Optical waveguides – With optical coupler – Switch
Reexamination Certificate
1998-09-18
2001-11-20
Font, Frank G. (Department: 2877)
Optical waveguides
With optical coupler
Switch
C385S022000, C385S016000
Reexamination Certificate
active
06320999
ABSTRACT:
TECHNICAL DOMAIN
The invention relates to the domain of optical microstructures and microtechnologies. In particularly it relates to the domain of integrated optical switches. It also relates to the domain of optomechanical micro-devices, for example microdeflectors.
STATE OF PRIOR ART
Document FR-A-2 660 444 divulges an optical microstructure composed of an optical switch. It includes a description of the optical switch represented in
FIG. 1
attached. This device receives an incident light beam I transported by fiber
2
and transmits a switched beam C either towards fiber
4
or towards fiber
6
. Switch
1
comprises a guide structure formed on a substrate
12
with an entry surface E and an exit surface S. It comprises an entry microguide
18
and two exit microguides
20
and
22
. In this example, microguides
18
and
20
are parallel to a direction x parallel to the largest surface
8
a
of the guide structure. Microguides
18
and
20
are laid out such that one continues on from the other and on each side of a recess
24
passing though the guide structure and extending into the substrate.
The exit microguide
22
located on the same side as the recess
24
and the microguide
20
and adjacent to this microguide, comprises a part
21
parallel to microguide
20
in this example on the exit side S of the switch, and a part
23
forming an elbow A with part
21
, on the side of the hollow part
24
. Thus the entry ends
20
a
and
22
a
of the exit microguides
20
and
22
respectively opening into hollow part
24
, are closer to each other than their exit ends, flush with the exit surface S of the guide structure.
Hollow part
24
defines a flexible beam
26
oriented at rest parallel to the x direction. This beam
26
can deform in hollow part
24
along a y direction, parallel to the surface
8
a
of the guide structure and perpendicular to the x direction. This beam
26
has a fixed end
28
fixed to the guide structure and substrate
12
, and a free end
30
capable of deforming in hollow part
24
. The beam
26
is defined in the guide structure and is provided with a central microguide
32
extending over its entire length and, at rest, oriented parallel to the x direction. This central microguide
32
is placed along the continuation of the entry microguide
18
such that their longitudinal axes parallel to the x direction are coincident.
The incident beam transported by the entry microguide
18
is switched towards the exit microguide
20
by bringing the free end
32
a
of the central microguide of the beam facing and coincident with the entry end
20
a
of the exit microguide
20
. Similarly, the incident beam transported by the entry microguide
18
is switched to the exit microguide
22
by bringing the free end
32
a
on the central microguide facing and coincident with the entry end
22
a
of the exit microguide
22
. This second configuration is shown in FIG.
1
.
For example, deformations of the beam to make end
32
a
of the central microguide coincide either with end
20
a
of the exit microguide
20
, or with end
22
a
of microguide
22
, are made using variable capacitors. This is done by applying metallizations
36
and
46
to each of the lateral surfaces of hollow part
24
on the guide structure
8
oriented along the x direction. Furthermore, metallizations
38
and
44
are applied to each of the lateral surfaces of the facing beam
26
oriented along the x direction when it is at rest. The facing metallizations
36
and
38
form the armatures of a first variable capacitor to which a voltage can be applied using an electrical power supply source
40
electrically connected to these armatures through conductors
42
placed on the surface
8
a
of the guide structure. Similarly, facing metallizations
44
and
46
form the armatures of a second variable capacitor to which a voltage can be applied using an electricity power supply source
48
connected using conducting wires
50
placed on the surface
8
a
of the guide structure.
Application of an appropriate voltage to the terminals of these capacitors creates an electrostatic force parallel to the y direction and causing deformation of the beam
26
along this y direction.
This type of optical switch may be made from a semi-conducting substrate using microelectronics methods. These methods can collectively obtain integrated optical switches.
At the present time, the problem of precise positioning of the optical switching microguide has been solved, either by controlling the control force on the moving beam or by bringing two etching planes into contact (in other words as a limit stop). The first solution makes it necessary to be able to apply a constant force and/or servocontrol the applied force as a function of a parameter representing the position. The second solution is sensitive to lateral under-etching and over-etching of the mechanical structure.
The optical switching microguide is only held in position by maintaining the force applied to the beam, which requires energy consumption to maintain this force. If an electrostatic force is applied, as in the case of the device shown in
FIG. 1
, once the capacitor has been charged it is still necessary to prevent it from becoming discharged in the long term.
DESCRIPTION OF THE INVENTION
The invention is designed to solve these problems by proposing a system for positioning an optical microstructure in a device under the action of control means, comprising an element supporting the optical microstructure and connected to the device, the orientation of the said element with respect to the device varying under the action of control means in order to put the optical microstructure in at least one determined position, mechanical means of fixing the said element in position with respect to the device being provided to hold the optical microstructure in the said determined position.
Advantageously, the mechanical immobilization means are designed to release the said element under the action of the control means.
Preferably, the mechanical immobilization means comprise a male part and a female part with a shape complementary to the male part, one of the said parts belonging to the said element and the other part belonging to the device, the microstructure being held in the said determined position by the male part penetrating into the female part. According to one preferred embodiment, the male part and the female part have axes of symmetry parallel to the optical axis of the optical microstructure. Thus, when the microstructure is immobilized, the axes of symmetry of the male and female parts are superposed and an over-etching or under-etching defect in the male or the female part has no incidence on the precise positioning of the microstructure. Operation is better if the male part has a pointed cross section, the female part being a housing with a complementary shape. The said element may comprise at least one beam, called the main beam, connected by one of its ends to the device and its other end being free. It may then comprise at least one secondary beam placed transversally with respect to the main beam and rigidly attached to the main beam, the secondary beam supporting one of the said parts of the mechanical immobilization means. Preferably, this secondary beam is located at the free end of the main beam. The secondary beam may be fixed by one of its ends to the main beam, its other end being free and comprising one of the said parts of the mechanical immobilization means, for example the male part. The secondary beam may be such that it does not deform during displacement of the microstructure under the action of the control means.
The control means may be capacitive devices developing an electrostatic force in response to an electrical control voltage. They may also be magnetic and/or piezoelectric means. They position the element in the determined position.
In some cases control means may also be used to cooperate with the mechanical means to hold the element in position.
The invention may be applied to the manufacture of an integr
Labeye Pierre
Pouteau Patrick
Burns Doane , Swecker, Mathis LLP
Commissariat A l'Energie Atomique
Font Frank G.
Lauchman Layla
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