Ultra wideband CW pumped optical supercontinuum source

Ultra wideband CW pumped optical supercontinuum source Yue Song Keyword: supercontinuum, ultra wide optical source, nonlinear optical effects, continuous wave pump, ring cavity laser; Optical supercontinuum (OSC) laser source is a new generation wideband laser which has various commercial applications such as telecommunication, biomedicine, and optical sensing systems. However the high costs of current OSC laser sources generally have impeded them to be used more widely. In this thesis, we demonstrated a low-cost OSC laser source based on a continuum wave (CW) pumped Erbium/Ytterbium co-doped fiber (EYCDF) ring cavity with a 1.2 km highly nonlinear fiber (HNLF). This OSC laser source has 350nm spectral coverage, from 1550nm to 1900nm in wavelength. This is the first CW pumped OSC that generates continuum spectrum above 1750nm. The wide spectral coverage in the long wavelength range allows more advanced utilization of OSC sources. In this thesis, the evolution mechanism of the CW pumped OSC is discussed. The analysis of the results shows that self-phase modulation (SPM), and stimulated Raman scattering (SRS) dominate the evolution of OSC. Therefore, the evolution pattern is different to those of previous CW pumped OSCs where the modulation instability (MI) and SRS effects, or purely SRS effect dominate OSC generation. In addition, the experimental results suggest that the OSC generated by this evolution pattern has high flatness, which is caused by two reasons. Firstly, the intense SRS effect suppresses the MI effect, which could induce spectral vibration. Secondly, SPM induced spectrum broadening produce a smooth spectrum. The intense SPM and SRS effect are benefited from the ring-cavity structure which effectively increases the effective length of nonlinear fiber.