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This work demonstrates the tunability of tapered single mode fiber (SMF) and tapered polarization maintaining fiber (PMF) filters based on fiber twisting method. One end of the tapered fiber was twisted from 0o until 100o using the Vytran Fiber Processing System. Observation on the spectral output shows that the fiber twisting technique is a viable option to impart tunability in tapered fibers with total shift of 15 and 10 nm, respectively for SMF and PMF. Better tunability is observed in the SMF filter due to its simple physical structure and more straightforward interferometry effect but a significantly higher extinction ratio is observed for the PMF filter. Both filters exhibited region of linear wavelength shift with corresponding R2 values of 0.9924 and 0.9294 for SMF and PMF. The simplicity and reliability of the filter may pave the way for the development of a practical and compact tunable all-fiber filter for laser systems.

Since a decade ago, there has been an everlasting manoeuvre to nurture cognitive skills among students across the globe using technology. Technology-assisted cognitive augmentation had crafted an online learning environment (OLE) as one of interactive learning tool equipped with unlimited learning materials for students to learn, engage and ultimately construct their cognitive skills. The dynamic nature of education from being knowledge-centred to nowadays fluidity of cognitive skills further intensifies the role of OLE in information age education ecosystem, as pedagogy per se is seem inadequate to nurture cognitive skills. The purpose of this paper is to present an OLE prototype, designed and developed to nurture cognitive skills among students in chemistry. The design and development process, implantation of 21st-century learning media, data collection enhancement using Internet of Thing (IoT) and the predicted data analysis technique (as the OLE is not yet tested) are presented. The proposed OLE is anticipated capable to nurture cognitive skills in chemistry such as HOTS, critical thinking and problem solving skill.

Mode-locked fiber laser incorporating a saturable absorber is an attractive configuration due to its stability and simple structure. In this work, we demonstrate a dual-wavelength passively mode-locked erbium-doped fiber laser employing a graphene/polymethyl-methacrylate saturable absorber. A laser resonator is developed based on dual cavity architecture with unidirectional signal oscillation, which is connected by a fiber branch sharing a common gain medium and saturable absorber. Dual wavelength mode-locked fiber lasers are observed at approximately 1530 and 1560 nm with 22.6 mW pump power threshold. Soliton pulse circulates in the laser cavity with pulse duration of 900 and 940 fs at shorter and longer wavelengths, respectively. This work presents a viable option in developing a low threshold mode-locked laser source with closely spaced dual wavelength femtosecond pulses in the C-band wavelength region.

In this paper, we report a Q-switched erbium-doped fiber laser incorporating tungsten disulfide (WS2) as the saturable absorber. A direct mechanical deposition technique using a scotch tape is employed to place the WS2 powder onto the tip of a fiber ferrule. Several runs of mechanical extraction are performed to reduce the thickness of WS2 powder on the fiber tip. The fabricated WS2 saturable absorber exhibits a saturation intensity of 548.6 MW/cm2, modulation depth of 4.1% and non-saturable loss of 67.8%. A ring cavity erbium-doped fiber laser integrating the WS2 saturable absorber yields continuous wave lasing and Q-switching threshold at pump power of 10 and 12.7 mW, respectively. This Q-switching pump power threshold is the lowest to the best of the authors’ knowledge. The proposed technique of direct mechanical deposition is inexpensive, significantly faster and simpler compared to previously reported methods.