JPH07333469A - Semiconductor laser module - Google Patents

Abstract

PURPOSE:To decrease the number of parts by constituting the end face of a fixing part having inclination in such a manner that the propagation optical axis of a optical fiber has a prescribed angle with the propagation optical axis of an optical system. CONSTITUTION:A ferrule holder 7 is mounted with the inclination in such a manner that this holder has the prescribed angle with the propagation optical axis of a system consisting of a semiconductor laser element 1 and the optical system 2. A ferrule 6 which is supported to a ferrule holder 7 in the same structure as the structure of the conventional semiconductor laser module and the optical fiber 3 which is held in this ferrule 6 is also inclined with the propagation optical axis of the optical system 2. The angle formed by the propagation optical axis of the optical system 2 and the propagation optical axis of the optical fiber 3 is an angle complementary with the refraction of the incident and exit light generated by a Snell's law at the end face of the optical fiber. Then, the incident laser on the end face of the optical fiber 3 via the optical system 2 from the semiconductor laser 1 is coupled to the optical fiber 3 with the extremely high efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser module. More specifically, the present invention relates to a novel structure of a semiconductor laser module that integrates a semiconductor laser, an optical system and an optical fiber.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view showing a typical structure of a conventional semiconductor laser module.

As shown in FIG. 1, the semiconductor laser module is constructed by integrating a semiconductor laser 1, an optical system 2 and an optical fiber 3. Here, the semiconductor laser 1
Are usually contained in the package 4. Optical system 2
Are supported and mounted by a lens holder 5 formed at one end of the package 4. On the other hand, the optical fiber 3
The ferrule 6 is supported by the ferrule holder 7 after being inserted into the ferrule 6 near the end thereof. The ferrule holder 7 is attached to the lens holder 5 at one end. With the above structure, the semiconductor laser 1, the optical system 2, and the optical fiber 3 are positioned so as to be arranged on one optical axis.

FIG. 5 is a diagram showing another structure of a conventional semiconductor laser module.

As shown in FIG. 1, in this semiconductor laser module, the monitor photodiode 10 and the first lens are used.
A semiconductor laser 1 mounted on a substrate 12 together with 11 and the like is housed in a metal case 13. A window sealed with hermetic glass 14 is formed at one end of case 13,
The second lens 16 supported by the lens holder 15 is mounted outside this window. The optical fiber 3 is supported by the ferrule holder 7 via the ferrule 6 attached to its end, which is the same configuration as the semiconductor laser module shown in FIG.

In the semiconductor laser module configured as described above, the laser light emitted from the semiconductor laser 1 is converged by the optical system including the first lens 11 and the second lens 16, and is arranged at the image forming position. The end face is coupled to the optical fiber 3.

By the way, the semiconductor laser used in the above-mentioned semiconductor laser module has an unstable oscillation state due to so-called return light noise increasing when the laser light emitted by itself is re-incident due to reflection or the like. Is known to become.

Therefore, as shown in FIG. 4 or FIG.
In general, the end face of the optical fiber 3 is inclined and polished so that the reflected light on the end face of the optical fiber 3, which is the strongest reflected light, does not return to the semiconductor laser.

However, when the end face of the optical fiber is inclined and polished, the propagation optical axis of the optical fiber and the optical axis of the light entering and exiting from the end face of the optical fiber do not coincide with each other according to the so-called Snell's law. That is, as shown in FIG. 6, even if the optical axis of the optical fiber and the optical axis of the incident light are matched,
In reality, the light tries to travel in the direction deviated by the angle β shown in the following Expression 2. Therefore, high coupling efficiency cannot be obtained at the inclined end surface of the optical fiber.

[Formula 2] β = θ− [sin ⁻¹ {(n ₀ / n ₁ ) · sin θ}] [where n ₀ and n ₁ are the atmosphere of the optical fiber and the refractive index of the optical fiber, respectively] , Θ is the angle formed by the end face of the optical fiber with respect to the plane perpendicular to the propagation optical axis of the optical fiber. ]

For the above-mentioned reason, the optical axis of the incident / emitted light with respect to the optical fiber having the inclined end face does not coincide with the propagation optical axis of the optical fiber. Therefore, in the semiconductor laser module having the above-mentioned structure, the semiconductor laser It is known that the coupling efficiency between the element and the optical fiber decreases.

Therefore, it has been proposed to reduce the above-mentioned decrease in coupling efficiency by inclining the optical fiber itself and mounting it in the optical module.

