Optical: systems and elements – Optical modulator – Light wave temporal modulation
Reexamination Certificate
2001-11-14
2003-05-06
Ben, Loha (Department: 2873)
Optical: systems and elements
Optical modulator
Light wave temporal modulation
C359S224200, C359S231000, C359S254000, C359S291000, C359S293000, C359S295000, C310S036000, C310S090000, C073S504020, C267S003000, C267S140500, C347S255000, C257S418000
Reexamination Certificate
active
06560002
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical switch used in changing the path of an optical signal, and more particularly, to an optical switch configured such that even if a vibration or oscillation should be transmitted to the optical switch, the operating or performance characteristic of the optical switch is not deteriorated.
2. Description of the Related Art
For the purpose of changing the path of an optical signal propagating through an optical waveguide such as an optical fiber, various types of optical switches have been heretofore used. An example of the prior art optical switch will be described with reference to
FIGS. 1
to
4
.
FIG. 1
is a plan view illustrating a construction of the prior art optical switch, and
FIG. 2
is a sectional view taken along the line
2
—
2
in FIG.
1
and looking in the direction indicated by the arrows. The illustrated switch SW comprises: a movable electrode supporting frame
10
of a generally square in plan; a stationary electrode substrate
8
of a generally square in plan that closes the interior space of the movable electrode supporting frame
10
; a movable electrode plate
2
of a generally square in plan that is disposed substantially in parallel with the stationary electrode substrate
8
with a space or gap between them generally in the center of the top surface of the stationary electrode substrate
8
, that is, generally in the center of the movable electrode supporting frame
10
; four elastic and flexible beams
21
for supporting the movable electrode plate
2
for up and down or vertical motion, each beam having a plurality of meanders or sharply turning portions, one end thereof being fixed to corresponding one of the four sides of the movable electrode plate
2
generally in the center of the side and the other end thereof being fixed to corresponding one of the four sides of the movable electrode supporting frame
10
generally in the center of the side; and a mirror
3
mounted on the center of the top surface of the movable electrode plate
2
along one diagonal line thereof.
Generally in the center of each of the four sides of the movable electrode supporting frame
10
is formed a post-like connecting portion
211
protruding upwardly and formed integrally with the supporting frame
10
. The other end of each beam
21
is fixed to corresponding one of these connecting portions
211
.
The movable electrode supporting frame
10
is configured by boring a generally square opening
12
through a silicon substrate of a generally square in plan, the opening
12
being bored concentrically with the silicon substrate. In case of boring the opening
12
, as will be easily understood from
FIG. 2
, it is preferable that the opening
12
is perforated such that the wall surface of the opening
12
has a taper or slant so that the bore (size) of the opening
12
is gradually increased toward the lower portion thereof, and also it is preferable that the outer wall surface of the generally square stationary electrode substrate
8
is formed so as to have the same taper or slant as that of the opening
12
. It is needless to say that the thickness of the stationary electrode substrate
8
is set to the same value as that of the silicon substrate (the depth of the opening
12
). By such arrangements, it is possible to fit and fix the stationary electrode substrate
8
in the opening
12
of the movable electrode supporting frame
10
in the state that the stationary electrode substrate
8
is electrically insulated from the supporting frame
10
by inserting the stationary electrode substrate
8
into the opening
12
from the bottom side thereof. As a result, the movable electrode supporting frame
10
and the stationary electrode substrate
8
are integrally coupled and become one plate-like body of a generally square.
Further, as one method of electrically insulating the junction between the movable electrode plate
2
and the stationary electrode substrate
8
, it is considered that the stationary electrode substrate
8
will be formed out of an n-type silicon semiconductor, for example, and the movable electrode plate
2
will be formed out of a p-type poly-silicon semiconductor, thereby to form the p-n junction therebetween, and a reverse bias voltage or current will be applied to the p-n junction, which results in the electrical insulation between the movable electrode plate
2
and the stationary electrode substrate
8
. It goes without saying that the junction between the movable electrode plate
2
and the stationary electrode substrate
8
may also be electrically insulated by use of other methods.
In addition, as will be easily understood from the sectional view of
FIG. 2
, the four beams
21
, the movable electrode plate
2
, the four connecting portions
211
, and the movable electrode supporting frame
10
are usually formed integrally with one another. That is, in case of forming the four connecting portions
211
on the movable electrode supporting frame
10
using a semiconductor integrated circuit manufacturing technique, the movable electrode plate
2
and the four beams
21
are formed at the same time. Consequently, the four beams
21
, the movable electrode plate
2
, the four connecting portions
211
and the movable electrode supporting frame
10
are formed integrally with one another. Since such manufacturing method for the optical switch SW is well known, the explanation thereof will be omitted here.
Next, the operation of the optical switch SW constructed as discussed above will be described with reference to
FIGS. 3 and 4
.
FIG. 3
is a plan view for explaining the above-constructed optical switch SW in practical use, wherein the optical switch SW is shown in plan view similar to FIG.
1
. An input side optical waveguide, namely an optical fiber
4
in this example, for inputting an optical signal L into the optical switch SW is positioned at the left side of the optical switch SW in the drawing. An output side optical waveguide, namely an optical fiber
5
in this example, for transmitting the optical signal L supplied from the optical switch SW is aligned with the input side optical fiber
4
along a straight line passing through the mirror
3
at an angle of about 45° with the surface of the mirror
3
, and another output side optical waveguide, namely an optical fiber
6
in this example, for transmitting the optical signal L supplied from the optical switch SW is disposed on a straight line passing through the mirror
3
and orthogonal to the aforesaid straight line.
FIG. 4
is a diagrammatical sectional view illustrating the manner that the optical switch SW shown in
FIG. 3
is accommodated in a package
9
which is shown by only a pedestal
91
for putting the optical switch on the top thereof and fixing it thereto, and the peripheral or neighboring portion of the pedestal
91
. Further, the optical switch SW is shown by a sectional view taken along the line
4
—
4
in FIG.
3
and looking in the direction indicated by the arrows. The input side optical fiber
4
and the output side optical fiber
5
are not sectioned.
As described above, since the mirror
3
is placed on the central portion of the movable electrode plate
2
along a diagonal line thereof, the optical signal L that is outputted from the output end of the input side optical fiber
4
and goes right on in a space is incident on the mirror
3
at an angle of about 45° with the surface of the mirror
3
. As a result, the optical signal L is reflected by the mirror
3
in the direction of forming an angle of 90° (forming a right angle) with the incident light (the optical signal L is outputted from the mirror
3
at an angle of about 45° which is the same as the incident angle), and is transmitted to the input end of the output side optical fiber
6
. In the specification, the transmission state of the optical signal L in which the optical signal L outputted from the input side optical fiber
4
is reflected by the mirror
3
and transmitted to the output side optical f
Ben Loha
Gallagher & Lathrop
Japan Aviation Electronics Industry Limited
Lathrop, Esq. David N.
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