摘要
A dynamically tunable fiber filter realizing complex spectra of phase-shifted long period fiber gratings （LPFGs） is proposed and demonstrated experimentally. The principle of the filter is based on two acousto-optic coupling processes occurring simultaneously. The first coupling process acts as a normal LPFG, while the second makes the coupling direction of the first process change continuously, leading to a similar transmission spectrum with the phase-shifted LPFGs, in which the changing of coupling direction is realized by the discrete phase shifts of the index modulation. By adjusting the acoustic tuned to realize the phase-shifted LPFGs＇ spectra drive signals, its transmission spectrum can be dynamically under different phase shift numbers and locations.
A dynamically tunable fiber filter realizing complex spectra of phase-shifted long period fiber gratings （LPFGs） is proposed and demonstrated experimentally. The principle of the filter is based on two acousto-optic coupling processes occurring simultaneously. The first coupling process acts as a normal LPFG, while the second makes the coupling direction of the first process change continuously, leading to a similar transmission spectrum with the phase-shifted LPFGs, in which the changing of coupling direction is realized by the discrete phase shifts of the index modulation. By adjusting the acoustic tuned to realize the phase-shifted LPFGs＇ spectra drive signals, its transmission spectrum can be dynamically under different phase shift numbers and locations.
