JPH05333245A - Optical device for optical communication and adjusting method therefor - Google Patents

Abstract

PURPOSE:To correct laser light which have elliptic or long circular divergence characteristics into almost circular luminous flux and to facilitate the assembling of optical components for the correction and the mutual positioning of the respective optical components. CONSTITUTION:A collimator lens 12 and a cylinder lens 13 are held by the same holding member 22 and mutually positioned, and also positioned about a semiconductor 11. The condenser lens 14 and the core 32 of an optical fiber are previously set coaxially. Then the position of the holding member 22 is adjusted on an X-Y plane to align optical axes O1 and O2 with each other in the Y direction and the quantity of deviation between the optical axes O1 and O2 is set in the X direction to put laser light, which is made incident on the slanting end surface 32a of the core 32, in phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device for optical communication used in an optical signal amplifying section and the like, and more particularly, it has a function of correcting a light flux emitted from a semiconductor laser into an elliptical or elliptical shape. Further, the present invention relates to an optical device for optical communication and an adjusting method thereof, which enables efficient assembling and adjusting work.

[0002]

2. Description of the Related Art FIG. 10 shows an optical signal amplifier in an optical communication device. In this amplification section, the laser light emitted from the excitation light source in the excitation optical device 1 is sent into the optical fiber F2, and the optical signal S transmitted in the optical fiber F1 and the excitation laser light are coupled by the coupler 2 And is sent to the Er (erbium) optical fiber Fe through the isolator 3. In the Er optical fiber Fe, the optical signal S is amplified by being excited by the excitation laser light, so that the optical signal S is amplified. In the excitation optical device 1, as shown in FIG. 9, the laser light from the semiconductor laser 1a, which is the excitation light source, is collimated by the collimator lens 1b, and is condensed by the condenser lens 1c. Is focused on and made incident.

[0003]

When a semiconductor laser such as a strained superlattice InGaAs having a wavelength of 0.98 μm is used as the semiconductor laser 1a of the excitation light source, as shown in FIG. The angle of the divergent light differs in each of the orthogonal directions, and the cross section of the light flux is not a perfect circle but an ellipse or an ellipse. In the optical device as shown in FIG. 9, when the elliptical or elliptical divergent light as shown in FIG. 7 is directly collected and incident on the core end face of the optical fiber F2, the coupling efficiency is lowered and the optical fiber F2 from the light source is emitted. The amount of light incident on the core is reduced. FIG. 8 shows the beam diameter ratio (ωv) of the divergent light from the semiconductor laser 1a.
/ Ωh) and the level decrease of the optical coupling efficiency to the optical fiber F2 (unit: dB) are shown by a diagram.
As shown in this diagram, the beam diameter ratio (ωv / ωh)
As becomes larger, the decrease in the level of coupling efficiency becomes more remarkable.

Therefore, the excitation optical device 1 is shown in FIG.
It is necessary to provide an optical component such as a prism for correcting a difference in divergence angle of an ellipse or an ellipse as shown in FIG. However, when this kind of optical component is provided in the optical device, the work of aligning the optical component with other optical components such as a lens and a semiconductor laser and the end face of the optical fiber F2 becomes very complicated.

The present invention solves the above-mentioned conventional problems. When a semiconductor laser that requires correction of the beam diameter ratio is used, an optical component for this correction can be easily incorporated in alignment. An object is to provide an optical device for optical communication and a method for adjusting the same.

[0006]

An optical device for optical communication according to the present invention is a semiconductor laser, a collimator lens for collimating divergent light from the semiconductor laser, and a semiconductor laser disposed next to the collimator lens. A cylinder lens that corrects the cross-sectional shape of the light flux based on the divergence characteristic of the optical fiber, and a condenser lens that condenses the light corrected by the cylinder lens on the end face of the optical fiber, the cylinder lens, and a collimator lens or It is characterized in that either one of the condenser lenses is held by the same holding member.

Further, the end face of the optical fiber is formed so as to be inclined with respect to the plane orthogonal to the fiber axis, and the axis of this optical fiber and the optical axis of the condenser lens are arranged coaxially, and the collimator lens and the condenser lens are arranged. The respective optical axes of the are displaced in the inclination direction of the end face of the optical fiber,
The condensed light beam is incident on the end face of the optical fiber at an angle at which the light beam is phase-matched.

Further, the adjusting method according to the present invention is characterized in that any one of the above optical devices for optical communication is used and the relative positions of the holding member and the other lens are aligned.

