KR100536141B1 - Passive optical-coupled structure and method for fabricating the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a passive optical coupling structure and a method for manufacturing the same. The present invention relates to microstructures for convex type optical coupling formed on a planar optical waveguide device, and to recessed optical coupling formed on a polymer platform. An electrical connection that generates a passive optical coupling between the optical fiber and the optical waveguide by the alignment with the microstructure, and generates the thermo-optic effect of the optical device through the automatic connection of the electrodes disposed on the iron-shaped microstructure and the recessed microstructure. Disclosed is an easily made passive optical coupling structure. In addition, the present invention discloses a fabrication method capable of producing an economical and highly efficient highly integrated optical device by fabricating an optical coupling structure using a hot embossing molding process using a mask having a multi-stage structure.

Description

Passive optical-coupled structure and method for fabricating the same

The present invention relates to a passive optical coupling structure and a method for fabricating the same. In particular, a passive optical coupling structure and a fabrication method for passive optical coupling between a planar optical waveguide device and an optical fiber and an automatic electrical connection can be efficiently implemented. It is about a method.

Implementation of a passive alignment structure of an optical device based on a silicon material additionally requires the construction of a separate optical coupling structure or a V-type guide groove capable of inducing optical coupling in the optical device. In the manufacture of such guide grooves, a dry etch or wet etch method used to fabricate a silicon microstructure is applied. This requires investment in process steps and process costs corresponding to the fabrication of optical devices based on silicon materials.

In addition, the optical coupling structure is generally manufactured in the state in which the optical device is manufactured or during the manufacturing process. Accordingly, there is a problem that the optical device in the already manufactured state is damaged during the manufacturing process of the optical coupling structure, or the efficiency is lowered. Furthermore, as the additional guide groove inserting auxiliary structure for coupling the optical coupling guide structure and the optical fiber array frame already manufactured is required to be manufactured in a separate process, a high cost and a multi-stage process are required.

In addition, in general, in order to operate the manufactured optical device, an electrical wiring process using a wire bonding process is required. However, wire bonding causes an increase in the process cost of fabricating an optical device as the channel integration of the optical device is improved.

Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to efficiently implement passive optical coupling of a planar optical waveguide device.

In addition, another object of the present invention is to efficiently implement electrical connection during passive optical coupling of a planar optical waveguide device.

In addition, the present invention has another object to implement a passive optical coupling of the planar optical waveguide device in a single process of high efficiency and low cost.

In addition, another object of the present invention is to implement the packaging of the optical device at a low cost.

According to an aspect of the present invention, an optical fiber consisting of an optical guide guide groove formed so that the optical fiber is seated, a plurality of recessed microstructures formed for optical coupling, and a first electrode disposed along the inner surface of the recessed microstructure, respectively. A coupling platform, an optical waveguide aligned with the optical fiber upon optical coupling, a plurality of convex microstructures that are inserted into the concave microstructure at a portion corresponding to the concave microstructure, and the outlet microstructure, respectively. And an optical device including a second electrode disposed along an upper surface of the structure, wherein the convex microstructure is inserted into the recessed microstructure during the optical coupling so that the first electrode and the second electrode are electrically connected. It provides a passive optical coupling structure characterized in that.

According to another aspect of the present invention, the glass transition of the first polymer sample by applying heat on the first polymer sample, and pressing the first cast mold to the first polymer sample recessed microstructure and optical fiber guide Forming a first polymer sample to form a groove, forming a first electrode along an inner surface of the recessed microstructure, and forming a platform for optical coupling, and heat on the second polymer sample. Adding a glass transition to the second polymer sample, pressing the second cast mold onto the second polymer sample, and molding the second polymer sample to form an iron-shaped microstructure and an optical waveguide; Forming a core to fill the inside of the optical waveguide, forming a cladding layer to cover the core, and forming an inner surface of the convex microstructure. And fabricating an optical device including forming a second electrode, and optically coupling the optical device such that the convex microstructure is inserted into the recessed microstructure to electrically connect the first electrode and the second electrode. It provides a method for manufacturing a passive optical coupling structure comprising the step of coupling with the dragon platform.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention and to those skilled in the art. It is provided for complete information. On the other hand, the same reference numerals among the reference numerals described below indicate the same member having the same function.

