KR101481148B1 - Arrayed Waveguide Collimators - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a collimator using an optical waveguide constructed in the form of an array and an array type optical component using the same. A lower cladding formed on the substrate; A first optical waveguide formed in a groove formed in a first direction through at least a part of the lower cladding; And a planar optical component coupled to the groove formed along a second direction different from the first direction through at least a part of the lower cladding and the first optical waveguide.

Description

[0001] Arrayed Waveguide Collimators [

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a collimator using an optical waveguide configured in an array form and an array type optical component using the same. Array type optical parts have the advantage of being able to manufacture multiple optical parts at the same time as individual optical parts, and are used for manufacturing various parts in order to increase the production amount of optical parts and lower the unit cost. In particular, in the WDM optical communication technology, a communication system for transmitting signals using a light source having a plurality of different wavelengths is used, wherein each light having a different wavelength is controlled through individual optical components connected to the respective channels , It is necessary to manufacture the individual optical parts in the form of an array, thereby reducing the area occupied by the parts and simplifying the assembling process.

Wavelength Division Multiplexing (WDM) optical communication systems have provided a very important technical solution for handling ever-increasing Internet traffic capacity. When data of 10 Gigabits per second can be transmitted at one wavelength, data can be generated using 40 wavelengths, multiplexed, and transmitted through one optical fiber. In the WDM optical communication system, 400 Gigabits of data can be transmitted And has the ability to transmit in one second. In a WDM optical communication system using several different wavelengths, a plurality of light sources having different wavelengths must be used, and various optical components for optical signal processing are required as many as the number of wavelengths. In recent optical communication systems, efforts have been made to reduce the manufacturing cost by increasing the capacity of the optical communication system and reducing the number of parts by fabricating a plurality of light sources and optical elements in an array form.

A typical array type optical component includes a variable optical attenuator (VOA) device used for adjusting the intensity of an optical signal. A VOA device is used to individually control each wavelength signal used in a WDM optical communication, and a VOA device corresponding to the number of optical wavelength channels is required for this purpose. These VOA devices are currently being developed as array type devices and will use four 10-channel VOA array elements for a 40-channel WDM optical communication system. As such, the optical module completed using only four array elements is easier to manufacture than the optical module completed by using 40 individual elements, and the size of the components is reduced, which is advantageous in terms of cost.

Attempts have been made to convert various optical components into array elements in order to take full advantage of the advantages of array type optical devices. Among them, studies have been made to increase the production efficiency of parts by fabricating laser diodes used as light sources in array form. Laser diodes, however, need to be assembled by assembling the optical isolator parts together during the packaging process, which requires a lens that allows the light from the laser diode to pass through the optical isolator into the optical fiber. In addition, when the laser diodes are fabricated in an array, since the distance between the respective light sources is very narrow, it is very difficult to solve the problem by using the lens array to make the light emitted from the plurality of laser diodes enter the optical fiber array through the optical isolator It becomes work.

The above-described background technology is technical information that the inventor holds for the derivation of the present invention or acquired in the process of deriving the present invention, and can not necessarily be a known technology disclosed to the general public prior to the filing of the present invention.

In order to solve the above problems, the present invention proposes a structure that allows light emitted from a laser diode array to be incident on an optical fiber through an optical isolator using an optical waveguide device.

Further, the present invention forms a collimated beam that advances light in an array-type optical component in one direction without using a lens, passes through a variety of flat-plate optical component arrays including an isolator, And an optical component in the form of being incident on and output from an optical fiber array positioned at a predetermined position.

The present invention relates to a substrate; A lower cladding formed on the substrate; A first optical waveguide formed in a groove formed in a first direction through at least a part of the lower cladding; And a planar optical component coupled to the groove formed along a second direction different from the first direction through at least a part of the lower cladding and the first optical waveguide.

In the present invention, the first optical waveguide is disconnected by the planar optical component, and light incident through one end of the first optical waveguide may be emitted to the other end via the planar optical component .

In the present invention, the planar optical component may include at least one of an optical isolator, an optical waveplate, a liquid crystal plate, a polarizer, and a wavelength filter.

The present invention may further include a second optical waveguide having a tapered portion formed at one end thereof so as to have a smaller sectional size toward an end of the end portion.

Here, the size of the cross section of the second optical waveguide may be smaller than the size of the cross section of the first optical waveguide.

