Optical waveguides – With optical coupler – With alignment device
Reexamination Certificate
1999-08-24
2003-07-15
Nguyen, Tu T. (Department: 2877)
Optical waveguides
With optical coupler
With alignment device
Reexamination Certificate
active
06594426
ABSTRACT:
The present invention relates to an apparatus and method for controlling the positioning of optical fiber blocks and a Planar Lightwave Circuit, having an arrangement between an input and output optical fiber block for accommodating an optical fiber, and a Planar Lightwave Circuit, respectively.
BACKGROUND OF THE INVENTION
In an optical fiber communication system which uses light, an optical fiber comprises a very fine strand or a cable of bundled-strands which are made of transparent resins such as glass, synthetic resins and the like. The optical fiber is used to transmit information signals and optical images etc. The thickness of the strand is about 3-60 &mgr;m in glass. The optical fiber is of a step index type and a graded index type, etc.
The structure of the step index type includes the following: a core of a high refractive index, a clad of a low refractive index for molding the core, and a jacket for optical absorption which accommodates the core and the clad.
The graded index type has a lower refractive index from its center to its outer circular periphery. The light, in each mode for relating to the length of a fiber or a refractive index distribution, is transmitted by means of meandering or total reflecting in the core with a low-loss. A single mode fiber is one in which a fiber transmits only the lowest mode by way of making the core of the step index type small, and one in which has no mode dispersions and has wide transmission bands.
To branch a path of the above-mentioned optical fiber into plural paths, various devices, apparatuses and methods exist. Particularly, a positioning apparatus and its corresponding method which uses the Planar Lightwave Circuit are widely used. The Planar Lightwave Circuit comprises one or more input parts and a plurality of output parts, cores for forming light-waveguides and a clad for molding the cores. Accordingly, by fixing each core at the input parts and the output parts of the Planar Lightwave Circuit, one or more light-waveguides are branched into plural paths.
FIG. 1
is a schematic diagram of a conventional apparatus for positioning optical fiber
10
blocks and a Planar Lightwave Circuit, and
FIGS. 2A and 2B
are flowcharts according to FIG.
1
.
As shown in
FIG. 1
, the reference numeral
10
is a laser source, the reference numeral
20
is an optical fiber, and the reference numeral
30
is an input optical fiber block. The optical fiber
20
comprises commonly a core (not shown) and a clad (not shown). One side of the optical fiber
20
is connected to the laser source
10
, and another side is accommodated in the input optical fiber block
30
. The laser source
10
generates light signals in order to generate an incident signal inside the optical fiber
20
that is the core and the clad. Accordingly, the optical fiber
20
makes the incident optical signals direct into the input optical fiber block
30
.
The reference numeral
40
is a Planar Lightwave Circuit, the reference numeral
50
is a lens, the reference numeral
51
is an infrared camera, and the reference numeral
52
is a charge coupled device (CCD) camera. The Planar Lightwave Circuit
40
comprises one or more input parts
41
a
and plural output parts
41
b
at both of its ends so as to form waveguides for branching one or more inputs of optical signals into plural paths. One side of the Planar Lightwave Circuit
40
is positioned with the input optical fiber block
30
. Here, the optical fiber
20
accommodated in the input optical fiber block
30
, and the input parts of the cores of the Planar Lightwave Circuit
40
, are positioned in accord with each other.
The CCD camera
52
receives image signals regarding to positioning the Planar Lightwave Circuit
40
and the input optical fiber block
30
. The lens
50
and the infrared camera
51
detect optical output signals introduced from the output parts
41
b
of the core of the Planar Lightwave Circuit
40
, and then check exactly the Planar Lightwave Circuit
40
and the input optical fiber block
30
.
The reference numeral
60
is an output optical fiber block, and the reference numeral
70
is a powermeter. The output optical fiber block
60
accommodates plural optical fibers
21
which are corresponded with output parts
41
b
of the core in the Planar Lightwave Circuit
40
. The powermeter
70
calculates the optical output signals introduced from the cores of the optical fibers
21
of the optical fiber block
60
, and then checks the final status of the input optical fiber block
30
, the Planar Lightwave Circuit
40
and the output optical fiber block
60
.
The reference numerals
81
and
82
are micro-positioners, and reference numeral
83
is an upholder. The upholder
83
fixes the Planar Lightwave Circuit
40
. The micro-positioners
81
and
82
fix the input and the output optical fiber blocks
30
and
60
, respectively, and drive their locations at 6-axes directions, and position both sides of the Planar Lightwave Circuit
40
and each location and angle of the input and the output optical fiber blocks
30
and
60
, respectively. The 6-axes, with reference to
FIG. 1
, are x, y and z axes at a side which is corresponded with each optical fiber block
30
and
60
and the Planar Lightwave Circuit
40
, and &thgr;x, &thgr;y and &thgr;z axes which are each angle of the x, y and z axes.
The reference numeral
80
is a microcomputer. The microcomputer
80
receives input signals introduced from the CCD camera
52
, the infrared camera
51
and the power meter
70
, and then controls each driving status of the micro-positioners
81
and
82
.
With reference to
FIGS. 2A and 2B
, the operations of the above-described conventional structure will be explained as follows.
When one part of the core of the optical fiber
20
is connected to the laser source
10
, and when another part of the core is accommodated in the input optical fiber block
30
, they are both positioned in the input optical fiber block
30
and the Planar Lightwave Circuit
40
(S
101
). In this case, it is preferable that the optical fiber
20
accommodated in the input optical fiber block
30
and the input part
41
a
of the core
40
in the Planar Lightwave Circuit
40
must be positioned to accord with each other in a straight line. Substantially, since the core of the optical fiber
20
is very small, it is difficult for the optical fiber
20
and the input part
41
a
of the core
40
to be accorded with each other.
In such a status, an operator detects each positioned image of the input optical fiber block
30
and the Planar Lightwave Circuit
40
by using the microcomputer
80
and the CCD camera
52
(S
102
), and then decides whether the positions of the images are good. If the position of each image is not satisfactory (S
103
), the operator controls the initial position of the input fiber block
30
to another position for acquiring the determined optical output signal by means of the micro-positioner
81
(S
104
). The initial position of the input fiber block
30
represents a position for acquiring a determined optical output signal passing by the noise areas. It is accomplished generally by a blind-search such as an eye measurement by the operator, and by intuition according to his experiments, and the like. Accordingly, a great deal of time is wasted at the controlling step of this initial position of the total steps, and more time is wasted if the operator is a novice.
Next, the operator positions the lens
50
and the infrared camera
51
to the output part
41
b
of the core
41
of the Planar Lightwave Circuit
40
(S
105
), and detects an optical signal which is introduced from the Planar Lightwave Circuit
40
, by means of the infrared camera
51
(S
106
). If the optical signal is not satisfied (S
107
), the operator detects exactly each position of the input optical fiber block
30
and the Planar Lightwave Circuit
40
(S
108
).
To explain the above-steps in detail, an explanation will follow. In a status that the input optical fiber block
30
, the Planar Lightwave Circuit
40
, the lens
Kim Jin-Soo
Kwon Oh-Dal
Park Hyun-Seob
Nguyen Tu T.
Samsung Electronics Co,. Ltd.
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