JPH08160235A - Plane light guide circuit with positioning marker - Google Patents

Abstract

PURPOSE: To provide a plane light guide circuit capable of being easily roughly aligned. CONSTITUTION: The plane light guide circuit 11 with a positioning marker is constituted by providing a light guide 15 for the marker to an underclad 13 on a substrate 17 across a core part 13 and providing an overclad 14 on it. Marker light is made incident from an input part 15 on the flank of the plane light guide circuit 11, projected from an end surface 16A of the light guide for the positioning marker, and made incident on the core part of a fiber block array gripped on an aligning device, thus performing alignment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar optical waveguide circuit,
In particular, an alignment marker that is important when coupling a planar optical waveguide circuit that combines an optical circuit with functions such as optical branching, optical switching, and wavelength multiplexing on a circuit board with an optical fiber that serves as an input / output unit is guided by an optical waveguide. The present invention relates to a planar optical waveguide circuit with a positioning marker provided in the circuit itself.

[0002]

2. Description of the Related Art Further, in constructing and providing an optical fiber communication network having an efficient and flexible network structure and a network compatible with multimedia, an optical branch (splitter), an optical switch wavelength multiplexing polymer waveguide, etc. The role played by the optical circuit of is very important. Conventionally, a bulk type or an optical circuit on an optical surface plate composed of a combination of prisms and microlenses, and a fiber optical circuit in which optical fibers are fused and stretched have been devised and used. However, these bulk-type and fiber-type optical circuits still have problems in occupying area, productivity, circuit stability, and functional expandability, and new functions are required one after another in the market. Is not fully supported.

In such a state, in recent years, a silica glass film is deposited on a silicon substrate or a silica glass substrate,
A glass film is processed into a pattern shape corresponding to the above various functions, and an upper clad layer is further deposited on the pattern to form a planar optical waveguide circuit (Pla).
Nar Lightwave Circuits (hereinafter abbreviated as “PLC circuits”) have been attracting attention.
The PLC circuit has been integrated with various functions such as an optical branch circuit, an optical interferometer circuit, an arrayed waveguide, and a grating circuit, and its actual operation has been confirmed and reported. As described above, the PLC circuit is a component that is expected to expand its capability and application range, but in connection with the existing optical fiber communication network,
If you do not use the interface section through the optical fiber,
The function of the PLC circuit cannot be exhibited. It is possible to use a simple optical connector for the connection interface part with the optical fiber network. However, as the integration of the PLC circuit progresses, the current PLC circuit can be built so that 8 to 32 circuits can be built in one PLC circuit. The technology is no longer dimensionally compatible. For this reason, at present, a component called an optical fiber block array, in which a plurality of optical fiber element wires are arranged and fixed in one fixed block, is configured at the end point of the fiber line, and this optical fiber block array is arranged at the end surface of the PLC circuit. It is the mainstream to make fine adjustments and then fix it by welding or using an optical adhesive. This series of fine adjustment steps is called a "centering" step of the PLC circuit and the fiber block array (hereinafter abbreviated as "FB component").

[0004]

However, in this aligning process, it is very difficult to align the PLC circuit and the FB component, which is a rate-determining step in the aligning process. This is because normally used single mode waveguides and single mode fibers (hereinafter abbreviated as “SM fibers”) are used for PLC circuits and FB parts, and their core diameters are up to 9 μm.
Since it is 10 μmφ, it takes skill to install the components and adjust the light so that the light passes through the predetermined core position. Conventionally, roughly speaking, two methods are used: a visual alignment method using a visible light laser (He-Ne, etc.) and a method of aligning with an FB component using a large multimode fiber with a core diameter of several tens of μmφ. It was being done.

The latter uses a multimode fiber component which is not used for connection because it receives light, and therefore alignment work is performed on each side, and simultaneous alignment of the input and output ends is impossible. In the former, since FB parts using SM fiber are arranged at both ends of the PLC and the optical power is checked visually, it takes a lot of time and labor to repeat the simple work of checking the light and fine adjustment of the position. It was very difficult to automate.

In order to efficiently connect the PLC circuit and the fiber component, it has been desired to develop an optical component capable of simple rough adjustment.

An object of the present invention is to provide a planar waveguide circuit (PLC).
In the alignment process for connecting the optical fiber block array (FB component) with the
An object of the present invention is to provide a planar optical waveguide circuit capable of easily performing rough adjustment alignment.

