JP3112155B2 - Connection method between optical waveguide and optical fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a simple connection method for connecting an input / output optical fiber to an optical waveguide circuit formed on a substrate.

[0002]

2. Description of the Related Art In order to actually use an optical waveguide circuit formed on a flat substrate, an input / output optical fiber must be connected to the optical circuit. When connecting the optical waveguide and the optical fiber, a light source such as a laser is incident on the optical fiber, and the optical waveguide and the optical fiber are aligned. Since the connection between the optical waveguide and the optical fiber is multi-core connection, the alignment is XY-
This is performed for the Z axis and the rotation (θ) axis.

FIG. 1 shows a conventional method for connecting an optical fiber and an optical waveguide. In FIG. 1, 11 is a multi-core single mode optical fiber tape, 12 is an optical fiber block,
13 is an optical waveguide circuit, 14 is an optical fiber block, 15
Is a multi-core multi-mode tape. FIG. 2 shows an enlarged view of the connecting portion in this case. In FIG. 2, 21 is a flat substrate,
22 is the cladding of the optical waveguide, 23 is the core of the optical waveguide, 2
4 is an optical fiber, 25 is an optical fiber block, and 26 is a holding cover of the optical fiber block. FIG. 2 shows only two optical fibers necessary for alignment for simplicity. By inputting light to the two optical fibers, alignment with respect to the rotation (θ) axis can be performed.

[0004] One of the biggest challenges in centering is
First, when the input side optical fiber is connected, in this case, the optical fiber must be adjusted to the optical waveguide from a state where no light is incident on the optical waveguide from the optical fiber. For that purpose, it is necessary to surely monitor the output from the optical waveguide on the opposite side. In the conventional method, first, a He-Ne laser having a wavelength of 633 nm was put into the optical fiber on the incident side, and the optical fiber on the incident side was roughly adjusted to the optical waveguide while visually observing the incident pattern from the optical waveguide. next,
The optical output was monitored by visually checking the multimode optical fiber having a large core diameter with the optical waveguide on the output side, and the XYZ axes and the θ axis were accurately aligned on the optical fiber on the incident side.

However, in this method, first, He is used.
There is a disadvantage that it takes time to enter a -Ne laser. Further, there is a disadvantage that a multi-core multi-mode optical fiber is required in accordance with the distance between the optical waveguides, and a multi-core multi-mode optical fiber must be prepared for each different optical waveguide. Further, there is a disadvantage that the rotation axis of the multi-core multi-mode optical fiber must be adjusted. Due to the above disadvantages, it has been difficult to automate the connection device.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to enable simple and accurate connection between an optical waveguide and an optical fiber, and to automate connection. It is an object of the present invention to provide a possible connection method between an optical waveguide and an optical fiber.

In the present invention, a method for more simply adjusting the optical fiber and the optical waveguide from the state where no light is incident on the optical waveguide from the optical fiber at the beginning of the connection will be described. For that purpose, it is necessary to reliably monitor the output from the optical waveguide on the opposite side, and the following method was adopted.

[0008]

In the present invention, a large-diameter optical receiver is used to monitor the output from the optical waveguide circuit. FIG. 3 shows a connection method using a light receiving element. FIG.
, 31 is a multi-core single mode optical fiber tape, 3
2 is an optical fiber block, 33 is an optical waveguide circuit, and 34 is an optical receiver. In the connection method shown in FIG. 3, a laser beam or the like is incident on the optical fiber, and the optical fiber block 32 and the optical waveguide circuit 33 are brought close to each other. While monitoring the output of the optical receiver 34, the optical fiber block 32 can be moved at random to find a position where the intensity of the emitted light is maximum.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method for connecting an optical waveguide to an optical fiber according to the present invention, the method for connecting an optical waveguide and an optical fiber fabricated on a flat substrate includes the steps of: A light receiver having a light receiving area equal to or larger than the width of the optical waveguide pattern is installed, and the optical fiber is monitored while monitoring light emitted from an optical fiber connected to a second end optically facing the first end. Is characterized in that it is centered.

