Wavelength-switchable operation of quadruple-wavelength EDF laser

A wavelength-switchable quadruple-wavelength erbium-doped fiber laser using linear-cavity configuration is proposed and demonstrated experimentally at room temperature. A Sagnac loop with a length of polarization-maintaining fiber acts as a comb filter and a broadband chirped fiber grating with low reflectivity acts as the flat reflective mirror in the resonant cavity. On the basis of the polarization hole burning effect, after adjusting a polarization controller, the laser can switch flexibl y to output six different modes from single-wavelength to quadruple-wavelength. All of lasing lines with narrow linewidth of less than 0.3 nm have the optical signal-to-noise ratio of more than 30 dB.