RANPOFIL · Science and applications of random polymer fiber lasers

Science and applications of random polymer fiber lasers

To simplify the structure of RFLs, in 2010, Turitsyn’s group has reported a novel type of RFLs in the randomly distributed refractive index inhomogeneities throughout the length of the silica fibre due to the Raman amplified Rayleigh backscattering in different types of cavities with and without conventional point-action reflector. However, the backscattering coefficient defined the part of the scattered radiation that is scattered back into the core of the optical fibre per unit length is as small as ~4.5×10-5 km-1. Therefore, I proposed one kind of new RFLs with high backscattering coefficient to decrease the pump threshold (reducing the power consumption) and pump fibre length (allowing building smaller devices easily integrable). RANPOFIL project aimed to build a new polymer RFLs configuration to enhance the performances of RFLs. Polymer optical fibres (POFs) have two merits: (1) high Rayleigh backscattering coefficient; (2) high negative thermo-optical coefficient. Thus the random lasing emission wavelength can been easily be controlled through temperature. Therefore, the new RPFLs with low pump threshold, short pumped fibre length, high stimulated Raman gain and controlled random lasing emission is designed based on stimulated Raman scattering in the POFs. First, we coated laser dye-doped polymethyl methacrylate on the surface of a bare polymer optical fiber (POF) to fabricate new POFs. Coherent random lasers were obtained for the gain POFs under the pump. The mechanism for the random lasers is based on the refractive index heterogeneity scattering of the coating gain polymer. Second, we used the band-gap of liquid crystal to control the random lasing emission wavelength. Third, we researched the glassy behavior in a RL with complex energy level structure in the electrospun polymer fibre system. Meanwhile, we also reported whispering gallery mode (WGM) lasing emission when a 532 nm pulse laser beam radially excited the single electrospun polymer fiber (EPF) created by this method. Last, we demonstrated the realization of a high-polarization RFL output based on the hybrid Raman and Erbium gain with the tailored effect provided by a 45°-tilted fiber Bragg grating (45°-TFBG), revealing an improvement in the polarization extinction ratio (PER) and achieving a PER of ~15.3 dB. The aim of RANPOFIL is to create two-way transfer of critical knowledge between the EU partners and me, and to train me in an area of high practical relevance. The project gives me an opportunity to establish long-term research links and networks with the EU partners, and to enhance my academic career in China after the project completion.

Data: CORDIS, © European Union