In the present invention, when a large-diameter light receiving element is used for the light receiving device, when the core of the optical fiber and the core of the optical waveguide do not match, the spatially propagating light or the propagating light of the cladding portion of the optical waveguide is also reduced. Received. In this case, it should be noted that the cladding light may have a distribution. That is, sometimes, the peak position of the clad light is mistaken for the core position, and the true core position cannot be found.
However, in this case, since both the space and the clad propagation light are divergent, only a part of the light is received by the light receiver. On the other hand, when the cores match, the output light concentrates on the light receiver. Therefore, when the alignment is performed at the peak position of the clad light, the output is lower than when the alignment is performed on the core. Therefore, by setting a threshold value for the output of the light receiving element, it is possible to distinguish between the case where the light enters the core and the other case, and it is possible to align the cores so that the cores can be more easily matched. Become.

Further, as a method of distinguishing the light propagated through the space or clad from the light propagated through the core, it is also effective to place a slit in front of the light receiver. By setting the slit, the allowable range of the threshold setting can be expanded.

According to the present invention, the following operations are provided.

(I) Initial alignment can be easily performed in the alignment of the optical fiber and the optical waveguide.

(Ii) When a multi-mode optical fiber is used, it is necessary to visually match the multi-mode optical fiber to the output side, and it is necessary to match the interval between the multi-mode optical fibers to the optical waveguide pattern. However, the use of the light receiver enables the alignment without being affected by the optical waveguide pattern.

(Iii) According to the present invention, since it is not necessary to visually match the emission pattern of the He-Ne laser, automation is easy.

[0016]

Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments.

(Embodiment 1) FIG. 4 is a diagram for explaining connection between a 2 × 8 PLC splitter and an incident side optical fiber in a first embodiment of the present invention. 41 is a two-core optical fiber,
42 is an optical fiber block, 43 is a 2 × 8 PLC splitter chip, 44 is a light receiving element, and 46 is an optical waveguide.

In order to connect the two-core input optical fiber 41 to the 2 × 8 splitter chip 43 by the method shown in FIG. 4, first, a 1.3 μm LD is inserted into one of the two-core optical fiber 41, and the PLC splitter is connected. The chip 43 was approached. P
The end face on the opposite side of the LC splitter chip 43 has a diameter of 3
mm InGaAs-PIN type light receiving element 44 was installed. In a state where the optical fiber 41 is first approached, the light propagating through the clad of the optical waveguide 46 enters the light receiving element 44 and has an output of about 100 μW. Thus, the threshold value of the light receiving element 44 was set to 150 μW, and the optical fiber 41 was randomly aligned. As a result, the cores of the optical fiber 41 and the optical waveguide 46 of the PLC splitter chip 43 could be aligned, and the cores could be matched. It was confirmed that the output after the alignment was 330 μW, which was sufficiently larger than the light propagated through the clad. Next, a 1.3 μm semiconductor laser (LD) was put in the other optical fiber 41, and the optical fiber 41 was similarly aligned. Coordinates at which the aligned outputs of the two optical fibers were maximized were recorded, and the rotation angles at which both ports were maximized were calculated. As a result, the two-core optical fiber could be aligned, and connected with a UV adhesive.

The alignment time is about 1 except for the time required for setting the optical fiber 41 and the PLC splitter chip 43.
Minutes, which is sufficiently shorter than the case where the emission pattern of the He-Ne laser was visually confirmed. In addition, the connection loss was 0.11 dB / point, and it was confirmed that the connection loss was almost equivalent to that of the related art.

As described above, the effectiveness of the present invention has been confirmed.

(Embodiment 2) FIG. 5 is a diagram for explaining a connection between a reflective WDM chip having a transceiver function and an optical fiber according to a second embodiment of the present invention. 51 is 2
Core optical fiber, 52 is an optical fiber block, 53 is a reflection type WDM chip, 54 is an optical fiber light guide connected to a light receiving element, 55 is an interference film filter, 56 is a filter insertion groove, 57 is an optical waveguide, and 58 is a substrate. A semiconductor laser (LD) mounted on the substrate 59 is a photodiode (PD) mounted on the substrate. In the reflection type WDM manufactured by the present invention, the interference film filter 55 that reflects 1.55 μm and transmits 1.3 μm is used, and the light enters the input port (P1) of one optical waveguide of the two-core optical fiber 51 1 .31 and 1.55 were split by the interference film filter 55. The 1.55 μm signal light passes through the input port (P2) of the other optical waveguide and returns to the other optical fiber. The 1.31 μm signal light passes through the filter 55 and is received by the PD 59 mounted on the optical waveguide substrate. Also,
The LD 58 can oscillate 1.31 μm signal light. In the reflection type WDM shown in FIG. 5, an optical waveguide for outputting to the optical fiber light guide 54 is formed.

