Optical gate based optical space division switch

Details Optical gate based optical space division switch Optical gate based optical space division switch

1999-08-23

2002-11-12

Wu, Daniel J. (Department: 2632)

Optical: systems and elements

Deflection using a moving element

Using a periodically moving element

C359S199200, C385S016000

Reexamination Certificate

active

06480309

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to optical gate based optical space division switches, and more particularly to an optical space division switch in which optical gates are connected in a two-stage manner to cross-couple optical signals, so that optical signals inputted through arbitrary input ports can be switched to a desired output port with no internal collision.
2. Description of the Prior Art
Generally, optical gate based optical space division switches function to switch optical signals inputted through arbitrary input ports to a desired output port in response to optical gates being turned on or off.
A 4×4 optical gate based optical space division switch has been proposed by Gustavsson et al., and it is shown in
FIG. 1
herein (see: “Monolithically integrated 4×4 InGaAs/InP laser amplifier gate switch arrays”, Electronic Letters, vol.28, no.24, pp.2223-2225, Nov. 1992).
As shown in
FIG. 1
, the 4×4 optical gate based optical space division switch comprises an optical gate
110
with four optical amplifiers
111
based on semiconductor devices, and 1×4 optical splitters
121
-
124
having their input terminals connected respectively to output terminals of the optical gate
110
. Optical gates
131
-
134
each includes four optical amplifiers
111
based on semiconductor devices and has its input terminals connected respectively to output terminals of a corresponding one of the 1×4 optical splitters
121
-
124
. The conventional optical space division switch further comprises 4×1 optical couplers
141
-
144
each having its input terminals connected respectively to corresponding ones of output terminals of the optical gates
131
-
134
. An optical gate
150
includes four optical amplifiers
111
based on semiconductor devices, and has its input terminals connected respectively to output terminals of the 4×1 optical couplers
141
-
144
.
Noticeably, the input optical gate
110
and the output optical gate
150
are always maintained at their ON state. For this reason, the input and output optical gates
110
and
150
are not operated as optical gates for selectively transferring optical signals, but only as optical amplifiers for compensating for signal loss by optical components.
The operation of the conventional 4×4 optical gate based optical space division switch with the above-mentioned construction will hereinafter be described.
First, the four optical amplifiers in the input optical gate
110
amplify optical signals inputted through input ports IP
1
-IP
4
and transfer the amplified optical signals to the 1×4 optical splitters
121
-
124
, respectively.
Each of the 1×4 optical splitters
121
-
124
splits a corresponding one of the output optical signals from the optical gate
110
into four optical signals and transfers the split optical signals to a corresponding one of the optical gates
131
-
134
.
The four optical amplifiers in each of the optical gates
131
-
134
amplify the output optical signals from a corresponding one of the 1×4 optical splitters
121
-
124
and transfer the amplified optical signals to the 4×1 optical couplers
141
-
144
, respectively. At this time, the optical gates
131
-
134
are turned on or off to selectively transfer the output optical signals from the 1×4 optical splitters
121
-
124
to the 4×1 optical couplers
141
-
144
.
Each of the 4×1 optical couplers
141
-
144
couples the four output optical signals from the optical gates
131
-
134
into one optical signal, which is then transferred to the output optical gate
150
.
The four optical amplifiers in the output optical gate
150
amplify the output optical signals from the 4×1 optical couplers
141
-
144
and transfer the amplified optical signals externally through output ports OP
1
-OP
4
, respectively.
However, the above-mentioned conventional optical sspace divisionswitch has a disadvantage in that, even if the optical gates
131
-
134
are turned off, they often transfer partially the optical signals due to their imperfect ON/OFF characteristic. Such crosstalk components degrade the performance of other signals.
SUMMARY OF THE INVENTION
Therefore, the present invention has been made in view of the above problem, and it is an object of the present invention to provide an optical gate based optical space division switch which is capable of switching optical signals inputted through arbitrary input ports to a desired output port with no internal collision. The transfer of the input optical signals is blocked by double gating so that they can hardly be transferred to undesired output ports. Hence, the input optical signals can be transferred only to a desired output port, resulting in a significant reduction in the number of their crosstalk components.
In accordance with one aspect of the present invention, there is provided an optical gate based optical space division switch for switching optical signals inputted through arbitrary input ports to a desired output port with no internal collision, comprising first splitting means for splitting the optical signals inputted through the input ports; first amplification means for selectively amplifying output optical signals from the first splitting means; second splitting means for splitting output optical signals from the first amplification means; second amplification means for selectively amplifying output optical signals from the second splitting means; coupling means for coupling output optical signals from the second amplification means; and third amplification means for amplifying an output optical signal from the coupling means and transferring the amplified optical signal to the output port.
In accordance with another aspect of the present invention, there is provided an optical gate based optical space division switch for switching optical signals inputted through arbitrary input ports to a desired output port with no internal collision, comprising first amplification means for amplifying the optical signals inputted through the input ports; signal splitting means for splitting output optical signals from the first amplification means; second amplification means for selectively amplifying output optical signals from the signal splitting means; first coupling means for coupling output optical signals from the second amplification means; third amplification means for selectively amplifying output optical signals from the first coupling means; and second coupling means for coupling output optical signals from the third amplification means and transferring the coupled result to the output port.


REFERENCES:
patent: 4934775 (1990-06-01), Koai
patent: 5341234 (1994-08-01), Suzuki et al.
patent: 5528710 (1996-06-01), Burton et al.
patent: 5905587 (1999-05-01), Maeno et al.
patent: 6243178 (2001-06-01), Suemura et al.
“Monolithically Integrated 4×4 InGaAsP/InP Laser Amplifier Gate Switch Arrays”, Electronic Letters, vol. 28, No. 24, pp. 2223-2225, Nov. 1992.
“Analysis of Input Power Dynamic Ranges in Two Types of Expanded Semiconductor Optical Amplifier Gate Switch Arrays”, Technology Letters, vol. 8, No. 4, pp. 536-538, Apr. 1996.
“Impact of Crosstalk Induced Beat Noise on the Size of Semiconductor Laser Amplifier Based Optical Space Switch Structures” Technology Letters, vol. 8, No. 7, pp. 894-896, Jul. 1996.

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