1 is a view showing an optical device and a polymer platform having a passive optical coupling and automatic electrical connection to explain the passive optical coupling structure according to a preferred embodiment of the present invention.

Referring to FIG. 1, the passive optical coupling structure according to the preferred embodiment of the present invention is a polymer optical coupling platform in which a polymer planar optical device 10 in which microstructures 14 for convex type optical coupling are formed is formed. Each of the recesses 20 has a structure inserted into each of the microstructures 24 for optical coupling. By such a geometric structure, passive optical coupling is performed between the polymer optical waveguide 13 and the optical fiber 30. In addition, the electrodes 16 'and 26 are respectively formed along the inner surfaces of the concave microstructure 14 and the recessed microstructure 24 in order to electrically connect with an external signal to generate a thermo-optic effect in the polymer optical waveguide 13. Is placed. As a result, the electrical connection between the two electrodes 16 ′ and 26 is made simultaneously with the optical coupling of the two microstructures 14 and 24. In this case, the electrode 16 ′ is disposed to extend along the inner surface of the concave microstructure 14 to the upper surface of the lower clad layer 12. The electrode 26 extends along the inner surface of the recessed microstructure 26 to the upper surface of the optical coupling platform 20.

As shown in FIG. 1, the convex microstructures 14 are arranged one by one in a pyramid shape at each corner portion of the lower clad layer 12. The recessed microstructures 24 are arranged in a pyramid form, one at each portion corresponding to the iron-shaped microstructures 14. In addition, the microstructures 14 and 24 for optical coupling may be modified in various forms. For example, when the number of channels increases, the number of microstructures also increases by the number of channels. In this case, as shown in FIG. 2 in consideration of an increase in the number of microstructures according to an increase in the number of channels, the convex microstructures 14 'are disposed on the upper and lower sides of the lower clad layer 12, respectively. Can be. Accordingly, the recessed microstructure 24 'is disposed one at each of the upper and lower portions at a portion corresponding to the convex microstructure 14'. At this time, each of the microstructures 14 'and 24' is formed to have a structure extending from the left to the right.

On the other hand, the passive optical coupling structure according to the preferred embodiment of the present invention is formed by a hot embossing molding process (to be described later). In the case of using the hot embossing molding process, it is possible to implement the cores (not shown) of the convex microstructure 14 and the optical waveguide 13 in a single process. Therefore, it is possible to reduce the cost of the high-cost optical device and the optical coupling structure forming process by the conventional silicon dry etching or wet etching method. However, when the polymer flat optical device 10 is formed by using a hot embossing molding process, the thickness of the lower clad layer 12 formed by the pressure applied to the polymer material during the molding process is changed so that the optical waveguide 13 is formed. And the gap between the silicon substrate 11 is likely to be narrowed. This change in thickness of the lower clad layer 12 can cause many problems in the dimension of alignment. Accordingly, there is a need for a light alignment method that is independent of the thickness change of the lower clad layer 12.

As shown in FIG. 3, in the present invention, the convex microstructures 14 and 14 ′, which are implemented in the optical device 10 for optical coupling, have edge portions of the lower clad layer 12 (that is, the outer edge of the optical waveguide). By disposing at the portion), the alignment problem during optical coupling can be solved regardless of the change in the height difference h 'between the bottom of the optical waveguide 13 and the upper portion of the silicon substrate 11 by the hot embossing molding process. The optical waveguide 13 must be maintained at a constant depth d for alignment during optical coupling between the optical element 10 and the optical coupling platform 20. For this purpose, the height difference h 'between the bottom of the optical waveguide 13 and the top of the silicon substrate 11 must be maintained at a predetermined size. The prior art optical coupling structure has a structure in which alignment is determined upon optical coupling by the height difference h 'between the bottom of the optical waveguide 13 and the upper portion of the silicon substrate 11. However, the present invention has a structure in which light alignment is determined upon optical coupling by controlling the height H of the convex microstructures 14 and 14 '. Therefore, the alignment is determined at the time of optical coupling regardless of the height difference h 'between the bottom of the optical waveguide 13 and the top of the silicon substrate 11.

