Bandpass filters based on pi-shifted long-period fiber gratings for actively mode-locked erbium fiber lasers.
We have fabricated bandpass filters based on pi-shifted long-period gratings for application in actively mode-locked erbium fiber lasers. Introducing the pi-phase shift in the middle of the grating opens a bandpass within the core-cladding mode resonance peaks. With a 22-nm bandwidth filter inserted in an actively mode-locked erbium fiber sigma laser, solitonlike pulses are generated, with a power-dependent duration of approximately 3-5 ps , at a 3-GHz repetition rate. These all-fiber filters have the advantages of low insertion loss (<0.5 dB) and a wide bandwidth (10-20 nm), and they do not require that a circulator be inserted into the laser cavity.
O
O
Deparis
R
R
Kiyan
O
O
Pottiez
M
M
Blondel
I G
IG
Korolev
S A
SA
Vasiliev
E M
EM
Dianov