JPS59166907A - Semiconductor laser coupling device - Google Patents

Abstract

PURPOSE:To reduce the number of parts and the adjusting places of a coupling device by providing a supporting member of a ferrule to which an optical fiber is installed so as to cover a spherical lens, on a holding member of the spherical lens which is used for an airtight sealing window, too. CONSTITUTION:A comparatively large spherical lens 43 which is used for a window, too is provided on a spherical lens holding member 42 for sealing airtightly a semiconductor laser element chip 1. On the other hand, a ferrule supporting member 44 for fixing a ferrule 45 to which an optical fiber strand 14, etc. are installed so as to cover the lens 43, by a cylindrical part is attached to this member 42, and optical axes of the lens 43 and the strand 14 coincide with each other. When this member 42 is adjusted as to its position and fixed to a package stem 41, a laser beam from the chip 1 and the optical axis of the lens 43 coincide with each other. According to the constitution by which this spherical lens is used for a window, too, and the optical axis is adjusted only through the member 42, the number of parts and the adjusting places of a semiconductor laser coupling device are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a semiconductor laser coupling device with a simple configuration in which a semiconductor laser and an optical fiber are stably coupled using a ball lens.

(Prior Art) In optical fiber communication systems, it is necessary to develop a semiconductor laser coupling device that efficiently couples semiconductor laser light to an optical fiber. In particular, when considering the introduction of such a device into a subscriber system, it is necessary to develop an LD coupling device with a simplified manufacturing process and low cost.

In conventional devices of this kind, when coupling a semiconductor laser, for example, a laser diode (hereinafter also abbreviated as LD) to an optical fiber, the core diameter of the optical fiber is 5θμ.
Since it is small (less than m), it is necessary to perform fine alignment using a fine adjustment table, etc.), and it may not come off unless you fix each part with adhesive etc. after alignment is completed. ,
It took a long time to assemble, did not improve manufacturability or yield, and made it difficult to reduce costs.

and Figure 3 shows this kind of conventional equipment.
In the LD coupling device shown in the figure, the LD, that is, the laser chip/-i is fixed onto the protrusion JA of the LD package stem 2, and power is supplied from the electrode 3 to the laser chip l. A ball lens holding member l is fixed to the two protrusions, and this holding member q
Adjust the ball lens j to the specified position above and fix it. Laser chip/and ball lens! A cap with a glass window is placed over the stem 2 so as to cover the stem 2, and its edges A and 6B are fixed to the system co by welding, thereby airtightly sealing the inside of the cap B. . 7 is the window 6 opened in the cap O
This is a window glass for airtight sealing fixed to C.

Furthermore, the SELFOC lens holding member t is placed over the cap B so as to cover the cap 6. The holding member r has a hole IG that runs through the hole IG facing the window C, and the SELFOC lens 9 is inserted into this hole IC and fixed with an adhesive.

Edge edges A and B of the holding member are attached to the stem with adhesive after adjusting the package stem with respect to the holding member L so that the optical axes of the ball lens and Selfoc lens 9 are aligned. Fix it.

Ferrule/θ to 7-work rule support member/l through hole//
Stick to A. The ferrule 10K is equipped with a fiber coating /3 from which the optical fiber cord /2 has been removed.

The tip of this fiber sheath 71213 is removed to expose the optical fiber /l. The ferrule support member is arranged so that the tip of the optical fiber 14t faces the self-occurring lens 9, and the end face of the optical fiber /l is located at the optical axis of both and at the convergence position of the emitted light from the self-occurring lens.
Selfoc lens support member! After adjusting for rK, secure the edges of both parts with adhesive. /S
is an optical fiber support member.

In this example, a ball lens S is mounted inside the package stem 2 to extract the laser beam from the LD/ as a parallel beam, and a self-occurring lens is used as the second lens to connect the optical fiber/
(This is an LD coupling device developed for a single mode optical fiber that narrows down to Then, attach the LD package stem 2 and the SELFOC lens 9 of the 82 lens to the digit holding member r and the ferrule/
Combine the support member // into which θ has been inserted, and adjust the optical axis of each component in the X, Y, and Z directions as shown by the arrows while using the fine movement table to achieve the optimal bonding state. Glue and fix the parts.

