JPH0827441B2 - Optical isolator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1). TECHNICAL FIELD OF THE INVENTION The present invention relates to an optical isolator with improved means for preventing reflected return light at the end of an optical fiber coupled to an optical isolator.

(2). BACKGROUND OF THE TECHNOLOGY When transmitting optical information via an optical fiber, it is customary that the optical information is reflected from the receiving end to the sending end. A means for blocking the reflected light through an optical isolator is adopted.

However, there is a problem in the conventional way of coupling the optical fiber and the optical isolator, and the fact that the reflected light is not blocked sufficiently is a fact, and further improvement of the means is demanded.

(3). Conventional technology and problems The end face of the optical fiber facing the conventional optical isolator is formed at right angles to the axis of the optical fiber, and in order to prevent the generation of reflected light due to this, a glass plate is attached to the end face or the end face is Has an anti-reflection coating on it. However, these are disadvantageous in that they are complicated to process, troublesome, and have a problem in their reliability.

(4). SUMMARY OF THE INVENTION The present invention was created in view of the drawbacks of the prior art as described above, and an object thereof is to provide an optical isolator capable of preventing the generation of reflected light at the end face of an optical fiber coupled to the optical isolator. To provide.

(5). Configuration of the invention And, the object is to have a rotor and a plurality of birefringent taper plates arranged so as to sandwich the rotor, the tapered surface of the birefringent taper plate, the light incident side and the light exit side light. In an optical isolator in which the end faces of the fibers are opposed to each other, the end face of each of the optical fibers is formed by inclining with respect to a face perpendicular to the axis of the optical fibers.

(6). Embodiments of the Invention Embodiments of the present invention will be described below with reference to the accompanying drawings.

The accompanying drawings illustrate one embodiment of the present invention. The optical isolator 1 includes a condenser lens 4, a birefringence taper plate 5, a 45 ° Faraday rotator 6, a birefringence taper plate 7, and a condenser lens 8 between an entrance side optical fiber 2 and an exit side optical fiber 3. Are arranged in this order from the fiber 2 to the fiber 3. The 45 ° Faraday rotator 6 is made of, for example, YIG, and 4,5, 6, 7, and 8 constitute the main body A of the optical isolator. Further, the normal line of the end surface of the fiber 2, 3 facing the optical isolator main body A is preferably formed by an inclined surface having the same inclination direction as that of the taper surface with respect to the axis of the fiber 2, 3. Good.

According to this configuration, even if a part of the light reaching the end face 2e of the light entering side optical fiber 2 is reflected by the end face 2e, the reflected light is reflected in the direction as shown in the figure. Can be effectively prevented from returning to the sending end side.

Further, the light passing through the end face 2e is refracted by the birefringent taper plates 5 and 7 constituting the optical isolator main body A so as to be returned in the optical axis direction of the optical isolator of the present invention, and passes through the lens 8 to the exit side optical fiber 3. Is propagated to.

The light incident on the optical fiber 3 is propagated to the receiving end through the light. Further, the end face 3e of the optical fiber 3 also has a reflected light return preventing effect as in the case of the end face 2e.

Further, as described above, the refraction effect of the birefringent tapered plates 5 and 7 is
The light propagated from the optical fiber 2 to the optical fiber 3 is received and returned in the optical axis direction, so that the axis of the optical fiber can be arranged in a straight line.

In the above embodiment, the example in which the inclination direction of the tapered surfaces of the birefringent tapered plates 5 and 7 is set to be the same as the end surfaces 2e and 3e has been described, but the inclination directions of the end surfaces 2e and 3e in the accompanying drawings are the same. Thus, the inclination direction of the tapered surface may be opposite to the inclination direction shown in the accompanying drawings. The arrangement of each element in this case differs from that in the accompanying drawings.

(7). EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to prevent the generation of reflected return light.

The effect of can be achieved without introducing complexity and troublesomeness in processing, which helps to improve reliability, and effects such as enabling the optical fiber to be arranged on the same axis can be obtained.

[Brief description of drawings]

The accompanying drawings illustrate an embodiment of the present invention. In the figure, 1 is an optical isolator, 2 is a light entering side optical fiber, A
Is an optical isolator main body, and 3 is a light output side optical isolator.

Claims (3)

[Claims] 1. A rotator and a plurality of birefringent taper plates arranged with the rotator sandwiched between the rotator, and a tapered surface of the birefringent taper plate and end faces of the optical fibers on the light incident side and the light outgoing side. An optical isolator in which the end faces of the respective optical fibers are formed to be inclined with respect to a plane perpendicular to the axis of the optical fibers. 2. The optical isolator according to claim 1, wherein the inclination directions of the end surface and the taper surface of the birefringent taper plate are the same or opposite to each other. 3. The optical isolator according to claim 1 or 2, wherein the end faces of the input fiber and the output fiber are formed in parallel.