  The quick rise of emerging technologies like spectrally efficient
multicarrier with a higher order modulation and bandwidth variable wavelength
selective switches have caused a shift of the optical network architecture from
fixed to the flexible elastic optical network (EON), in terms of bit rate,
center frequency spacing, modulation format, and optical reach. By using
bandwidth-variable transceivers, colorless flexible-grid reconfigurable optical
add-drop multiplexers (ROADM), as well as a choice of different optical source
types, operators can provide a range of service types and improve network
efficiency. Implementation of the EON network requires careful consideration,
especially in terms of the ROADM structure to achieve optimal performance. We
propose a low-cost ROADM structure with an order-based connection method that
includes a high degree with a blocking probability of less than 10-4. Then, we
applied the new design of ROADM in EON that transported 1 Tb/s. In the final
step, we conclude that our system accommodated 20 percent more traffic demand
over an average of the low-rate wavelength approach.
