Optimized pulse source for 40-Gb/s systems based on a gain-switched laser diode in conjunction with a nonlinearly chirped grating

Abstract

Abstract-The authors demonstrate the generation of short optical pulses, which display spectral sidemode suppression ratio, and temporal pedestal suppression ratio, well in excess of 30 dB. The exceptional spectral and temporal characteristics exhibited by these pulses are attained by employing a novel technology, based on an externally injected gain-switched laser in conjunction with a nonlinearly chirped grating. Using this technique, near transform limited 7-ps optical pulses, exhibiting a time bandwidth product of 0.49, are generated.

Optimized pulse source employing an externally injected gain-switched laser diode in conjunction with a nonlinearly chirped grating

“…The pulse source comprises a nonlinearly chirped fiber Bragg grating (NC FBG) in conjunction with an externally injected gain-switched laser [20]. The design of the NC FBG is determined by the complete characterization of the gain-switched pulse using the technique of frequency resolved optical gating (FROG) [21].…”

System-Performance Analysis of Optimized Gain-Switched Pulse Source Employed in 40- and 80-Gb/s OTDM Systems

“…It has been reported how this chirp can be used to compress the pulses using dispersion compensating fiber [16] or linearly chirped fiber Bragg gratings (LC FBGs) [17] to obtain near transformlimited pulses. However, due to the chirp being nonlinear in the wings of the pulse, this compression typically results in pedestal formation on either side of the pulse [18]. By using more elaborate arrangements involving nonlinear amplifying loop mirrors [19], [20], external modulators [21], spectral windowing [22], or semiconductor optical amplifiers in conjunction with shifted 0733-8724/$25.00 © 2007 IEEE filtering [23] after the linearly compressed pulse, it is possible to greatly reduce the pedestal.…”