JPH05333246A - Optical coupler - Google Patents

Abstract

PURPOSE:To easily and surely perform the optical coupling of a semiconductor laser element and a spherical lens and to obtain stable parallel rays of light from the spherical lens. CONSTITUTION:As to plural spherical lenses 5, a pit is formed on a metallic plate 6 by a photo-etching method, and plural spherical lenses 5 are fixed on the metallic plate 6 with glass having a low fusion point. Next, by positioning and fixing the metallic plate 6 provided with the spherical lens near the light emitting part of the semiconductor laser element 2, the stable parallel rays of light from the spherical lenses are obtained. By fixing the spherical lens 5 on the metallic plate 6, the rays of light which are stabilized for a long term can be obtained without causing a lens breakdown due to a thermal stress even in the case that the temperature changes. And also, by positioning and fixing the tip part of a fiber by use of a ferrule guide 9, the light can be efficiently taken out from the fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical coupling device for coupling a semiconductor laser device and an optical fiber via a spherical lens, and an assembling method thereof.

[0002]

2. Description of the Related Art In an optical communication system using an optical fiber as a transmission line, an optical coupling device for taking in light oscillated from a semiconductor laser into the optical fiber as efficiently as possible is required. For this reason, a method of optically coupling with a spherical fiber having a lens effect by giving a curvature to the tip of the optical fiber, or a method of coupling with an optical fiber through a lens is used. In the method using the front spherical fiber, the relative allowable positional deviation amount between the semiconductor laser and the front spherical fiber is only about ± 2 μm, whereas in the method using the lens, the relative allowable positional deviation amount can be made large. , Easy to assemble.

As disclosed in Japanese Examined Patent Publication No. 3-63044 (FIG. 8), this type of prior art has a lens holding member in the form of a cylindrical cap after the semiconductor laser is fixed to the center of the package stem. Attach a hole in the center of the lens holding member, fix a ball lens in this hole, adjust the ball lens so that it matches the optical axis from the semiconductor laser element, and place a cylinder on the upper surface of the lens holding member. A ferrule support member having a hole is fixed so as to cover the spherical lens, and a ferrule with an optical fiber is inserted into the cylindrical hole so that the end face of the optical fiber faces the spherical lens. After adjusting the optical axes of the light and the spherical lens, the positions of the ferrule and the ferrule supporting member are further adjusted so that the light is focused on the end face of the optical fiber, and then the package stem and the lens holding member. It has a structure to secure the.

[0004]

In the above-mentioned prior art, the spherical lens holding member is configured to be suitable for holding a single lens. When a plurality of laser beams oscillate from a single semiconductor laser device with this configuration, the conventional technique does not have a structure in which the lens interval can be adjusted, and the lens holding member does not have a structure for adjusting the lens interval. Even if it can be fixed, the lens holding member is rotated to align the optical axes of the semiconductor laser element and the spherical lens, and there is a problem that alignment is difficult and time-consuming.

Further, if the semiconductor laser device and the plurality of lenses are misaligned, the plurality of lights that have passed through the lenses are not emitted in parallel and, as a result, the optical coupling with the fiber may vary. There was a nature. Furthermore, when a plurality of laser beams are arranged and emitted, for example, 250
There is a problem that a structure for fixing a plurality of μm diameter spherical lenses to a lens holding member is not considered.

An object of the present invention is to provide an optical coupling device for coupling a semiconductor laser element and an optical fiber through a spherical lens, in the case of optically coupling through a plurality of minute spherical lenses,
Providing an optical coupling device that can obtain stable parallel light by forming pits at regular intervals and adjusting and fixing a spherical lens in this pit. It is an object of the present invention to provide a coupling device and an assembling method thereof.

[0007]

The above-mentioned object is, for example,
As shown in the schematic view of FIG. 2, a semiconductor laser element arranged in the central portion of the stem, a spherical lens arranged and fixed in the laser light emitting portion of the semiconductor laser element, an IC element for controlling the semiconductor laser element, and a semiconductor laser. Element, ball lens, IC
In an optical coupling device consisting of a cap with a glass window provided so as to cover the element, a plurality of cylindrical pits or cross slits were formed in advance on a metal plate at regular intervals, and a spherical lens was seated on this pit or slit. After that, the metal plate and the ball lens are fixed, and the metal plate with the ball lens is positioned so as to face the laser beam emitting portion of the semiconductor laser device.

