Jawaharlal Nehru Technological University Hyderabad B.Tech IV OPTICAL COMMUNICATIONS Previous Question Paper (July - 2021 - R16)

Optical fibers offer several significant advantages over traditional copper-based communication systems: high bandwidth, which allows for massive data transmission rates; low signal attenuation, enabling longer distances between repeaters; electromagnetic interference (EMI) immunity, as they use light rather than electricity; small size and light weight; and high security, as they are difficult to tap without detection.

Contrary to the premise, optical fibers are actually the primary medium for long-distance communications (such as transoceanic cables) due to their low loss. However, if the question refers to historical or specific deployment constraints, it may be due to the high installation costs, the complexity of splicing and connectorization, or the requirement for specialized opto-electronic transceivers at each end, which historically made them less accessible for short-range or local-loop applications compared to existing copper infrastructure.

Modified Chemical Vapor Deposition (MCVD) is a critical process used to fabricate high-purity optical fiber preforms. It involves the deposition of high-purity silica and dopants (such as germanium dioxide) inside a rotating silica glass tube. By heating the tube with an external oxy-hydrogen torch, chemical vapors react to form glass soot layers on the inner wall. The process ensures precise control over the refractive index profile of the fiber core, which is essential for minimizing signal attenuation and achieving the desired light-guiding properties in the finished fiber.