Abstract

Current modulation of a laser diode (LD) may lead to pulse chirping effects at wavelengths matched to the bandgap wavelength. From this point of view, the intracavity pump LD yields some compromise: the phase modulation may be sufficiently high to mode-lock the fiber laser, however chirping is low at the signal wavelength. This method has recently been demonstated to achieve active modelocking in an Er³⁺-doped fiber laser with a 980-nm laser diode acting as pump source and phase modulator.^1,2 However, pulse duration (≈400 ps) was limited by the low depth of phase modulation since the index change decreases for wavelengths far from the band-gap wavelength. It is expected that the level of phase modulation will be higher with 1.48-p.m MQW LDs because their bandgap wavelength is closer to the operating wavelength of the Er-doped fiber laser.

© 1994 IEEE