Optical waveguides – Integrated optical circuit
Patent
1997-03-11
1999-04-06
Lee, John D.
Optical waveguides
Integrated optical circuit
385 40, G02B 635
Patent
active
058928642
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an optical 1.times.N and N.times.N switching matrix having a tree structure, with an optical input/output and a plurality of optical outputs/inputs.
Such switching matrices are generally known.
Optical switching matrices are key components of future optical communications networks. They enable the optical data stream to be directed in a flexible manner between different optical glass fibers or other optical waveguides without any limitation of the data rate.
Solid-state switching matrices which are integrated on a substrate are particularly compact and promise cost advantages over currently available electromechanical components (available, for example, from JDS FITEL, ASTARTE, OptiVideo, BT&D). Such solid-state switching matrices have been implemented on substrates composed, for example, of LiNbO.sub.3 (see P. J. Duthie, M. J. Wale "16.times.16 single chip optical switch array in Lithium Niobate", Electron. Lett., Vol. 27, pages 1265-1266, 1991), silicon (see R. Nagase, A. Himeno, K. Kato, O. Okuno "Silica-based 8.times.8 optical-matrix-switch module with hybrid integrated driving circuits", ECOC '93, Montreux, Paper MoP1.2, pages 17-20) or III-V semiconductors (see K. Komatsu, K. Hamamoto, M. Sugimoto, A. Ajisawy, Y. Kohga, A. Suzuki "4.times.4GaAs/AlGaAs optical matrix switches with uniform device characteristics using alternating .DELTA..beta. electrooptic wave directional couplers", J.Lightwave Technol., Vol. LT-9, pages 871-878, 1991 and L. Stoll, G. Muller, M. Hoilsberg, M. Schienle, S. Eichinger, U. Wolff "4.times.4 optical switch matrix on InP with low switching current", AEU, Vol. 46, pages 116-118).
SUMMARY OF THE INVENTION
The invention is based on the object of providing switching matrices of the said type having crosstalk suppression which is greater than that of the known switching matrices of this type.
In general terms the present invention is an optical 1.times.N switching matrix having a tree structure with an optical input/output and a number N of optical outputs/inputs. An optical waveguide structure connects the input/output to each output/input and is composed of optical waveguides which branch like a tree from the input/output in the direction of the outputs/inputs at junction points. One optical changeover switch is provided per junction point for optionally switching over between waveguides which branch off from this junction point. An optical gate switch is assigned to at least one output/input for optional optical release and blocking of this output/input as a function of a switching state of the changeover switch of a junction point from which one branching waveguide is connected to this output/input.
In each case one gate switch is assigned to each output/input for optional release and blocking of this output/input as a function of a switching state of the changeover switch of a junction point from which a branching waveguide is connected to this output/input.
The present invention is also an optical N.times.N switching matrix having a tree structure with a number N of optical inputs and N of optical outputs. Two matrix rows have in each case N optical 1.times.N switching matrices, each 1.times.N switching matrix having in each case one optical input/output and in each case N optical outputs/inputs. An optical switching network has two connection rows having in each case N.times.N optical connections, each of which is used as an optical input and/or output. It is possible to connect each connection in a connection row optically to each connection in the other connection row. The total of N.times.N optical outputs/inputs of the N optical 1.times.N switching matrices in each matrix row is connected in parallel to the N.times.N optical connections of in each case one connection row. The total of N optical inputs/outputs of the N optical 1.times.N switching matrices of each matrix row form the N inputs and/or N outputs of the N.times.N switching matrix. At least one optical 1.times.N switching matrix is a 1.times.N switching
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Muller Gustav
Schienle Meinrad
Stoll Lothar
Kang Ellen E.
Lee John D.
Siemens Aktiengesellschaft
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