KR100480284B1 - Method for aligning optical axis with optical module - Google Patents

Abstract

The optical axis alignment method of the optical module according to the present invention comprises the first step of forming a groove on the submount for mounting the lens system at a position spaced apart from the position where the semiconductor laser is seated by a predetermined distance, and the semiconductor laser A second step of fixing the mount on the mount, a third step of fixing the lens system to the groove by applying an epoxy resin to the groove, and covering the lens system with a groove-shaped groove lead (Love) of the bottom open; And a fourth step of fixing the home lead to the upper surface of the submount.

Description

Optical axis alignment of optical module {METHOD FOR ALIGNING OPTICAL AXIS WITH OPTICAL MODULE}

The present invention relates to a packaging method of an optical device, and more particularly, to an optical axis alignment method between a flip chip bonded semiconductor laser and an optical system in an optical module that is an optical communication light source.

In an optical communication system, a general optical module for optical transmission includes a semiconductor laser, a plurality of optical elements, and an optical fiber or ferrol for transmitting a light source output from the semiconductor laser.

The optical communication network using optical fiber is excessively large in the long distance transmission of the optical signal due to the dispersion of the optical signal due to the dispersion of the wavelength used, and the dispersion of the material of the optical fiber material itself.

Among the methods for overcoming the above-mentioned disadvantages, a method of improving the coupling efficiency between an optical fiber and a semiconductor laser by mounting a lens system capable of condensing an optical signal in an optical module used as an optical communication light source, and an optical signal is incident The method of improving the condensing efficiency, etc. are used by cutting | disconnecting the incidence surface of the optical fiber made into a square.

In particular, in the optical axis alignment method of the optical module mounted with a lens system, an aspherical lens system or a GRIN lens system is laser welded or soldered onto a substrate made of KOVAR material coated with Au on its upper surface. And active alignment of the lens using the

The error range of the optical axis alignment described above is limited to within about 1 μm from the optimum optical coupling position irrespective of the transmission speed of the optical module. There are two methods of aligning the optical axis within a limited error range, an active alignment method and a passive alignment method. The active alignment method is a method of aligning an optical axis in a state in which an optical module is operating. The active alignment method has a high accuracy, but the complexity of the process increases the time and cost.

1 is a side view showing an optical module by a conventional optical axis alignment method, Figure 2 is a perspective view showing an optical module by a conventional optical axis alignment method. 1 and 2, the optical module includes a submount 130, a pedestal 112 for adjusting the height and the Y axis of the semiconductor laser 111 on the submount 130, and the pedestal ( A semiconductor laser 111 is provided on the upper surface of the 112, and the lens system 120 spaced apart from the semiconductor laser 111 by a predetermined interval.

The lens system 120 includes a lens 122 for converging an optical signal and a metal housing 121 for mounting the lens 122.

A conventional optical axis alignment method of an optical module includes a first process of fixing the semiconductor laser 111 on a submount 130, and a lens system including a metal housing 121 and a lens 122. A second process of aligning the optical axis on the 130 and a third process of fixing the lens system 122 on the submount 130 by laser welding.

The first process is a gold coating on the submount (130) made of KOVAR, Cu-W material, and then the semiconductor laser 111 is placed on the submount (130) The semiconductor laser 111 is bonded to an upper surface of the pedestal 112 made of a dielectric material by a flip chip bond method.

The direction of travel of the light output from the semiconductor laser 111 is defined as a z-axis, and then the reference of the optical axis alignment between the optical elements constituting the optical module. A height direction of the semiconductor laser 111 perpendicular to the z axis is defined as a y axis, and a width direction of the semiconductor laser 111 is defined as an x axis.

The second process is a process for optically aligning the lens system 120 on the submount 130 based on the semiconductor laser 111 constituting the optical module.

The lens system 120 includes a lens 122 for converging light output from the semiconductor laser 111 to an input surface of an optical fiber, and a metal housing 121 for mounting the lens 122. The lens 122 may be a plano-convex-type green (GRIN) or aspherical lens used as a light focusing lens.

