amplifier (SOA) 24 Semiconductor substrate 26 Cleavage line 28 Laser bar 30 Multi-wavelength light source optical circuit (optical circuit) of the embodiment 32A-D DFB laser 34 First redundant circuit 36 Second redundant circuit 38 Third redundant circuit 40A-D First MMI coupler 42 Optical waveguide 44A-D First optical element circuit 46A-D Second MMI coupler 48 Optical waveguide 50A-D Second optical element circuit 52A-D Semiconductor optical amplifier (SOA) 54 Optical waveguide 56A-D Third optical element circuit 58 Laser region 60 Substrate 62 Specified DFB laser 64 Cleavage line 70 Implementation Optical Circuit of Embodiment 2 72 Semiconductor Optical Amplifier 74 MMI Coupler 76 Semiconductor Optical Amplifier 78 First Redundant Circuit 80 optical circuit 84 photodetector 86 the diffraction grating of the second redundant circuit 82 embodiment 3

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04B 10/16 H04B 9/00 J 10/17 10/18 F term (Reference) 2H047 LA18 MA07 PA00 QA02 QA07 5F073 AA64 AA74 AB01 AB12 AB21 AB25 5K002 AA06 BA04 CA01 CA13 DA02 FA02

Claims (7)

[Claims] An optical device includes a plurality of first optical elements and two or more types of second optical elements, and the first optical element and two or more types of second optical elements.
In the optical circuit, the first optical element is connected to an optical element circuit selected from a redundant circuit composed of a plurality of optical element circuits, The element circuit has a second optical element and the first optical element and the second optical element, or the second optical element and the first optical element via another second optical element. An optical circuit, comprising: an optical waveguide that optically connects the optical circuit and the optical waveguide. 2. The optical circuit according to claim 1, wherein the second optical element is an optical element having a different function from that of the first optical element. 3. The optical circuit according to claim 2, wherein the first optical device is a semiconductor laser device, and the second optical device is an MMI coupler. 4. The optical circuit according to claim 2, wherein the first optical element is a semiconductor optical amplifier element, and the second optical element is an MMI coupler. 5. A semiconductor device comprising a plurality of first optical elements and two or more second optical elements, wherein the first optical element and two or more second optical elements are provided.
A multi-wavelength light source optical circuit in which the optical elements are sequentially optically connected by an optical waveguide, wherein the first optical element is a plurality of semiconductor laser elements having oscillation wavelengths different from each other; The element has an MMI coupler and one of a semiconductor optical amplifier and an optical waveguide output unit, and the redundant circuit is composed of a first redundant circuit and a second redundant circuit connected to the first redundant circuit. Wherein the first redundant circuit is configured as a plurality of first optical element circuits having an MMI coupler and an optical waveguide connecting the MMI coupler and the semiconductor laser element, and the second redundant circuit is configured as a semiconductor optical circuit. A first optical element circuit configured as a plurality of second optical element circuits having an amplifier and an optical waveguide connecting the semiconductor optical amplifier and the MMI coupler, wherein the semiconductor laser element is selected from a first redundant circuit; Through the second Multi-wavelength light source optical circuit, characterized in that it is optically connected to the second optical element circuit selected from the long circuit. 6. The plurality of first optical elements and the first optical element include two or more types of second optical elements having different functions, and the first optical element and the two or more types of second optical elements. A method for producing an optical circuit, comprising: forming a plurality of first optical elements on a substrate and optically connecting the first optical element to the second optical element; A plurality of optical waveguides that optically connect the first optical element and the second optical element, or the second optical element and the first optical element via another second optical element. Forming a redundant circuit composed of optical element circuits on a substrate; inspecting a plurality of first optical elements to identify a first optical element having predetermined performance; A step of selecting an optical element circuit connected to one optical element from a redundant circuit to configure an optical circuit, and a step of separating the configured optical circuit from a substrate Manufacturing method of the optical circuit, characterized in that there. 7. A method for fabricating a multi-wavelength light source optical circuit having a semiconductor laser device, an MMI coupler, and a semiconductor optical amplifier having oscillation wavelengths different from each other, comprising: A first redundant circuit including a plurality of first optical element circuits having an MMI coupler, and an optical waveguide connecting the MMI coupler and the semiconductor laser element; and Forming a semiconductor optical amplifier and a second redundant circuit including a plurality of second optical element circuits having an optical waveguide connecting the semiconductor optical amplifier and the first optical element circuit on a substrate; Inspecting the device to specify a semiconductor laser device having predetermined laser characteristics; and selecting a first optical device circuit connected to the specified semiconductor laser device from the first redundant circuit. Selecting a second optical element circuit to be connected to the selected first optical element circuit from the second redundant circuit to configure a multi-wavelength light source optical circuit; And a method of manufacturing a multi-wavelength light source optical circuit.