Executive Summary : | The project is dedicated to designing the spectrally efficient backbone transport network for 6G communication. India will launch 5G (30-300 GHz band) services in 13 cities in 2022, which is expected to reach a data transmission rate of up to 10 Gbit/s. But, the exponential increase in internet users (expected to reach 5 billion users by 2023: as per the latest Cisco report) demands more data transmission rate to avoid network congestion. So, to sustain the trend, a data transmission rate beyond 100 Gbit/s to Tb/s is required, which is not possible with the available bandwidth of 10 GHz in the existing 5G technology. So, the range of 0.3 THz to 10 THz is recognized as a promising candidate to accommodate the exponentially increasing network traffic, abbreviated as 6G communication. The work over THz wireless communication also evolved rapidly in recent years. However, the success of the 6G communication strictly depends on the backbone network between the base station to the central exchange and inter-central exchanges. The fiber-based multicarrier data transmission system, which exploits the WDM system, is the only possible solution to realize the high-speed backbone network. But the problem associated with the established system is the spectrally inefficient, bulky, costly, and higher power consumption multicarrier generator at the backbone transport network. A multicarrier system should have tunable carrier frequency, line spacing, flat spectrum, and broad spectral range for a spectrally efficient multicarrier system. None of those, as mentioned earlier requirements are possible with the existing multicarrier generator, which is just an array of discrete laser sources. But, as per the requirements, an electro-optic frequency comb is the only solution for the multicarrier generator, which is our proposal's prime objective. The single electro-optic modulators based comb has limited frequency lines (ranges from 7-11), which can be enhanced by using multiple cascaded modulators (conditionally: all the cascaded modulators should be controlled by the periodic RF source having equal or integer multiple of the minimum RF frequency). But this induces the complexity due to the requirement of simultaneous control over multiple parameters or RF signals. A comb can also be expanded using the optical nonlinearities, but such techniques due not have much flatness and less control to enhance the flatness further. So, we plan to use the Nobel hybrid comb expansion technique, in which we exploit both i.e. modulator and gain modulation in SOA to enhance the spectral bandwidth and flatness. Further, we plan to exploit the comb as a multichannel source in a backbone network suitable for the 6G communication. Successful completion of the project has the capability to reduce the dependency of our country over other countries to import the technology of establishing 6G technology. |