In this paper, we fabricated GeTe based optical modulator, named saturable absorbers (SAs), and utilize it in the Er-dopted fiber laser cavity for passively Q-switched and mode-locked pulse trains generation. We systemically investigated the nonlinear optical properties of GeTe-SA by OA Z-scan measurement at 800 nm and 1550 nm, respectively. GeTe-SA displays obvious saturable absorption signal with modulation depth of 16.5 % for 800 nm and 3.7% for 1550 nm, respectively. Mode-locking performance is achieved with the ultrashort pulse duration of 680 fs centered at 1562 nm. Stable Q-switched pulse trains are also observed with the maximum output power of 43.2 mW, maximum pulse energy of 315 nJ, shortest pulse duration of 0.978 μs and repetition rate ranging from 74.5-137 kHz. The results would contribute to extend the practical applications of metal monochalcogenides from nanoelectronic devices to optoelectronic devices.