JPS61189517A - Manufacture of semiconductor laser device with optical isolator - Google Patents

Abstract

PURPOSE:To suppress the rays of light which are reflected back to a semiconductor laser by fixing two positions between an optical fiber core and a fiber holder and, the end part between an optical fiber element wire and the holder. CONSTITUTION:A lens 2 is arranged at the distance of >=1mm from the semiconductor laser and consists of three divided parts; semiconductor laser part, lens and isolator part, and optical fiber part. An adjustment perpendicular to the optical axis of the lens isolator part and adjustments parallel and perpendicular to the optical axis of the optical fiber are so made that projection light from the laser 1 is passed through the lens 2, magneto-optic crystal 5, and a polarizer 7 and is made incident on the optical fiber from the end part of the fiber element wire 8 at a maximum, and then a fixing part 10' is fixed. The fiber element wire 8 and fiber holder 9 are fixed by the fixing part 8, the position of the optical fiber is adjusted, and the laser part and isolator part, and the isolator part and holder 9 are fixed respectively. Consequently, the quantity of reflected light is suppressed at a specified value or below.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a semiconductor laser device with an optical isolator used as a light source for optical signal transmission in optical communications and the like.

2. Description of the Related Art A conventional semiconductor laser device with an optical isolator is disclosed in Japanese Unexamined Patent Publication No. 56-21107, for example.
The configuration is as shown in the figure.

That is, the emitted light 16 from the semiconductor laser 14 is transmitted through the coupling lens 16. Glass plate 18. Incident side lens 12, optical isolator main body 20. The light passes through the exit lens 12', is focused on the optical fiber 17, and is transmitted.

On the other hand, the light reflected from the optical isolator main body 20 onwards at each connection portion is blocked by the magneto-optic effect of the optical isolator main body 2o and does not return to the semiconductor laser 14.

Problems to be Solved by the Invention However, in such a configuration, a part of the light emitted from the semiconductor laser 14 is reflected between, for example, the incident side lens 12 and the optical isolator main body 2o.

There was a problem in that the semiconductor laser 14 returned to the original state and the semiconductor laser 14 operated unstablely.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention arranges a focusing rod lens with one end surface having a curved surface at a distance of 1n or more from the semiconductor laser. The fiber holder, which has the function of holding the optical fiber, is basically cylindrical in shape, and the central axis of the optical fiber is on the central axis of the fiber holder. and the center of the light emitting part of the semiconductor laser is located, and in the process of fixing the optical fiber and the fiber holder, there are The first step is to fix each part.

Effect of the Invention The present invention uses the method described above to minimize the amount of light reflected back to the semiconductor laser between the semiconductor laser and the optical isolator body out of the light emitted from the semiconductor laser, and is easy to manufacture. This makes it possible to realize a semiconductor laser module with an optical isolator that is highly reliable.

Embodiment FIG. 1 is a sectional view showing an embodiment of a semiconductor laser device with an optical isolator manufactured by the method of the present invention. 1st
The figure shows a semiconductor laser 1.0 fixed to a semiconductor laser mount 1'. It has the function of fixing the lens 2 and is a magneto-optic crystal 6. Magnet 4. and a cylindrical lens holder 3 which has the function of integrating the polarizer 7 and the crystal holder 6. It has a function of fixing the fiber core wire 1o reinforced with a metal sleeve 11 made of stainless steel or the like and the fiber wire 8, and also has a function of fixing itself to the lens isolator section. It has a fiber holder 9.

An example of a specific manufacturing method will be described below.

A step of fixing the semiconductor laser 1 to the semiconductor laser mount 1', fixing the lens 2 at a position where the distance between the curved end face and the semiconductor laser 1 is 1 mm or more, and fixing the lens 2 together with the crystal holder 6 to the magneto-optic crystal. 6 with the magnet 4 and polarizer 7, and the step of integrating the optical fiber with the metal sleeve 11 and the fiber holder 9, are divided and carried out separately, and the subsequent steps are performed separately as shown in FIG. The light emitted from the semiconductor laser 1 is transmitted through the lens 2°, the magneto-optic crystal 5. Adjustment in the direction perpendicular to the optical axis of the lens isolator part and in the direction of the optical axis of the optical fiber so that the maximum incidence on the optical fiber passes through the polarizer 7 and enters the optical fiber from the end of the optical fiber strand 8. After adjusting the vertical direction, fix the fixing part 10' with resin and solder.

