Author: Arvind Kumar MishraPublisher:
ISBN:
Category : Lasers
Languages : en
Pages : 204
Book Description
The rapid expansion and ever-growing demand of bandwidth consuming internet applications will require optical packet switching technology to efficiently support scalable bursty traffic and offer improved link utilization, functionality and flexibility over existing optical circuit-switching networks. The advanced modulation formats can be used to overcome problems associated with limited channel capacity by transmitting several times more information bits per symbol. And, the routing functionality of packets can be simplified by introduction of low rate label-controlled packet routing by eliminating the need for digital circuits operating at the payload data rate. In packet switching systems, the fast wavelength switching sampled grating distributed Bragg reflector (SGDBR) tunable lasers are the key components. However, the switching characteristics of these lasers are critical and may limit the minimum guard time needed between adjacent packets. This thesis is focused on suitability of SGDBR tunable lasers in optical packet switched networks employing spectrally efficient modulation formats (AMPSK and DQPSK) at data rate of 40Gbit/s. Several novel time-resolved measurement techniques were developed to investigate the wavelength drift; linewidth; bit-error, and Q-factor dynamics throughout packet length. The time-resolved Q-factor results demonstrated that the influence of linewidth dynamics degrade the system performance for AMPSK packets, while DQPSK packet performance was limited by rate of frequency drift as the SGDBR laser was switched between channels. It was found that DQPSK packets would require a longer blanking/guard time to obtain penalty free performance resulting lower link utilization than for AMPSK packets. Also, a novel multi-channel label controlled packet switching transmitter was demonstrated employing a spectrally compact subcarrier multiplexed labeling with 40Gbit/s payload with 2.5Gbit/s label to route packets in a 100GHz spaced WDM system. The time-resolved bit error performance of the label showed the detrimental influence of wavelength drift as the laser was switching from distant channel to adjacent channel.
