Quantum and Data Signals in a Single Fiber—Multiplexing by Smart Use of High-Grade Filters

Abstract

In this letter, we present the latest findings in coexistence of two rather different classes of optical signals in one fiber – classical data signals and quantum signals. The most significant and notable difference between the two is the optical power, which is several orders (7 or more) of magnitude distinct from each other. There are several approaches to address this issue – in this letter, at a glance, the realistic and practical approach, which relies on the selection of high-grade optical filters, was chosen. Rigorous, however affordable, optical filtering is required to avoid any possible crosstalk, not only from the classical data signals but also from the spontaneous nonlinear Raman scattering effect. In our experimental verification, it has been demonstrated that the selection of high-grade transmission components is a crucial element in the success of multiplexing strong and weak optical signals in a single fiber. In real-world applications, this approach significantly reduces infrastructure costs by eliminating the need for additional fiber.