FIG. 7 is a sectional view showing the structure of a semiconductor laser module proposed for improving the coupling efficiency which has been lowered due to the above-mentioned reasons. In addition, in FIG.
The same reference numerals are attached to the components common to the.

As shown in the figure, this semiconductor laser module basically has the same components as the general semiconductor laser module shown in FIG. 4, but is mounted on the end of the optical fiber 3. The ferrule 6 is replaced with the adapter 8
Is different from the ferrule holder 7 in that it is tilted and supported with respect to the ferrule holder 7. That is, the inclinations of the ferrule 6 and the optical fiber 3 coincide with the deviation of the optical axis caused by the Snell's law described above, and the decrease in coupling efficiency at the end face of the obliquely polished optical fiber 3 is improved. .

[0015]

As described above, various improvements have been proposed for the semiconductor laser module and many problems have been solved. However, even for the semiconductor laser module shown in FIG. The following problems are still pointed out.

That is, in the structure of the conventional semiconductor laser module shown in FIG. 7, since the adapter 8 is a new component added, the number of fixing points necessary for positioning the optical fiber 3 itself increases, and the positioning is performed. The accuracy and strength after fixing tend to deteriorate. Further, the number of manufacturing processes is increased, which leads to an increase in cost.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a novel semiconductor laser module having a simpler structure and good characteristics.

[0018]

According to the present invention, a semiconductor laser device housed in a package and a lens holder mounted on the package support a laser beam emitted from the semiconductor laser device at a predetermined position. An optical system arranged so as to converge the light into a ferrule, and the tip end face is inserted into a ferrule, and the tip end face is obliquely polished so as to form a constant angle from a plane perpendicular to the propagation optical axis. A semiconductor laser module comprising: an optical fiber whose end face is positioned so as to match the convergent position of the laser beam; and a ferrule holder for positioning and fixing the ferrule with respect to the package or the lens holder. A holder has a tubular shape coaxial with the ferrule and supports the ferrule from a side surface; A fixed part that is coupled to the ferrule support part and has the other surface abutting against the package or the lens holder, wherein the propagation optical axis of the optical fiber is relative to the propagation optical axis in the optical system. A semiconductor laser module is provided in which an end surface of the fixing portion is inclined so as to form a predetermined angle.

[0019]

In the semiconductor laser module according to the present invention, the support structure of the optical fiber ferrule is changed so that not only the number of parts is simply reduced, but also the manufacturing process is simplified and the strength is improved.

In the conventional semiconductor laser module shown in FIG. 7, instead of using the same part as the ferrule holder used in the conventional module, a new adapter part is used so that the relative length of the optical fiber can be improved. I was tilting my posture.

On the other hand, in the semiconductor laser module according to the present invention, the ferrule holder itself is mounted at an angle to the package or lens holder,
The ferrule is directly supported by this ferrule holder. Therefore, it is not necessary to prepare a new member such as an adapter for holding the ferrule.

As described later in detail, such a ferrule holder can be easily manufactured only by slantingly polishing the end surface of a normal ferrule holder, and it is not necessary to manufacture a new part. Further, since the end face processing of the ferrule holder has been conventionally performed, this semiconductor laser module is completely the same as the manufacturing process of the conventional module.

Hereinafter, the present invention will be described more specifically with reference to the drawings, but the following disclosure is merely an example of the present invention and does not limit the technical scope of the present invention.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a concrete configuration example of a semiconductor laser module according to the present invention. Note that, in FIG. 1, the same reference numerals are given to constituent elements common to FIG.

As shown in the figure, this semiconductor laser module basically has a common structure with the most general semiconductor laser module shown in FIG. 4 or FIG. However, the ferrule holder 7a is mounted so as to be inclined with respect to the propagation optical axis of the system including the semiconductor laser device 1 and the optical system 2 so as to form a predetermined angle described later.
Therefore, the ferrule 6 supported by the ferrule holder 7a has the same structure as the conventional semiconductor laser module.
And the optical fiber 3 held by the ferrule 6
Also tilts with respect to the propagation optical axis of the optical system 2.

In the above structure, the angle formed by the propagation optical axis of the optical system 2 and the propagation optical axis of the optical fiber 3 is, as shown in FIG. 2, refraction of incident and outgoing light generated by Snell's law at the end face of the optical fiber. Is an angle complementary to. That is, it is an angle represented by the following formula 1 with respect to an angle θ formed by the end face of the optical fiber 3 with respect to a plane perpendicular to the propagation optical axis of the optical fiber 3.

