Interval-adjustable and switchable multi-wavelength erbium-doped fiber laser based on lyot filter cascaded mpm filter

A novel interval-adjustable and switchable multi-wavelength Erbium-doped fiber laser (EDFL) is experimentally demonstrated in this paper. The proposed EDFL is based on the cascaded structure of a Lyot filter and a MPM filter. The MPM filter consists of multimode fiber—polarization maintaining fiber—multimode fiber (MMF-PMF-MMF). Here the filter is used as the polarization-dependent element to induce the polarization hole burning (PHB) effect. By adjusting the polarization controllers (PCs), the wavelength interval and number of output wavelengths can be changed. The output wavelengths can be switched from single-wavelength to eight wavelengths. Additionally, dual, three, four, five, six, seven, and eight wavelengths with wavelength intervals can be obtained. The MPM filter is placed in the temperature control box, and the single wavelength tuning can be realized by changing the temperature, and the tuning range is from 1528.73 to 1562.17 nm. The multi-wavelength EDFL, based on cascaded Lyot filter and MPM filter, holds significant application value in optical fiber sensing, device testing, and optical signal processing.