JPS6076707A - Semiconductor laser duplex module - Google Patents

Abstract

PURPOSE:To improve reliability by mounting two laser chips onto the heat sink of a semiconductor laser module and adding a 90 deg. polarizing rotor and a polarizing element thereto. CONSTITUTION:A semiconductor laser duplex module is constituted of two semiconductor laser chips 12, 13, a 90 deg. polarizing rotor 14, a polarizing element 15 and a lens 17. The chips 12, 13 are disposed on a heat sink 11 having a flat main plane in such a way that the optical axis of the linearly polarized exit light and the plane of polarization are in parallel with each other and that the positions of the laser end faces coincide with each other. The rotor 14 is placed on the front surface of the one laser chip and rotates 90 deg. the plane of polarization of the laser light. The element 15 consists of a double refracting material and joins the two beams having the orthogonally intersecting planes of polarization. The lens 17 focuses the laser light and couples the same to an optical fiber 16 on the output side.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a semiconductor laser device that converts an electrical signal into an optical signal and an optical fiber that is an optical signal transmission medium.

A semiconductor laser module that combines efficiently and stably.

In particular, the present invention relates to a dual semiconductor laser module used in a highly reliable optical fiber communication system.

[Prior art]

Highly reliable optical fiber communication systems, such as optical fiber Kasol submarine relay systems, require extremely high reliability from the components used in the system. Semiconductor lasers that convert electrical signals into optical signals have recently become highly reliable, with some achieving a mean time-to-failure (MTTF) of 500,000 to 1,000,000 hours, but compared to other electrical components, I can't say it's enough.

For this reason, a plurality of semiconductor laser modules are stacked in 92 layers using optical switches or optical couplers. They are used in parallel, that is, multiplexed, to bring their reliability closer to that of other electrical system components.

FIG. 1 is a diagram showing an example of the configuration of a conventional semiconductor laser duplex monole, in which laser light from two semiconductor monooles 1 and 2 passes through individual optical fibers 3 and is connected to an optical switch 4. The signals are combined and sent to the optical fiber 5.

FIG. 2 is a diagram showing another example of the configuration of a conventional semiconductor laser duplexing module, in which two laser beams are coupled by an optical coupler 6 using a half mirror or a polarization separation element. The other details are the same as in the case of FIG.

In the multiplex optical circuit system for the light source as described above, the number of components that make up the multiplex optical circuit system increases, and in order to achieve the target reliability, these optical components and elements must have extremely high reliability. It is necessary to be present.

Also, the space occupied by the multiplexed optical circuit system is very small.

It is difficult to miniaturize optical systems and implement high-density packaging.

[Purpose of the invention]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to overcome the drawbacks of the above-mentioned light source multiplexing optical circuit system and to provide a compact, highly reliable semiconductor laser monolayer system with fewer components and elements that cannot be multiplexed.

[Structure of the invention]

In order to achieve the above object, the present invention uses a polarizing element having a birefringence effect to combine semiconductor laser light.

That is, according to the present invention, the first and second laser beams are disposed on a heat sink having a flat principal surface, and are close to each other, the optical axes and the polarization planes of the linearly polarized light are parallel to each other, and the emission end surfaces are substantially coincident. a semiconductor laser means for emitting light, and a semiconductor laser means placed in the optical path of the first laser beam and rotating the plane of polarization of the first laser beam by 90' to make it perpendicular to the plane of polarization of the second laser beam. ° A polarization rotator, a polarization element that merges the optical paths of the first and second laser beams whose polarization planes are perpendicular to each other using a birefringence effect, an output side optical fiber, and an image of the laser beams that merge with the polarization element. A semiconductor laser duplication module having a lens for converting and coupling to the output side optical fiber is obtained.

〔Example〕

FIG. 3 is a diagram showing the basic configuration of a semiconductor laser duplex module which is an embodiment of the present invention. The semiconductor laser mozole shown in Fig. 3 is mounted on a heat sink with a flat principal surface so that the optical axis and polarization plane of the emitted linearly polarized light are parallel to each other.
- Two semiconductor laser chips 12 and 137 arranged so that the positions of the laser end faces almost match (when both chips are the same, the deflection planes substantially overlap), and the front surface of one laser chip. A 90° polarization rotator 14 (for example, a quartz plate with a thickness of 140 microns when the wavelength of the laser light is 1.3 microns) is placed in the 90° polarization rotator 14 to rotate the light control surface of the laser beam by 90°.
, a polarizing element 15 (a calcite plate approximately 2.5 mm thick) made of a birefringent material that combines two beams with orthogonal polarization planes, and a lens that focuses the laser beam and couples it to the output optical fiber 16. It consists of 17.