Fixed by fixing means such as welding.

After that, one end of the optical fiber integrally fixed to the fiber holder 9 is removed from the adjustment jig, and the fiber wire 8 and the fiber holder 9 are connected at the fixed part 8'.

It is fixed by the fixing means. Thereafter, the optical fiber is mounted on the adjustment jig again and its position is adjusted, and the semiconductor laser section and the lens isolator section, and the lens isolator section and the fiber holder 9 are each fixed by the above-mentioned fixing means.

Regarding the distance between the semiconductor laser 1 and the end face of the lens 2, as shown in Figure 2, if the distance between the semiconductor laser and the reflective surface is d2 and the reflectance of the reflective surface is R, then the amount of light reflected back to the semiconductor laser is η is expressed as follows.

Here, r is the radius of curvature of the reflecting surface, λ is the oscillation wavelength of the semiconductor laser, and ω and ω/ are the beam spot sizes in the direction perpendicular and parallel to the junction surface of the semiconductor laser. From the results of transmission experiments, in order for the semiconductor laser to operate stably, it is necessary to suppress the amount of light reflected back to the semiconductor laser to below -75 (IB), but the reflectance is 1%2 the radius of curvature is 2
When using a converging rod lens with a curved surface of ff, the calculation result using the above formula is as shown in Figure 2, where a distance of 1'In1 or more is required to reduce the amount of reflected return light to -75 dB or less. It is.

Effects of the Invention As described above, according to the present invention, (1) one end surface is curved and the lens serves as a lens for condensing the emitted light from the semiconductor laser onto the optical fiber; The distance between the semiconductor laser and the focusing rod lens whose refractive index distribution decreases in proportion to the square of the distance from the central axis is 1H.
By doing so, the amount of reflected light reflected from the lens end face and returning to the semiconductor laser can be suppressed to -75 (1B) or less, and stable operation of the semiconductor laser is possible. (2
) In the step of fabricating the semiconductor laser section, lens and isolator section, and optical fiber section by dividing them into three parts, and adjusting and fixing the position of the optical fiber, the process involves adjusting the position of the optical fiber in the optical axis direction and attaching it to the fiber holder. By making fixation the first step, the manufacturing process becomes easier. (3) The shape of the fiber holder is basically cylindrical, the central axis of the optical fiber and the center of the light emitting part of the semiconductor laser are located on the central axis, and the tip of the optical fiber is fixed. Therefore, the positional shift of the optical fiber due to changes in ambient temperature can be suppressed as much as possible, and a highly reliable semiconductor laser device with an optical isolator can be realized.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of a device constructed based on the method of manufacturing a semiconductor laser device with an optical isolator of the present invention, and FIG. 2 is a diagram showing the reflection on the semiconductor laser with respect to the distance between the semiconductor laser and the end face of the lens. FIG. 3, which is a diagram showing the relationship between the returned views, is a sectional view of a main part of a conventional semiconductor laser device with an optical isolator. 1...Semiconductor v-sa, 2...Lens, 3...Lens holder, 4...Magnet,
6...Magneto-optical crystal, 6...Crystal holder, 7...Polarizer, 8...Fiber strand, 9...Fiber Holder, 10. Old... fiber core wire. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] A semiconductor laser with an optical isolator, which is composed of a semiconductor laser, a lens for condensing light from the semiconductor laser onto an end face of an optical fiber, a magneto-optic crystal, a magnet, a polarizer, and an optical fiber. When manufacturing the device, (a) it is divided into three parts: a semiconductor laser part, a lens and isolator part, and an optical fiber part, and (b) one end surface of the lens is curved and the refraction within the cross section is made. one focusing rod lens whose rate distribution decreases in proportion to the square of the distance from the central axis; (c) an end surface of the active layer of the semiconductor laser and a curved end surface of the focusing rod lens; (d) The shape of the fiber holder having the function of holding the optical fiber is basically cylindrical, and the central axis of the optical fiber and the semiconductor laser are located on the central axis of the fiber holder. (e) in the step of adjusting and fixing the position of the optical fiber, adjusting the position of the optical fiber in the optical axis direction and fixing it to the fiber holder as a first step; f) A method for fixing the optical fiber and the fiber holder is to fix them at two places: between the optical fiber core and the fiber holder, and between the tip of the optical fiber and the fiber holder. A method of manufacturing a semiconductor laser device with an optical isolator, characterized in that: