JPH0511111U - Optical device for single-core two-way communication - Google Patents

Abstract

(57) [Abstract] [Purpose] The purpose is to reduce the transmission error rate in a full-duplex single-core bidirectional optical system to an extremely low level and to transmit information accurately. [Structure] Light emitted from a single-core bidirectional optical device on the local station side is transmitted to a single-core bidirectional optical device on the partner station side by a transmission optical fiber 4, and a polarization beam splitter 1
When the light is transmitted through 6 and enters the light emitting element 18, the light reflected by the light emitting element 18 is returned to the transmission optical fiber 4 by holding the light emitting element 18 tilted with respect to the optical axis of the optical device. It becomes a non-existent structure and there is no interference S
The N ratio is improved. [Effect] By using the single-core bidirectional optical device according to the present invention, the S / N ratio can be made very large, so that the transmission error rate of the full-duplex single-core bidirectional optical system can be lowered, and the information can be transmitted. It has the effect that it can be transmitted accurately.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical dataway connecting terminals having a transmitting / receiving function with an optical fiber, and particularly to an optical device for single-core bidirectional communication (hereinafter referred to as an optical device) used for single-core bidirectional optical communication.

[0002]

[Prior Art]

 Conventionally, an optical device has a structure as shown in FIG. The optical device has two through holes with high precision such as hole diameter and straightness that are orthogonal to each other. The four openings of the two through holes are receptacles for fastening optical fiber connector plugs. The second collimator 7 holding the first collimator 3 having the above, the polarization beam splitter 6 and the light emitting element 8, the light receiving element 5, and the light absorber 2 are respectively inserted.

In FIG. 2, the optical devices are distinguished from the own station side and the partner station side, but these are exactly the same and are distinguished for the sake of explanation. Next, the operation of this optical device will be described. This optical device simultaneously functions as a transmitter and a receiver for optical signals. First, the operation as a transmitter will be described based on the local station side. The light emitted from the light emitting element 8 constituting the second collimator 7 of the local side optical device becomes parallel light by the optical lens 9 arranged so as to come to the front focal position, and the parallel light is polarized beam splitter 6. Is divided into two light fluxes. One of the divided light beams is absorbed by the light absorber 2. The other light beam is incident on the optical lens 10 forming the first collimator 3, is focused on the transmission optical fiber 4 arranged at the back focal point of the optical lens 10, and is transmitted to the optical device on the partner station side.

Next, the operation as a receiver will be described based on the partner station side. The light transmitted through the transmission optical fiber 4 is incident on the first collimator 13 of the optical device on the partner station side. The incident light is collimated by the optical lens 19 forming the first collimator 13. The parallel light is split into two light beams by the polarization beam splitter 16. One of the divided light beams enters the light receiving element 15 as signal light. The other light flux is incident on the optical lens 20 and is incident on the light emitting element 18 arranged at the back focal point of the optical lens 20.

When the partner station side is the transmitter and the own station side is the receiver, the operation is performed by following a route reverse to these operations. By connecting this optical device to both sides of the transmission optical fiber 4, it becomes possible to simultaneously perform bidirectional communication with one optical fiber. Hereinafter, such a communication mode will be referred to as full-duplex single-core bidirectional.

[0006]

[Problems to be solved by the device]

 It is self-evident that in order to realize full-duplex single-core bidirectional communication, the interference between two signals transmitted in the transmission optical fiber must be suppressed. In the case of full-duplex single-core bidirectional communication, both of the two optical devices connected to both ends of the transmission optical fiber transmit an optical signal and both receive an optical signal. In such a case, if the optical signal transmitted from the local station side is reflected by a reflection point in the optical path and enters the light receiving element on the local station side, it becomes indistinguishable from the signal light from the other station side, and interference will occur. Occurs.

The main reflection points in the optical path are the optical device on the partner station side and both end faces of the transmission optical fiber. Of these, the ratio of the reflected light from the optical device on the partner station is large, and this reflected light has a great influence on the interference. The behavior of the reflected light from the partner station will be described with reference to FIG. The light transmitted from the own station side to the other station side and emitted from the end surface of the transmission optical fiber 4 on the other station side becomes parallel light by the optical lens 20, and the light transmitted through the polarization beam splitter 16 is converged by the optical lens 19. Then, the light is incident on the light emitting element 18. Since the light emitting element 18 is held perpendicular to the optical axis of the first collimator, the light incident on the light emitting element 18 is reflected by the end face of the light emitting element 18, and the reflected light is transmitted. The same route as that when it travels is followed in the opposite direction to return to the own station side, and the light is received by the light receiving element 5 on the own station side. This causes interference and increases the transmission error rate.

Therefore, an object of the present invention is to solve such a conventional problem and reduce interference due to reflected light from the light emitting element in the optical device on the partner station side to reduce the transmission error rate.

[0009]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention has a configuration in which the light emitting element is held while being inclined with respect to the optical axis of the first collimator.

[0010]

[Action]

 With the above configuration, part of the light reflected by the local optical device penetrates the core of the optical fiber and leaks to the clad, and the reflected light is reduced.

[0011]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment according to the present invention. The polarization beam splitter 6 is held by adhesion on the end face of the second collimator 7 from which the parallel light is emitted. The light emitting elements 18 and 8 are held by the solders 25 and 26 after the shaft alignment using the shaft alignment jig is completed. Since the axis alignment jig is tilted in advance with respect to the optical axis of the first collimator, when the light emitting element is mounted on the jig, the light emitting element is naturally inclined with respect to the optical axis of the optical device. The tilted state allows the light emitting element to be held obliquely with respect to the optical axis of the optical device.

As a means for holding the light emitting element, solder or adhesive can be used. It goes without saying that other than that, it is sufficient if the element can be fixed firmly. Next, the operation will be described. In FIG. 4, the reflected light when the signal light from the own station side enters the light emitting element 18 on the opposite station side is 21 (a to c). The direction perpendicular to the optical axis of the first collimator is designated by + -Z axis direction. As described above, the light emitting element 18 is held so as to be tilted with respect to the optical axis of the first collimator, so that the reflected light 21 is not incident on the optical lens 19 as in 21 (c). Further, even when the light enters the optical lens 19, the reflected light 21 (a) returns in the opposite direction along the same path as when the light enters, and the reflected light 21 (b) shows the first collimator. There is a portion that returns on a path deviated in the-direction of the Z-axis with respect to the optical axis that it has entered from the time of incidence. The reflected lights 21 (a) and (b) incident on the optical lens 19 are transmitted to the optical lens 20 in FIG.

The operation of this part will be described with reference to FIG. The reflected light 22 (a) enters the transmission optical fiber 4 and is transmitted to the optical device on the local side, but the reflected light 22 (b) is at an angle exceeding the numerical aperture of the transmission optical fiber 4. Since it is incident, it penetrates through the core portion 23 and leaks toward the cladding portion 24. Therefore, it is not transmitted to the local optical device.

In this way, by holding the light emitting element 18 of the optical device on the partner station side while being inclined with respect to the optical axis of the first collimator, reflection by the light emitting element 18 on the partner station side that causes interference may occur. The proportion of light that returns to the local optical device is extremely low.

[0015]

[Effect of the device]

 As described above, the present invention has a structure in which the light emitting element that constitutes the optical device is held by being tilted with respect to the optical axis of the first collimator. Therefore, the optical device according to the present invention is a full-duplex single device. By using the optical communication system for two-way optical communication, the SN ratio can be made very large and the transmission error rate can be made extremely low, so that information can be transmitted accurately.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of an optical device according to the present invention.

FIG. 2 is an explanatory diagram of a conventional method of an optical device.

FIG. 3 is an explanatory diagram showing a problem of a conventional example.

FIG. 4 is an explanatory view showing the operation of the present invention.

FIG. 5 is an explanatory view showing the operation of the present invention.

[Explanation of symbols]

 2 Optical Absorber 3 First Collimator 4 Transmission Optical Fiber 5 Light-Receiving Element 6 Polarizing Beam Splitter 7 Second Collimator 8 Light-Emitting Element 9 Optical Lens 10 Optical Lens 12 Light Absorber 13 First Collimator 15 Light-Receiving Element 16 Polarizing Beam Splitter 17 Second Collimator 18 Light Emitting Element 19 Optical Lens 20 Optical Lens 21 Reflected Light 22 Reflected Light 23 Core Part 24 Clad Part 25 Solder 26 Solder

Claims (1)

Claims for utility model registration: 1. A first collimator having a receptacle to which an optical fiber connector plug can be fastened, a second collimator having a light emitting element, and polarization planes for making incident light orthogonal to each other. A polarization beam splitter that splits the light into two emitted lights and a light receiving element, and the polarization beam splitter is disposed on the optical path of the first collimator.
In a single-core two-way communication optical device in which the second collimator is arranged on one optical path from the first collimator divided by the polarization beam splitter and the light receiving element is arranged on the other optical path, The light-emitting element is held by being tilted with respect to the optical axis of the first collimator, and the single-core bidirectional communication optical device is characterized.