All-fiber passively mode-locked laser based on an electron beam evaporation grown Co2+:ZnSe film saturable absorber

We experimentally demonstrated an all-fiber mode-locked erbium-doped laser based on Co2+:ZnSe (Cobalt, Zinc Selenide) thin film as the saturable absorber (SA), which was grown on the fiber taper by electron beam (e-beam) evaporation technology. The modulation depth, non-saturable loss and saturation intensity were found to be similar to 12%, 76% and 1.89 MW/cm(2), respectively. The X ray diffraction (XRD) results showed that the Co2+:ZnSe thin film was provided with the cubic zinc blende structure. The scanning electron microscope (SEM) and atomic force microscopy (AFM) images showed the prepared thin film has a smooth and uniform surface. When the fiber-taper Co2+:ZnSe SA was inserted into an erbium-doped fiber laser cavity, a stable mode-locked pulse was obtained. The mode-locked pulses had a pulse repetition rate of 17.83 MHz and pulse duration of similar to 4ns throughout the mode-locked operation range of 200-600 mW. The recorded maximum average output power was similar to 4.88 mW. The signal to noise ratio (SNR) was obtained to be 64.9 dB, which indicates the favorable stability of the mode-locked pulse. These results demonstrate the Co2+:ZnSe thin film grown on a fiber taper has high optical quality and implementation of stable pulse operation on passively mode-locked Er-doped fiber lasers. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

An all-fiber mode-locked erbium-doped laser using Co2+:ZnSe thin film as the saturable absorber was experimentally demonstrated, showing stable pulse operation. The thin film exhibited high optical quality and effective mode-locking performance, providing a new research direction in the field of fiber lasers.