JPH04118621A - Optical coupler - Google Patents

Abstract

PURPOSE:To reduce the size of the optical coupler and to improve the reliability as optical equipment by coupling multiplexed light and external light optically through a dichroic mirror and a converging rod lens. CONSTITUTION:A polarization multiplexer 4 multiplexes laser light emitted by a 1st semiconductor laser 2 and laser light emitted by a 2nd semiconductor laser 3 at right angles to the projection direction of the laser light. The multiplexed light incidence surface of the converging rod lens 21 which converges the multiplexed light on a 1st optical fiber 22 is formed of a slanting surface and the dichroic mirror which couples projection light projected from a 2nd optical fiber 24 with the multiplexed light optically is provided on the slanting surface. Consequently, the need for a wavelength multiplexer demultiplexer which is required before is eliminated, so the constituent components can be stored in a single housing to reduce the size of the optical equipment and also improve the reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical coupler suitable for use in a wavelength multiplexing system in the field of optical communications.

[Conventional technology]

Conventionally, this type of optical coupler has been constructed as shown in FIG. To explain this based on the same figure, in the same figure, inside the first casing indicated by reference numeral 1, there is a first semiconductor laser 2 that emits a laser beam at (wavelength λ), and a first semiconductor laser 2 that emits a laser beam at (wavelength λ,). a second semiconductor laser 3 that emits laser light ax (wavelength λ1) in a direction perpendicular to the laser light emission direction;
A polarization combiner 4 that combines laser light a1 emitted from this semiconductor laser 3 and laser light a2 that is emitted from the first semiconductor laser 2, and a combined light a (wavelength λ,) emitted from this polarization combiner 4. A condensing lens 5 for condensing light is housed therein. Further, 6 is a lens that condenses the laser beam a1 emitted from the first semiconductor laser 2, and 7 is a lens that condenses the laser beam a2 that is emitted from the second semiconductor laser 3.

On the other hand, inside the housing indicated by reference numeral 8, there is a lens 10 that condenses the composite light a (wavelength λI) that has passed through the optical connector 9, and a condenser lens 11 that extends in a direction perpendicular to the composite light a that is emitted from this lens 10. Combine external light b (wavelength λt) emitted from
A wavelength multiplexer/demultiplexer 12 for demultiplexing, and a lens 13 for condensing the multiplexed/demultiplexed light (a+b) emitted from the wavelength multiplexer/demultiplexer 12 are housed. Further, 14 is an optical fiber for introducing the multiplexed/separated light emitted from the lens 13, and 15 is an optical fiber for emitting external light in the optical axis direction of the lens 10. Note that 16 and 17 are respectively coupled to the optical systems of the two cylindrical bodies 1 and 8, and are connected to the optical connector 9.
It is an optical fiber connected to

[Problem to be solved by the invention]

By the way, in this type of optical coupler, the polarization combiner 4
In addition, since the structure includes a wavelength multiplexer/demultiplexer 12, two casings 1 and 8 are required, which not only increases the number of parts but also increases the size of the entire coupler.

Furthermore, since the optical connector 9 is required in addition to the prism and fiber coupler used in the wavelength multiplexer/demultiplexer 12, the number of optical connection points increases accordingly, reducing the reliability of the optical device. There was also the problem.

The present invention has been made in view of these circumstances, and it is an object of the present invention to provide an optical coupler that can be downsized and improve reliability as an optical device.

[Means to solve the problem]

The optical coupler according to the present invention includes a polarization combiner that combines a laser beam emitted from a first semiconductor laser and a laser beam emitted from a second semiconductor laser in a direction perpendicular to the emission direction of this laser beam; The combined light emitted from the polarization combiner is
Equipped with a focusing rod lens that focuses light on the optical fiber,
The combined light incident surface of this rod lens is formed as an inclined surface, and a dichroic mirror is installed on this slope to optically couple the output light emitted from the second optical fiber and the combined light.

[For production]

In the present invention, optical coupling of combined light and external light is performed via a dichroic mirror and a focusing rod lens.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the structure etc. of this invention will be explained in detail by the Example shown in the figure.