Here, the tapered portion may be formed to be inserted into the first optical waveguide.

Here, the other end of the second optical waveguide is connected to the optical fiber, and the light incident through the other end of the second optical waveguide may proceed in the order of the taper portion, the first optical waveguide, and the planar optical component have.

According to the present invention, an optical signal output from a dense optical component such as a laser diode fabricated in an array form can be converted into collimated light without spreading in free space. In this way, a desired type of optical component can be inserted into the path through which the collimated light passes, and the resulting optical loss can be kept at a very small value. An optical component that can be inserted into an optical path includes an optical isolator and includes a liquid crystal element, a polarizing plate, a wave plate, a wavelength filter, and the like, and can be used to fabricate various functional array type optical components.

1 is a perspective view showing an arrayed optical waveguide collimator according to an embodiment of the present invention.
FIG. 2 is a graph showing a result of designing through a three-dimensional beam propagation method (BPM) numerical analysis in order to examine how the influence of grooves due to the size of an optical waveguide appears.
FIG. 3 shows a structure in which a first optical waveguide is connected to a second optical waveguide array of a small core having a tapered portion formed at one end thereof for input / output of the arrayed optical waveguide collimator of FIG.
Fig. 4 shows a mode in which the mode of the waveguide mode evolves along the traveling direction when the large core optical waveguide and the small core optical waveguide are connected by the tapered optical waveguide.
FIG. 5 shows the structure of the arrayed waveguide collimators of the present invention for carrying out a numerical analysis of a three-dimensional beam propagation method, and a change in the light wave propagated through the arrayed waveguide collimators.
6 shows the result of calculation of the light wave loss occurring in the arrayed waveguide collimators of the present invention while changing the tapered structure.

The following detailed description of the invention refers to the accompanying drawings, which are given by way of illustration of specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, the specific shapes, structures, and characteristics described herein may be implemented by changing from one embodiment to another without departing from the spirit and scope of the invention. It should also be understood that the location or arrangement of individual components within each embodiment may be varied without departing from the spirit and scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present invention should be construed as encompassing the scope of the appended claims and all equivalents thereof. In the drawings, like reference numbers designate the same or similar components throughout the several views.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to facilitate a person skilled in the art to which the present invention pertains.

1 is a perspective view showing an arrayed optical waveguide collimator according to an embodiment of the present invention. 1, an array type optical waveguide collimator 10 according to an embodiment of the present invention includes a substrate 11, a lower cladding 12, a first optical waveguide 13, a groove 14, And an optical component 15.

On the substrate 11, a lower cladding 12 is formed. Specifically, a substrate 11 made of glass or plastic, which is an insulator material having no influence on the distribution of an electric field, is prepared, and then a polymer material is coated on the substrate 11 and cured to form a lower cladding 12.

A predetermined groove is patterned in the Y-axis direction of FIG. 1 on the upper portion of the lower cladding 12, and a first optical waveguide 13 is formed to fill the groove. More specifically, the first optical waveguide 13 is formed by coating a polymer material having a refractive index higher than that of the lower cladding 12 on the lower cladding 12 to fill the grooves. Here, the first optical waveguide 13 may include at least one of a polymer material or a silica material. The first optical waveguide 13 will be described later in more detail.

Next, after the groove 14 is formed in the X-axis direction of FIG. 1 through the first optical waveguide 13 and the lower cladding 12, the plate-like optical component 15 is inserted into the groove 14 . Here, the planar optical component 15 that can be inserted into the optical path includes an optical isolator and includes a liquid crystal element, a polarizing plate, a wave plate, a wavelength filter, and the like, and can be used for manufacturing array optical components of various functions .

The lower cladding 12, the core 13, and the planar optical component 15 are formed on the lower cladding 12, the first optical waveguide 13, and the planar optical component 15, An upper cladding (not shown) is formed. That is, a polymer material is coated on the lower cladding 12, the core 13, and the planar optical component 15, and the polymer material is cured to form an upper cladding (not shown) It completes.

Here, in an embodiment of the present invention, a first optical waveguide 13 of a large core having an enlarged core size is introduced and a groove 14 is formed at the center of the first optical waveguide 13 of the large core, Like optical component 15 such as a metal plate. In such a large-sized core optical waveguide, even when a groove is formed at the center of the optical waveguide to break the optical waveguide, most of the light travels through the optical waveguide short-circuit portion and travels to the optical waveguide of the output portion. .

