Fiber laser is a laser light source with wavelengths in 1500-1950 nm region. This wavelength region is interesting because optical fiber has minimal attenuation, so it is suitable for optical communication and as component of fiber sensor.
The fiber laser that are currently being developed are Q-Switched fiber laser with nanosecond (ns) pulse width and mode-locked fiber lasers with picosecond (ps) width pulse until femtosecond (fs). Ultrafast fiber laser (PS) is a very active field of research in the field of photonics. Mode-locking can be achieved by using a passive saturable absorber (SA).
Although several SAs have been used to generate short pulses, many new SA materials have been studied for ultrafast fiber lasers at 2-micron wavelength.
In this study, the authors and their team have successfully demonstrated the generation of mode-locked Thulium-Doped Fibre Laser by employing a newly developed saturable absorber (SA) based on copper (Cu) thin film. The SA was prepared by depositing nano-sized particles of Cu onto the surface of polyvinyl alcohol (PVA) film through the E-Beam evaporation process.
A stable mode-locking pulse train operating at 1951 nm was successfully generated by introducing the Cu PVA SA into a laser cavity. The laser generated a pulse train at the fundamental frequency of 8.5 MHz with a calculated minimum pulse width of 14.8 ps. This demonstration proves that the Cu PVA based SA is suitable for generating mode-locked fibre laser at 2 µm region. The result of this study proves that copper metal can be applied as a good SA material for laser generation as well as mode-locking.
Author: Moh. Yasin
Related article: https://www.tandfonline.com/doi/full/10.1080/09500340.2019.1622048