FIG. 1 is a diagram schematically showing an optical coupler according to the present invention. In the figure, the same members as in FIG. 2 are denoted by the same reference numerals, and detailed explanations are omitted. In the figure, the reference numeral 21 is a focusing rod lens that focuses the combined light a emitted from the polarization combiner 4 onto the first optical fiber 22. As shown in FIG. Combined light incidence surface 21a of this converging rod lens 21
is formed by an inclined surface having a slope with respect to the optical axis of the polarization combiner 4. 23 is a second optical fiber 24
A dielectric dichroic ink mirror optically couples the output light and the composite light emitted from the mirror, and is bonded to the composite input surface 21a. Further, 25 is a focusing rod lens that focuses the laser beam a emitted from the first semiconductor laser 2, and 26 is a focusing rod lens that focuses the laser beam a! emitted from the second semiconductor laser 3. A focusing rod lens that focuses the light, 2
Reference numeral 7 denotes a converging rod lens that condenses external light emitted from the second optical fiber 24. These focusing rod lenses 25 to 27 and the focusing rod lens 21
The lens pitches are 0.2, 0.2°0.3, and
It is 0.18. In addition, each laser beam aI+a! A chip (not shown) is built in so that the beams are emitted at right angles to each other.

In the optical coupler configured in this way, the combined light a and the external light are optically coupled via the dichroic mirror 23 and the focusing rod lens 21. In this case, the combined light a passes through the dichroic mirror 23, and the external light is reflected by the dichroic mirror 23.

Therefore, in this embodiment, the wavelength multiplexer/demultiplexer 12 that is conventionally required is not required, so the components can be housed in a single housing (not shown).

Further, in this embodiment, since the wavelength multiplexer/demultiplexer 12 and the optical connector 9 are not required, the number of optical connection points can be reduced.

The present invention can be applied to, for example, a light source for an El doped optical fiber amplifier, but it goes without saying that it can also be applied to other light sources. Here, E,
To apply to the light source for doped optical fiber amplifier, λ
1 and λ2 are 1.48 μm and 1.536 μm.

Incidentally, in this embodiment, an optical isolator may be inserted between the polarization combiner 4 and the focusing rod lens 21.

Furthermore, in the present invention, duplication by polarization synthesis is useful in order to double the power of the bombing light incident on the E-doped optical fiber.

〔Effect of the invention〕

As explained above, according to the present invention, the polarization synthesizer combines the laser light emitted from the first semiconductor laser and the laser light emitted from the second semiconductor laser in a direction perpendicular to the emission direction of this laser light. and a focusing rod lens that focuses the combined light emitted from the polarization combiner onto a first optical fiber, the combined light incident surface of this rod lens is formed by an inclined surface, and a second Since a dichroic mirror was installed to optically couple the output light emitted from the optical fiber and the composite light, the composite light and the external light are optically coupled via the dichroic mirror and the focusing loft lens. Therefore, the wavelength multiplexer/demultiplexer that was conventionally required is no longer necessary, and the components can be housed in a single housing, making it possible to downsize the optical device. Furthermore, since the conventionally required wavelength multiplexer/demultiplexer and optical connector are no longer necessary, the number of optical connection points can be reduced, and reliability as an optical device can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an optical coupler according to the present invention, and FIG. 2 is a diagram schematically showing a conventional optical coupler. 2... First semiconductor laser, 3... Second semiconductor laser, 4... Polarization combiner, 21... Focusing rod lens, 21a... Combined light incident surface, 22... First optical fiber, 24... second optical fiber. Patent applicant: NEC Corporation

Claims (1)

[Claims] a polarization combiner that combines a laser beam emitted from a first semiconductor laser and a laser beam emitted from a second semiconductor laser in a direction perpendicular to the emission direction of the first semiconductor laser; a converging rod lens that condenses light onto a first optical fiber, a composite light incident surface of the converging rod lens is formed by an inclined surface, and the output light emitted from the second optical fiber and the An optical coupler characterized by installing a dichroic mirror that optically couples combined light.