[0008]

A marker-equipped planar optical waveguide circuit according to a first solution of the present invention is a planar optical waveguide circuit having a connection interface with an optical fiber,
A positioning marker made of the same material as that of the core is provided on the same plane as the core for guiding the signal light of the planar optical waveguide circuit.

In the marker-equipped planar optical waveguide circuit according to the second solving means of the present invention, in the first solving means, the alignment marker has a cross-sectional area larger than that of the core in the interface portion. Characterize.

According to a third aspect of the present invention, there is provided a marker-equipped planar optical waveguide circuit according to the first or second solving means, wherein the alignment marker has a light incident surface on a side surface of the planar optical waveguide circuit. It is characterized by having.

According to a fourth aspect of the present invention, there is provided a marker-equipped planar optical waveguide circuit according to any one of the first to third means, wherein the positioning marker has a bent portion. It is characterized in that a diffraction grating is provided in the part.

[0012]

The main feature of the present invention is that the planar optical waveguide circuit to which the optical fiber parts are connected is provided with the positioning marker for facilitating the alignment process. , Photolithography accuracy (~
This is different from the conventional circuit in that the circuit itself has extremely accurate position information because the reference marker is built into the circuit chip itself at 0.1 μm).

At the same time, since the large-diameter light-receiving fiber block array (using multi-mode fiber) that has been conventionally used at the time of aligning work is not used on the temporary light receiver side, the connection end face of the connected PLC circuit is Since rough alignment can be performed at the same time, there is an advantage that the time required for the work can be shortened.

The conventional aligning method and the aligning work using the planar optical waveguide circuit with alignment markers according to the present invention will be compared with reference to the accompanying drawings to show the planar optical waveguide circuit with alignment markers according to the present invention. Explain the benefits.

FIG. 4 is a schematic perspective view of a conventional planar optical waveguide chip, showing an aligning process work in connection thereof. In the figure, 41 is a planar optical waveguide circuit, 42 is a single mode fiber block array, 43 is a multimode fiber block array, 44 is a single mode fiber ribbon tape, 45 is a multimode fiber tape, and 46 is The core end surface (for single mode) of a planar optical waveguide circuit is shown. The alignment process work proceeds according to the following procedure.

(1) Single mode fiber block array 4 to be connected to one side of the optical waveguide circuit 41 on the chip side
2 is installed at a rough position.

(2) A multimode fiber block array 43 for optical monitoring is set on the opposite side of the circuit chip, and inspection light such as laser light from a light source (not shown) is fed from a single mode fiber tape 44 on the left side of FIG. Through, Figure 4
Right side of the multimode fiber block array 43
When the light power is received at, and the light power comes to the right side, the power is intensity monitored, that is, the position of the single mode fiber block array 42 is finely adjusted, and the light power is maximized. This fine adjustment operation is called a peak search operation.

If a centering device with a peak search mechanism, which is directly connected to the operation of the fine movement table, is used, the optical power is passed (the inspection light, that is, the marker light passes through the optical waveguide circuit 41 to the multimode fiber block array 43). In the (reached) state, it is left to the mechanical operation, so it is essential to shorten the working time whether this optical power can be passed and monitored. Figure 5
[Fig. 3] is a schematic view of a cross-sectional image of a conventional multi-mode alignment. In the figure, 51 is a planar optical waveguide circuit, 52
Is a multimode fiber block array for detecting optical power, 53 is a connecting fiber block array (for single mode), 54 is a rectangular core portion of the planar optical waveguide circuit 51, and 55 is a cross section of the core portion of the multimode fiber. (Indicated by a small circle in the figure). Reference numeral 56 indicates a single-mode fiber core cross section (indicated by a small circle in the middle black in the figure). Since the cross section of the multimode fiber core is larger than the cross section of the single mode core, if there is an overlap between the small circle (56) and the rectangular portion (54) in the middle black of FIG. 5, the above optical power is captured and the mechanical alignment (peak・ Searching is ready for operation.

If the multimode fiber core cross section 55 in FIG. 5 is changed to a single mode fiber core cross section 56, it can be easily inferred that the overlapping portion becomes extremely small and light cannot pass therethrough. In order to simplify this, it is possible to make a rough alignment based on the fiber block array, the outer shape of the optical waveguide circuit, etc., but considering the allowable crossing of the component dimensions, it is only necessary to set the components in the aligning device. It was impossible to obtain the positional accuracy that allows optical power to pass through.