[0009]

In the above means, the cylinder lens is used as an optical component for correcting the shape of the divergent beam from the semiconductor laser. Since the cylinder lens is held by the same holding member as the collimator lens or the condenser lens, the optical axes of the cylinder lens and one of the lenses can be aligned at the stage of incorporating the holding member. Therefore, as the adjustment at the time of assembling the device, only by aligning the holding member with the other lens or the semiconductor laser, the positional adjustment between the optical components can be easily and highly accurately performed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 and the following figures show, as an embodiment of the present invention, a pumping optical device used in an amplifying section of an optical communication device. Figure 1
6 is a plan sectional view showing the structure of the excitation optical device 10, and FIG. 6 is a perspective view showing the arrangement of the optical components incorporated in the excitation optical device 10. As shown in FIG. 6, this optical device 1
Reference numeral 0 indicates a semiconductor laser 11 having a strained superlattice InGaAs having a wavelength of 0.98 μm as a light source for excitation, a collimator lens 12 for collimating divergent light from the semiconductor laser 11 into a parallel light flux, and a beam emitted from the semiconductor laser 11. A cylinder lens 13 for correcting the diameter ratio, and a condenser lens 14 for converging the laser light corrected by the cylinder lens 13 on the end face 15 of the optical fiber F2 and making the laser light incident.
And are provided.

Semiconductor laser 11 and cylinder lens 1
3, the major axis direction of the laser beam emitted from the semiconductor laser 11 (the beam diameter ωv direction) is oriented along the circumferential surface of the cylinder lens 13, and the minor axis direction of the laser beam (the beam diameter). The ωh direction) is oriented in a direction orthogonal to the circumferential surface of the cylinder lens 13 (axial direction of the circumferential surface). Therefore, the major axis direction of the laser light is focused by the cylinder lens 13 and is corrected so that the cross section becomes substantially a perfect circle. The corrected light flux is condensed by the condenser lens 14 and is incident on the end face 15 of the optical fiber F2.

The excitation optical device 10 shown in FIG. 1 is of a connector type in which the optical fiber F2 can be attached and detached. In the embodiment shown in FIG. 1, the semiconductor laser 11 is a metal case 2.
It is stored in 1. The collimating lens 12 and the cylinder lens 13 are adjusted so that their optical axes coincide with each other, and the holding member 2 is set in a state where the distance in the optical axis direction is set.
Held within 2. The holding member 22 is fixed to the front end portion of the metal case 21 by welding or adhesion, and during the fixing work, the holding member 22 is positioned so that the light emitting point of the semiconductor laser 11 and the optical axis of the collimator lens 12 coincide with each other. The distance between the semiconductor laser 11 and the collimator lens 12 in the optical axis direction is adjusted and set. The metal case 21 and the holding member 22 form a support cylinder 23.
Fixed inside the. The support cylinder 23 is attached to the outer circumference of the small diameter block 24, and the support cylinder 23 is attached to the small diameter block 24.
It is attached so that it can move back and forth in the Z direction.

The small diameter block 24 is a large diameter block 25.
Are abutted against the abutting surface A of the and are fixed to each other by adhesion or welding after adjustment of the relative position. Large diameter block 2
A condenser lens 14 is held in the unit 5. A spacer 26 is provided on the right side of the optical fiber F2, and a sleeve 27 fitted to the spacer 26 is fitted with the tip of the optical fiber F2. This optical fiber F2 clad 31
The tip end surface of the core 32 is formed into a substantially spherical surface.
Although not shown in FIG. 1, the front end of the optical fiber F2 is held by a connector, and when this connector is mounted on the connector block 28, the tip of the optical fiber F2 is fitted into the sleeve 27 and the core 32 is attached. And condenser lens 1
4 is aligned with the optical axis and the optical fiber F
The second tip (the tip surface 32a of the core 32) is abutted against the spacer 26, so that the distance L1 between the condenser lens 14 and the core tip surface 32a is determined.

As described above, on the large diameter block 25 side, the mounting position of the condenser lens 14 and the spacer 26 are arranged.
Also, depending on the dimensions of the sleeve 27, the optical axis of the condenser lens 14 and the optical axis of the core 32 coincide with each other in the state where the optical fiber F2 is fitted in the sleeve 27, and the tip surfaces 32a of the condenser lens 14 and the core 32 are the same. The distance L1 between the and can be set. On the other hand, on the side of the small-diameter block 24, the optical axes of the semiconductor laser 11, the collimator lens 12, and the cylinder lens 13 coincide with each other and their respective positions in the optical axis direction are set by the mutual position setting of the metal case 21 and the holding member 22. It is set.