In the structure shown in FIG. 5, in order to connect the two-core input / output optical fiber 51 and the reflection type WDM chip 53, first, the input port (P
The optical fiber connected to 2) was connected to an optical channel selector, and the other optical fiber 51 was put into an optical power meter. Wavelengths 1.3 and 1.55 for the optical channel selector
A μm LD was connected. An optical fiber light guide 54 was installed near the output port P3 on the opposite end face of the WDM chip 53, and then the two-core optical fiber 51 was moved closer to the WDM chip 53.

In alignment, L of 1.3 μm and 1.55 μm
Switch the input of D with the channel selector, 1.3μmL
The output power of D58 was read by the light receiving element connected to the optical fiber light guide 54, and the power of the LD of 1.55 μm was read by the optical power meter connected to the other optical fiber 51. Then, the optical fiber block was aligned by controlling the X-Y and θ axes. Note that 150 μW was set as the threshold value of the light receiving element.

With the above-described method, the cores of the two-core optical fiber array and the WDM chip can be aligned with each other, and an input / output optical fiber can be connected to one end at a position where the optical power is maximized. In the result of evaluating the connection loss,
0.15 dB / point was obtained, which was equivalent to the conventional method.

As described above, it has been conventionally difficult according to the present invention. An optical fiber can be connected to an optical waveguide circuit having a reflection type filter and having an input / output at one end. According to the present invention, as shown in FIG.
By setting the optical waveguide for the output end of 3), even if the other optical waveguide is blocked with a PD or another optical element, the output from the optical waveguide of P3 can be monitored. Thereby, the optical fiber 51 can be connected to one end. As described above, if an optical waveguide for output is formed on a side different from the input / output side in the optical waveguide circuit, an optical fiber can be connected to one end according to the present invention.

As a result, the effectiveness of the present invention was confirmed.

(Embodiment 3 (AWG)) In this embodiment, 1
An optical fiber was mounted on a 6 × 16 channel array optical waveguide type optical multiplexer / demultiplexer. FIG. 6 is a diagram for explaining the connection between the array optical waveguide type WDM chip and the optical fiber in the present embodiment. 61 is two sets of 8-core optical fibers, 62 is an optical fiber block, 63 is an array optical waveguide type WDM chip,
Reference numeral 64 denotes an optical fiber light guide for two-part light reception connected to an optical receiver, 65 denotes a light receiving element, and 66 denotes an optical waveguide.

In the N × N array type WDM, when signal light having N different wavelengths is input to one input port, it can be split into N output ports in accordance with the wavelength.
Conversely, if N signal lights are separately input to N ports, they can be combined into one port.

When an optical fiber is connected to an array optical waveguide type WDM using a multi-mode optical fiber by a conventional method, it is necessary to define an input / output port using a wavelength tunable laser. Also, it was difficult to visually check the emission pattern using a He-Ne laser.

In this embodiment, an optical fiber 61 is easily connected to an array optical waveguide type WDM chip 63 using a normal Fabry-Perot LD and a light receiving element. The array optical waveguide type WDM chip 63 used is for multiplexing / demultiplexing signal light having a wavelength interval of 0.8 nm in a 1.55 μm band. Since the Fabry-Perot LD oscillates in a plurality of modes having different wavelengths, when the output of the Fabry-Perot LD is put into the array waveguide type WDM chip 63, it is unclear which port to output. And it was difficult to receive light with a multimode optical fiber). However, as shown in FIG. 6, when a large-area optical fiber light guide 64 that covers all output ports is used, it is possible to receive the output of the Fabry-Perot LD incident on the array optical waveguide type WDM chip 63, Optical fiber 61
Can be aligned.

