Complete characterization of ultrashort pulse sources at 1550 nm

摘要

This paper reviews the use of frequency-resolved optical gatingn(FROG) to characterize mode-locked lasers producing ultrashort pulsesnsuitable for high-capacity optical communications systems at wavelengthsnaround 1550 nm, Second harmonic generation (SHG) FROG is used toncharacterize pulses from a passively mode-locked erbium-doped fibernlaser, and both single-mode and dual-mode gain-switched semiconductornlasers. The compression of gain-switched pulses in dispersionncompensating fiber is also studied using SHG-FROG, allowing optimalncompression conditions to be determined without a priori assumptionsnabout pulse characteristics. We also describe a fiber-based FROGngeometry exploiting cross-phase modulation and show that it is ideallynsuited to pulse characterization at optical communications wavelengths.nThis technique has been used to characterize picosecond pulses withnenergy as low as 24 pJ, giving results in excellent agreement withnSHG-FROG characterization, and without any temporal ambiguity in thenretrieved pulse