JPH0345913A - Semiconductor laser module - Google Patents

Abstract

PURPOSE:To reduce reflection noise and cost with simple constitution by arranging a receptacle where a connector can be attached and detached directly and a semiconductor laser element eccentrically in mutually opposite directions along the optical axis of a lens. CONSTITUTION:A ferrule 14 where the terminal of the optical fiber 13 is processed is fitted in the receptacle 12 and this ferrule 14 can be attached to and detached from the receptacle 12. Further, an LD pellet and the receptacle 12 are arranged so that their optical axes are eccentric in the mutually opposite direction along the optical axis 15 of the lens 11. Thus, the LD pellet 10 and the optical fiber 13 fitted in the receptacle 12 are coupled together where the receptacle 12 and LD pellet 10 have their optical axes eccentric in the mutually opposite directions along the optical axis 15 of the lens 11. Consequently, the low-cost connector attachment/detachment type semiconductor module of simple constitution which generate small reflection noise is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light source for optical communication, and particularly to a semiconductor laser module having a function of efficiently coupling a semiconductor laser (hereinafter referred to as LD) and an optical fiber.

[Conventional technology]

Semiconductor laser modules have already been widely put into practical use as light sources for optical communications, and the basic configuration as shown in FIG. 4 is common. That is, the beam emitted from the LD pellet 1, which is an LD element, is focused onto the end face of the optical fiber 3 by the lens 2.

LD has the characteristic that the near-end reflected light is re-injected, causing reflection noise and deteriorating the modulation characteristics.
By obliquely polishing the end face 3a of , near-end reflected light (broken line) is suppressed.

FIG. 5 shows a specific example of the structure of a conventional semiconductor laser module. Holder 5 that accommodates the ball lens 4
An LD package 6 that accommodates an LD bellet (LD bellet) 1 is fixed to one end, and a ferrule 8 in which an optical fiber 7 is terminated is inserted from the other end, and a holding member 9 is screwed into the holder 5. This ferrule 8 is permanently fixed to the holder 5. Note that the end surface 8a of the ferrule 8 is obliquely polished for the reason described above.

[Problem to be solved by the invention]

In the past, oblique polishing of the ferrule 8 was required in this way, and it was not possible to adopt a structure in which a versatile standard connector whose tip was polished at a right angle could be directly attached and detached. That is, as shown in FIG. 5, the conventional semiconductor laser module has a pigtail structure in which one end of the optical fiber 7 is permanently fixed to the holder 5 of the semiconductor laser module, and the other end has a connector.

A semiconductor laser module is mounted on a circuit board together with a drive circuit, a digital circuit, etc., and constitutes an optical panel. Conventionally, since the semiconductor laser module has a pigtail structure, the connector at the end of the pigtail is connected to the °r adapter mounted on the side of the optical panel, and after processing the excess length of the optical fiber 7, the semiconductor laser module is mounted on the circuit board. Although the module main body is now mounted, the conventional structure has the drawback that the semiconductor laser module main body cannot be mounted on the side surface of the optical panel, that is, the degree of freedom in mounting position is low. Another drawback is that it requires a mounting space equal to the length of the optical fiber 7. Furthermore, since the connector cannot be attached to or detached from the semiconductor laser module main body, parts such as an adapter, an optical connector at the end of the pigtail, and the ferrule 8 inside the semiconductor laser module are required, resulting in high costs. Furthermore, since the length of the optical fiber 7 varies depending on the design of the optical panel, there is also the drawback of poor versatility.

The object of the present invention has been made in view of the above-mentioned drawbacks.
It is an object of the present invention to provide a semiconductor laser module that has a high degree of freedom in mounting position on an optical panel, can reduce the mounting space, can reduce the cost of the optical panel, and has excellent versatility.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention employs a semiconductor laser device, at least one lens that focuses an emitted beam of the semiconductor laser device, and a ferrule having an optical fiber terminated therein, and the ferrule can be attached and detached. In a semiconductor laser module equipped with a receptacle capable of
The structure is such that the optical axes of the semiconductor laser element and the receptacle are eccentric in opposite directions with respect to the optical axis of the lens.

