Biblio

A new kind of Square Lattice Photonic Crystal Fiber (SLPCF) is proposed, the first ring is formed by elliptical holes filled with ethanol. To regulate the dispersion and the confinement loss we put a circular air-holes with small diameters into the third ring of the cladding area. The diameter of the core is arranged as d2=2*A-d, where A is the pitch and d diameter of the air-holes. After simulations, we got a dispersion low as 0.0494 (ps/Km. nm) and a confinement loss also low as 2.6×10-7(dB/m) at a wavelength of 1.55 $μ$m. At 0.8 $μ$m we obtained a nonlinearity high as 60.95 (1/km. w) and a strong guiding light. Also, we compare the filled ethanol elliptical holes with the air filled elliptical holes of our proposed square lattice photonic crystal fiber. We use as a simulation method in this manuscript the two-dimensional FDTD method. The utilization of the proposed fiber is in the telecommunication transmission because of its low dispersion and low loss at the c-band and in the nonlinear applications.

We propose a secure key generation and distribution scheme for data encryption in classical optical fiber channel. A Delay interferometer (DI) is used to track the random phase fluctuation inside fiber, while the reconfigurable lengths of polarization-maintaining (PM) fiber are set as the source of optical phase fluctuations. The output signals from DI are extracted as the secret key and shared between the two-legal transmitter and receiver. Because of the randomness of local environment and the uniqueness of fiber channel, the phase fluctuation between orthogonal polarization modes (OPMs) can be used as secure keys to enhance the level of security in physical layer. Experimentally, we realize the random key generation and distribution over 25-km standard single-mode fiber (SSMF). Moreover, the proposed key generation scheme has the advantages of low cost, compatible with current optical fiber networks and long distance transmission with optical amplifiers.

In multicarrier direct modulation direct detection systems, interaction between laser chirp and fiber group velocity dispersion induces subcarrier-to-subcarrier intermixing interferences (SSII) after detection. Such SSII become a major impairment in orthogonal frequency division multiplexing-based access systems, where a high modulation index, leading to large chirp, is required to maximize the system power budget. In this letter, we present and experimentally verify an analytical formulation to predict the level of signal and SSII and estimate the signal to noise ratio of each subcarrier, enabling improved bit-and-power loading and subcarrier attribution. The reported model is compact, and only requires the knowledge of basic link characteristics and laser parameters that can easily be measured.