GB2120400A

GB2120400A - A connection between a generator of optical rays and an optical waveguide

Info

Publication number: GB2120400A
Application number: GB08312476A
Authority: GB
Inventors: Pierre Nory
Original assignee: Compagnie Industriel des Lasers CILAS SA
Current assignee: Compagnie Industriel des Lasers CILAS SA
Priority date: 1982-05-14
Filing date: 1983-05-06
Publication date: 1983-11-30
Also published as: GB8312476D0; GB2120400B; FR2526961A1; JPS58208717A; FR2526961B1; DE3317093A1

Abstract

The connection between an optical ray generator (e.g. a laser generator 1) and an optical waveguide (e.g. an optical fibre 12) includes means (4) for concentrating the rays. Said means (4) comprise a transparent element or assembly of elements (5, 6) having a convex input face (8) and a concave output face (9) of smaller size. The various dimensions are chosen so as to produce an afocal optical system, thereby reducing the accuracy required in the relative positions of the parts to be connected and the means for concentrating the rays. <IMAGE>

Description

SPECIFICATION A connection between a generator of optical rays and an optical waveguide The present invention relates to a connection between a generator of optical rays and an optical waveguide.

A known connection of this type comprises a laser beam emitter and a convergent optical system aligned on a common axis, with the optical system being suitable for concentrating the beam onto the input to an optical fibre.

This connection has drawbacks. In particular, it requires the distance between the optical system and the input to the fibre to be accurately adjusted. Also, the distribution of laser energy in the beam concentration zone depends on said adjustment.

Preferred embodiments of the present invention mitigate these drawbacks.

The present invention provides a connection between an optical ray generator and an opticai waveguide, the connection comprising: an optical ray generator; means for concentrating the rays; and an optical waveguide having an end disposed to receive the concentrated rays; wherein said means for concentrating the rays is constituted by a block which is transparent to said rays, the outside surface of said block comprising first and second opposite curved faces which are respectively convex and concave, the first face being larger than the second face and being disposed to receive light rays in a parallel input beam, the curvature of the first face being so determined that the refracted input beam in the block is concentrated onto the second face, and the curvature of the second face being so determined that the concentrated beam leaves the block via the second face in a parallel output beam, whereby the entire output beam is capable of entering into the waveguide via said end thereof.

Particular embodiments of the invention are described below, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a longitudinal section through a first connection in accordance with the invention; and Figure 2 is a perspective view of a second connection in accordance with the invention.

In Figure 1, a laser ernitter 1 emits a parallel beam 2 along an axis 3. A cylindrical block 4 which is transparent to the laser rays, is centered on the axis 3 and lies on the path of the beam 2.

The block 4 comprises two elements 5 and 6 which ara made of respective materials having different optical properties: for example they may have different refractive indices, or different dispersive powers, or both different refractive indices and dispersive powers simultaneously. The elements 5 and 6 are glued together along a joint surface 7. One end of the outside surface of the block 4 has a convex curved face 8, eg. of spherical curvature, which is centered on the axis 3 and through which the beam 2 enters the block.

The other end of the outside surface of the block 4 has a concave curved face 9, likewise of spherical curvature, which is centered on the axis 3 and which is opposite to the face 8. The beam 2 is refracted into the block 4 to become a converging beam 10 which concentrates the laser energy on the face 9 which is smaller than the face 8. The curvature of the face 9 is so determined that the beam 10 leaves the block 4 along a parallel beam 11 which is of smaller cross section than the beam 2. The input face 1 3 of an optical fibre 12 is centered on the axis 3 to receive the beam 1 The diameter of the beam 11 is smaller than or equal to the diameter of the fibre 12, whereby the entire laser energy is transmitted by the fibre.

The block 4 thus constitutes a compact afocal optical system. The purpose of making the block from two elements having different optical properties adhering to each other is to correct any possible chromatic or geometrical aberrations.

It is clear that the operation of the connection is unaffected by the position of the block 4 along the axis 3 between the emitter 1 and the fibre 2.

Further, the position of the block along the axis has no effect of the transverse distribution of laser energy in the beam 11.

In Figure 2, a semiconductor laser emitter 14 has an emission surface 15 in the form of an elongate rectangle. In this case, the transparent block is in the shape of a thin parallelepiped 1 6.

The laser rays (not shown) from the emitter 14 enter the block 1 6 via a convex face 1 7 disposed facing the emission surface 15 of the laser 14. The rays leave via a concave output face 1 8. As can be seen in the figure, the faces 17 and 1 8 are disposed on two opposite sides of the large cross section of the block 1 6. The beam of rays leaving the block 16 is generally in the shape of a parallelepiped so that the entire beam enters a flattened waveguide 1 9 which is likewise in the shape of a parallelepiped via an end face thereof.

Naturally, the transparent block may be made of a singie element, or may comprise more than two elements of different optical properties.

Further, the curved faces 8 and 9 may be aspherical.

