Search

In this work, we report the effect of four-wave mixing (FWM) in MoTe2 deposited on a side-polished fibre (SPF). The MoTe2 layer has a nonlinear coefficient of 17.368 W−1 km−1 at 1550 nm, while the coated SPF has a conversion efficiency of – 38 dB and output tuning range of 5 nm. The generated idlers from the induced FWM effect were observed to be highly stable with minimal peak fluctuations and only minor changes in their measured conversion efficiency. The proposed MoTe2 based SPF is thus a suitable device for inducing the FWM effect in an optical fibre laser cavity and could also serve to induce other non-linear optical effects for use in optical communications networks. [ABSTRACT FROM AUTHOR]

The fabrication of a silver (Ag) based photodetector on a silicon dioxide/p-silicon (SiO2/p-Si) substrate using direct current (DC) magnetron sputtering is demonstrated. The proposed method deposits a nanoparticle-like Ag thin film that favours the photoconduction mechanism under light illumination at 468 nm and laser illumination at 660 and 980 nm. The thin film is characterized using scanning electron microscope (SEM), energy dispersive x-ray (EDX), x-ray diffraction (XRD), Raman scattering, photoluminescence (PL) and ultraviolet–visible (UV–VIS) analysis. Current–voltage (I–V) analysis and the calculated rectifying ratio (RR) suggests the establishment of good Schottky contacts for incident light/laser at 468, 660 and 980 nm, with good responsivity towards light and laser illumination in the forward and reverse DC bias regions. The responsivity increases as the wavelength decreases from 980 nm → 660 nm → 468 nm, with the highest responsivity of 213.7 mAW−1 at 468 nm indicating better photoconduction at low light powers. [ABSTRACT FROM AUTHOR]

In this work, a passively Q-switched Thulium/Holmium-doped fibre laser (THDFL) using a molybdenum tungsten disulphide (MoWS2) saturable absorber (SA) is proposed and demonstrated. The MoWS2 nanosheets are prepared by hydrothermal exfoliation and then suspended in a polyvinyl alcohol (PVA) thin film host. Q-switching of the THDFL at a maximum 1550 nm pump power of 445.2 mW gives a maximum repetition rate and minimum pulse width of 36.3 kHz and 2.8 µs with a corresponding pulse energy of 86.4 nJ and peak power of 31.1 mW. The MoWS2 based Q-switched THDFL's output has a very high signal-to-noise value of ∼62.2 dB which strongly indicates that the laser is working in a stable operation. To the best of our knowledge, this is the first demonstration of MoWS2 as a passive SA in a THDFL for operation in the 2.0 µm region. The proposed laser would have significant medical and sensing applications, particularly at the biologically active 2.0–2.1 µm regions. [ABSTRACT FROM AUTHOR]

A C-band mode-locked fibre laser incorporating a boron nitride-doped graphene oxide (BN-GO)-based saturable absorber (SA) is proposed and demonstrated. The SA is fabricated by depositing multiple layers of synthesized BN-GO nanoparticles onto the polished surface of a side-polished fibre, which is then inserted into an erbium-doped fibre laser cavity to generate the desired pulsed output. The strong nonlinear optical response and light absorption of the BN-GO nanoparticles induces the generation of a highly stable mode-locked pulse at 1567.32 nm with visible Kelly’s sidebands. The pulses have a measured repetition rate of 13.56 MHz and a pulse width of 1.18 ps at the maximum pump power of 280.5 mW. The pulses have a frequency signal-to-noise ratio of ∼53 dB, indicating a highly stable output. The proposed laser would find significant telecommunications applications, particularly for dense wavelength division multiplexing systems. [ABSTRACT FROM AUTHOR]

This paper demonstrates the use of a tapered fibre in generating a highly stable and tunable dual-wavelength fibre laser. By unique arrangement of polarization controller, adjustable spacing range between 0.94 and 3.32 nm and side mode suppression ratio (SMSR) up to 50 dB were recorded. The results were achieved at laser pump power of 94.7 mW. The inter-modal interference is achieved through the use of a non-adiabatic tapered fibre, made by a systematic flame brushing technique. The tapered fibre suppresses the mode competition in the 3-m erbium-doped fibre (EDF) gain medium. Over 60 min, the laser exhibited very high stability with acceptable peak power and SMSR. The proposed EDF laser operates from 1556.71 to 1562.13 nm range. [ABSTRACT FROM PUBLISHER]

In this paper, a microfibre polarizer based on graphene oxide (GO) is proposed and demonstrated. A microfibre was coated with GO using the drop-casting technique. The extinction ratio (ER) has been measured at wideband range of 1310, 1460, 1550 and 1600 nm. The highest ER obtained in this experiment was 37.0 dB measured at 1480 nm wavelength. The result has been achieved with a GO coating thickness of 24 μm and coating length of 12 mm. This work demonstrates a polarizing effect of GO-coated microfibre. [ABSTRACT FROM AUTHOR]

A novel frequency and pattern reconfigurable Yagi antenna is proposed. The antenna is formed by a driver, a reflector and two directors. The introduction of switches using a PIN diode at the arms of the driver element produces three switchable frequencies at 1.25 GHz, 1.85 GHz and 2.45 GHz. By controlling the switches at the directors and reflector, the radiation pattern can be configured to near omni-directional pattern or directional pattern at those three frequencies. Simulated and measured results are used to demonstrate the performance of the antenna. The simulated and measured return losses and the radiation patterns, are presented and compared. It was found that the gain of the antenna increases from 3.3 dB to 5 dB in a directional pattern, when compared to the near omni-directional pattern. [ABSTRACT FROM AUTHOR]