Passively mode locked thulium and thulium/holmium doped fiber lasers using MXene Nb2C coated microfiber.

As a result of the emergence of two-dimensional (2D) materials for various opto-electronics applications, a new class of materials named MXenes have been attracting interests due to their outstanding nonlinear properties. In this work, an MXene niobium carbide (Nb2C) was proposed and demonstrated as a saturable absorber to induce mode-locking in thulium- and thulium/holmium-doped fiber lasers. The Nb2C solution was first prepared using the liquid exfoliation technique, and then deposited onto a microfiber for integration into the laser cavity. Stable mode-locking operation was observed in both laser cavities, where the center wavelengths of the laser were recorded at 1944 nm for the TDFL and 1950 nm for the THDFL. The generated pulses in the TDFL and THDFL had repetition rates of 9.35 and 11.76 MHz respectively, while their corresponding pulse widths were 1.67 and 1.34 ps. Both of the lasers were highly stable, having SNR values of more than 52 dB and showed no major fluctuations when tested for their long-term stabilities. The results demonstrate an excellent performance of the Nb2C as a saturable absorber, offering opportunities to further explore MXenes for future photonics devices.

Low birth weight in Kuala Lumpur.

Low birth weight babies are defined as those weighing under 2,500 g. They make 13.5% of all births at the Maternity Hospital, Kuala Lumpur but contribute to 74.8% of all deaths. They are most likely to be Indian babies and least likely to be Chinese. Among all 3 communities, the primigravidae tend to produce smaller babies than multiparae but this is also true for the Indian of parity more than 3. The Malay teenager is more likely to produce small babies than their older counterparts but not so with the Indian and Chinese. There are definite clinical factors associated with or causing the births of small babies and the lighter the baby, the more influential are these factors. Maternal hypertension, antepartum haemorrhage, multiple pregnancy and unexplained intrauterine death are the 4 outstanding associations with both low birth weight and perinatal death. Although the spontaneous (often premature) onset of labour was the commonest preceding factor, it was much less important in the lowest birth weight groups of babies and was a less important contributor to perinatal death.