On the other hand, according to the present invention, in order to facilitate the centering operation of the above-described conventional planar optical waveguide and fiber block array, a positioning marker for rough alignment is provided on the core end face side of the planar optical waveguide circuit. However, its configuration and alignment method are significantly improved and shortened compared to conventional work.
Hereinafter, the planar optical waveguide circuit with alignment marker of the present invention will be described in detail with reference to the accompanying drawings, and its convenience will be clarified.

FIG. 1 is a schematic perspective view of a planar optical waveguide circuit with an alignment marker according to the present invention. In the figure, 11 is a planar optical waveguide circuit (chip), 12 is a waveguide circuit core portion, 12
A is an end face of the waveguide circuit core portion, 13 is an underclad portion of the circuit, 14 is an overclad portion, 15 is a side surface portion of the waveguide circuit with alignment kerker, 16 is a waveguide for alignment marker, and 16A is for alignment. The end faces of the core of the marker waveguide, and 17 are substrates.

The planar optical waveguide circuit 11 shown in FIG.
An underclad portion 13 is provided on the upper portion of the underclad portion 13, and a plurality of waveguide core portions 12 are provided on the underclad portion 13 in parallel with the waveguide direction.
Two waveguides for alignment markers, which are divided into two, are provided on both sides of 2, respectively, and an overclad portion is formed on them. The alignment marker 16 may be provided on only one side, or may be in a shape of being connected at the center in the waveguide direction or in the vicinity of the center without being divided.

FIG. 2 is a core circuit pattern of a planar optical waveguide circuit in which the planar shape of the alignment marker waveguide (sometimes simply referred to as “marker”) is changed from that of the planar optical waveguide circuit shown in FIG. It is a top view which shows. In the figure, 21 is the whole planar optical waveguide circuit, 22 is a connecting core (single mode), and 23A to 23G are alignment marker waveguide patterns. The alignment marker waveguide pattern 23A has a shape branched left and right at an input portion 25 at or near the center of the chip side surface 24, and a bent portion 26 is provided at the branched portion. The input section 25 may be provided at one place like the waveguide pattern 23 in FIG. 2A, or may be provided in the waveguide patterns 23B to 23 in FIGS. 2B to 2G.
You may provide separately, such as G. The bent portion 26 of the input portion 25 may be a continuous core forming portion, but if the light is efficiently guided to the end face portion, patterning of a circuit grid or the like may be performed as shown by 27 in FIG. 2D. Good. Further, the shape near the end face of the core of the alignment marker waveguide is shown in FIG.
As in (E) to (G), the input / output area may be increased by widening toward the end surface. As in (E) and (F), the width may be increased until the side surface is reached. Furthermore, the alignment marker waveguides do not always have to have the same width,
As shown in (C), the narrow portion 2 having the same width as the connecting core 22.
8 may be included. Further, each of the above-mentioned patterns may be provided on one side or both sides. Alternatively, different patterns may be provided on the same chip.

In the planar optical waveguide circuit with alignment marker of the present invention, the alignment marker waveguide can be made of the same material as the material of the signal optical waveguide core. Can be made.

The alignment of this planar optical waveguide circuit is shown in FIG.
This is performed as shown in (A) to (C). In FIG. 3, 30
Is a grip of the aligning device, 31 is a planar optical waveguide circuit, 32A,
32B is a single mode fiber block array,
33 is a single mode core part, 34 is an offset amount in advance, 35 is an alignment marker, 36 is a bent part, 37 is an input part, and 38 is a marker light. (A) shows an initial process. The fiber blocks 32A and 32B are set to the approximate positions. (B) shows a coarse alignment process, in which the marker light 38 is input from the input unit 37 and detected by a photodetector (not shown) connected to the fiber block array,
Find the position where power passes. (C) shows the main alignment step, in which the core portion to be connected can be captured by searching for the peak of the power of the marker light, pressing the peak position, and then moving the offset amount in plane to return it.
As shown by the arrow in FIG. 3C of the present invention, peak search can be performed simultaneously in both directions. The planar arrangement shape of the core of the alignment marker waveguide of the planar optical waveguide circuit shown in FIG. 3A is slightly different from that of FIG. 2, and the bent portion 36 connecting the input portion 37 and the core DC portion 35B is circular. It has an arc shape. The marker light 38 is incident on the alignment waveguide from the input portion 37 (corresponding to 15 in FIG. 1) on the side surface of the circuit. Incident light to the marker 35 is bent 36, a diffraction grating (see FIG. 2).
And the like, and reaches the core end surface portion 35A of the marker.
When the light emitted from 35A is incident on the outermost core portion 39A or 39B of the fiber block array 32A or 32B held by the holding portion 30 of the aligning device, the connected core is directed to the corresponding initial core portion. The offset amount 34 is set in advance so as to be aligned, and the position marker waveguide is arranged. The offset amount is 500 μm in advance. Since the positions of the waveguide core layer in the circuit thickness direction (the y direction in FIG. 1) are at the same height, the position of the emitted light in the y direction is the same as the connected core portion 33 in terms of the circuit manufacturing process accuracy. Further, since the emitting end is made wider than the ordinary connected core portion (single mode), the emitted light can be easily captured by the photodetector and the optical power can be easily grasped.

