We investigate a technique to improve the information confidentiality in optical fiber telecommunications. Starting from a basic scheme of unconventional coding technique [1] applied to a three-dimensional polarization shift keying, we extend the method to a four-dimensional physical space [2] to demonstrate the general applicability of the cryptographic method and to achieve better performance in terms of transmission throughput. Bit error rate (BER) is calculated for hypercube constellation modulation in two, three, and four dimensions, and an interesting relation among BER, transmission power, and space dimension is derived.

We present an application scenario of a Passive Optical Metropolitan Area Network (PO-MAN). Multilevel Polarization Shift Keying (M-PolSK) is used to obtain 40 and 100 Gbps per single channel. Moreover, M-PolSKs allow to implement advanced protection techniques based on birefringence, an intrinsic electro-optical effect of optical fiber usually considered a constraint [1]. Nevertheless, we can exploit this effect to our advantage to protect the information. Unlike spread-spectrum technique in which information is protected by exploiting noise, this new paradigm exploits the birefringence effects specific of the optical fibers. These technological solutions are able to replace or coexist with the current ones and those under development, ensuring backward compatibility and flexibility of the networks.

Transmission demand continues to grow and higher capacity optical communication systems are required to economically meet this ever-increasing need for communication services. This article expands and deepens the study of a novel optical communication system for high-capacity Local Area Networks (LANs), based on twisted optical fibers. The complete statistical behavior of this system is shown, designed for more efficient use of the fiber single-channel capacity by adopting an unconventional multilevel polarization modulation (called “bands of polarization”). Starting from simulative results, a possible reference mathematical model is proposed. Finally, the system performance is analyzed in the presence of shot-noise (coherent detection) or thermal noise (direct detection).

The authors study some electromagnetic field representations with a focus on optical communications, light polarisation and phase. Well‐known three‐ and four‐dimensional representations are compared with each other and with new ones that are presented and analysed from an analytical point of view. A symmetry emerges in the relationships between the various representations, showing that they are closely related formulas. In fact, different representations point out different characteristics or domains of the same phenomenon. This study results in a more accurate description of the electromagnetic field and especially in its capacity to carry information for telecommunications purposes. From a technological point of view, the partial orthogonality of the described spaces suggests the possibility of exploiting simultaneously more than one representation in order to carry more information or the possibility of using these representations as a natural codifying system with the aim of increasing reliability or confidentiality of communications.