A novel tunable gain equalizer based on a long-period fiber grating written by high-frequency CO2 laser pulses

A novel tunable gain equalizer based on the long-period fiber grating (LPFG) induced by high-frequency CO2 laser pulses is demonstrated, for the first time, to our knowledge. Both the resonant wavelength and the resonant peak amplitude of the novel LPFG have a good linearity with temperature and transverse load, respectively. The wavelength and the peak amplitude of the gain equalizer can be tuned by the means of adjusting temperature and transverse load independently, showing that this tunable equalizer is a practical approach to realizing dynamic gain equalization in erbium-doped fiber amplifier systems.