Wavelength-swept Tm-doped fiber laser operating in the two-micron wavelength band

A wavelength-swept thulium-doped silica fiber laser using an intracavity rotating slotted-disk wavelength scanning filter in combination with an intracavity solid etalon for passive control of temporal and spectral profiles is reported. The laser yielded a wavelength swept output in a step-wise fashion with each laser pulse separated from the previous pulse by a frequency interval equal to the free-spectral-range of the etalon and with an instantaneous linewidth of <0.05 nm. Scanning ranges from 1905 nm to 2049 nm for a cladding-pumping laser configuration, and from 1768 nm to 1956 nm for a core-pumping laser configuration were achieved at average output powers up to ~1 W

Ultra-broadband wavelength-swept Tm-doped fiber laser using wavelength-combined gain stages

A wavelength-swept thulium-doped fiber laser system employing two parallel cavities with two different fiber gain stages is reported. The fiber gain stages were tailored to provide emission in complementary bands with external wavelength-dependent feedback cavities sharing a common rotating polygon mirror for wavelength scanning. The wavelength-swept laser outputs from the fiber gain elements were spectrally combined by means of a dichroic mirror and yielded over 500 mW of output with a scanning range from ~1740 nm to ~2070 nm for a scanning frequency of ~340 Hz

Problem-based learning module of organic insecticide for the aborigine students in Malaysia

Problem-based learning (PBL) is a teaching model that uses real-world problems to lead students toward the learning objective of a course. It has been widely adopted in Malaysian education. However, PBL module for aboriginal people is scarce. This study aimed to provide suitable PBL activities in learning environmental problems by developing a PBL teaching module for the aborigine community and accessing its suitability. In this study, data was collected through an online validation form that was given to four validators, all of them have science or chemistry education backgrounds. The online questionnaires collected were further analyzed to investigate their responses to the module. The result has shown positive feedback (95.83%) as the responses are very encouraging. All respondents give approbation to the objectives of the module which are clearly stated and are parallel with the content. Many of them also strongly agree that the PBL model and the language used are suitable in this module. There is no doubt that PBL is a valuable tool to teach chemistry to improve students’ critical thinking and problem-solving skills effectively