M. F. M. Rusdi

Generation of Mode-Locked Ytterbium Doped Fiber Ring Laser Using Few-Layer Black Phosphorus as a Saturable Absorber

We demonstrate the generation of mode-locked pulses from a double-clad ytterbium-doped fiber laser (YDFL) employing a saturable absorber (SA) made of a few layers of black phosphorus (BP). The BP SA was prepared by mechanically exfoliating BP crystal and spreading the acquired BP flakes on a piece of scotch tape. The tape was then sandwiched between two ferrules and incorporated in a YDFL cavity to achieve a stable mode-locked operation at 1085.58 nm with a repetition rate of 13.5 MHz. A maximum pulse energy of 5.93 nJ was obtained at pump power of 1322 mW with the output power of 80 mW. Our study may well be the first demonstration of the BP-based mode-locked fiber laser that should shed some new insights into two-dimensional layer materials related photonics.

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.

Holmium Oxide Film as a Saturable Absorber for 2μm Q-Switched Fiber Laser

This work reports on the use of the holmium oxide (Ho2 O3) polymer film as a saturable absorber (SA) for generating stable Q-switching pulses operating in a 2-μm region in a thulium-doped fiber laser cavity. The SA is prepared by diluting a commercial Ho2 O3 powder and then mixing it with polyvinyl alcohol (PVA) solution to form a Ho2 O3 -PVA film. A tiny part of the film about 1 mm×1 mm in size is sandwiched between two fiber ferrules with the help of index matching gel. When incorporated in a laser cavity driven by a 1552-nm pump, stable Q-switching pulses are observed at 1955 nm within the pump power range of 363-491 mW. As the pump power increases within this range, the repetition rate rises from 26 kHz to 39 kHz, as the pulse width drops from 4.22 μs to 2.57 μs. The laser operates with a signal-to-noise ratio of 47 dB, and the maximum output power and the pulse energy obtained are 2.67 mW and 69 nJ, respectively. Our results successfully demonstrate that the Ho2 O3 film can be used as a passive SA to generate a 2-μm pulse laser.

Molybdenum Disulphide Tape Saturable Absorber for Mode-Locked Double-Clad Ytterbium-Doped All-Fiber Laser Generation

We demonstrate the generation of passive mode-locked double-clad ytterbium-doped fiber laser operating in a 1-micron region. We prepare the saturable absorber from commercial crystal of molybdenum disulphide (MoS2). Without chemical procedure, the MoS2 is mechanically exfoliated by using a clear scotch tape. A few layers of MoS2 flakes are obtained on the tape. Then, a piece of 1 × 1 mm tape containing MoS2 thin flakes is inserted between two fiber ferrules and is integrated in the ring cavity. Stable mode-locking operation is attained at 1090 nm with a repetition rate of 13.2 MHz. Our mode-locked laser has a maximum output power of 20 mW with 1.48 nJ pulse energy. These results validate that the MoS2 has a broad operating wavelength which covers the 1-micron region, and it is also able to work in a high-power cavity.

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 1558 nm is described. The proposed laser utilizes an 11 cm long erbium-doped fibre as saturable absorber (SA). The fibre SA features a linear optical absorption of about 13 dB in the Q-switched EDFL operating regime. By elevating the input pump power from the threshold of 60 mW to the maximum available power of 142 mW, a pulse train with a maximum repetition rate of 86 kHz, minimum pulse width of 3.39 µs, maximum average output power of 10.5 mW, maximum pulse energy of 122 nJ and maximum peak power of 36 mW are obtained. The signal to noise ratio (SNR) of the spectrum is measured to be around 70 dB. This fibre SA is simple, reliable, compact and alignment free. Thus it is suitable for making a portable pulse laser source.

Graphene Oxide saturable absorber for generating eye-safe Q-switched fiber laser

This paper reports the generation of Q-switched fiber laser using thulium doped fiber (TDF) as a gain medium and graphene oxide (GO) as a saturable absorber (SA). The GO powder is embedded into polyvinyl alcohol (PVA) to form an SA film based on a drop-casting technique. GO-SA film is sandwiched between two fiber connectors and tighten by FC adapter before it is incorporated into an TDF laser cavity for Q-switching pulse generation. At 344 mW pump level, a stable Q-switching regime presence at 1943 nm with a 3-dB spectral bandwidth of 9 nm. The maximum repetition rate, pulse width, and pulse energy are at 25 kHz, 4.2 µs, and 0.68 µJ, respectively. All finding results are comparable with other reported pulse fiber lasers.

Black phosphorus as a saturable absorber for generating mode-locked fiber laser in normal dispersion regime

This paper reports a few-layer black phosphorus (BP) as a saturable absorber (SA) or phase-locker in generating modelocked pulses from a double-clad ytterbium-doped fiber laser (YDFL). We mechanically exfoliated the BP flakes from BP crystal through a scotch tape, and repeatedly press until the flakes thin and spread homogenously. Then, a piece of BP tape was inserted in the cavity between two fiber connectors end facet. Under 810 mW to 1320 mW pump power, stable mode-locked operation at 1085 nm with a repetition rate of 13.4 MHz is successfully achieved in normal dispersion regime. Before mode-locked operation disappears above maximum pump, the output power and pulse energy is about 80 mW and 6 nJ, respectively. This mode-locked laser produces peak power of 0.74 kW. Our work may validates BP SA as a phase-locker related to two-dimensional nanomaterials and pulsed generation in normal dispersion regime.

Generating 2 micron continuous-wave ytterbium-doped fiber laser-based optical parametric effect

We report an efficient method for generating a 2 micron laser based on an optical parametric oscillator (OPO). It uses a long piece of a newly developed double-clad ytterbium-doped fiber (YDF), which is obtained by doping multi-elements of ZrO2, CeO2 and CaO in a phospho-alumina-silica glass as a gain medium. The efficient 2 micron laser generation is successful due to the presence of partially crystalline Yb-doped ZrO2 nano-particles that serve as a nonlinear material in a linear cavity configuration and high watt-level pump power. Stable self-wavelength double lasing at 2122 nm with an efficiency of 7.15% is successfully recorded. At a maximum pump power of 4.1 W, the output power is about 201 mW.