Hereinafter, the principle of passive optical coupling and automatic electrode connection in a passive optical coupling structure according to a preferred embodiment of the present invention will be described with reference to the drawings shown in FIGS. 4A and 4B.

As shown in FIGS. 4A and 4B, a pattern for pyramidal anisotropic convex and recessed microstructures having the same angle using an etching angle (54.74 °) implemented by a silicon wet etching method (not shown) ). Then, a metal casting mold (hereinafter, referred to as a 'mold') is manufactured through a plating process using the pattern for the microstructure, and the convex and recessed microstructures 14 and 24 are formed by a hot embossing molding process using the mold. ). In addition, the convex and recessed microstructures 14 and 24 may be formed by a hot embossing molding process using a silicon casting mold manufactured by a dry etching or a wet etching method instead of the casting mold made of the mold.

The optical waveguide 13 is a height difference h '(see FIG. 3) between the bottom of the optical waveguide 13 and the upper portion of the silicon substrate 11 in the lower clad layer 12, or the height between the two microstructures 14 and 24. Alignment is performed by the (or depth) difference H to complete vertical optical coupling with the optical fiber 30 inserted in the optical coupling platform 20. In addition, the right and left alignment between the optical fiber core 32 and the optical waveguide 13 is precisely performed by the geometrical connection of the rectangular cross sections of the convex and recessed microstructures 14 and 24.

Left and right alignment between the optical waveguide 13 and the optical fiber 30 is determined by the precision of the mold and the precision of the hot embossing molding process. Specifically, the precision of the mold considering the horizontal precision of ± 0.15㎛ of the general photo-mask lithography used for pattern formation for silicon wet etching and the molding precision of ± 0.1㎛ of the hot embossing molding process, the tolerance is ± 0.25 μm. In this case, a tolerance of ± 0.5 μm is provided for easy coupling between the microstructures 14 and 24, and the maximum possible tolerance is ± 0.9 μm. In addition, the vertical alignment error is determined by the height error of the microstructures 14 and 24 implemented by the hot embossing molding process, which is closely related to the precision of the mold. The depth precision by the silicon wet etching method used before manufacturing the mold can be adjusted up to ± 0.1㎛ level. This satisfies the error range ± 1.4 μm to satisfy the optical coupling efficiency of 0.5 dB of a typical single mode optical device.

Hereinafter, a manufacturing process of the optical device 10 as an example of the passive optical coupling structure according to the preferred embodiment of the present invention shown in FIG. 1 will be described with reference to FIGS. 5A to 5I.

Referring to FIG. 5A, the lower clad layer 12 is coated on the silicon substrate 11 using a polymer capable of a hot embossing molding process. Then, the mold 40 prepared in advance as shown in FIG. 5B is prepared. Here, a silicon casting mold may be prepared instead of the mold 40. The mold 40 can be produced using LIGA (lithographic (etching), Galvanoformung (plating), Abformung (molding)) method. For example, as described above, after forming a pattern for a microstructure by using a wet etching method, it is produced through a plating process using the pattern for the microstructure. In the mold 40, a pattern 14 ′ for an optical waveguide and a pattern 13 ′ for an optical waveguide are formed.