As is clear from FIG. 1, this device has many parts, so there are many adjustment points, making it difficult to simplify the assembly process. Furthermore, since each component is fixed with adhesive, the optical axis is likely to be misaligned during assembly, and furthermore, it takes time to manufacture.

FIG. 2 shows a second conventional example, in which a first holding member n is welded and fixed to a package stem J having a laser chip l fixed to a protrusion 2/A. A first holding member n is airtightly attached to this first holding member n via indium J. The second holding member n has a window blade facing the laser chip l, and the hermetic sealing window glass I is fixed to this window r. A ball lens S is fixed onto this window glass with an adhesive. A ferrule 1 is fixed with adhesive to cover the window Δ.

An optical fiber t whose fiber coating 13 has been stripped off is inserted into this ferrule. N/3 of the optical fibers are supported by an optical fiber support member I, and this support member J is fixed to a first holding member n.

In this example, in order to adjust the position in the optical axis direction of the spherical lens 5 attached to the window glass, a spherical lens holding member is constituted by λ holding members n and 8. Therefore, while monitoring the optical output, the relative position of the LD package stem I and the ball lens holding members n and n was adjusted by X.

The λ-th holding member n is attached to the first holding member n with optimal adjustment in the Y and Z directions. Next, the whole package stem
sticks to. In this example, there is no Selfoc lens, so
It is difficult to adjust how the output light from the ball lens j enters the optical fiber/ll, and the number of parts and adjustment points are large, resulting in poor assembly work efficiency and manufacturing yield. moreover,
Since the distance between the LD/ and the microball lens S is narrow, mounting accuracy is difficult, and there is a risk that the LD chip/ may be damaged due to contact with the microsphere lens 5.

FIG. 3 shows a third conventional example. In this example, a laser chip is placed on a protrusion 31k of an LD package stem 3, and power is supplied to the laser chip from an electrode 32. A ball lens j is fixed with adhesive to the tip of a ball lens holding member 33 made of a glass tube, and this holding member 33 is inserted into a through hole j4'A made in the optical fiber support member. After adjusting the optical fiber support member 341 with respect to the stem 3/ as shown by the arrow so that j faces the laser chip l, both are fixed with adhesive. An optical fiber /'l is inserted into the glass tube serving as the ball lens holding member 33, and the optical fiber puffer is adjusted as shown by the arrow with respect to the holding member 33, so that the light emitted from the ball lens S is connected to the optical fiber l.
It is made to focus on the opposite end face of lI.

Here, the microsphere lens and the optical fiber/4t are integrated with a holding member 33 made of a glass tube, and by setting the ball lens S slightly larger than the inner diameter of the glass tube 33, the optical axis of both is automatically adjusted. It can be fixed in a state that matches the target. However, since the ball lens j is close to the end face of the LD chip, mounting accuracy is difficult. Still a ball lens
Since adhesive is used to fix the holding member 33 and the stem 31 to the supporting member 3, the LD chip is not completely hermetically sealed. In addition, optical fiber/Il.

The ball lens holding member 33, which also functions as a guide, is long and narrow, and the fiber supporting member 3g is large in size.

(Purpose) Therefore, in order to eliminate these above-mentioned drawbacks, the purpose of the present invention is to reduce the number of parts and adjustment points by using a spherical lens with relatively large external dimensions that also serves as an airtight sealing nitrogen. Another object of the present invention is to provide a semiconductor laser coupling device with a simple configuration that reduces manufacturing time and costs of the device.

(Structure of the Invention) In order to achieve the above object, the present invention includes a package stem in which a semiconductor laser element is disposed, and a lens in the form of a cylindrical cap covering the semiconductor laser element. A holding member is attached to the lens holding member, a hole is made in the center of the upper surface of the lens holding member, a ball lens is seated and fixed in the hole, and the ball lens is attached so that its optical axis is aligned with the laser beam from the semiconductor laser element. A ferrule support member having a cylindrical hole is fixed to the upper surface of the lens holding member so as to face the semiconductor laser element so as to match the optical axis of the light, and covering the spherical lens. A ferrule equipped with an optical fiber is inserted into the cylindrical hole, so that the end face of the optical fiber faces the ball lens, and the optical axis of the ball lens is aligned with the optical axis of the laser beam from the semiconductor laser element. moving and adjusting the lens holding member relative to the package stem so that they match, and moving the ferrule relative to the ferrule supporting member so that the output light from the ball lens is focused on the end face of the optical fiber; After the adjustment, the lens holding member is fixed to the package stem, thereby hermetically sealing the semiconductor laser element within the front lens holding member, and transmitting laser light from the semiconductor laser element through the ball lens. and is configured to guide the optical fiber into the optical fiber.

