JPH0815582A - Optical bidirectional module - Google Patents

Abstract

PURPOSE:To obtain an optical bidirectional module having good spatial resolution by disposing a lens on a light emitting element and light receiving element side of a large numerical aperture and disposing a polarizing element on an optical fiber side of a small numerical aperture. CONSTITUTION:This optical bidirectional is formed by successively disposing a semiconductor laser 2, a photodiode 3, a lens 4, a diffraction grating 5 and an optical fiber 6. As a result, the light signal emitted from this semiconductor laser 2 is condensed through the lens 4 and is passed through the diffraction grating 5; thereafter, only the diffracted light of zero order is emitted to the optical fiber 6. On the other hand, the light signal propagating the optical fiber 6 is emitted from the optical fiber 6 and is passed through the diffraction grating 5; thereafter, the incidence of the diffracted light of the first order on the photodiode 3 is made possible. In such a case, the lens 4 is disposed on the semiconductor laser 2 side of the large numerical aperture and the exit light from the semiconductor laser 2 is condensed before diffusing, by which the permissible range of the relative positions of the semiconductor laser 2 and the diffraction grating 5 is increased and the resolution efficiency is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical bidirectional module for performing optical bidirectional communication using a light emitting element and a light receiving element and an optical fiber for bidirectionally transmitting an optical signal.

[0002]

2. Description of the Related Art Conventionally, there is a method of transmitting both upstream and downstream signals with one optical fiber when performing bidirectional communication using the optical fiber. Both the light emitting element and the light receiving element need to be optically coupled. In this bidirectional optical module, as shown in FIG. 2, the light of the light emitting element 12 passes through a beam splitter or a half prism 15 to form a lens. While the light is condensed by 14 and sent to the optical fiber 16, the light of the optical fiber 16 passes through the lens 14 and is reflected by the beam splitter or the half prism 15 to enter the light receiving element 13.

However, in the structure shown in FIG. 2, the light emitting element 1
2 and the light receiving element 13 are at a right angle position, and the entire module for optical bidirectionalization becomes large. Therefore, as shown in FIG. 3, the nth order light (n is an integer) of the deflection element 17 such as a diffraction grating is transmitted. By using the light emitting element 12 and the light receiving element 13
There is an optical bidirectional module having a structure in which is arranged in the vicinity.

[0004]

However, in the case of the configuration shown in FIG. 3, the numerical aperture of the optical fiber 16 is usually smaller than the numerical apertures of the light emitting element 12 and the light receiving element 13.
If the deflecting element 17 and the lens 14 are not provided in consideration of this, the pattern of the deflecting element 17 becomes fine and the spatial resolution may deteriorate. However, none of the conventional optical bidirectional modules specifically shows the arrangement in consideration of the numerical aperture.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is an optical bidirectional module including at least a light emitting element and a light receiving element, and an optical fiber for bidirectionally transmitting an optical signal. In the above, a light emitting element and a light receiving element, a lens for condensing light, a deflecting element for deflecting light, and an optical fiber are arranged in this order, and the light emitting element and the light receiving element are the nth order light (n is an integer) of the deflecting element. This is an optical bidirectional module that utilizes the optical fiber to transmit and receive.

The lens for condensing the light of the present invention includes both a lens for collimating the incident light and a lens for converging the incident light at a certain point.

[0007]

According to the present invention, by disposing a lens on the side of a light emitting element and a light receiving element having a large numerical aperture, and arranging a deflecting element on the side of an optical fiber having a small numerical aperture, the lattice spacing of the deflecting elements or The phase distribution array does not become fine, and the optical bidirectional module has good spatial resolution.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, an optical bidirectional module 1 of the present invention comprises a semiconductor laser 2, a photodiode 3, a lens 4, a diffraction grating 5 and an optical fiber 6 which are arranged in this order. With such a configuration, the optical signal emitted from the semiconductor laser 2 is condensed through the lens 4,
After passing through the diffraction grating 5, only the 0th order diffracted light is emitted to the optical fiber 6. On the other hand, the optical signal transmitted through the optical fiber 6 is emitted from the optical fiber 6, passes through the diffraction grating 5, and then the first-order diffracted light can enter the photodiode 3.