According to the present invention, a semiconductor laser element arranged in the center of a stem, a spherical lens with a metal plate arranged and fixed in the laser beam emitting portion of the semiconductor laser element, an IC element for controlling the semiconductor laser element, and a semiconductor laser element. , Ball lens, I
In an optical coupling device comprising a glass window cap provided so as to cover a C element and a fiber whose end face is polished flat, a plurality of columnar pits or cross slits are formed in advance on the metal plate at regular intervals. After the ball lens is seated in the pit or slit, the metal plate and the ball lens are fixed, and further, the metal plate with the ball lens is positioned to face the laser light emitting part of the semiconductor laser device, and the ball lens collects. After the light is emitted, the light is made incident on the end face of the fiber.

The present invention is also directed to a semiconductor laser element arranged in the center of the stem, a spherical lens arranged and fixed in the laser beam emitting portion of the semiconductor laser element, an IC element for controlling the semiconductor laser element, a semiconductor laser element, and a ball. In an optical coupling device comprising a glass window cap provided so as to cover a lens and an IC element and a fiber whose end face is polished flat, first, the semiconductor laser element is Au-Sn, Pb-Sn (4
0:60) and then fix the IC element with Pb-Sn.
(40:60), followed by semiconductor laser device, I
The C element and the external electrode are electrically connected to each other, and the position of the metal plate with the spherical lens is adjusted while oscillating the semiconductor laser device, and the stem and the metal plate are fixed by welding or In-Pb
After fixing with a solder such as -Ag, the glass window cap is resistance-welded and fixed to the stem, and the light after passing through the glass window is coupled to the fiber end.

[0010]

[Function] Cylindrical pits are provided on the metal plate at regular intervals.
The shape of the pit should be smaller than that of the spherical lens. Photoetching is used to form pits at regular intervals.
That is, an etching mask is made in advance from a material such as glass, and the resist applied on a metal plate is exposed to ultraviolet rays through the mask to expose only the pit resist, and the metal is etched to form a columnar shape. Form a pit. If a ball lens is seated in this pit, the lens will be in a stable state. When a small amount of low melting point glass or Au—Sn solder is put in the pit and the metal plate and the lens are joined together, the lens becomes more stable. The array of spherical lenses fixed to the metal plate is straight and has a constant interval. The lens-equipped metal plate is aligned with the vicinity of the emitting portion of the semiconductor laser element, and the stem and the metal plate are fixed by soldering or welding. Further, as another method of fixing the spherical lens to the metal plate, there is a method of forming a cross slit in the metal plate. The slits are formed by photo etching or electric discharge machining. After the lens is seated at the intersection of the slits, it is bonded and fixed with solder.
By aligning and fixing the thus-fixed spherical lens with a metal plate near the laser element, there is no relative displacement between the semiconductor laser element and the lens, and a reliable and stable collimated light can be obtained. An optical coupling device optically coupled with the fiber is obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, a semiconductor laser device 2 is fixed to a central portion of a disc-shaped stem 1 via a submount 3 so that a semiconductor laser device 2 can oscillate in a direction perpendicular to the stem. In order to control the output of the semiconductor laser element 2, the IC element 4 is arranged and fixed side by side with the laser element. Therefore, an electric signal from the outside is supplied to the semiconductor laser element 2 from the lead 4'through the IC element 4. A plurality of lights oscillate simultaneously from the semiconductor laser device 2. The oscillation interval of the laser light is set to a multiple that is in consideration of the fiber outer diameter of 125 μm. The oscillating light has a spread of 30 to 40 °. Therefore, even if the fiber end faces are brought close to each other as it is, only a coupling efficiency of 3 to 5% can be obtained. Therefore, a microsphere lens is installed near the light emitting portion of the semiconductor laser element 2.