Referring to FIG. 5B, the substrate 11 to which the lower clad layer 12 is applied is placed at a lower end of a hot embossing molding apparatus (not shown), and the mold 40 having a multi-stage structure is placed at the upper end of the hot embossing molding apparatus. Place in and apply heat. At this time, the heat to be applied is preferably heated above the glass transition temperature of the lower clad layer 12. Then, as shown in FIG. 5C, the mold 40 is pressed against the lower clad layer 12 at an appropriate pressure while maintaining the temperature of the heat applied in FIG. 5B. Then, as shown in FIG. 5D, after the temperature of the compressed substrate 11 and the mold 40 is cooled to below the glass transition temperature of the lower clad layer 12, the mold 40 is lowered to the lower clad layer ( 12). As a result, as shown in FIG. 5E, the lower clad layer 12 is formed with the iron-shaped fine structure 14 and the optical waveguide 13 at the same time. The forming process of the lower clad layer 12 in FIGS. 5B to 5E is closely related to the glass transition temperature of the polymer material, and the process temperature is changed according to the characteristics of each material.

Referring to FIG. 5F, a core 17 is manufactured by applying a polymer material into the optical waveguide 13. In this case, the polymer material for the core uses a material that is cured by ultraviolet (UV) or cured by heat. Then, the slab shape, i.e., the polymer material for the core overflows to the edge of the recess-type optical waveguide 13, does not form a true shape of the core 17, and the lower portion other than the optical waveguide 13 In order to remove the core polymer material applied to the upper surface of the cladding layer 12, the core curing mask is pressed using a core curing mask so that a portion corresponding to the optical waveguide 13 is opened. In this case, the core curing mask uses a material to which the polymer material for core is not attached or chemically treats the surface so that the polymer material is not attached. Then, ultraviolet (UV) or heat treatment process is performed to cure the core 17 and a cleaning process is performed to remove unnecessary polymer materials except for the polymer material serving as the core 17. Then, as shown in FIG. 5G, an upper clad layer (not shown) is fabricated on the entire structure by spin coating using a polymer material. Then, the upper clad layer corresponding to the portion where the core 17 is formed except for the portion where the iron-shaped microstructure 14 is formed through ultraviolet rays or thermal processes is cured. At this time, the core 17 is also cured. Then, the upper cladding layer which is not cured through the cleaning process is removed, and the upper cladding layer remains only at the portion where the core 17 is formed.

Referring to FIG. 5H, a pre-fabricated electrode formation mask 50 is prepared. The mask 50 is formed with an electrode and a pattern 52 for hot wire. Then, the mask 50 is placed on the upper clad layer, and a deposition process using the mask 50 is performed to heat the heat ray 16 and the electrode 16 'used for the optical attenuator as shown in FIG. 5I. This is formed at the same time. Then, the surface of the end of the optical waveguide 13 is subjected to precise surface treatment, the final polymer planar optical device 10 is completed.

6 is a view showing the optical coupling platform 20 in the optical coupling structure according to a preferred embodiment of the present invention. The optical coupling platform 20 of the present invention is formed through a hot embossing molding process similarly to the manufacturing process of the optical device 10 described with reference to FIGS. 5A through 5E. That is, the wet etching method is used to form a recessed microstructure pattern (not shown) and an optical fiber guide groove pattern (not shown), and a mold is formed through a plating process using the recessed microstructure pattern. . The optical fiber guide groove 22 and the recessed microstructure 24 are simultaneously formed through a hot embossing molding process using the mold.

Hereinafter, various examples of the passive optical coupling structure according to the preferred embodiment of the present invention will be described with reference to FIGS. 7A and 7B.

FIG. 7A is a view illustrating another example of the polymer optical coupling platform 20 when the optical device 10 includes the optical fiber array frame 60 such as a ribbon optical fiber in the optical coupling structure of the present invention. As shown in FIG. 7A, the optical fiber guide portion of the polymer optical coupling platform 20 is formed with an optical fiber guide groove 22 and an optical fiber array guide rail 23. As a result, the optical fiber array guide pin 62 formed on the optical fiber array frame 60 and the optical fiber array guide rail 23 formed on the polymer optical coupling platform 20 are combined to simplify the time-consuming packaging process required for individual optical coupling. You can. At this time, the optical structure of the optical waveguide 13 and the optical waveguide 13 in the optical device 10 may be precisely coupled by the geometric structure of the optical fiber array frame 60 and the optical fiber array guide pin 62 and the optical fiber array guide rail 23. It can be designed to be configured, the optical coupling principle at this time has been described above.

