Generation of Q-switched fiber laser at 1.0-, 1.55- and 2.0-µm employing a spent coffee ground based saturable absorber

• Main Authors: Mohd. Rusdi, Muhammad Farid, Jafry, Afiq Arif Aminuddin, Abdul Latiff, Anas, Rosol, Ahmad Haziq Aiman, Ab. Rahman, Mohd. Fauzi, Kasim, Nabilah, Abdul Khudus, Muhammad Imran Mustafa, Ahmad, Harith, Harun, Sulaiman Wadi
• Format: Article
• Published: Academic Press Inc. 2021
• Subjects: QC Physics
• Online Access: http://eprints.utm.my/id/eprint/97849/; http://dx.doi.org/10.1016/j.yofte.2020.102434

Spent coffee ground (SCG) was demonstrated as saturable absorber (SA) for Wideband Q-switched fiber lasers generation. The SCG SA has a broad linear absorption that covers from 1000 nm to 2000 nm wavelength and a modulation depth of 30% at 1.55-µm region. Through purification process, the finer SCG powder is obtained, and be embedded with a polyvinyl alcohol for thin film formation. To realize Q-switching operation lasers, a fabricated SCG film was integrated into three different fiber laser cavities including ytterbium-doped fiber laser, erbium-doped fiber laser, and thulium-doped fiber laser. A peak wavelength has obtainable at 1031 nm, 1563 nm, and 1976 nm for 1-, 1.55-, and 2- µm regions, respectively. The shortest pulse width of 4.80 µs and maximum pulse energy of 0.152 µJ are observed from the YDFL cavity. RF spectrum shows the signal-to-noise ratio for all regions is above 35 dB, indicates a stable pulsing generation. Our technique opens the door for unlimited materials SA from environmentally friendly resources which contribute to sustainable effort.