As the spherical lens 5, one fixed to a metal plate 6 in advance is used. FIG. 3 shows a state of assembling the lens and the metal plate. First, a resist is applied to the surface of the metal plate 6 on which pits are to be formed. A mask prepared in advance is supported on a metal plate, and ultraviolet rays are irradiated from above the mask toward the metal plate. The resist film on the metal plate changes in quality only in the portion exposed to ultraviolet light and can be removed by etching. Next, the metal is immersed in an etching solution for etching. The material of the metal plate 6 is Fe-42Ni, Fe-4.
5Ni, Fe-50Ni, Fe-29Ni-17Co, etc. are suitable, and HF,
A mixture of HNO ₃ is suitable. The pit has an outer diameter of 0.1 to 0.05 and a depth of 0.1 when the outer diameter of the spherical lens is 0.2.
~ 0.05 is suitable. The material of the spherical lens is TaF-
3, SF-8. After etching the metal plate 6, the resist remaining on the surface is removed. Metal plate 6 and ball lens 5
To fix and so that the lenses do not break, it is important to match the linear expansion coefficients of each, and 7 × 10 ~ ⁶ (/
A low melting point glass made of PbO, B ₂ O ₃ having a coefficient of (° C.) is suitable. A low melting point glass is inserted into the pits of the formed metal plate 6, a ball lens is seated, and baked at about 450 ° C. to bond the metal plate and the lens. Another method of fixing the metal plate 6 and the ball lens 5 is to attach a sputtering film of Ti-Pt-Au to the lower surface of the ball lens 5 in advance, and to form the pits of the metal plate 6 plated with Ni-Au. A
After inserting the u-Sn solder, the sputter surface of the ball lens is seated in the pit and fixed with Au-Sn. Bonding temperature is 30
A temperature of 0 to 320 ° C is suitable.

As another fixing method for fixing the spherical lens 5 to the metal plate 6, as shown in FIG. 4, there is a method of forming a cross slit instead of the pit and fixing the lens at the center of the slit. The material used is low melting glass or A
u-Sn solder is suitable. The slit processing method includes photo etching, electric discharge processing, press processing, and the like.

While oscillating the semiconductor laser element 2, the metal plate with the spherical lens is aligned so that parallel light can be obtained, and is joined and fixed to the stem 1. The fixing material is In-P
b-Ag solder or YAG welding is suitable.

A semiconductor laser device 2, which is bonded to the stem 1.
The IC element 4 is covered with a cap 8 having a glass window 7 in order to protect it from moisture, dust or external force in the atmosphere.
A resistance welding method is suitable for fixing the cap 8 and the stem 1. In this structure, when the cap is fixed, the atmosphere is nitrogen gas and the cap is welded, so that the inside has a nitrogen atmosphere and is not affected by the outside.

In this way, by aligning and fixing the metal plate 6 with the spherical lens 5 to the light emitting portion of the semiconductor laser element 2 fixed to the center of the stem 1, a plurality of parallel lights are obtained in the direction perpendicular to the stem 1. be able to.

As an example of using this optical coupling device for optical fiber transmission, a structure in which a plurality of optical fibers are incorporated as shown in FIG. 5 can be considered. A ferrule holder 9 is provided so as to cover the glass window cap 8. The tips of the plurality of fibers 11 are fixed in the cylindrical or plate-shaped ferrule 10 in advance, and then end-polished. Alumina, zirconia ceramics 12 or Si single crystal plate is suitable for the material of the ferrule 10. In the case of alumina and zirconia ceramics, as shown in FIG. 6, a plurality of holes 13 having diameters of 125 μm and 250 μm are used, and in the case of Si single crystal plate 14, as shown in FIG. A suitable method is to form the V-shaped groove 15 on the plate surface and fix the fiber 11 so as to be sandwiched between the V grooves of the Si plate. Therefore, the portion of the ferrule holder 9 into which the ferrule is inserted has a cylindrical or angular shape that matches the outer shape of the ferrule.

The light from the spherical lens 5 and the end face of the fiber 11 are aligned with each other by welding and fixing the contact face 16 between the stem 1 and the ferrule holder 9 in the direction perpendicular to the optical axis. Next, the optical axis direction is adjusted by taking the ferrule 11 in and out of the ferrule holder 9, and the fixing part 17 fixes the solder.

According to the embodiment, in the optical coupling between the semiconductor laser element 2 and the spherical lens 5, the spherical lens is formed on the metal plate 6 by forming a cylindrical pit or a cross slit, and is seated on this to stabilize the lens. What we have achieved is that low-melting glass or Au-Sn solder is used to bond the metal plate and the ball lens so that the metal plate can be securely bonded and cracks do not occur. By fixing, optical coupling is easy, and stable coupling can be obtained even for long-term use.