1. A connection between an optical ray generator and an optical waveguide, the connection comprising: an optical ray generator; means for concentrating the rays; and an optical waveguide having an end disposed to receive the concentrated rays; wherein said means for concentrating the rays is constituted by a block which is transparent to said rays, the outside surface of said block comprising first and second opposite curved faces which are respectively convex and concave, the first face being larger than the second face and being disposed to receive light rays in a parallel input beam, the curvature of the first face being so determined that the refracted input beam in the block is concentrated onto the second face, and

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A connection between a generator of optical rays and an optical waveguide The present invention relates to a connection between a generator of optical rays and an optical waveguide. A known connection of this type comprises a laser beam emitter and a convergent optical system aligned on a common axis, with the optical system being suitable for concentrating the beam onto the input to an optical fibre. This connection has drawbacks. In particular, it requires the distance between the optical system and the input to the fibre to be accurately adjusted. Also, the distribution of laser energy in the beam concentration zone depends on said adjustment. Preferred embodiments of the present invention mitigate these drawbacks. The present invention provides a connection between an optical ray generator and an opticai waveguide, the connection comprising: an optical ray generator; means for concentrating the rays; and an optical waveguide having an end disposed to receive the concentrated rays; wherein said means for concentrating the rays is constituted by a block which is transparent to said rays, the outside surface of said block comprising first and second opposite curved faces which are respectively convex and concave, the first face being larger than the second face and being disposed to receive light rays in a parallel input beam, the curvature of the first face being so determined that the refracted input beam in the block is concentrated onto the second face, and the curvature of the second face being so determined that the concentrated beam leaves the block via the second face in a parallel output beam, whereby the entire output beam is capable of entering into the waveguide via said end thereof. Particular embodiments of the invention are described below, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a longitudinal section through a first connection in accordance with the invention; and Figure 2 is a perspective view of a second connection in accordance with the invention. In Figure 1, a laser ernitter 1 emits a parallel beam 2 along an axis 3. A cylindrical block 4 which is transparent to the laser rays, is centered on the axis 3 and lies on the path of the beam 2. The block 4 comprises two elements 5 and 6 which ara made of respective materials having different optical properties: for example they may have different refractive indices, or different dispersive powers, or both different refractive indices and dispersive powers simultaneously. The elements 5 and 6 are glued together along a joint surface 7. One end of the outside surface of the block 4 has a convex curved face 8, eg. of spherical curvature, which is centered on the axis 3 and through which the beam 2 enters the block. The other end of the outside surface of the block 4 has a concave curved face 9, likewise of spherical curvature, which is centered on the axis 3 and which is opposite to the face 8. The beam 2 is refracted into the block 4 to become a converging beam 10 which concentrates the laser energy on the face 9 which is smaller than the face 8. The curvature of the face 9 is so determined that the beam 10 leaves the block 4 along a parallel beam 11 which is of smaller cross section than the beam 2. The input face 1 3 of an optical fibre 12 is centered on the axis 3 to receive the beam 1 The diameter of the beam 11 is smaller than or equal to the diameter of the fibre 12, whereby the entire laser energy is transmitted by the fibre. The block 4 thus constitutes a compact afocal optical system. The purpose of making the block from two elements having different optical properties adhering to each other is to correct any possible chromatic or geometrical aberrations. It is clear that the operation of the connection is unaffected by the position of the block 4 along the axis 3 between the emitter 1 and the fibre 2. Further, the position of the block along the axis has no effect of the transverse distribution of laser energy in the beam 11. In Figure 2, a semiconductor laser emitter 14 has an emission surface 15 in the form of an elongate rectangle. In this case, the transparent block is in the shape of a thin parallelepiped 1 6. The laser rays (not shown) from the emitter 14 enter the block 1 6 via a convex face 1 7 disposed facing the emission surface 15 of the laser 14. The rays leave via a concave output face 1 8. As can be seen in the figure, the faces 17 and 1 8 are disposed on two opposite sides of the large cross section of the block 1 6. The beam of rays leaving the block 16 is generally in the shape of a parallelepiped so that the entire beam enters a flattened waveguide 1 9 which is likewise in the shape of a parallelepiped via an end face thereof. Naturally, the transparent block may be made of a singie element, or may comprise more than two elements of different optical properties. Further, the curved faces 8 and 9 may be aspherical. CLAIMS

1. A connection between an optical ray generator and an optical waveguide, the connection comprising: an optical ray generator; means for concentrating the rays; and an optical waveguide having an end disposed to receive the concentrated rays; wherein said means for concentrating the rays is constituted by a block which is transparent to said rays, the outside surface of said block comprising first and second opposite curved faces which are respectively convex and concave, the first face being larger than the second face and being disposed to receive light rays in a parallel input beam, the curvature of the first face being so determined that the refracted input beam in the block is concentrated onto the second face, and the curvature of the second face being so determined that the concentrated beam leaves the block via the second face in a parallel output beam, whereby the entire output beam is capable of entering into the waveguide via said end thereof.

2. A connection according to claim 1, wherein the transparent block comprises a plurality of elements adhering to one another, said elements adhering to one another, said elements being being made of materials having different optical properties.

3. A connection according to claim 1 or 2, wherein the block is generally cylindrical in shape, with the first and second curved faces being disposed on the end faces of the cylindrical block.

4. A connection according to claim 1 or 2, wherein the block is in the shape of a thin parallelepiped, with the first and second curved faces being disposed on two opposite sides of the large cross section of the block.

5. A connection according to any preceding claim, wherein the input beam, the first and second faces and said end of the waveguide are centered on a common axis.

6. A connection according to claim 5, wherein the first and second curved faces are spherical.

7. A connection according to any preceding claim, wherein the generator is a laser emitter, and the waveguide is an optical fibre.

8. A connection between an optical ray generator and an optical waveguide substantially as herein described with reference to the accompanying drawing.