KR20020020085A - Collimation interface of optical beam from a fiber using an integrated micro lens - Google Patents

Abstract

PURPOSE: A parallel beam interface device and manufacturing method thereof are provided to simplify the parallel beam interface device by integrally uniting an optical fiber bundle substrate and a micro lens substrate to embody a parallel beam. CONSTITUTION: An optical fiber(202) is inserted and fixed into and to an optical fiber bundle substrate(201). An optical fiber inserting groove(202a) is formed at the optical fiber bundle substrate(201) in order to insert the optical fiber(202) into the optical fiber bundle substrate(201). A ball lens inserting groove(204) is formed at a lens substrate(203). A spherical ball lens(203) is inserted into the ball lens inserting groove(204). A circular waveguide(206) is formed at a substrate surface. A spacer(207) is formed between the optical fiber bundle substrate(201) and a lens substrate(205). When the optical fiber bundle substrate(201) is united with the lens substrate(205), an optical fiber longitudinal section(202a) is located far from the lens substrate(205) by a predetermined distance.

Description

Parallel beam interface structure using integrated micro lens and its manufacturing method {COLLIMATION INTERFACE OF OPTICAL BEAM FROM A FIBER USING AN INTEGRATED MICRO LENS}

The present invention relates to a method of manufacturing a parallel beam interface for parallelizing a laser beam using an integrated micro lens, and a structure of the parallel beam interface.

In particular, the present invention implements a parallel beam interface structure and parallel beam for parallelizing a laser beam (light) emitted (or incident) from an optical fiber bundle when switching multiple optical signals in a wavelength division multiplexing optical communication system. It relates to a manufacturing method of the interface structure for.

More specifically, the present invention provides a technique for fabricating a lens substrate by integrating a microlens into a silicon substrate, and parallelizing a laser beam using an interface structure in which the lens substrate is bonded to an optical fiber substrate to which an optical fiber bundle is inserted. do.

At present, the amount of communication information is exploding due to the spread of internet and electronic commerce. Dense Wavelength Division Multiplexing (DWMD) optical communication system has been studied as one of the ways to efficiently and economically transmit a huge amount of information. In wavelength division multiplexing systems, it is necessary to switch several optical signals.

Conventional technology for optical signal exchange includes optical / electric / transmitting an optical signal once to an electrical signal, electrically switching the converted electrical signal, and then reconverting the switched electrical signal back to an optical signal. There is a light conversion method.

However, since the optical / electric / optical conversion has to convert the optical signal into an electrical signal and converts the electrical signal back into the optical signal, the components related to photoelectric conversion and all-optical conversion act as burdens, and also the signal conversion process Are exposed to problems such as energy loss, signal distortion, error generation and noise interference.

Another conventional technique for optical signal exchange uses a cross connect switch capable of all-optcal switching without optical / electric / optical conversion.

Fig. 1 conceptually illustrates the structure of a cross connect switch using a micro-optic-electro-mechanical system (MOEMS).

In this switch structure, a plurality of optical fibers 102 are fixed to the optical fiber bundle substrate 101 in the form of longitudinal cross-section bonding, and the lens substrate 103 is spaced apart from the optical fiber bundle substrate 101 at a predetermined distance and arranged side by side. Ball lenses 104 for parallelizing the laser beam are provided in an array form, and a plurality of driving mirrors integrated in the driving mirror substrate 105 spaced apart from the lens substrate 103 at a predetermined distance and arranged side by side An actuating micro-mirror 106 is provided, and a reflecting mirror 107 is provided between the lens substrate 103 and the driving mirror substrate 105 to form a transmission path of the laser beam. . The substrates are silicon substrates, and lenses or driving mirrors are integrated on the silicon substrates.

Light switching by the cross connect switch of FIG. 1 is performed as follows.

The input signal IN transmitted through the optical fiber 102 is emitted from the end of the optical fiber and passes through the ball lens 104 to form a parallel beam. The parallelized laser beam is reflected from the driving mirror 106 to reflect the reflection mirror ( The transmission path is changed by the 107, reflected by the driving mirror 106, and transmitted to the optical fiber 102 through the ball lens 104 to be transmitted as the output signal OUT.

At this time, the optical signal can be switched by appropriately adjusting the angle of each mirror.

However, in this switching system, since the laser beams must travel a distance of several tens of centimeters or more, a parallel beam is required in which the size of the beam hardly changes according to the traveling distance, and the ball lens 104 is used to implement such a parallel beam. .