[0020]

According to the present invention, a spherical lens for condensing light from a semiconductor laser element can be securely and stably fixed near the laser oscillation portion for a long period of time. The alignment with the ball lens can be easily performed in a short time. Furthermore, the light from the spherical lens can be efficiently coupled to the fiber.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a perspective view of an embodiment of the present invention.

FIG. 3 is an explanatory view showing assembly of a metal plate with a spherical lens according to an embodiment of the present invention.

FIG. 4 is a perspective view showing another spherical lens metal plate of one embodiment of the present invention.

FIG. 5 is a cross-sectional view of another embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a fiber with a ferrule according to an embodiment of the present invention.

FIG. 7 is a perspective view showing another fiber with a ferrule according to an embodiment of the present invention.

FIG. 8 is a sectional view showing a conventional technique.

[Explanation of symbols]

1 ... Stem, 2 ... Semiconductor laser element, 3 ... Submount, 4 ... IC element, 5 ... Ball lens, 8 ... Cap, 9 ...
Ferrule guide, 10 ... Ferrule, 11 ... Fiber.

Claims (6)

[Claims] 1. A semiconductor laser element arranged in the center of a stem, a spherical lens arranged and fixed in a laser beam emitting portion of the semiconductor laser element, and I for controlling the semiconductor laser element.
C element, the semiconductor laser element, the spherical lens, the I
In an optical coupling device comprising a cap with a glass window provided so as to cover a C element, a plurality of cylindrical pits or cross slits are formed in advance on a metal plate at regular intervals, and the cylindrical pits or cross slits are provided with the above-mentioned After the ball lens is seated, the metal plate and the ball lens are fixed, and the metal plate with the ball lens is positioned and fixed so as to face the laser light emitting portion of the semiconductor laser device. Coupling device. 2. A semiconductor laser element arranged in the center of a stem, a spherical lens with a metal plate arranged and fixed in a laser beam emitting portion of the semiconductor laser element, an IC element for controlling the semiconductor laser element, and the semiconductor laser. An optical coupling device comprising an element, the spherical lens, a cap with a glass window provided so as to cover the IC element, and a fiber whose end face is flatly polished, and a plurality of columnar pits or After forming a cross slit and seating the ball lens in the columnar pit or the cross slit, the metal plate and the ball lens are fixed, and a metal with a ball lens is provided in the laser light emitting portion of the semiconductor laser device. Positioning and fixing of the plates facing each other, and light after being condensed by the spherical lens is incident on the end face of the fiber. Coupling devices. 3. The optical coupling device according to claim 1, wherein the emitted light of the semiconductor laser device is coupled with four or a multiple of 4 of the same number of the metal plates with spherical lenses, and then optically coupled with a fiber. 4. The light according to claim 1, wherein the distance between the semiconductor laser element emitting portions is 250 μm, which is equal to the lens distance of the metal plate with the spherical lens and the distance between the fibers. Coupling device. 5. The material of the spherical lens is TaF-3, SF-8, and the material of the metal plate is Fe-42Ni, Fe-45Ni, Fe-.
50Ni, Fe-29Ni-17Co at fixed between the metal plate and the spherical lens PbO, B ₂ O ₃ made of a low-melting-point glass or Au-Sn, Au-Ge optical coupling device fixed using a bonding material, such as .. 6. A semiconductor laser element arranged at the center of a stem, a spherical lens arranged and fixed at a laser beam emitting portion of the semiconductor laser element, and I for controlling the semiconductor laser element.
C element, the semiconductor laser element, the spherical lens, the I
In an optical coupling device comprising a glass window cap provided so as to cover the C element and a fiber whose end face is polished flat, the semiconductor laser element is Au-Sn, Pb-Sn.
After fixing at a predetermined position with (40:60), the IC element is fixed with Pb-Sn (40:60), and subsequently, the semiconductor laser element, the IC element, and an external electrode are electrically connected, respectively, The position of the metal plate with a spherical lens is adjusted while oscillating a laser element, and the stem and the metal plate are fixed by welding or soldering such as In-Pb-Ag, and then a cap with a glass window is attached to the stem. A method for assembling an optical coupling device, characterized in that the light after being fixed by resistance welding is optically coupled to the end of the fiber after passing through the glass window.