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A silver sulfide saturable absorber (SA) was successfully employed in an Erbium‐doped fiber laser (EDFL) cavity for short and ultrashort pulse generations. The Q‐switched laser was obtained with an operation wavelength of 1566 nm, pulse rate of 93.81 kHz, and pulse duration of 1.68 μs at a 187.04 mW pump. As the EDFL cavity was optimized for mode‐locking operation by adding 100 m long single mode fiber, a stable soliton pulse train operating at 1564 nm was realized with a constant repetition rate of 1.88 MHz and pulse duration of 3.01 ps. The good nonlinear characteristics of the SA make synergetic contributions to the generation of high‐performance Q‐switched and mode‐locked lasers. [ABSTRACT FROM AUTHOR]

• Combination of single-mode fibre with step-index multimode fibre as saturable absorber. • The Q-switching is caused by the Kerr-effect of multimode interference. • Repetition rate of the Q-switched laser is tunable from 87 to 158 kHz. • The minimum pulse width is 2.5 µs. A passively Q-switched Erbium-doped fiber laser (EDFL) was successfully demonstrated using SMF (single-mode fiber)-SIMF (step-index multimode fiber)-SMF or SMS structure as a saturable absorber (SA). The SMS structure operates on the Kerr-effect of multimode interference (MMI). To modulate the cavity loss, a 158 mm length of SIMF was fusion spliced into a ring cavity. By properly adjusting the in-line polarization controller (PC) that holds the SIMF, we were able to generate steady Q-switched pulses. As the input pump power increased from 115 to 343 mW, the repetition rate of the Q-switched laser increased from 87 to 158 kHz, while the corresponding pulse width decreased from 4.2 µs to 2.5 µs. The signal-to-noise ratio (SNR) of the fundamental mode for the pulsed laser was around 72 dB at a central wavelength of 1530 nm. Our results indicate that the SMS structure can be used as an SA to generate stable Q-switched EDFL with very simple cavity settings. [ABSTRACT FROM AUTHOR]

A stable passive Q‐switched thulium‐doped fibre laser (TDFL) operating at the 1900 nm region is demonstrated by using a multi‐layer graphene film‐based saturable absorber (SA). The graphene is synthesised by electrochemical exfoliation of graphite at room temperature in 1% sodium dodecyl sulphate aqueous solution. Graphene flakes obtained from the process are mixed with polyethylene oxide as the host polymer to produce free standing composite thin film which acts as a passive Q‐switcher in the TDFL ring cavity. At 793 nm pump power of 186 mW, the TDFL generates an optical pulse train with a repetition rate of 7.5 kHz, pulse width of 19.7 μs and a pulse energy of 66.6 nJ. A higher performance Q‐switched TDFL could be achieved with the optimisation of the graphene SA and the laser cavity. [ABSTRACT FROM AUTHOR]

We successfully demonstrated a stable Q-switched erbium-doped fiber laser (EDFL) using Molybdenum Aluminum Boride (MoAIB), a metal ceramic-based material as saturable absorber (SA). The thin layer of MoAIB was obtained by mechanical exfoliation method and acquired onto the end surface of a standard FC/PC fiber connector to function as SA. The features of MoAIB-SA are experimentally evaluated in two output coupling ratios, which are 50:50 and 95:5. From the experimental results, MoAIB-SA is well-functioning as SA to modulate the CW lasing into Q-switching operation. The 95:5 coupler setup presented better pulse quality, in term of pulse repetition rate and pulse width. Additionally, 50:50 coupler setup allows higher pump power and pulse energy to extract from the fiber laser system. [ABSTRACT FROM AUTHOR]