This will be described in more detail as follows.

In order to insert a flat optical component into a groove in the central portion of the optical waveguide, loss of light due to a groove that is broken in the optical waveguide must be small. However, a general optical waveguide is manufactured to have a waveguide mode having the same size as that of the optical waveguide mode, and thus the core size of a general optical waveguide is only about 6 to 8 μm. However, if a groove is formed in the central portion of the optical waveguide having such a small core, light passing through the groove portion without the optical waveguide inevitably causes diffraction, and the size of light input to the optical waveguide again after passing through the groove is reduced, Resulting in optical loss. At this time, the degree of the diffraction of the light emitted from the optical waveguide into the groove is affected by the degree of distribution of the light existing in the optical waveguide. When the light is spread in a larger space than when the light is gathered in the narrow space Has a characteristic of causing less diffraction. Considering such characteristics of light, if the size of the optical waveguide is enlarged to enlarge the waveguide mode, when the light propagates through the groove where the optical waveguide is removed, less diffraction occurs, It will become more.

Accordingly, in an embodiment of the present invention, a first optical waveguide 13 of a large core having an enlarged core size is introduced and a groove 14 is formed at the center of the first optical waveguide 13 of the large core, Shaped optical component 15 such as a flat plate-like optical component 15 is inserted, most of the light passes through the optical waveguide short-circuit part and proceeds to the optical waveguide of the output part even if there occurs a situation where the optical waveguide breaks by punching the groove in the center of the optical waveguide.

FIG. 2 is a graph showing a result of designing through a three-dimensional beam propagation method (BPM) numerical analysis in order to examine how the influence of grooves due to the size of an optical waveguide appears.

The size of the optical waveguide core is set to 6 μm in the case of a general compact optical waveguide, and the difference in refractive index from the cladding for a single module optical waveguide is set to 0.003. On the other hand, the core size of the large-core optical waveguide is set at 25 μm and the refractive index difference is set at 0.001.

Referring to FIG. 2, when the transmission loss according to the width of the groove is calculated for the two optical waveguides, the loss due to the grooves is significantly smaller in the large core optical waveguide than in the small core. In the case of a large core optical waveguide having a core size of 25 x 25 um ² as in the present invention, even if the groove width is as large as about 300 μm, the loss value resulting from the large core optical waveguide is less than 0.5 db. The thickness of a typical planar optical isolator device is about 300 μm. Therefore, according to the above-described design results, it is expected that the increase in optical loss will be only about 0.5 db when the grooves are inserted into the proposed large-core optical waveguide and the optical isolator is inserted.

As described above, according to the array type optical waveguide collimator according to the embodiment of the present invention, it is possible to insert a desired optical component into a path through which collimated light passes, and the resulting optical loss can be maintained at a very small value It will be.

FIG. 3 shows a structure in which a first optical waveguide is connected to a second optical waveguide array of a small core in which a tapered portion is formed at one end for input / output of the arrayed optical waveguide collimator of FIG. 1, And the small-core optical waveguide are connected by a tapered optical waveguide, the mode of the waveguide mode evolves along the traveling direction.

Referring to FIG. 3, the array type optical waveguide collimator 10 according to the embodiment of the present invention further includes a second optical waveguide 16 of a small-sized core. This will be described in more detail as follows.

As described above, in the case of introducing the first optical waveguide 13 of the large core, most of the light passes through the optical waveguide short-circuit part, and the optical waveguide of the output part, However, when the first optical waveguide 13 of the large core is directly connected to the optical fiber, large coupling loss due to mode mismatch is generated.

Therefore, it is necessary to connect the first optical waveguide 13 of the large core to the small core optical waveguide to reduce the size of the mode. For this purpose, the size of the optical waveguide core varies along the traveling direction And a second optical waveguide having a tapered portion which is gradually changed.