The polarization planes of the output beams from the semiconductor laser chips 12 and 13 are parallel to each other (parallel to the paper plane in the figure), but the 90° polarization rotator 14 is placed so that only the light from the laser chip f12 passes through. Because it is.

The polarization plane of the light from the laser chip 12 is rotated by 9 Q', but the light from the laser chip 13 is not rotated, so that the polarization planes of the light from both laser chips become perpendicular to each other. In the polarizing element 15, the light from the laser chip 12 with polarization perpendicular to the paper plane travels straight, and the light from the laser chip f13 with polarization parallel to the paper plane is refracted, so that the two optical paths coincide at the output end. A confluence circuit using this polarizing element 15 has no loss in principle. The two linearly polarized lights whose optical paths coincide are appropriately image-converted by the lens 17 with negligible birefringence, and are efficiently coupled to the output fiber 16.

In the configuration of the above embodiment, only two optical elements are required for duplication of the semiconductor laser: a 9o0 polarization rotator and a polarizing element, and the configuration is simple. Moreover, only a space equivalent to one laser module is required. Although the explanation of the lens corresponding to the lens 17 is omitted, it is shown in FIGS. 1 and 2.
It is also used in conventional semiconductor laser modules 1 and 2 shown in the figure.

Unlike the embodiment shown in FIG. 3, it is theoretically possible to arrange the two laser chips 12 and 13 so that their polarization directions are perpendicular to each other without using the 90' polarization rotator 14. Further, although the number of elements can be reduced, it is necessary to make the shape of the heat sink L-shaped and to precisely control the mounting accuracy of the chip, which is not preferable in practice.

FIG. 4 shows a semiconductor laser and a polarization rotator of the semiconductor laser module according to the embodiment of FIG. 1 of the present invention.

FIG. 3 is a diagram illustrating a configuration in which a polarizing element is sealed inside a patch. In FIG. 4, semiconductor laser elements 22 and 23 provided in a cage 21 are scribed in the middle to form the same chip, and are mounted on a heat sink 11. This ensures the reproducibility of the relative distance between the laser elements and the position of the laser beam emitting end face.

Furthermore, it is possible to ensure uniformity of the characteristics of the two laser elements. The distance between the laser chips at this time is set to 1, for example, 250 microns if the numbers shown in FIG. 3 are used as they are. The 90° polarization rotator (quartz plate) 14 is bonded to a polarizing element (calcite plate) 15.
is also used as an external blocking member. Note that 24 is a photodiode for monitoring laser output.

As explained above, in the semiconductor laser module of the present invention, two laser chips or elements are mounted on a heat sink in a conventional semiconductor laser module structure, and the two laser chips or elements are mounted at 90 degrees.
This is a simple optical circuit configuration that only requires the addition of a polarization rotator and a polarization element. Therefore, there is little increase in the number of optical circuit components due to duplication of light sources, and a highly reliable semiconductor laser/single optical circuit can be realized which is small and almost the same size as a conventional semiconductor laser. That is, the present invention is extremely useful as a semiconductor laser module for highly reliable optical fiber communication systems.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing the configuration of a conventional single light source optical circuit, Figure 3 is a diagram showing the configuration of a semiconductor laser module that is an embodiment of the present invention, and Figure 4 is a laser package. 1 is a diagram illustrating a configuration of an embodiment of the present invention having a structure. Explanation of symbols: 11 is a heat sink, 12 and 13 are semiconductor laser chips, and 14 is a 90° polarization rotator. 15 is a polarizing element, 16 is an optical fiber, 17 is a lens, 21 is a package case, 22 and 23 are semiconductor laser elements, and 24 is a photodiode. Figure 2 Figure 3 Figure 4

Claims (3)

[Claims] (1) The main surface is placed on a flat heat sink. Semiconductor laser means for emitting first and second laser beams which are close to each other and whose optical axes and polarization planes of linearly polarized light are parallel to each other and whose emission end surfaces substantially coincide. a 90° polarization rotator that is placed in the optical path of the first laser beam and rotates the polarization plane of the first laser beam by 9 (7') to be perpendicular to the polarization plane of the second laser beam; , a polarizing element that merges the optical paths of the first and second laser beams whose polarization planes are perpendicular to each other by a birefringence effect; an output side optical fiber; and an image conversion of the merged laser beams by the polarizing element and the output. A semiconductor laser duplex module having a lens coupled to a side optical fiber. (2) The device according to items (1) and (2) above. A semiconductor laser duplex module, characterized in that the polarizing element is provided as an output window when the semiconductor laser means, the 90° polarization rotator, and the polarizing element are sealed in a package. (3) The device according to (0) and (2) above, wherein the semiconductor laser means is a semiconductor laser means in which two semiconductor laser elements are configured as a single chip. Duplex module.