When this research was performed the author was with the Department of Electrical Engineering, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom. He is now with Telecom Research Laboratories, 770 Blackburn Road, Clayton, Victoria, 3168, Australia.
S. J. Madden, "Properties of nonblocking single-substrate optical space switching networks constructed from directional couplers," Appl. Opt. 33, 8375-8386 (1994)
Some of the properties of single-substrate nonblocking optical space switching networks that are constructed from directional couplers, waveguide bends, and waveguide crossovers are considered. Expressions are given for the ratio of network output signal to cross talk, insertion loss, and total switch count for ten different structures. Based on these expressions, estimates of the maximum switch sizes attainable are made. Consideration is also given to the factors that govern the practical implementation of such structures, and this shows that rearrangeably nonblocking single-substrate switches of up to 128 × 128 should be possible if technologies other than Ti:LiNbO3 are used.
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Expressions Giving the Network Output Signal to Cross Talk Ratio in Decibels as a Function of Matrix Size, Single-Switch Cross Talk, and Intersection Cross Talk for the Ten Networks Studied
This assumes the physical layout that is consistent with the lowest possible number of crossovers. This is, however, a very inefficient topology on space utilization grounds.
First-order approximation to cross talk only.
Table 2
Expressions Giving the Network Insertion Loss in Decibels as a Function of Single-Switch, Bend and Waveguide Intersection Insertion Loss and Switch Dimensions for the Ten Network Types Studied
N is the switch dimension, k = Log2N, n = √N, Ls is the single-switch loss (dB), Lb is the single unit bend loss (dB), and Li is the waveguide intersection loss (dB).
Assumes minimum crossover layout, as noted in Table 1.
Table 3
Expressions Giving the Total Coupler Counts in Each Network Design as a Function of Space Switch Dimension
Single-switch cross-talk ratio is 25 dB.
Element loss is 0.1 dB.
Tables (4)
Table 1
Expressions Giving the Network Output Signal to Cross Talk Ratio in Decibels as a Function of Matrix Size, Single-Switch Cross Talk, and Intersection Cross Talk for the Ten Networks Studied
This assumes the physical layout that is consistent with the lowest possible number of crossovers. This is, however, a very inefficient topology on space utilization grounds.
First-order approximation to cross talk only.
Table 2
Expressions Giving the Network Insertion Loss in Decibels as a Function of Single-Switch, Bend and Waveguide Intersection Insertion Loss and Switch Dimensions for the Ten Network Types Studied
N is the switch dimension, k = Log2N, n = √N, Ls is the single-switch loss (dB), Lb is the single unit bend loss (dB), and Li is the waveguide intersection loss (dB).
Assumes minimum crossover layout, as noted in Table 1.
Table 3
Expressions Giving the Total Coupler Counts in Each Network Design as a Function of Space Switch Dimension