Therefore, once the optical power from the core end face 35A is detected, the core position can be almost captured by moving the marker 34 and the waveguide pattern position offset amount 34 in advance at the y height. Since the marker light incident port is provided on the side surface of this alignment marker waveguide, the power for monitor light is input from the side surface and the fiber block to be connected is aligned on both sides with the configuration shown in FIG. If it is a required process, since the right and left fiber blocks can be aligned at the same time, it has an advantage that the time can be shortened compared to the conventional process of aligning one side at a time.

[0027]

EXAMPLES The planar optical waveguide circuit with alignment marker of the present invention will be described in detail below with reference to examples.

[Example 1] A rectangular waveguide circuit having a length of 6 mm, a width of 4 mm and a thickness of 1.1 mm was produced. The waveguide was a single mode waveguide having a core diameter of 8 mm □ and a refractive index difference of 0.3%, and eight linear circuits were provided in the center. Two alignment waveguides having an end face portion having a thickness of 8 mm and a width of 30 μm were placed at both ends of this core portion at a distance of 500 μm. The curved portion that bends to the side was a curved waveguide with R = 10 mm ^R. An 8-core single-mode fiber block array was installed on both ends of the rectangular waveguide in a centering device, and the fiber at each end was connected to a photodetector of the centering device.

In this state, 1.
A near-infrared laser of 3 μm was incident according to the shape of the aperture. Near-infrared light could be detected from the fiber block arrays at both ends, which were offset by about 500 μm from the outer shape in advance. The peak search of the centering device was moved simultaneously to the left and right to maximize this near infrared light power. The time required is 6
It took 0 seconds. Next, the offset amount (500 μm) is returned, and this time when the near-infrared light enters from the single-mode fiber block array at one end and is received in the single mode through the waveguide circuit, the passing light power is detected and the normal peak search operation is performed. Was possible. After that, repeating peak search at both ends, repeating the incident and detection alternately,
It took 5 minutes to complete the alignment work.

[Comparative Example 1] The circuit having the same shape as that used in Example 1 was prepared by the same apparatus without using a built-in alignment marker.

Set the circuit on the fixed pedestal and press He-Ne.
Visible light (wavelength 630 nm) was made incident from the fiber block array, radiated to the side surface of the PLC circuit, and adjusted to be emitted to the opposite side manually. Next, P that He-Ne passed through
Set the fiber block array at the opposite end of the LC circuit (5 minutes), and put He-N from the end surface of the fiber block array.
It took 5 minutes before e was emitted. After that, it took 5 minutes to replace the He-Ne with near-infrared light and perform peak search on both ends, as in Example 1 (total required time: 15 minutes).

[Comparative Example 2] A circuit having the same shape as in Example 1 and Comparative Example 1 was aligned with a centering device using a multimode fiber block array.

It took 5 minutes for He-Ne light to enter the circuit from the input side fiber block array and to see He-Ne through the circuit.

It took 3 minutes to place a multimode fiber block array on the opposite side, inject a near infrared laser from the input side, and perform a peak search on the incident side.

Next, the multimode fiber block array on the opposite side was changed to a single mode fiber block array, and it took 3 minutes for the peak search (total required time 13 minutes).

Example 2 A rectangular waveguide having the same length and width as in Example 1 was produced. The waveguide was designed in the same manner as in Example 1, but the side surface bent portions of the alignment waveguide at both ends of the core portion formed a 60 ° diffraction Fresnel convergent lens type diffraction grating, and the core diameter at the exit end of the core end face portion was formed. Was set to 1/2 of Example 1. The total amount of emitted light was the same as in Example 1, but the core width was halved, so that the peak search operation converged quickly and was completed in 20 seconds by simultaneous operation at both ends.