Here, the outer circumferential surface of the spherical lens is metalized in a band shape,
It is preferable that the band-shaped metallized portion is seated in the hole of the lens holding member and brazed.

Further, the lens holding member may be fixed to the package stem by welding.

In that case, it is preferable to perform the welding after temporarily fixing the lens holding member to the package stem.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the invention, where g/ is the package stem, ! /A is a protrusion of the stem /, and the laser chip / is placed and fixed on this protrusion tlA. Group 2
package stem 4 so as to cover the laser chip/
A ball lens holding member in the form of a cylindrical cap fixed to 1'/. A coupling ball lens 3 is seated and fixed in the window L2A formed on the central axis of the upper surface of the holding member tag 2, and the polarization of this ball lens allows it to receive laser light from the laser chip. , hermetically sealing window 11.2A. Here, the bulb 'l'' L12 faces the LD chip/ with its optical axis matching the optical axis of the laser beam from the LD chip/. A hollow cylindrical ferrule support member is fixed so as to cover the spherical lens p.A ferrule ring 5 is fixed to the hollow part of the ferrule support member with an adhesive, and an optical fiber coating /3 and Attach the optical fiber bare wire/Hiro.Thereby, the end face of the optical fiber puffer is opposed to the ball lens Y-3, and the optical axes of both are aligned, and the light from the ball lens Y-3 is directed to the light 7. The holding member '12 that focuses on the end face of the eyeglass lens is one that has been integrated in advance by brazing, resistance welding, etc. Therefore, the in-plane position of the ferrule, that is, the original fiber /41, is the same as that of the ball lens I13. Since the position of the holding member 2 is determined by the position of the holding member 2, it is necessary to adjust the relative position of the holding member 2 and the package stem in order to adjust the optical fiber 41 in the plane. Now, with the ferrule aS inserted into the ferrule support part qtt that is integrated with the ball lens holding member t12, in-plane adjustment can be made by moving the holding member in the direction shown by the arrow. It is preferable to temporarily fix the holding member Q, stem L/and ferrule S with adhesive, and then completely fix it with resistance welding.According to the data of CanSeal using a resistance welding machine, instant adhesive If temporary fixation is carried out with an agent, an axis misalignment of at most 10 μm will not occur, so the deterioration of the coupling efficiency due to an axis misalignment in the direction perpendicular to the optical axis of the optical fiber is sufficiently small, and it is fully applicable. When the ball lens p is mounted on the stem 'l/, the positioning of the optical fiber lIl with a large tolerance in the optical axis direction can also be performed, so the efficiency of the assembly work is extremely high.

As the diameter of the ball lens 3 increases, the coupling efficiency generally deteriorates, but the mounting accuracy of the ball lens 3 becomes looser. Here, the diameter of the ball lens 3 is determined by considering both the coupling efficiency to the optical fiber/ll and the C/N (carrier-to-noise ratio) characteristics of the LD chip l when there is reflection from the surface of the ball lens R. It is necessary to decide together.

Figure 5 uses light and the distance d [μm] between the LD/ and the ball lens 3, and the reflectance is 0.077 between the diameters of the ball lens punch.
The case using the ball lens 3 is shown below.

From this 0/N characteristic, it can be seen that the spacing d needs to be approximately SOO μm or more.

FIG. 6 shows the relationship between the distance d [μm] and the coupling efficiency (dB) using the diameter of the ball lens 13 as a parameter, and the diameter of the ball lens 3 is 80 mm.

The measurement results at 2.0, 3.2, and lt are indicated by ×, e, ○, and Δ marks. In addition, when the distance d was changed, the position of the end face of the optical fiber puffer was shifted to the position where the efficiency was highest, and measurements were taken. Considering this result and the result shown in FIG. 5, it is found that it is preferable to set the distance d to about 500 to 600 μm and the diameter of the spherical lens to about 2 mm.

Fixing in the present invention is not limited to fixing by resistance welding as shown above, but also by YAG laser.