That is, in general, the light output from the optical fiber is spread out in space by a Gaussian distribution when it is not a parallel beam, and when it is coupled to the optical fiber, the optical loss increases rapidly. The micro lenses such as ball lenses are installed at appropriate intervals.

However, in such a cross-connect switch structure, not only is the lens alignment difficult and complicated to align the end of the optical fiber bundle and the ball lens array, but the performance and reliability of the entire system depend on the exact alignment of the micro lens array and the optical fiber end. In addition, since it is difficult to accurately align the lens and the optical fiber, there is a problem in that the optical transmission path switching performance of the system is inferior.

The present invention implements a parallel beam by integrally bonding the optical fiber bundle substrate and the micro lens substrate, thereby simplifying the interface structure for implementing the parallel beam, as well as easy and accurate lens alignment to achieve a highly reliable parallel beam. We propose a parallel beam interface structure and a method of manufacturing the same.

The present invention integrally bonds a silicon substrate (bundle substrate) into which an optical fiber bundle is inserted and a silicon substrate (lens substrate) to which a microlens is inserted and fixed, and in this case, a distance between the lens and the optical fiber end surface by interposing a spacer between the two substrates. We propose a parallel beam interface structure and a method of manufacturing the same, which can maintain the precision.

1 conceptually illustrates the structure of an optical cross connect switch;

2 is a view showing a structure in which an optical fiber bundle and a spherical ball lens are bonded as a first embodiment of the present invention;

3 is a view showing another example of a structure in which an optical fiber bundle and a spherical ball lens are bonded as a second embodiment of the present invention;

4 is a view showing a structure in which an optical fiber bundle and a hemispherical ball lens are bonded as a third embodiment of the present invention.

5 is a view showing another example of a structure in which an optical fiber bundle and a hemispherical ball lens are bonded as a fourth embodiment of the present invention;

Figure 6 is a process chart showing a spherical ball lens groove manufacturing process in the present invention

7 is a process chart showing a process for manufacturing a hemispherical ball lens groove in the present invention

The present invention provides a parallel beam interface structure and a method of manufacturing the optical fiber bundle substrate and a lens substrate having a microlens integrated structure.

The present invention provides a parallel beam interface structure and a method of manufacturing the microlens by inserting and fixing a microlens into a silicon substrate and bonding a lens substrate into which a microlens is inserted and bonded to an optical fiber bundle substrate.

In addition, the present invention is a parallel beam interface structure and its manufacturing method characterized in that the lens groove and the lens structure of the lens substrate into which the microlens is inserted into a variety of structures, such as spherical, hemispherical, trapezoidal.

In addition, the present invention by forming an optical waveguide in the silicon substrate the same as the size of the parallel beam, the parallel beam characterized in that the beam parallelized by the microlenses can be stably propagated in a free space and stable Interface structure and its manufacturing method.

In another aspect, the present invention further comprises a spacer for bonding the microlens substrate and the optical fiber bundle substrate, the spacer further allows precise adjustment of the distance between the optical fiber end face and the microlens, and a manufacturing method thereof. to be.

In addition, in the present invention, the lens groove is a parallel beam interface structure and a method of manufacturing the same, which are formed by using dry etching and wet etching.

In addition, in the present invention, the spacer for precisely adjusting the distance between the microlens and the optical fiber is a parallel beam interface structure and a method of manufacturing the same, characterized in that it is made of a material that is photosensitive and mechanically robust, such as SU-8. .

In another aspect, the present invention is the step of inserting and fixing the optical fiber to the bundle substrate to form a fiber bundle, forming a space for the microlens to be inserted into the lens substrate and inserting the microlens in the space, the spacer between the bundle substrate and the lens substrate Forming a step of bonding the optical fiber bundle substrate and the lens substrate through the spacers.

In the present invention, it is characterized in that to form a waveguide of the parallel beam emitted through the micro lens on the surface of the light output substrate.

Also, in the present invention, the lens insertion space is formed by exposing a portion to be etched on the silicon substrate using a mask and performing anisotropic etching to a predetermined depth to form a lens insertion space having an inclined structure. And patterning the other opposite surface of the lens insertion space and penetrating the lens insertion space by dry etching.

In the present invention, the formation of the lens insertion space, patterning the portion to be etched on the silicon substrate and performing isotropic etching to form a hemispherical lens insertion space, through the hemispherical lens insertion space through a dry etching process Characterized in that the step consisting of.

Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings.

2 shows a structure of a parallel beam interface for explaining the first embodiment of the present invention.

The optical fiber 202 is inserted into and fixed to the optical fiber bundle substrate 201. The optical fiber insertion groove 202a is formed to insert the optical fiber 202 into the optical fiber bundle substrate 201. In the method of inserting and fixing the optical fiber bundle into the bundle substrate 201, optical fiber insertion grooves and insertion holes are formed in the silicon substrate using wet etching and dry etching, and the ends of the optical fiber bundle are inserted and fixed thereto.

A ball lens insertion groove 204 was formed in the lens substrate 203, and a spherical ball lens 205 was inserted and fixed thereto. In order to insert and fix the spherical ball lens 205 to the lens substrate 203, the ball lens insertion groove is formed in the silicon substrate into a funnel-shaped inclined structure using dry etching and wet etching processes, The ball lens was inserted and fixed.

The circular waveguide 206 having a diameter 'D' is formed on the surface of the substrate on which the light is output through the microlens (ball lens) so that the tube naturally serves as an optical waveguide. It was.

On the other hand, in order to make the light emitted from the optical fiber 202 into a parallel beam, the end face 202a of the optical fiber and the lens 205 should be separated exactly by a constant distance f.

For this purpose, the optical fiber bundle 201 and the lens substrate 205 are bonded to each other through the spacer 207 between the optical fiber bundle substrate 201 and the lens substrate 205, and the optical fiber end surface 202a and the lens 205 are bonded together. ) Are precisely spaced apart by a constant distance (f).

The spacer 207 is made of a material having photosensitivity and mechanical robustness, such as SU-8, and a film having a suitable thickness on the optical fiber bundle substrate 201 is formed by spin coating. In this case, the thickness of the spacer 207 can be freely and precisely adjusted by adjusting the speed of spin coating.

A parallel beam having a structure in which the optical fiber bundle substrate 201 and the lens substrate 203 are bonded to each other by permanently bonding the optical fiber bundle substrate 201 and the lens substrate 203 through the spacer 207 (using an anodic bonding process). The interface structure is complete.

In the parallel beam interface structure of the first embodiment of the present invention shown in FIG. 2, a part of the spacer corresponding to a portion where light emitted from the optical fiber end surface 202a is incident on the spherical ball lens 205 is removed. In FIG. 2, this portion is indicated by reference numeral 207a.

FIG. 3 is a diagram illustrating a parallel beam interface structure for explaining a second embodiment of the present invention. The same parts as those in FIG. 2 are denoted by the same reference numerals, and description thereof will not be repeated.

In the second embodiment of the present invention of Fig. 3, the spherical ball lens 205 is fixed to the lens insertion groove 204 inclined in a funnel shape, and the end 202a and the lens 205 of the optical fiber 202 are fixed. This is a case where the spacer 207 remains in between, and this portion is indicated by reference numeral 301.

In this manner, even if the spacer 207 remains, the light loss is minimized because the thickness of the spacer 207 is sufficiently small and the light absorption is small. In addition, since the refractive index of air is 1.0 and the refractive index of the optical fiber is about 1.4, the refractive index of SU-8 used as the spacer 207 is about 1.6 to 1.9, so the fresnel reflection loss occurring in the cross section is reduced.

4 is a diagram illustrating a parallel beam interface structure for explaining a third embodiment of the present invention. The same parts as those in FIGS. 2 and 3 are denoted by the same reference numerals and redundant descriptions thereof will be omitted.

In the third embodiment of the present invention of FIG. 4, a vertical tube penetrating the substrate is formed by making a funnel-shaped inclined lens insertion groove 204 by using wet etching directly on the silicon substrate 203 without vertical etching. 206 is formed, and the hemispherical lens 401 is used instead of the spherical ball lens.

FIG. 5 is a diagram illustrating a parallel beam interface structure for explaining a fourth embodiment of the present invention. The same parts as those in FIGS. 2 to 4 are denoted by the same reference numerals, and description thereof will not be repeated.

In the fourth embodiment of the present invention of FIG. 5, the silicon substrate 206 is itself isotropically etched to make a hemispherical lens insertion groove, and a hemispherical lens 401 is inserted therein.