The following procedure was the same as in Example 1 and required 5 minutes, and the time required for all steps was 5 minutes and 20 seconds.

[0038]

As described above, since the planar optical waveguide circuit with alignment marker according to the present invention is formed in the same height direction as the connected single mode core portion, the positional accuracy in the y direction is high, If the light-receiving unit catches the marker, the position in the y direction can be easily determined with high accuracy. In addition, since the light for the alignment marker is incident from the side surface and can be received at both ends, the left and right fiber block arrays can be simultaneously peak-cell aligned using the left and right independent peak search mechanisms. The aligning time can be reduced to half or less of the conventional one. In addition, since the marker uses the blank space at the end of the waveguide, the circuit does not need to be unnecessarily enlarged. In addition, the waveguide for marker alignment is made by patterning the core part, so a metal mirror is vapor-deposited. It has the advantage that the burden on the entire process does not increase at all, as compared with other marker production provided in the process.

As described above, in the planar waveguide circuit with alignment marker according to the present invention, a coarse alignment marker is formed in advance in the margin of the circuit in order to shorten the post-process for connecting the fibers. According to the mask accuracy of photolithography, the position accuracy is about 0.1 μm, which is extremely high, and it is an excellent component that can reduce the post-process by about 1/2.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a planar optical waveguide circuit with an alignment marker according to the present invention.

FIGS. 2A to 2G are schematic top views of a planar optical waveguide circuit with alignment markers according to the present invention.

FIG. 3 is a cross-sectional view showing a fiber connecting step to a planar optical waveguide circuit with a positioning marker according to the present invention,
(A) shows an initial process, (B) shows a coarse alignment process, and (C) shows a state of each planar optical waveguide circuit in the offset amount returning and main alignment process.

FIG. 4 is a schematic perspective view of a conventional planar optical waveguide circuit chip.

FIG. 5 is a schematic cross-sectional view of a conventional planar optical waveguide circuit chip during alignment.

[Explanation of symbols]

11 Planar Optical Waveguide Circuit (Chip) 12 Waveguide Circuit Core Section 12A Waveguide Circuit Core Section 13 Underclad Section 14 Overclad Section 15 Side Surface Section of Alignment Marker Waveguide 16 Core End Surface of Alignment Marker Waveguide 16A Core End face 17 Substrate 21 Planar optical waveguide circuit (whole) 22 Connection core (single mode) 23A to 23G Waveguide pattern 24 Chip side surface 25 Input part 26 Bent part 27 Diffraction grating 28 Narrow part 30 Gripping part 31 of alignment device 31 Plane Optical waveguide circuit 32A, 32B Single mode fiber block array 33 Single mode core part 34 Offset amount in advance 35 Alignment marker 35A Alignment marker core end face 35B Core DC part 36 Bent part 37 Input part 38 Marker light ( Laser light) 39A, 3 B Outermost core part 41 Planar optical waveguide circuit 42 Single mode fiber block array 43 Multimode fiber block array 44 Single mode fiber tape 45 Multimode fiber tape 46 Core end face of the planar optical waveguide circuit (single mode 51 Planar optical waveguide circuit 52 Multimode fiber block array 53 Single mode fiber block array 54 Rectangular core part 55 Multimode fiber core part (small circle) 56 Single mode fiber core part (center black) Komaru)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazunori Chida 1-1-6 Uchiyuki-cho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corp. (72) Norio Takato 1-1-6 Uchiyuki-cho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Naoyuki Atobe 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Naoki Nakao 1-1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Fumiwa Ohira 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Kunio Koyabu 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo No. Japan Nippon Telegraph and Telephone Corporation (72) Inventor Kazuki Kudo 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72 ) Inventor Koji Matsunaga 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (4)

[Claims] 1. A planar optical waveguide circuit having a connection interface with an optical fiber, wherein a positioning marker made of the same material as the core is provided on the same plane as a core for signal optical waveguide of the planar optical waveguide circuit. A planar optical waveguide circuit with an alignment marker, characterized in that 2. The planar optical waveguide circuit with a positioning marker according to claim 1, wherein the positioning marker has a cross-sectional area larger than that of the core in the interface portion. 3. The planar optical waveguide circuit with an alignment marker according to claim 1, wherein the alignment marker has a light incident surface on a side surface of the planar optical waveguide circuit. 4. The planar light guide with alignment marker according to any one of claims 1 to 3, wherein the alignment marker has a bent portion, and the bent portion is provided with a diffraction grating. Wave circuit.