The optical axis alignment of the lens system 120 is based on an active alignment method in which the semiconductor laser 111 continuously irradiates light and aligns the optical axis, while changing the distance between the lens system 120 and the semiconductor laser 111, x The lens system 120 is aligned in the axial and y-axis directions.

However, in the active alignment method, the optical axis alignment is precise, but it takes a long time to align the optical axis, which acts as a factor of the increase in unit cost.

The third process is a process for fixing the lens system 120, which is optically aligned, on the submount 130 in an optimal state.

The third process is a process of melting bonding by irradiating a laser welder 123 of a metal material inserted between the submount 130 and the lens system 122 with a laser beam such as a welding yag (YAG). . That is, the laser welder 123 is a medium of laser welding for coupling the submount 130 and the lens system 120, and is melted by a laser beam such as the above-described welding yag. 120 is bonded to an upper surface of the submount 130.

However, in the optical axis alignment method of the conventional optical module, there is a risk that the optical axis of the lens system 122 is distorted in the third process for fusion bonding the laser welder 123 after the optical axis alignment, and the housing is not housed using a metal case. In the case of a non-lens system, optical axis alignment and fixation are impossible. In addition, the active alignment method for aligning the optical axis in the state in which the optical module is operated when the optical axis is aligned, while the accuracy of the optical axis alignment is improved, there is a problem that productivity is lowered due to a process time delay.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical axis alignment method of an optical module that is easy to align and fix the optical axis.

In order to achieve the above objects, the optical axis alignment method of the optical module according to the present invention, the first forming a groove on the submount for mounting the lens system at a position separated by a predetermined distance from the position where the semiconductor laser is seated And a second step of fixing the semiconductor laser on the submount; and a third step of fixing the lens system to the groove by applying an epoxy resin to the groove;

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And a fourth process of covering the lens system with a groove-shaped groove lead (Groove-Lid) having a lower opening, and fixing the groove lead to an upper surface of the submount.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention; In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the subject matter of the present invention.

3A to 3E are plan views of optical modules illustrating an optical axis alignment process according to the present invention. 4A is a side view of the optical module shown in FIG. 3D, and FIG. 4B is a side view of the optical module shown in FIG. 3E. In particular, Figures 3e and 4b shows the optical module in the optical axis aligned state. Referring to this, the optical module according to the present invention includes a groove 320 formed to seat the lens system 330 on the submount 300 made of silica, a semiconductor laser 310 fixed at a predetermined position, and The intensity of the laser system 310, the lens system 330 seated in the groove 320, a box-shaped groove lead (Groove-Lid) 350 having an open lower portion covering the upper surface of the lens system 330, and the laser 310 are monitored. It includes a photodiode 360 for. The submount 300 uses a material such as SiOB.

Hereinafter, descriptions will be made of FIGS. 3A to 3E and 4A to 4B to describe the manufacturing process of the optical module according to the present invention. 6 is a flowchart illustrating a manufacturing process of an optical module according to the present invention. Referring to FIG. 6, in the optical axis alignment method of the optical module according to the present invention, a first process 510 of forming a groove (V-groove) on the submount and a sub-chip of the semiconductor laser are performed by flip chip bonding. A second process 520 for bonding to the mount and a third process 530 for mounting the lens system in the groove.

The submount 300 perpendicular to the z axis and the depth of the groove 320, which is the height direction of the semiconductor laser 310, is perpendicular to the y axis and the z and y axes. ) Is defined as the x-axis, and the reference is then used to align and mount the lens system 330.

Referring to FIG. 3A, the first process 510 may include a groove 320 for seating the lens system 330 at a position spaced apart by a predetermined distance from a position at which the semiconductor laser 310 is to be seated. 300) on the process.

The first process includes forming a first alignment groove 321 along a width and a depth direction of the submount 300, a position at which the semiconductor laser 310 is to be seated, and a lens system 330 to be seated. And forming a second alignment groove 322 for adjusting the distance between the positions.

The first alignment groove 321 may be formed by etching or the like, and the first alignment groove 321 may be formed by the light output from the semiconductor laser 310 to the center of the lens system 330. Adjust the width and depth to allow passage.

