Harmonic injection-locking behavior of frequency-detuned optical pulse in erbium-doped fiber laser

Abstract

The harmonic injection-locking dynamics of a gain-switched laser diode (GSLD) pulse-injection-locked Erbium-doped fiber amplifier-based laser (EDFL) are studied. Under GSLD injection with a pulsewidth and an average power of 17.6ps and 0.2 mW, respectively, at a repetition frequency corresponding to the 223rd harmonic (996.8635971 MHz) of the EDFL, the pulsewidth, peak power, and phase noise of the injection-locked EDFL are broadening from 34.3 ps to 130 ps, decreasing from 1.8 W to 500 mW, and increasing from - 101.5 dBc/Hz to -86 dBc/Hz, respectively, as the repetition frequency detunes toward the injection-locking margin. The injection-locking range is from -13 kHz to +27 kHz. The peak power of the broadened pulses is greatly reduced to one third of that at the zero-detuning condition even with a detuning frequency of 5 kHz. The injection-locked EDFL pulse-train eventually disappears as the repetition frequency of the GSLD detuned beyond the injection-locking bandwidth. The timing jitter of the GSLD harmonic injection-locked EDFL remains unchanged (<0.5ps) within a positive detuning frequency of <25kHz, which is less stable at a negatively frequency-detuned regime.