In this embodiment, in order to connect the 16-core optical fiber 61 on the input side, a Fabry-Perot LD is connected to one fiber.
Input was made to ports 2 and 15 of a 6-core optical fiber. In the alignment, first, the maximum value of the output of the optical receiver is searched for in a state where only the port 2 is input, and the cores are matched with each other. Aligned similarly. The coordinates at which the output at ports 2 and 15 became maximum were recorded, and the rotation angle at which both ports became maximum was calculated. As a result, the 16-core optical fiber 61 could be aligned and connected with a UV adhesive. The connection on the output side was made in the same manner as usual.

According to the above-described method, the time required for connecting the multimode optical fiber to the output port is reduced, and the input optical fiber can be easily connected.

From these results, the effectiveness of the present invention was confirmed.

As shown in the above embodiment, a semiconductor light receiving element may be used for the light receiving portion and may be directly installed near the optical waveguide, or a large-diameter optical fiber light guide may be installed near the optical waveguide. It may be installed to introduce output light to the light receiving element.
In the latter case, the output of the distant optical waveguide can be monitored by one light receiving element by using a two-part light guide. In the embodiment, one light receiving element is used, but a plurality of light receiving elements may be used.

[0035]

As described above, in the method for connecting an optical fiber and an optical waveguide according to the present invention, the alignment of the optical fiber and the optical waveguide on one side to be connected first is performed, and light is received at the end of the opposite optical waveguide. This is performed by installing an optical unit and monitoring the output from the optical waveguide. According to this method, the following effects are obtained.

(I) The connection between the input side optical waveguide and the optical fiber can be simplified.

(Ii) At the time of connection, there is no need to match a multimode optical fiber with the optical waveguide pattern.
Optical fibers can be connected even when the input / output ports are not facing each other. In particular, it is possible to connect even a circuit pattern in which input / output ports are concentrated on one side.

(Iii) Since there is no need to visually check the initial input, automation is easy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conventional optical fiber connection method.

FIG. 2 is an enlarged view of a connection part in the connection method shown in FIG.

FIG. 3 is a diagram showing a connection method using a light receiving element according to the present invention.

FIG. 4 is a diagram illustrating connection between a 2 × 8 PLC splitter and an incident side optical fiber according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating connection between a reflective WDM chip and an optical fiber according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating a connection between an array optical waveguide type WDM chip and an optical fiber according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Multi-core single mode optical fiber tape 12 Optical fiber block 13 Optical waveguide circuit 14 Optical fiber block 15 Multi-core multi-mode tape 21 Flat substrate 22 Optical waveguide clad 23 Core of optical waveguide 24 Optical fiber 25 Optical fiber block 26 Optical fiber Block cover 31 Multi-core single-mode optical fiber tape 32 Optical fiber block 33 Optical waveguide circuit 34 Optical receiver 41 2-core optical fiber 42 Optical fiber block 43 2 × 8 PLC splitter chip 44 Optical receiver 46 Optical waveguide 51 2-core Optical fiber 52 Optical fiber block 53 Reflective WDM chip 54 Optical fiber light guide connected to light receiving element 55 Interference film filter 56 Filter insertion groove 57 Optical waveguide 58 Semiconductor laser (LD) 59 Photodiode (PD 61 16-core optical fiber 62 the optical fiber block 63 array waveguide type WDM chips 64 led to the light receiving device divided into two light receiving optical fiber guide 65 the light receiving element 66 optical waveguide

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-6-94936 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 6/24-6/42

Claims (2)

(57) [Claims] 1. A light receiver having a light receiving area equal to or larger than a pattern width of an optical waveguide is provided at a first end of an optical waveguide formed on a flat substrate, and optically opposed to the first end. Second
A method of connecting an optical waveguide and an optical fiber, wherein the optical fiber is aligned with respect to the optical waveguide while monitoring emitted light from the optical fiber connected to an end of the optical waveguide, and the optical waveguide and the optical fiber are connected. By setting a threshold value for the output of the light receiver, it is easy to determine whether the light monitored by the light receiver is the light emitted from the optical fiber incident on the core of the optical waveguide or not. A method for connecting an optical waveguide and an optical fiber, wherein 2. The method of connecting an optical waveguide to an optical fiber according to claim 1, wherein a slit is provided in front of the light receiver to widen an allowable range for setting an output threshold of the light receiver. .