The second alignment groove 322 may be formed by a method such as dicing or etching, and may be formed to be spaced apart from the position where the semiconductor laser 310 is to be seated by a predetermined distance. That is, the second alignment groove 322 is formed at a position spaced apart by the focal length of the lens system 330 from the position where the semiconductor laser 310 is to be seated.

That is, the groove 320 is formed at a predetermined position on the submount 300 based on the position at which the semiconductor laser 310 is to be seated, so that the light can be incident on the center of the lens system 330. The width and height of the groove 320 are adjusted by etching and dicing. The groove 320 may be formed by dicing or etching, and may be formed into various shapes such as a V-groove.

Referring to FIG. 3B, the second process 520 may be performed by a flip chip bonding method in which the semiconductor laser 310 is spaced apart from the position where the groove 320 is formed on the submount 300 by a predetermined distance. It is a process of fixing.

The mounting position of the semiconductor laser 310 is set at a position that can be spaced apart from the lens system 330 by the focal length of the lens system 330. In addition, the semiconductor laser 310 is positioned so that its light emitting surface can span the end of the first alignment groove, so that the light output from the semiconductor laser 310 is reflected or scattered by the first alignment groove. To prevent them.

In the above-described flip chip bonding method, a pad (not shown) having the same size and shape as that of the semiconductor laser 310 is positioned at a position where the semiconductor laser 310 is to be mounted on the upper surface of the submount 300. After attaching to the substrate 300, the semiconductor laser 310 is placed on an upper surface of the pad (not shown) to melt-bond at a high temperature. The pads generate surface tension upon hot melting, which greatly reduces horizontal alignment errors without additional adjustment. In addition, the photodiode 360 is positioned to face the lens system 330 based on the semiconductor laser 310, thereby monitoring the intensity change of the semiconductor laser 310.

3C and 3D, in the third process 530, an epoxy resin is applied to a portion of the groove 320 on which the lens system 330 is to be seated, thereby allowing the lens system 330 to pass through the groove 320. The lens system 330 is seated in the groove 320 so that the light output from the semiconductor laser 310 passes through the center of the lens system 330. In the third process 530, the lens system 330 is seated in the groove 320, and then the optical axis is finely adjusted so that the light output from the semiconductor laser 310 minimizes the optical axis of the lens system 330. Adjust to pass within the margin of error. In this case, a thermosetting epoxy resin or the like is used as the epoxy resin 340, and is applied to a seating part and a boundary part of the lens system 330 and the groove 320.

That is, after the lens system 330 is seated in the first alignment groove 321, the lens system 330 may be disposed so that the light output from the semiconductor laser 310 may pass through the center of the lens system 330. Align and fix finely.

5 is a front view illustrating a front surface of the optical module covered with the home lead 350, and FIG. 7 illustrates an optical axis alignment process of the optical module as a first embodiment of the present invention. Referring to FIGS. 7 and 5, the optical axis alignment method of the optical module includes a first process 610, a second process 620, and a third process 630. And a fourth process 640 for fixing Groove-Lid to the upper surface of the submount, and a fifth process 650 for curing the adhesive.

Referring to FIG. 3A, the first process 610 is a process of forming a groove (V-groove) 320 for mounting the lens system 330 on the submount 300. Referring to FIG. 3B, the second process 620 is a process of bonding the semiconductor laser 310 to the submount 300 by a flip chip bonding method. Referring to FIG. 3C, in a third process 630, an epoxy resin 340 is applied to a portion of the groove 320 where the lens system 330 is to be seated, thereby seating the lens system 330 in the groove 320. It is the process of making. The submount 300 uses a material such as SiOB. The photodiode 360 is positioned to face the lens system 330 with respect to the semiconductor laser 310, thereby monitoring a change in intensity of the semiconductor laser 310.

