H. Haris

Passively Q-Switched EDFL Using a Multi-Walled Carbon Nanotube Polymer Composite Based on a Saturable Absorber

A stable passive Q-switched erbium-doped fiber laser (EDFL) operating at 1563.5 nm is demonstrated by using a multi-walled carbon nanotube (MWCNT) polymer composite film based saturable absorber for the first time. The composite is prepared by mixing the MWCNTs homogeneous solution into a dilute PEO polymer solution before it is left to dry at room temperature to produce thin film. Then the film is sandwiched between two FC/PC fiber connectors and is integrated into the laser cavity for Q-switching pulse generation. The EDFL generates a stable pulse train with repetition rates ranging from 4.5 kHz to 20.0 kHz by varying the 1480 nm pump power from 35mW to 53mW. At the 53mW pump power, the pulse width and pulse energy are 8.8 μs and 15.3 nJ, respectively.

Generation of soliton and bound soliton pulses in mode-locked erbium-doped fiber laser using graphene film as saturable absorber

We report an observation of soliton and bound-state soliton in passive mode-locked fibre laser employing graphene film as a passive saturable absorber (SA). The SA was fabricated from the graphene flakes, which were obtained from electrochemical exfoliation process. The graphene flakes was mixed with polyethylene oxide solution to form a polymer composite, which was then dried at room temperature to produce a film. The film was then integrated in a laser cavity by attaching it to the end of a fibre ferrule with the aid of index matching gel. The fibre laser generated soliton pulses with a 20.7 MHz repetition rate, 0.88 ps pulse width, 0.0158 mW average output power, 0.175 pJ pulse energy and 18.72 W peak power at the wavelength of 1564 nm. A bound soliton with pulse duration of ~1.04 ps was also obtained at the pump power of 110.85 mW by carefully adjusting the polarization of the oscillating laser. The formation of bound soliton is due to the direct pulse to pulse interaction. The results show that the proposed graphene-based SA offers a simple and cost efficient approach of generating soliton and bound soliton in mode-locked EDFL set-up.

Q-switched erbium-doped fiber laser using multi-layer graphene based saturable absorber

The performance of a stable passive Q-switched Erbium Ytterbium co-doped fiber laser (EYFL) operating at 1532.5 nm is demonstrated using a multi-layer graphene film based saturable absorber. The graphene is synthesized by electrochemical exfoliation of graphite at room temperature in 1% sodium dodecyl sulphate (SDS) aqueous solution. Graphene flakes obtained from the process are mixed with polyethylene oxide (PEO) as the host polymer to produce free standing composite thin film which acts as a passive Q-switcher in the EYFL ring cavity. At 980 nm pump power of 44 mW, the EYFL generates optical pulse train with a repetition rate of 12.33 kHz and pulse width of 9.36 μs. The highest energy of 5.8 nJ and the lowest pulse width of 2.68 μs are achieved at the maximum pump power of 78 mW. Further increase in the pump power is expected to further improve both the pulse energy and pulse width.

All-fibre Q-switching YDFL operation with bismuth-doped fibre as saturable absorber

Abstract We demonstrate the generation of a passively Q-switched ytterbium-doped fibre laser (YDFL) using a bismuth-doped fibre (BDF) as a solid-state fibre saturable absorber (FSA) in a ring cavity. The BDF used has a wide and low absorption band of 5 dB/m at the 1.0 μm region due to the ion transition of that occurs around the region. When introduced into a YDFL laser cavity, a stable Q-switched pulse operation was observed and the pulse repetition rate was proportional to the input pump power. It was limited to 72.99 kHz by the maximum power that the laser diode could supply. Meanwhile, the pulse width decreased from 12.22 to 4.85 μs as the pump power was increased from 215.6 to 475.6 mW. The finding suggests that BDF could be used as a potential SA for the development of robust, compact, efficient and low cost Q-switched fibre lasers operating at 1 micron region.

Experimental Observation of Bright and Dark Solitons Mode-Locked with Zirconia-Based Erbium-Doped Fiber Laser

We demonstrate the generation of dark and bright solitons with our homemade zirconia-based erbium-doped fiber and graphene oxide (GO) saturable absorber in anomalous dispersion region. The GO is fabricated using an abridged Hummers method, which is combined with polyethylene oxide to produce a composite film. The film is sandwiched between two optical ferrules and embedded in the laser cavity to enhance its birefringence and nonlinearity. The self-starting bright soliton is easily generated at pump power of 78mW with the whole length cavity of 14.7 m. The laser produces the bright pulse train with repetition rate, pulse width, pulse energy and central wavelength being 13.9 MHz, 0.6 ps, 2.74 pJ and 1577.46 nm, respectively. Then, by adding the 10m of single mode fiber into the laser cavity, dark soliton pulse is produced. For the formation of dark pulse train, the measured repetition rate, pulse width, pulse energy and central wavelength are 8.3 MHz, 20 ns and 4.98 pJ and 1596.82 nm, respectively. Both pulses operate in the anomalous region