Optically tunable fiber grating transmission filters

We propose and demonstrate single- and multiple-passband fiber grating transmission filters that are remotely tunable by exploitation of the optical pump-induced thermal effects in Er/Yb-codoped fiber sections. A repeatable, wavelength-independent induced phase shift of $0.1\pi /\mathrm{mW}$ is obtained without hysteresis and anisotropic effects. A transmission extinction ratio of $>23 \mathrm{dB}$ with a 3-mW change in pump power is achieved.