Anas Abdul Latiff

A generation of 2 μm Q-switched thulium-doped fibre laser based on anatase titanium(IV) oxide film saturable absorber

Abstract We demonstrate a Q-switched thulium-doped fibre laser operating at approximately 1935 nm wavelength using anatase titanium(IV) oxide (TiO2) embedded in polyvinyl alcohol as the passive newly saturable absorber (SA). The film has absorption loss of 3.5 dB and modulation depth of 33%. It is sandwiched between two fibre ferrules in a ring laser cavity to produce self-started pulse train with a repetition rate that is tuned from 30.12 to 36.96 kHz as the 1552-nm pump power is increased from 289 to 485 mW. At maximum pump power, the laser produced a Q-switching pulse train with pulse duration, output power, pulse energy and peak power of 1.91 μs, 11 mW, 0.3 μJ and 146 mW, respectively. These results show that the TiO2 is a new potential SA material for pulsed laser applications.

Switchable soliton mode-locked and multi-wavelength operation in thulium-doped all-fiber ring laser

A switchable soliton mode-locked and multi-wavelength operation in thulium-doped fiber laser (TDFL) is demonstrated based on nonlinear polarization rotation (NPR) technique. The TDFL produces a soliton pulse operating at 1917.66nm using a 5m long thulium-doped fiber (TDF) as a gain medium as well as nonlinear medium. The solitonic behavior is further identified with two orders of Kelly sidebands in the output spectrum. The mode-locked emission is obtained from threshold pump power of 522–1052mW with consistent pulse repetition rate of 14.7MHz. Maximum pulse energy is calculated as 0.89nJ at pump power of 1052mW, whereas the maximum pulse width is estimated to be approximately 1.36ps corresponding to sech2 pulse profile. By shifting the polarization orientation, the cavity can change to multi-wavelength operation with signal-to-noise ratio (SNR) higher than 53dB. At pump power of 1037mW, three stable peak wavelengths are generated with a power fluctuation and constant spacing of ± 1 dB and 7.4nm, respectively.

Q-switched erbium-doped fiber laser operating at 1502nm with molybdenum disulfide saturable absorber

We demonstrate a Q-switched Erbium-doped fiber laser (EDFL) using a molybdenum disulfide (MoS2)-based saturable absorber (SA) as a Q-switcher. The SA is prepared from commercial available MoS2 pristine flakes with final solution concentration of ∼0.02mg/ml. The Q-switcher is assembled by depositing a dried MoS2 onto a fiber ferule facet before it is matched with another clean ferrule via a connector. By increasing the pump power from 120mW to 160mW, stable generation of Q-switched EDFL incorporating MoS2 SA has been obtained at 1502nm wavelength. The pulse repetition rate also varies from 45.2kHz to 66.0kHz with pulse width which is increased from 2.73μs to 3.19μs. At pump power of 160mW, we successfully generated the maximum average output power of 0.51mW, corresponding to a pulse energy of 7.8nJ.

Q-switched thulium-doped fiber laser operating at 1940 nm region using a pencil-core as saturable absorber

Q-switched thulium-doped fiber laser (TDFL) is demonstrated using pencil-core flakes as a saturable absorber (SA) for the first time. The SA was fabricated by exfoliating pencil-core flakes on adhesive tape surface, then repeatedly folded over the tape until the flakes homogenously deposited on the tape. A small piece of the tape is sandwiched between two ferrules and incorporated in TDFL cavity to realize a stable Q-switching pulse train. By increasing the 1552-nm pump power from 389 to 431 mW, the repetition rate of the TDFL increases from 14.95 to 34.60 kHz while the pulse width decreases from 6.70 to 4.69 μs. The maximum pulse energy of 46.05 nJ is generated with repetition rate and pulse width of 21.25 kHz and 6.27 μs, respectively. To the best our knowledge, this is a first demonstration SA from mundane object as alternative to commercial bulk graphite for Q-switched fiber laser.

Nickel oxide nanoparticles thin film saturable absorber for 1-micron pulsed all-fibre lasers operation

Abstract A passive Q-switched and mode-locked ytterbium-doped fibre laser (YDFL) pulse generation using a nickel oxide thin film as a saturable absorber is reported. The nickel oxide nanoparticle thin film was fabricated by a simple processing technique, and it has a modulation depth of 39% and saturation intensity of 0.04 MW/cm2. The saturable absorber was constructed by inserting a small piece of the film between two fibre ferrules. Then it was integrated in a YDFL cavity. The Q-switching operation started at a threshold pump power of 117.73 mW with an initial wavelength of 1073.5 nm. When the pump power was raised from 117.73 to 133 mW, the repetition rate grew from 9.5 to 15.8 kHz. The pulses had a maximum pulse energy of 478 nJ. Furthermore, a stable self-started mode-locked pulse was also succesfully generated at the threshold pump power of 97.3 mW. The central wavelength and repetition rate of the laser were 1037.72 nm and 23 MHz, respectively. The maximum pulse energy of 0.56 nJ and a peak power of 26.4 W were recorded at a pump power of 137.5 mW.

Passively Q-switched fibre laser utilizing erbium-doped fibre saturable absorber for operation in C-band region

ABSTRACT In this paper, a stable and robust all-fibre passively Q-switched erbium-doped fibre laser (EDFL) emitting at 1558u2009nm is described. The proposed laser utilizes an 11u2009cm long erbium-doped fibre as saturable absorber (SA). The fibre SA features a linear optical absorption of about 13u2009dB in the Q-switched EDFL operating regime. By elevating the input pump power from the threshold of 60u2009mW to the maximum available power of 142u2009mW, a pulse train with a maximum repetition rate of 86u2009kHz, minimum pulse width of 3.39u2009µs, maximum average output power of 10.5u2009mW, maximum pulse energy of 122u2009nJ and maximum peak power of 36u2009mW are obtained. The signal to noise ratio (SNR) of the spectrum is measured to be around 70u2009dB. This fibre SA is simple, reliable, compact and alignment free. Thus it is suitable for making a portable pulse laser source.