In the fourth embodiment of the present invention, not only the hemispherical lens 401 but also the spherical ball lens may be inserted and the distance from the optical fiber may be adjusted by the spacer.

6 is a process chart showing a spherical ball lens groove manufacturing process in the present invention.

A portion of the silicon substrate 601 to be etched is exposed using the mask 600, and anisotropic etching is performed by a predetermined depth using the Deep RIE device. This makes a preliminary groove 602 for inserting the ball lens groove once (Fig. 6A).

Next, wet etching is performed on the KOH solution to form a funnel-shaped inclined lens insertion groove 603 into which the spherical ball lens is inserted (b of FIG. 6).

Then, the other substrate surface opposite the lens insertion groove 603 is patterned, and a through hole 604 is formed by dry etching using the Deep RIE apparatus (FIG. 6C).

In this way, the funnel-shaped lens insertion groove is completed, and the ball lens is inserted and fixed as described above in the lens insertion groove, and the optical waveguide can be configured in the through hole.

7 is a process chart showing a hemispherical ball lens groove manufacturing process in the present invention.

This method is to process the structure that can insert the hemispherical ball lens.

The surface of the silicon substrate 701 is patterned, and isotropic etching is performed using a solution of the mask 700 and the nitric acid series (HNA) (FIG. 7A). As a result of the isotropic etching process, a hemispherical lens insertion groove 702 is formed.

Next, through holes 703 are formed through the dry etching process to completely pass through the silicon substrate 701 (Fig. 7B).

In this way, the hemispherical lens insertion groove is completed. As described above, the hemispherical ball lens can be inserted into the lens insertion groove, and the optical waveguide described above can be formed in the through hole.

The present invention integrally bonded the optical fiber bundle substrate and the lens substrate in which the micro lens is integrated. Therefore, the interface structure for implementing the bouncing beam has become very simple, and the parallel beam implementation is precise as well as easy because the lens can be aligned with the optical fiber longitudinal section.

In the present invention, the optical fiber bundle substrate and the lens substrate in which the microlenses are integrated are integrally bonded through the spacer. Therefore, it is possible to maintain the correct distance between the optical fiber end face and the lens for parallel beam implementation, thereby enabling stable parallel beam exit (incident).

Claims (12)

And an optical fiber bundle substrate in which an optical fiber bundle is inserted and fixed, and a lens substrate in which a microlens for inserting light input and output from the optical fiber ends into a parallel beam is bonded to the optical fiber bundle substrate. The parallel beam interface structure of claim 1, further comprising a spacer for maintaining a distance between the optical fiber end surface and the lens between the optical fiber bundle substrate and the lens substrate. 3. The lens substrate according to claim 1 or 2, wherein the lens substrate has a lens insertion groove formed in an silicon substrate by an etching process, and a spherical or hemispherical micro lens is inserted into and fixed to the lens insertion groove. Beam interface structure. 4. The parallel beam interface structure of claim 3, wherein a waveguide of a parallel beam is formed through the lens insertion groove and output through the microlens. 4. The parallel beam interface structure of claim 3, wherein the lens insertion groove has a funnel-shaped inclined structure. 4. The parallel beam interface structure of claim 3, wherein the lens insertion groove has a hemispherical groove structure. 3. The parallel beam interface structure of claim 2, wherein the spacer remains free space by removing a portion between the optical fiber end and the lens. 3. The parallel beam interface structure of claim 2, wherein the spacer is filled with a portion between the optical fiber end and the lens. Inserting and fixing the optical fiber to the bundle substrate to form an optical fiber bundle, forming a space in which the microlens is to be inserted into the lens substrate and inserting the microlens into the space, forming a spacer between the bundle substrate and the lens substrate And bonding the optical fiber bundle substrate and the lens substrate through the spacers. 10. The method of claim 9, wherein a waveguide of parallel beams emitted through the microlens is formed on the surface of the light output substrate. The method of claim 9, wherein the formation of the lens insertion space comprises exposing a portion to be etched on the silicon substrate with a mask and performing anisotropic etching to a predetermined depth to form a lens insertion space having an inclined structure. And patterning the other opposite surface of the lens insertion space and penetrating the lens insertion space by dry etching. The method of claim 9, wherein the forming of the lens insertion space comprises: patterning a portion to be etched on the silicon substrate and performing isotropic etching to form a hemispherical lens insertion space, using the dry etching process of the hemispherical lens insertion space. Parallel beam interface manufacturing method comprising the step of passing through.