A fusion fixing method using a C02 laser and metal solder fixing using a high frequency heating device can also be used.

Further, the means for ensuring the airtightness of the bulb 3 is not limited to the brazing method, and glass soldering or other methods may also be used. In addition, in the present invention, instead of the airtight window used in a normal package, a ball lens Q is used as the window, which allows a large distance d between the LD chip and the LD chip.
The noise characteristics of the LD itself will not deteriorate due to reflection from the airtight window, which has been a problem for analog optical transmission. Therefore, it is also effective as a semiconductor laser coupling device for analog transmission.

(Effects) As explained above, the present invention has a simple configuration,
In addition, the number of parts is small, only one location requires position adjustment, and assembly can be performed by ordinary resistance welding, so the semiconductor laser coupler can be constructed extremely easily. Therefore, it is expected that the manufacturing yield will be improved and the cost will be significantly reduced, so that it is effective for wide use as a transmission device for optical subscriber systems and civilian use.

[Brief explanation of drawings]

Figures 1 to 3 are cross-sectional views showing three examples of conventional devices, Figure 5 is a cross-sectional view showing an embodiment of the present invention, Figure 5 is a graph showing measurement results of C/N characteristics, and Figure 2 is a cross-sectional view showing three examples of conventional devices. The figure is a graph showing the measurement results of overall efficiency. (Fig. 1) L...Laser chip (LD), C...Package stem, 2 people...Protrusion, 3...Electrode, l...Ball lens holding member, S...Ball lens, B... Cap with glass window, Otsu A, gB... Edge of cap, Otsu C... Window, 7... Window glass for airtight sealing, and... SELFOC lens holding member, D , to B...
・Edge, IrC...window, water...selfoc lens, /θ...ferrule, //...ferrule support member, //A...through hole 1/2・- Optical fiber cord, /3... Optical fiber coating, /l... Optical fiber bare wire, /S... Optical fiber support member, (Fig. 2) 2/... Package stem, 2/ A--Protrusion, 〃--First holding member, n--Second holding member, 2--Indium, Δ...Window, P...Hermetic sealing window, 〃... - Ferrule...Optical fiber support member, (Fig. 3) 3/...Package stem 1,? /A...Protrusion, 32...Electrode, 33...Ball lens holding member, 3...Optical fiber support member, (Figure 1) Il/...Package stem, G/A--・Protrusion, F/B...Step part, Intrusion...Ball lens holding member, '72A...Window, Ko3...Ball lens, Matter...Ferrule support member, G...Ferrule . Patent applicant: Nippon Telegraph and Telephone Public Corporation Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1) A package stem having a semiconductor laser element arranged thereon, a lens holding member in the form of a cylindrical cap attached to the package stem so as to cover the semiconductor laser element, and the lens holding member A hole is made in the center of the upper surface, a ball lens is seated and fixed in the hole, and the ball lens is arranged such that its optical axis coincides with the optical axis of the laser beam from the semiconductor laser element. , a ferrule support member having a cylindrical hole facing the semiconductor laser element and having a cylindrical hole is fixed to the upper surface of the lens holding member so as to cover the spherical lens, and a ferrule with an optical fiber attached to the cylindrical hole is fixed. The lens holding member is attached to the package so that the end surface of the optical fiber faces the ball lens, and the optical axis of the ball lens matches the optical axis of the laser beam from the semiconductor laser element. After adjusting the movement relative to the stem and adjusting the movement of the ferrule relative to the ferrule support member so that the output light from the spherical lens is focused on the end face of the optical fiber, the lens holding member is The semiconductor laser device is fixed to the package stem, thereby hermetically sealing the semiconductor laser device within the lens holding member, and guiding laser light from the semiconductor laser device to the optical fiber via the ball lens. Semiconductor laser coupling device. 2. The semiconductor laser coupling device according to claim 1, characterized in that the outer circumferential surface of the spherical lens is metallized in a band shape, and the band-shaped metallized portion is seated in the hole of the lens holding member and brazed. Semiconductor laser coupling device. 3) A semiconductor laser coupling device according to claim 1 or 2, wherein the lens holding member is fixed to the package stem by welding. 4) The semiconductor laser coupling device according to claim 6, wherein the welding is performed after the lens holding member is temporarily fixed to the package stem.