Spectral Tailoring of Random Fiber Laser Based on the Multimode Interference Filter

In this paper, we propose and experimentally demonstrate a novel scheme to tailor the spectrum of random fiber laser (RFL) based on the multimode interference effect. A fiber loop mirror (FLM) incorporating multimode interference filter (MMIF) with single mode fiber (SMF)-MMF-SMF structure acts as a wavelength-dependent point reflector in half-opened RFL. By varying the length of MMF, either single wavelength random lasing with specific wavelength or multiwavelength random lasing with selective wavelength spacing can be generated in MMIF-FLM-based RFL. Due to the wide wavelength range of the MMIF, cascaded multiwavelength random lasing can also be realized. The spectrum adjustable all fiberized RFL based on the MMIF shows distinct advantages, such as easy fabrication, wide operating wavelength range, and low-cost. Besides, the MMIF-FLM can has good power handling ability, by combining the MMIF-FLM and the short-length cavity, the proposed MMIF-based forward-pumping RFL also has a great potential to generate high power, high efficiency random lasing with the adjustable spectral property.