Optical Fiber Impulse Propagation: An Interaction Between the Third-Order Dispersion and Nonlinear Chirp

This article investigates the interaction between the third-order dispersion in optical fiber and the nonlinear (quadratic) chirp of Gaussian impulses. A formula is obtained for the impulse form at the fiber far end. The impulse propagation in nonlinear fiber is also examined by means of a computer simulation. The obtained results indicate that the interaction may lead to significant distortion of optical impulses at the fiber output even when the second-order dispersion is entirely canceled and the input impulse has no linear chirp. This distortion is more pronounced when the dispersion slope, fiber length, and nonlinear chirp parameter increase.     

ISI and polarization switching in high bit rate optical fiber transmission systems

In the paper, there is investigated inter-symbol interference (ISI) in high bit rate optical transmission systems employing standard optical fibers with no dispersion compensation. Two types of systems are examined: a typical system with external light modulator and a system with additional polarization switching. The dependence of the optical path loss and horizontal eye pattern opening on the fiber length and input impulse shape is found for both the systems via computer simulation. The polarization switched system has better parameters for greater transmission distances (L > 70,***,100 km) whereas for smaller distances the parameters for both systems are comparable. The optimum impulse shape that minimizes ISI is also found.     

Influence of mode coupling on mode group diversity multiplexing in multimode fibers

In this paper, the influence of mode coupling on mode group diversity multiplexing (MGDM) in multimode fibers is investigated. It is found experimentally, that in step index fibers mode coupling is very strong among the lowest mode groups. It is confirmed that mode coupling in graded index fibers is negligible. Theoretical and numerical investigation of the system performance in strong mode coupling conditions, indicates need for greater separation of the lowest MGDM channels.     

Multiphoton ionization studies of amines with UV-VIS lasers

Three and four photon ionization studies at 355 and 532 nm are presented for the isomeric propylamines and n-pentylamine. Ionic fragmentation patterns and ion yields are presented as a function of laser wavelength and fluence. These time-of-flight (TOF) mass spectra are compared with both electron impact data and the TOF mass spectra of the previously reported butylamines. A brief discussion of the dynamics of the decomposition process is presented in light of the butylamine results and competitive ionic fragmentation pathways.