[Formula 1] α = [sin ⁻¹ {(n ₁ / n ₀ ) · sin θ}] − θ [where n ₀ and n ₁ are the atmosphere of the optical fiber and the refractive index of the optical fiber, respectively] , Θ is the angle formed by the end face of the optical fiber with respect to the plane perpendicular to the propagation optical axis of the optical fiber. ]

Therefore, the laser light incident on the end face of the optical fiber 3 from the semiconductor laser 1 via the optical system 2 is coupled to the optical fiber 3 with extremely high efficiency.

FIG. 3 is a diagram showing another concrete configuration example of the semiconductor laser module according to the present invention, which corresponds to the configuration of the conventional semiconductor laser module shown in FIG.

That is, this semiconductor laser module also has the same basic structure as the conventional semiconductor laser module shown in FIG. 5, but the ferrule holder 7a has a semiconductor laser element 1 and an optical system 2. Is installed so as to be inclined at a predetermined angle α with respect to the propagation optical axis of the system. Therefore, the ferrule 6 supported by the ferrule holder 7a with the same structure as the conventional semiconductor laser module and the optical fiber 3 held by the ferrule 6 are also inclined with respect to the propagation optical axis of the optical system 2. .

In this case as well, the angle α formed by the propagation optical axis of the optical system 2 and the propagation optical axis of the optical fiber 3 is, as shown in FIG. 2, refracted by the Snell's law at the end face of the optical fiber. Is an angle complementary to.

[0032]

As described above, the semiconductor laser module according to the present invention has a smaller number of parts and is easier to manufacture than the conventional semiconductor laser module having the same function. Further, the mechanical strength of the final product is high, and the present invention contributes widely to the entire field of use of the semiconductor laser module.

[Brief description of drawings]

FIG. 1 is a diagram showing a specific configuration example of a semiconductor laser module according to the present invention.

FIG. 2 is a partial enlarged view showing a structure near an end of an optical fiber in a semiconductor laser module according to the present invention.

FIG. 3 is a cross-sectional view showing another configuration example of the semiconductor laser module according to the present invention.

FIG. 4 is a cross-sectional view showing a typical configuration of a conventional semiconductor laser module.

FIG. 5 is a sectional view showing another configuration of a conventional semiconductor laser module.

FIG. 6 is a diagram for explaining an end face shape of an optical fiber in a conventional semiconductor laser module.

FIG. 7 is a cross-sectional view showing a configuration of a conventional improved semiconductor laser module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser element, 2 ... Optical system, 3 ... Optical fiber, 4 ... Package, 5 ... Lens holder, 6 ... Ferrule, 7 ... Ferrule holder, 8. ..Adapter 11 ... first lens, 12 ... substrate, 13 ... case, 14 ... hermetic glass, 15 ... lens holder, 16 ... second lens,

Claims (3)

[Claims] 1. A semiconductor laser element housed in a package and supported by a lens holder mounted in the package,
An optical system arranged so as to converge the laser light emitted from the semiconductor laser device to a predetermined position, and the tip end portion is inserted into a ferrule, and the tip end face is a plane perpendicular to the propagation optical axis. An optical fiber that is obliquely polished so as to have a certain angle, and is positioned so that the tip end face matches the convergence position of the laser light, and the ferrule is positioned and fixed with respect to the package or the lens holder. In a semiconductor laser module including a ferrule holder for the ferrule holder, the ferrule holder has a cylindrical shape coaxial with the ferrule and supports the ferrule from a side surface, and one surface is used as the ferrule support portion. A propagating optical axis of the optical fiber, including a fixing part that is coupled to the other surface of the optical fiber and contacts the other surface with the package or the lens holder. A semiconductor laser module wherein the end face of the fixed portion to form a predetermined angle with respect to the propagation optical axis in the optical system has a slope. 2. The semiconductor laser module according to claim 1, wherein the end surface of the fixed portion is inclined so as to form an angle α represented by the following formula 1. [Equation 1] α = [sin ⁻¹ {(n ₁ / n ₀ ) · sin θ}] − θ [where n ₀ and n ₁ are the refractive indices of the propagation medium of the laser light outside and inside the optical fiber, respectively] And θ is an angle formed by the end face of the optical fiber with respect to a plane perpendicular to the propagation optical axis of the optical fiber. ] 3. The semiconductor laser module according to claim 1 or 2, wherein the inclined end surface of the ferrule holder is a surface formed by polishing the end surface of the ferrule holder. Semiconductor laser module.