Tunable polarization-dependent loss element based on acoustooptic mode coupling in a polarization-maintaining fiber

We demonstrate a tunable polarization-dependent loss (PDL) element based on the polarization-dependent coupling of the fundamental core mode to the cladding mode by the flexural acoustic wave in a polarization-maintaining fiber with an elliptical stress member. The resonant wavelength of PDL is tunable by adjusting the frequency of radio-frequency (RF) signal applied to the acoustic transducer, while the magnitude of PDL is variable by the voltage of the same RF signal. Over the wavelength from 1530 to 1570 nm, the variable ranges of PDL for two linear orthogonal polarizations are 16 and 17 dB, respectively.