Switchable quadruple-wavelength erbium-doped photonic crystal fiber laser based on a polarization-maintaining photonic crystal fiber Sagnac loop filter

•The laser is a multi-wavelength erbium-doped photonic crystal fiber laser.•The laser can be switched from single-wavelength to quadruple-wavelength.•Lasing lines locate at fixed wavelength positions from 1556 nm to 1560 nm.•The laser has a kind of single- or quadruple-wavelength output mode.•It has three or two kinds of dual-wavelength or triple-wavelength output modes.

A switchable quadruple-wavelength erbium-doped photonic crystal fiber laser is proposed and demonstrated experimentally by employing a simple linear cavity configuration incorporating a polarization-maintaining photonic crystal fiber Sagnac loop filter. The laser can be switched flexibly from single-wavelength to quadruple-wavelength by adjusting a polarization controller and all of lasing lines locate at fixed wavelength positions in the range of 1556 nm to 1560 nm. The laser individually has a kind of single wavelength and quadruple-wavelength output mode. It also has three and two kinds of dual-wavelength and triple-wavelength output modes, respectively. The laser with good intensity uniformity exhibits excellent wavelength and power stabilities in the experiment.