13.5 Schemes for Optical Add/Drop Multiplexing
541
Fig. 13.24 Example of ROADM based on a 4 × 4 array of MEMS mirrors
Fig. 13.25 Wavelength-tunable ROADM for adding and dropping small channel counts
number of drop channels; otherwise the accumulated optical loss through the series
of switching elements may be fairly large.
Wavelength-Selective Switch Configuration
In the evolution of add/drop multiplexer technology to enable more sophisticated
mesh network applications, wavelength-selective switch (WSS) technology was
introduced [26, 27]. A key feature of a WSS is that it can direct each wavelength
entering a common input port to any one of a multiple number of output ports, as indicated generically in Fig. 13.26. A basic ROADM is formed using one WSS module
541
Fig. 13.24 Example of ROADM based on a 4 × 4 array of MEMS mirrors
Fig. 13.25 Wavelength-tunable ROADM for adding and dropping small channel counts
number of drop channels; otherwise the accumulated optical loss through the series
of switching elements may be fairly large.
Wavelength-Selective Switch Configuration
In the evolution of add/drop multiplexer technology to enable more sophisticated
mesh network applications, wavelength-selective switch (WSS) technology was
introduced [26, 27]. A key feature of a WSS is that it can direct each wavelength
entering a common input port to any one of a multiple number of output ports, as indicated generically in Fig. 13.26. A basic ROADM is formed using one WSS module