FIG. 7B replaces the optical fiber guide portion on the polymer optical coupling platform 20 shown in FIG. 1 with a photodiode or a light emitting element (VCSEL, LD; Laser Diode), thereby passive light on the same principle as the optical waveguide element. The figure shows to illustrate an example in which the coupling and automatic electrical connection are configured. Similar to the polymer planar optical device 10, the convex-shaped optical coupling microstructure 14 '' is fabricated by using a hot embossing molding process, and then the top, side, and elements of the convex microstructure 14 '' are fabricated. The electric wiring 18 for operating the passive element (or light emitting element) 19 on the plane is implemented by the sputtering method. Then, the light receiving element 19 is adhered to the electrical wiring 18 to complete the light receiving module (or light emitting module). Passive optical coupling and electrical connection between the optical waveguide 13 and the light receiving element 19 is achieved by inserting the completed module into the recessed optical coupling microstructure 24 ′ shown in FIG. 1. At this time, the substrate of the light receiving module uses a heat-resistant polymer material or silicon which is advantageous for thermal bonding of the light receiving element, for example, solder ball bonding.

Although the technical spirit of the present invention described above has been described in detail in the preferred embodiments, it should be noted that the above-described embodiments are for the purpose of description and not of limitation. In addition, the present invention will be understood by those of ordinary skill in the art that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, the present invention can achieve a high efficiency low-cost vertical / horizontal passive optical coupling by providing an optical coupling structure and a method of manufacturing the same, which simultaneously realize the passive optical coupling structure and the automatic electrical connection.

In addition, the present invention enables the low-cost packaging of the optical device by automatically performing the electrical wiring connection according to the high integration of the optical waveguide.

In addition, the present invention can simplify the optical device manufacturing process by reducing the optical waveguide and the optical coupling structure in a single process using a hot embossing molding process, it is possible to reduce the cost of manufacturing the optical device.

1 is a perspective view of an optical element and optical coupling platform having passive optical coupling and automatic electrode connection shown for explaining the passive optical coupling structure according to the first embodiment of the present invention.

FIG. 2 is a perspective view of an optical element and optical coupling platform having passive optical coupling and automatic electrode connection shown for explaining the passive optical coupling structure according to the second embodiment of the present invention.

3 is a side view of a lower clad layer of a planar optical device formed by an embossing molding process.

4A and 4B are cross-sectional views of optical devices and optical coupling platforms shown to illustrate the principles of passive optical coupling and automatic electrode connection applied in preferred embodiments of the present invention.

5A to 5I are perspective views illustrating a method of manufacturing the optical device shown in FIG. 1 step by step.

FIG. 6 is a perspective view illustrating a method of manufacturing the light coupling platform shown in FIG. 1.

FIG. 7A is a perspective view of an optical element, an optical fiber array frame, and an optical coupling platform having passive optical coupling and automatic electrode connection shown for explaining the passive optical coupling structure according to the third embodiment of the present invention.

FIG. 7B is a perspective view of an optical element and optical coupling platform having passive optical coupling and automatic electrode connection shown for explaining the passive optical coupling structure according to the fourth embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

10, 10 ': optical element 11: substrate

12: lower clad layer 13: optical waveguide

14, 14 ', 14' ': Microstructure for iron coupling optical coupling

       16: heating wire 16 ': electrode

       17 core 18 electric wiring

       19: light receiving / light emitting device 20: optical coupling platform

       22: optical fiber guide groove 23: optical fiber array guide rail

       24, 24 ': microstructure for recessed optical coupling

       26 electrode 30 optical fiber

       40: mold 50: electrode mask

       52 electrode pattern 60 fiber array frame

       62: fiber array guide pin

Claims (18)