That is, as shown in FIG. 3, the second optical waveguide 16 is a general small-size core optical waveguide, and the size of the optical waveguide core can be set to 6 um. One end of the second optical waveguide 16 is connected to the optical fiber and a tapered portion 14a is formed at the other end of the second optical waveguide 16 so that the size of the core varies along the traveling direction. The tapered portion 14a is inserted into the first optical waveguide 13 of the large core and transmits the light transmitted from the optical fiber to the first optical waveguide 13. [

Here, the tapered portion 14a according to an embodiment of the present invention is formed in such a manner that the core size gradually decreases from the core size equal to the size of the small core optical waveguide. When the core size of the optical waveguide is reduced, the waveguide mode gradually exits to the outside of the optical waveguide. At the moment when the size of the optical waveguide core becomes zero at the end of the tapered portion 14a, . At this time, if the large core optical waveguide is placed in the cladding portion, the optical waveguide mode emerging from the core is deformed into the optical waveguide mode of the large core. This process is illustrated in FIG. 4 and schematically shows how the vertical direction distribution of the waveguide mode is formed and transformed in each part of the first optical waveguide and the second optical waveguide.

Through this process, the light incident on the small core optical waveguide is gradually changed in the shape of the mode while passing through the tapered portion, and finally converted into the large core optical waveguide mode. If the structure of the tapered optical waveguide is appropriately designed, an adiabetic mode conversion structure in which light can proceed between two optical waveguides without loss of optical power is obtained even if the shape of the waveguide mode is changed .

FIG. 5 shows a structure of an arrayed waveguide collimator of the present invention for performing a numerical analysis of a three-dimensional beam propagation method, and FIG. 6 shows changes in light wave propagated through the arrayed waveguide collimators. FIG. And shows the result of calculating the light wave loss occurring in the arrayed waveguide collimators of the present invention.

The green portion starting from the leftmost side in FIG. 5 (a) is a small-core optical waveguide, and the width of the optical waveguide is reduced through the two tapered structures and finally disappears. The portion represented by yellow corresponds to a large core optical waveguide, and a large core optical waveguide exists in a portion where a small core optical waveguide disappears. 5 (b), it can be seen that the guided light spreads outward as the optical waveguide becomes narrower in the tapered structure portion. Thereafter, an optical waveguide groove having a width of 400 μm is formed in the center portion. Here, it is seen that the light does not pass out to the outside and passes through the portion without the optical waveguide as it is without collimation . In the latter half, the inverted tapered optical waveguide begins to appear, and the spread optical power is gathered again inside the small-core optical waveguide. Through this process, the light wave inevitably causes loss, and optimization of the taper structure is necessary to minimize this loss.

FIG. 6 shows the result of calculating the light wave loss occurring in the arrayed waveguide collimators while changing the taper structure. From this result, it was confirmed that the additional loss due to the collimator element can be reduced to about 10% (0.45 dB) by selecting the appropriate tapered structure. Therefore, by using the arrayed waveguide collimators, it is possible to reduce the additional loss to 0.5 dB even when a desired planar optical component is sandwiched by forming an optical waveguide gap of 400 μm in width.

Although the present invention has been described with reference to the limited embodiments, various embodiments are possible within the scope of the present invention. It will also be understood that, although not described, equivalent means are also incorporated into the present invention. Therefore, the true scope of protection of the present invention should be defined by the following claims.

10: Array type optical waveguide collimator
11: substrate
12: Lower cladding
13: first optical waveguide
14: Home
15: Plate type optical part
16: second optical waveguide
16a:

Claims (7)

Board;
A lower cladding formed on the substrate;
A first optical waveguide formed in a groove formed in a first direction through at least a part of the lower cladding; And
And a flat optical component coupled to the groove formed along a second direction different from the first direction through at least a part of the lower cladding and the first optical waveguide,
Wherein the first optical waveguide is disconnected by the planar optical component and the light incident through one end of the first optical waveguide is emitted to the other end via the planar optical component,
Wherein the planar optical component includes at least one of an optical isolator, an optical waveplate, a liquid crystal plate, a polarizer, and a wavelength filter,
And a second optical waveguide having a tapered portion formed at one end thereof so as to have a smaller cross-sectional size toward an end of the end portion,
The size of the cross section of the second optical waveguide is smaller than the size of the cross section of the first optical waveguide,
The tapered portion is formed to be inserted into the first optical waveguide,
And the other end of the second optical waveguide is connected to the optical fiber, and the light incident through the other end of the second optical waveguide travels in the order of the taper portion, the first optical waveguide, and the planar optical component And the optical waveguide collimator is an array type optical waveguide collimator. delete delete delete delete delete delete

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