Short pulse generation and high speed communication system

Date of Completion

January 1999


Engineering, Electronics and Electrical|Physics, Condensed Matter|Physics, Optics




Ultrahigh-speed optical time-division-multiplexing (TDM) transmission technologies are essential to construct ultrahigh-speed all-optical networks needed in the multimedia era. In order to realize high-speed optical TDM systems, ultra-short pulses should be generated. In this dissertation, the gain switching and mode locking techniques have been analyzed and used to produce ultra-short pulses. Gain-switched pulses with a width of ∼18ps have been obtained. The theoretical analysis on gain-switching phenomena has been carried out. A new approach for the simulation of the spectrum of a gain-switched laser has been developed. ^ The principle of mode locking has been discussed. ∼6.5ps, pulses have been obtained from a monolithic mode-locked distributed Bragg reflector (DBR) laser, which are the shortest pulses from the actively mode-locked DBR lasers as we know. ∼1.1ps pulses have been achieved from a colliding-pulse mode-locked (CPM) laser. The operation principle of CPM lasers has been discussed. Pulse compression using dispersion-compensating fiber has been applied in order to get shorter pulses. ^ The semiconductor optical amplifier (SOA) plays a very important role in TDM systems. The cross gain modulation (XGM) measurements on a 2-section SOA, using both cw and pulsed pump and probe beams, have been performed. A theoretical analysis has been carried out. Wavelength conversion and fiber transmission experiments have been achieved at different bit rates. ^ The basic idea of TDM system has been discussed. Multiplexing has been achieved using fibers. Demulitplexing has been demonstrated using XGM in SOA, four-wave mixing (FWM) in SOA, and cascaded modulators. The operation principles have been discussed in detail. The FWM experiments between two optical pulses have been performed. ^