[Effect]

In this way, in the present invention, by arranging the receptacle to which the connector can be directly attached and detached and one semiconductor laser element eccentrically in opposite directions with respect to the optical axis of the lens,
A connector-removable semiconductor laser module with a simple configuration, low reflection noise, and low cost can be realized. As a result, compared to conventional pigtail type semiconductor laser modules, an adapter, a connector at the tip of the pigtail, and a ferrule inside the semiconductor laser module are not required, and the cost of the optical panel can be significantly reduced. Further, since there is no pigtail portion, the mounting space can be reduced, and the degree of freedom in mounting position on the optical panel is increased, and versatility is not reduced due to changes in the pigtail length.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a basic configuration diagram of a semiconductor laser module according to the present invention. A lens 11 that focuses the output beam of the LD pellet 10 is arranged in front of the LD pellet 10 at a predetermined distance apart, and this lens 11
A receptacle 12 is placed in front of the receptacle 12 at a predetermined distance apart. A ferrule 14 in which the optical fiber 13 is terminated is fitted into the receptacle 12, and the ferrule 14 has a structure that can be attached to and detached from the receptacle 12.

Further, the LD pellet 10 and the receptacle 12 are arranged such that their optical axes are eccentric in opposite directions with respect to the optical axis 15 of the lens 11. Therefore, the LD pellet 10 and the optical fiber 13 fitted in the receptacle 12 are coupled to each other at a position where the optical axes of the receptacle 12 and the LD pellet 10 are eccentrically opposite to each other with respect to the optical axis 15 of the lens 11. It looks like this.

Now, the principle of suppressing recombination of the near-end reflected light to the LD pellet will be explained using FIG. Figure 2 shows the LD when the LD Pellet) 10 and the optical fiber 13 are coupled with each other eccentrically by ΔX in opposite directions with respect to the optical axis 15 of the lens 11.
It shows changes in the pellet-optical fiber coupling loss L1 and the recombination loss L2 of the near-end reflected light to the LD pellet IO with respect to ΔX. Generally, the rate of increase in L2 is greater than the increase in Ll. Therefore, there is a ΔXo in which the desired L20 can be obtained within a range where Ll does not increase.

Therefore, L is adjusted so that the eccentricity ΔX0 is as described above
By configuring a semiconductor laser module by arranging a D-bellet and a receptacle, a semiconductor laser module with low reflection noise can be realized even if a ferrule of a general optical connector having a vertical end face is inserted.

FIG. 3 is a sectional view showing an embodiment of a semiconductor laser module according to the present invention. A stopper 17 for abutting the end face of the optical fiber is screwed into the receptacle 16.
Further, a holder 19 containing a ball lens 18 is welded and fixed to the receptacle 16 in an eccentric state. Further, the LD package 2 in which the LD pellet 20 is hermetically sealed
1 is positioned so as to optimally couple with the optical fiber (not shown) inserted into the receptacle 16, and then inserted into the holder 19.
is fixed by welding means.

In experiments, when the angle of incidence on the optical fiber end face exceeds 5 degrees, the reflection noise becomes sufficiently small and the increase in force coupling loss becomes 0.
5 dB, confirming that the structure of the present invention is effective as a countermeasure against near-end reflection.

〔Effect of the invention〕

As explained above, according to the semiconductor laser module according to the present invention, the receptacle to which the connector can be directly attached and detached and the semiconductor laser element are arranged eccentrically in opposite directions with respect to the optical axis of the lens. It has become possible to realize a connector-removable semiconductor laser module with a simple configuration, low reflection noise, and low cost.

As a result, compared to conventional pigtail type semiconductor laser modules, an adapter, a connector at the end of the pigtail, and a ferrule inside the semiconductor laser module are not required, and the cost of the optical panel can be significantly reduced. Further, since there is no pigtail portion, the mounting space can be reduced, the degree of freedom in mounting position on the optical panel can be increased, and further, it has various effects such as preventing a decrease in versatility due to changes in the pigtail length. Therefore, the semiconductor laser module of the present invention has a high possibility of being widely put into practical use, and its industrial value is extremely high.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of a semiconductor laser module according to the present invention, FIG. 2 is a diagram explaining the principle of the present invention, FIG. 3 is a sectional view showing an embodiment of a semiconductor laser module according to the present invention, and FIG. 5 is a basic configuration diagram of a conventional semiconductor laser module, and FIG. 5 is a sectional view showing an example of a conventional semiconductor laser module. 0.20...LD bellet, 1...Lens, 2.16...Receptacle, 3...Optical fiber, 14...Ferrule , 5... Optical axis, 18... Ball lens,
9...Holder, 21...LD package.

Claims (1)

[Claims] A semiconductor laser module comprising a receptacle in which a semiconductor laser element, at least one lens that focuses an emitted beam of the semiconductor laser element, and a ferrule in which an optical fiber is terminated are fitted, and in which the ferrule can be attached and detached, A semiconductor laser module characterized in that the optical axes of the semiconductor laser element and the receptacle are arranged eccentrically in opposite directions with respect to the optical axis of the lens.