Erbium-doped chalcogenide fiber ring laser for mid-IR applications

In recent years, infrared light sources have attracted great attention for their application in remote sensing, sensors, optical communication, medical and military technology, and so on. Innovative erbium-doped microstructured optical fiber ring lasers (EDFRLs) have been proposed in order to increase the performance of the conventional fiber lasers, enabling a number of advantages such as smaller size, higher power, better beam quality. In a previous work, the authors proposed a design of a Fabry Perot laser made of a novel erbium-doped Ga5Ge20Sb10S65 chalcogenide glass, operating in the Mid-IR wavelength range. This work reports the design of a ring laser, made of the same glass, operating at the signal wavelength λs = 4600 nm and at the pump wavelength λp = 806 nm. The design and optimization has been performed in order to improve the laser performance. The numerical computer code, implemented ad-hoc to investigate the fiber ring laser, takes into account the rate equations of the 5-level erbium ion system, the pump and signal power propagation, the energy transfer of the up-conversion and cross-relaxation phenomena, the cavity losses and the coupling losses. The measured amplified spontaneous emission ASE power spectrum has been accurately sampled in 150 wavelength slots from λ1=4200 nm to λ2=4800 nm, to obtain more realistic simulations.