CWDM applications were expanded to include use in what band, where a large absorption loss occurred with older single mode fibers?

The correct choice is E-band. The E-band, which encompasses wavelengths typically around 70 to 90 GHz, is known for its potential in fiber optic transmission where absorption losses present challenges in older single-mode fiber technologies. CWDM (Coarse Wavelength Division Multiplexing) systems are tailored to operate in this band because they allow for high data rates and efficiency, significantly minimizing the impact of absorption losses that affect signal quality at these wavelengths.

Integration of CWDM technologies in this band enhances the capacity and reach of fiber optic communication systems, making it a key solution for modern telecommunications and data services. By exploiting the E-band, network operators can maximize performance in scenarios where older fibers may not perform optimally, thereby meeting the increasing demand for broadband connectivity.