Therefore, when the optical device 10 is assembled, the small-diameter block 24 abutting on the abutting surface A is finely moved in the XY plane with respect to the large-diameter block 25, so that the optical axes of all the optical parts are made. Can be matched. Further, the distance L2 between the cylinder lens 13 and the condenser lens 14 can be adjusted by finely moving the support cylinder 23 fitted in the small diameter block 24 in the Z direction.

2 and 3 show the optical device 1 shown in FIG.
The positional relationship of each optical component at 0 is shown for each example. In each of FIG. 2 and FIG. 3, (A) is a of FIG.
A plan view in the arrow direction, (B) shows a side view in the arrow direction b in FIG. 2A and 2B show a collimator lens 12, a cylinder lens 13, a condenser lens 14, and a core 3.
2 shows the case where all 2 are located coaxially. As described above, the collimator lens 12 and the cylinder lens 13 are pre-aligned on the small diameter block 24 side, and the optical axis of the condenser lens 14 and the core 32 are pre-aligned on the large diameter block 25 side. Therefore, in the assembling work of the optical device 10 shown in FIG.
The optical components can be adjusted so as to be coaxial with each other simply by finely moving the optical components in the XY plane. Note that FIG. 2 (A)
In (B), the tip surface 32a of the core 32 is a surface perpendicular to the axis. Therefore, it is necessary to prevent the reflected light of the light incident on the tip surface 32a of the core 32 from returning to the semiconductor laser 11 by applying an antireflection treatment such as an antireflection film to the tip surface 32a.

In FIGS. 3A and 3B, in order to prevent the light incident on the core 32 from being reflected by the tip surface 32a and returning to the semiconductor laser 11 side, the tip surface 32a of the core 32 is an axis. It is formed to be inclined with respect to the orthogonal plane. In FIG. 3, the inclination direction of the front end surface 32a of the core 32 is oriented in the X direction. The optical axes O2 of the condenser lens 14 and the core 32 are deviated in the X direction from the optical axes O1 of the collimator lens 12 and the cylinder lens 13. This deviation is
It is set so that the laser light can enter the core 32 from the inclined tip surface 32a in a state where the phases of the laser light are matched.
That is, as shown in FIG. 4, the optical axis of the focused light incident on the tip surface 32a is B, the incident angle is α, the exit angle along the axis O2 of the core 32 is β, and the refractive index of the core 32 is nc. Then, sin (α) = nc · sin (β). As shown in FIG. 3B, the optical axis O1 and the optical axis O2 are
Match in the Y direction. The setting of the optical axes O1 and O2 as shown in FIG.
This is possible by finely moving 4 along the abutting surface A and adjusting.

Next, FIGS. 5A and 5B show a second embodiment of the present invention. In this embodiment, on the left side of the abutting surface A, the collimator lens 12 has the semiconductor laser 11
It is installed in alignment with. That is, the holding member 41 holding the collimator lens 12 is the semiconductor laser 11
The shafts of the two are made to coincide with each other by being fixed to the tip end surface of the metal case 21 and the metal case 21 and the holding member 41.
Are supported by the small-diameter block 24 shown in FIG. 1, for example. Further, on the right side of the abutting surface A, a cylinder lens 13, a condenser lens 14 and a core 32 are provided so as to be positioned relative to each other. That is, cylinder lens 1
3 and the condenser lens 14 are held by a common holding member 42, and inside the holding member 42, both lenses 13 and 14 are held.
The optical axes of are set to match.

The holding member 42 is held by, for example, the large-diameter block 25 shown in FIG. 1, and the holding member 42 and the optical fiber F2 held by the sleeve 27 are preliminarily set to be coaxial with each other. Further, the tip end surface 32a of the core 32 is inclined with respect to the plane orthogonal to the axis, and the inclination direction is set to be along the Y direction. In the assembly adjustment, the small-diameter block 24 is moved along the abutting surface A by X-
By moving in the Y plane, the relationship between the optical axes O1 and O2 of the left and right optical components that sandwich the abutting surface A is adjusted. In this adjustment, as shown in FIG. 5B, the optical axes O1 and O2 are
Set so that and shift in the Y direction. This shift amount is adjusted so that the optical axis B of the incident light with respect to the tip surface 32a of the core 32 has the same relationship as that shown in FIG. Also in FIG.
As shown in (A), the optical axes O1 and O2 are adjusted so as to coincide with each other in the X direction.