An optical coupling platform including an optical fiber guide groove formed to seat an optical fiber, a plurality of recessed microstructures formed for optical coupling, and a first electrode disposed along an inner surface of the recessed microstructure; And An optical waveguide aligned with the optical fiber during optical coupling, a plurality of convex microstructures that are inserted into the concave microstructure in a portion corresponding to the concave microstructure, and an upper surface of the convex microstructure, respectively Including an optical element consisting of a second electrode disposed along, And the iron-shaped microstructure is inserted into the recessed microstructure during the optical coupling so that the first electrode and the second electrode are electrically connected. The method of claim 1, Passive optical coupling structure further comprises an optical fiber array frame for aligning the optical fiber in the optical fiber guide groove when the optical coupling. The method of claim 2, The Guam fiber array frame is a passive optical coupling structure characterized in that it has an optical fiber array guide pin to be coupled to the optical coupling platform when the optical coupling. The method of claim 3, wherein And said optical coupling platform has an optical fiber array guide rail to which said optical fiber array guide pin is detached during said optical coupling. The method of claim 1, The iron / recessed microstructure is a passive optical coupling structure, characterized in that formed in a pyramid structure. The method of claim 1, The iron-type microstructures are passive optical coupling structure, characterized in that each one formed in the corner portion of the optical device. The method of claim 1, The iron-type microstructure is a passive optical coupling structure, characterized in that each one formed in the form of a long length on each side edge of the optical device. The method of claim 1, And the second electrode is electrically connected to each other with the heat wires formed in the number of the optical waveguides on the optical waveguide in the longitudinal direction of the optical waveguide. The method of claim 1, The iron-type microstructure is passive optical coupling structure, characterized in that formed on the outer portion of the optical waveguide. The method of claim 1, Passive optical coupling structure, characterized in that the height of the concave-type microstructure is the same as the depth of the recessed microstructure for precise optical coupling. The method of claim 1, Passive optical coupling structure, characterized in that the first electrode extends to the upper surface of the optical device. The method of claim 1, And said second electrode extends to an upper surface of said optical coupling platform. The method of claim 1, And said first electrode extends to correspond to said second electrode. The method of claim 1, The optical device is passive optical coupling structure characterized in that it further comprises a light receiving or light emitting device bonded on the first electrode. Applying a heat on a first polymer sample to glass transition the first polymer sample, and compressing a first cast mold to the first polymer sample to form recessed microstructures and optical fiber guide grooves. Forming a sample and forming a first electrode along an inner surface of the recessed microstructure; Performing glass transition on the second polymer sample by applying heat on a second polymer sample, and pressing the second cast mold onto the second polymer sample to form an iron-shaped microstructure and an optical waveguide. Forming a core, forming a core to fill the inside of the optical waveguide, forming a cladding layer to cover the core, and forming a second electrode along an inner surface of the convex microstructure. Optical device manufacturing step comprising a; And  And coupling the optical device with the optical coupling platform such that the convex microstructure is inserted into the recessed microstructure to electrically connect the first electrode and the second electrode. Method of making the structure. The method of claim 15, The molding of the first and second polymer samples is a method of manufacturing a passive optical coupling structure, characterized in that using a hot embossing molding equipment. The method of claim 16, wherein forming the core, Coating a polymer material for a core inside the optical waveguide; Pressing the core curing mask with an open portion corresponding to the optical waveguide to remove the core polymer material applied to the upper surface of the polymer sample other than the optical waveguide; Curing the core polymer material by subjecting the core polymer material to UV or heat treatment; And A method of fabricating a passive optical coupling structure comprising performing a cleaning process on an upper portion of an entire structure to remove an uncured unnecessary core polymer material. The method of claim 17, The core curing mask is a material to which the core polymer material is not attached, or a surface is chemically treated so that the core polymer material is not attached.