JPH0580231A - Optical coupler and its coupling method - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain an optical coupler in which the ferrule is fixed at the position where the coupling loss is minimized by collimating while measuring the optical coupling loss. [Structure] A spherical part is formed at the tip, and the ferrule holding member in which the optical fiber and the optical fiber protection member for inserting the tip into the central axis through hole are inserted and fixed is rotatable, and the light collecting function is in the optimum state. After adjusting the ferrule holding member to a position that realizes, the connecting portion by the cap and the flange inscribed in the spherical surface of the spherical portion is fixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an optical coupler for various optical parts such as an optical switch, an optical multiplexer / demultiplexer, an optical isolator and a coupling method thereof.

[0002]

2. Description of the Related Art Miniaturization of optical devices and optical components used with the development of optical communication is desired. Especially in optical isolators, optical circulators, optical multiplexers / demultiplexers, etc.
There is a demand for downsizing and simplification of the structure in the state of being coupled with an optical fiber. In recent years, distributed feedback lasers with a narrow spectrum width have been used in high-speed systems for optical communication, but since they are sensitive to back reflection, it is also required that the ends of optical fibers have high return loss. Has become.

Generally, in a pigtailed optical isolator with an optical fiber, the light emitted from the optical fiber 1 is made to enter the optical device 4 as parallel light by the spherical lens 2 or the gradient index lens 3 as shown in FIG. The emitted light is similarly focused again on the optical fiber 1 to be coupled.

[0004]

In the conventional optical collimator system, in order to obtain a high optical coupling, the optical fiber and the lens must be independent parts and they must be adjusted to the optimum positions, as shown in FIG. As described above, since the two optical fibers and the two lenses have to be aligned with each other, the productivity is low, and as a result, the collimating system is expensive. In addition, the optical coupling between the optical fiber and the lens is greatly reduced due to the optical axis shift and the angle shift, and there is a demand for an optical coupler that is less affected by the optical axis shift and the angle shift.

FIG. 3 shows an optical collimating system previously proposed by the present inventor for the purpose of improving the drawbacks of the conventional optical fiber coupling system, which has a converging sphere portion integrally fused to the optical fiber. This is a fiber collimator that is compatible with mass production. Here, a state is shown in which two fiber converging portions are butted and faced each other to perform optical coupling, and the coupling loss with respect to the coupling angle deviation θ is shown in FIG. As is clear from Fig. 4, a slight angle deviation parabolically increases the optical coupling loss, and in order to realize the currently required coupling loss of 0.2 dB or less, an angle deviation of 0.1 ° or less must be achieved. I have to.

[0006]

According to the present invention, a ferrule in which an optical fiber and a fiber collimator are inserted into this optical coupler and the tip is formed into a spherical shape, and the spherical portion is a connecting portion consisting of a flange and a cap inscribed with each other. It is a structure that is sandwiched and fixed, and by using a coupling structure that forms a rotatable spherical surface at the connecting part, the ferrule is collimated while measuring the optical coupling loss and the position where the coupling loss is the smallest, that is, the position where the angle deviation is the smallest. This is a method of fixing the spherical portion and the connecting portion.

According to the structure of the optical coupler of the present invention, a ferrule holding member having a spherical portion formed at its tip and an optical fiber having a light collecting function at the tip and an optical fiber protection member inserted and fixed in the through hole of the central axis is provided. Inscribed in the spherical surface of the spherical part,
One is sandwiched and fixed by a flange and a cap connected from the fiber side and the other from the spherical tip side.

In the optical coupling method of the present invention, the spherical portion is formed at the tip, and the ferrule holding member in which the optical fiber and the optical fiber protection member having the tip condensing function are inserted and fixed in the through hole of the central axis, the spherical portion is formed. Inscribed in the spherical surface of each other, one from the fiber side, the other from the spherical tip side in the connecting portion formed by the flange and the cap,
This is achieved by making the distal spherical ferrule holding portion rotatable and adjusting and fixing the ferrule holding member and the connecting portion to a position where the converging function realizes an optimum state.

[0009]

FIG. 1 shows an embodiment of the present invention, in which a spherical portion 5 is formed at the tip, and an optical fiber 7 and an optical fiber protection member forming a spherical portion 6 having a tip condensing function in the central axis through hole. The ferrule holding member 9 in which 8 is inserted and fixed connects and holds the cap 10 inscribed with the spherical surface of the spherical portion 5 from the optical fiber side, and the flange 11 inscribed in the same from the spherical tip side. ing.

[0010]

According to the structure and method of the present invention, the optical coupling loss is measured while being collimated and adjusted at the position where the coupling loss is the smallest, that is, the position where the angular deviation is the minimum, and the ferrule spherical portion and the coupling portion are mass-produced. And an optical coupler that can be easily fixed was realized.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical coupler according to the present invention.

FIG. 2 is a schematic diagram of an optical fiber optical system.

FIG. 3 is a sectional view of a conventional optical fiber collimator.

FIG. 4 shows the coupling loss with respect to the coupling angle deviation θ of the optical coupler.

[Explanation of symbols]

 1 optical fiber 2 spherical lens 3 gradient index lens 4 optical device 5 spherical part 6 fiber spherical part 7 optical fiber 8 optical fiber protection member 9 ferrule holding member 10 cap 11 flange

Claims (2)

[Claims] 1. A ferrule holding member in which a spherical portion is formed at a tip and an optical fiber having a light condensing function for the tip and an optical fiber protection member is inserted and fixed in a through hole of a central axis of the ferrule holding member and the spherical surface of the spherical portion. An optical coupler characterized in that one side is connected to the fiber side and the other side is connected from the spherical tip side by a flange and a cap that are connected. 2. A ferrule holding member in which a spherical portion is formed at the tip and an optical fiber and an optical fiber protective member having a tip condensing function are inserted and fixed in a through hole of a central axis of the ferrule holding member and the spherical surface of the spherical portion. The tip spherical ferrule holding portion is rotatable in the connecting portion formed by the flange and the cap that are connected, one from the fiber side and the other from the spherical tip side, and at the position where the condensing function achieves the optimum state. A method of coupling an optical coupler, characterized in that the ferrule holding member and the connecting portion are adjusted and then fixed.