In the embodiment shown in FIG. 5, the optical axis of the collimating lens 12 and the optical axis of the condensing lens 14 are displaced from each other in the same manner as in FIG.
The phase of the laser light is matched so that it can be incident. Here, in FIG. 3, the optical axes of the collimator lens 12 and the cylinder lens 13 are matched with each other in advance, but in FIG. 5, the optical axis of the collimator lens 12 and the optical axis of the cylinder lens 13 are displaced from each other by the later adjustment. Become.
Here, if the direction of deviation of the optical axis is the direction along the circumferential surface of the cylinder lens 13 (X direction), the circumferential surface of the cylinder lens 13 causes aberration in the laser light. Therefore, in the embodiment shown in FIG. 5, as shown in FIG.
1 and O2 are displaced in the direction orthogonal to the circumferential surface of the cylinder lens 13, and both optical axes O1 and O2 are aligned in the X direction as shown in FIG. In this way, the optical axis is shifted in the cylinder axis direction, which is irrelevant to the condensing of the cylinder lens 13, so that no aberration occurs.

In the embodiment of FIG. 3, if the inclination direction of the tip end surface 32a of the core 32 and the displacement direction of the optical axes O1 and O2 coincide with each other, the inclination direction and the displacement direction of the optical axis are X-. It may be in any direction on the Y plane. In addition, although the above-described embodiments describe the pumping optical device in the amplification section of optical communication, the present invention is applicable to any application as long as it is an optical module using a semiconductor laser that emits divergent light of an ellipse or an ellipse. However, it can be implemented.

[0022]

As described above, according to the present invention, a cylinder lens is used as an optical member for correcting the divergence characteristic of a semiconductor laser, and this cylinder lens is held by a holding member common to a collimating lens or a condenser lens. Therefore, the optical axes of both lenses can be adjusted in advance. Therefore, for the adjustment of the entire apparatus, it suffices to align the cylinder lens and one lens held by this holding member with the other lens, the semiconductor laser or the like. Therefore, it is possible to configure an optical device that can be easily adjusted and can perform optical coupling with high precision.

[Brief description of drawings]

FIG. 1 is a plan sectional view showing a first embodiment of an optical device according to the present invention,

2A and 2B are a plan view and a side view showing a setting state of an optical axis of an optical component,

3A and 3B are a plan view and a side view showing an optical axis setting state of an optical component according to another embodiment,

FIG. 4 is an explanatory view of an incident angle on the inclined end surface of the core,

5A and 5B are a plan view and a side view showing a setting state of an optical axis of an optical component in an optical device according to a second embodiment of the present invention,

FIG. 6 is a perspective view showing a component structure of an optical device,

FIG. 7 is a perspective view showing divergence characteristics of a semiconductor laser,

FIG. 8 is a diagram showing the relationship between the beam diameter ratio of divergent light from a semiconductor laser and the coupling efficiency with an optical fiber;

FIG. 9 is an explanatory view of component arrangement of a conventional optical device,

FIG. 10 is an explanatory diagram showing a signal amplification unit in the optical communication device.

[Explanation of symbols]

 10 Excitation Optical Device 11 Semiconductor Laser 12 Collimating Lens 13 Cylinder Lens 14 Condensing Lens 21 Metal Case 22 Holding Member 23 Support Tube 24 Small Diameter Block 25 Large Diameter Block 26 Spacer 27 Sleeve 28 Connector Block F2 Optical Fiber 31 Cladding 32 Core 32a Tip Surface

Claims (3)

[Claims] 1. A semiconductor laser, a collimator lens for collimating divergent light from the semiconductor laser, and a cylinder lens arranged next to the collimator lens for correcting the cross-sectional shape of a light beam based on the divergence characteristic of the semiconductor laser. ,
A condensing lens that condenses the light corrected by this cylinder lens on the end face of the optical fiber is provided,
An optical device for optical communication, wherein the cylinder lens and one of a collimating lens and a condenser lens are held by the same holding member. 2. The end face of the optical fiber is formed to be inclined with respect to the plane orthogonal to the fiber axis, and the axis of this optical fiber and the optical axis of the condenser lens are arranged coaxially, and the end face of the collimator lens and the condenser lens are arranged. 2. The optical device for optical communication according to claim 1, wherein the respective optical axes are arranged so as to be offset from each other in the inclination direction of the end face of the optical fiber, and the condensed light beam is incident on the end face of the optical fiber at an angle at which the light beam is phase-matched. 3. An optical communication optical device adjusting method, wherein the optical communication optical device according to claim 1 is used, and the relative position of the holding member and the other lens is adjusted.