Referring to FIGS. 3D and 4A, the fourth process 640 covers the lens system 330 with a groove-shaped groove lead (Groove-Lid) 350 having an open bottom, and covers the groove lead 350 with the groove lead 350. The process is fixed on the submount (300). The groove lead (Groove-Lid) 350 is a box shape in which a lower end is opened to allow the upper surface of the lens system 330 to be inserted thereinto, and has the same width as that of the submount 300. Thus, the state of the optical axis aligned lens system 330 is prevented from being disturbed, and the lens system 330 can be stably fixed to the groove 320.

Referring to FIGS. 3E and 4B, the fifth process 650 may be performed by heating the optical module to a predetermined temperature, and the epoxy resin 340 applied to the bottom surface of the groove 320 and the top surface of the lens system 330. It is a process of curing. As the epoxy resin 340, a thermosetting epoxy resin or the like is used. In order to cure the epoxy resin 340, the epoxy resin 340 is heated by heating the submount 300 to a predetermined temperature in a heating plate (not shown) or a thermal chamber (not shown). Harden.

 8 is a graph showing the results of thermal shock test of the optical module using the home-lead manufactured by the present invention. The horizontal axis of the graph represents the number of repetitions of applying the optical module to the temperature change from minus 45 ° C to the image 85 ° C. The vertical axis represents the amount of optical signal loss of the optical module measured at that time.

 Referring to Figure 8, the thermal shock test of the optical module was repeated for a predetermined time interval of temperature between -45 ~ +85 ℃, the number of repetitions of 100 times, 200 times, 300 times, 400 times, 500 times The amount of light loss of the optical module was measured.

The pass criterion for the thermal shock test of the optical module should be between -0.5 and 0.5 광 when 500 thermal shock tests are performed on 11 samples. Referring to the graph, it can be seen that all 11 samples are between -0.5 and 0.5 Hz even after 500 runs.

As described above, the optical axis alignment and adjustment is made by using a manual optical axis alignment method in which a groove is formed on the submount to mount the lens system at a predetermined position, the optical axis is aligned with the groove, and then epoxy is applied by bonding. This is easy and has the advantage of reducing cost and process delay time. In addition, it can be seen that by using the home lead, the optical axis alignment of the optical module is more stable, and the reliability of the product according to the environmental change is improved.

As described above, the optical axis alignment method of the optical module according to the present invention is easy to align the optical axis of the lens system, there is an advantage that the productivity is reduced due to cost reduction and assembly time. Furthermore, it can be seen that by using the home lead, the optical axis alignment of the optical module is more stably performed, and the reliability of the product according to the environmental change is improved.

1 is a side view showing a side of an optical module by a conventional optical axis alignment method,

2 is a perspective view showing an optical module by a conventional optical axis alignment method;

3A to 3E are plan views of an optical module illustrating an optical axis alignment process according to the present invention;

Figure 4a is a side view showing the side of the optical module is coated with the adhesive shown in Figure 3d,

4B is a side view illustrating a side surface of the optical module covered with the groove lead shown in FIG. 3E;

5 is a front view showing the front of the optical module is covered with the groove lead shown in Figure 4b,

6 is a flow chart showing a manufacturing process of the optical module according to the present invention;

7 is a flowchart illustrating a fourth process of seating a groove-lead and a fifth process of hardening as a first embodiment of the present invention;

8 is a graph for explaining a thermal shock test of the optical module according to the present invention.

Claims (7)

delete delete delete delete In the optical axis alignment method of the optical module, Forming a groove on the submount for mounting the lens system at a position separated by a predetermined distance from the position at which the semiconductor laser is seated; A second step of fixing the semiconductor laser on the submount; A third step of fixing the lens system to the groove by applying an epoxy resin to the groove; And a fourth step of covering the lens system with a groove-shaped groove lead (Groove-Lid) having a lower opening, and fixing the groove lead to an upper surface of the submount. The method of claim 5, The epoxy resin may further include a fifth step of curing the epoxy resin by using a thermosetting epoxy resin and placing the sub-mount on a thermal plate and heating the substrate to a predetermined temperature. How to align the optical axis of the module. The method of claim 5, The epoxy resin further comprises a fifth step of curing the adhesive by using a thermosetting epoxy resin and placing the sub-mount in a thermal chamber and heating to a predetermined temperature. Optical axis alignment method.