Here, in order to deflect the light emitted from the semiconductor laser having a large numerical aperture by using the diffraction grating, it is necessary to narrow the gap between the semiconductor laser and the diffraction grating and to make the grating spacing of the diffraction grating fine. is there. However, as in the configuration of the present embodiment, by disposing the lens 4 on the side of the semiconductor laser 2 having a large numerical aperture so that the emitted light from the semiconductor laser 2 is condensed before being diffused, the semiconductor laser 2 and the semiconductor laser 2 are diffracted. Since the allowable range of the relative position with respect to the grating 5 is increased and the grating spacing of the diffraction grating 5 is prevented from becoming fine, the diffraction grating 5 is easily manufactured, and the resolution efficiency of the nth-order light (n is an integer) is improved. Has improved,
Spatial resolution is improved. Further, since the incident angle to the optical fiber 6 is small, even if the optical fiber 6 moves back and forth in the optical axis direction, the amount of received light does not change so much, the allowable placement range of the optical fiber 6 increases, and a plurality of optical fibers are installed. Even when doing so, the tolerance of the optical fiber can be largely obtained.

In this embodiment, the lens 4 is a lens that collimates incident light into parallel light, and the diffraction grating 5 has a lens function. As a result, the light between the lens 4 and the diffraction grating 5 becomes parallel light, so that the allowable placement range of the diffraction grating 5 increases, and the diffraction grating 5 can be moved so as to be adjusted to a preferable position with respect to the optical fiber 6. . A lens that collects incident light at one point may be used as the lens 4, and by using such a lens, the distance between the lens 4 and the diffraction grating 5 can be shortened, and the entire optical bidirectional module can be made compact. Can be converted.

In this embodiment, the semiconductor laser 2 is used as the light emitting element, but the light emitting diode may be used, and the photodiode 3 is used as the light receiving element, but another light receiving element may be used, and the diffraction element is used as the diffraction element. Although the grating 5 is used, a hologram may be used. The 0th order light and the 1st order light of the diffraction grating 5 are used, but other nth order light (n is an integer) may be used. Further, by disposing another lens between the optical fiber 6 and the diffraction grating 5, the distance between the optical fiber 6 and the diffraction grating 5 can be shortened, and the entire optical bidirectional module 1 can be further downsized. . Further, since the semiconductor laser 2 and the photodiode 3 are close to each other, they can be modularized, and the optical bidirectional module 1 can be further miniaturized.

[0013]

As described above, according to the optical bidirectional module of the present invention, the light emitting element and the light receiving element, the lens for condensing the light, the deflecting element for deflecting the light, and the optical fiber are arranged in this order. , The light emitting element and the light receiving element transmit and receive to and from the optical fiber by using the nth-order light (n is an integer) of the deflection element, thereby facilitating the manufacture of the deflection element. The decomposition efficiency is improved and the spatial resolution is improved. Furthermore, it is possible to provide an optical bidirectional module in which the allowable placement range of the optical fiber and the deflection element is increased.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an optical bidirectional module of the present invention.

FIG. 2 is a schematic configuration diagram showing a conventional bidirectional optical module.

FIG. 3 is a schematic configuration diagram showing a conventional bidirectional optical module.

[Explanation of symbols]

 1: Optical bidirectional module 2: Semiconductor laser 3: Photodiode 4, 14: Lens 5: Diffraction grating 6, 16: Optical fiber 12: Light emitting element 13: Light receiving element 15: Beam splitter or half prism 17: Deflection element

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H04B 10/14 10/04 10/06

Claims (1)

[Claims] 1. An optical bidirectional module comprising at least a light emitting element and a light receiving element and an optical fiber for bidirectionally transmitting an optical signal, wherein the light emitting element and the light receiving element are provided.
A lens for condensing light, a deflecting element for deflecting light, and the optical fiber are arranged in this order, and the light emitting element and the light receiving element are connected to the optical fiber by using the nth-order light (n is an integer) of the deflecting element. An optical bidirectional module characterized by transmitting and receiving between.