Black phosphorus film as Q-switcher in neodymium-doped fiber laser.

We present the successful development of a 1089.4 nm Q-switched laser employing a neodymium-doped fiber (NDF) as the active fiber and black phosphorus (BP) as the saturable absorber (SA). The BP SA was fabricated by inserting BP compound into a polyvinyl alcohol (PVA) host polymer, exhibiting a saturable absorption of 2.8 %. Integrated into an NDFL ring cavity, the SA modified the cavity loss, enabling the production of Q-switched pulses. With an increase in the 808 nm pumping power from 108.6 to 155.9 mW, the laser output pulse duration decreased from 3.74 to 3.54 µs, while the repetition rate improved from 40.6 to 51.0 kHz. The laser demonstrated a stable pulse train output, with a fundamental frequency signal to background noise ratio of 45.78 dB. The highest pulse energy of 1.3 nJ was recorded at 155.9 mW pump power. To the best of our knowledge, this represents the first utilization of BP as a SA or Q-switcher within an NDFL cavity.

Copper phthalocyanines as a mode-locker in an Er-doped fiber laser.

We demonstrate a mode-locked erbium-doped fiber laser (EDFL) utilizing copper phthalocyanines (CuPc) as a saturable absorber (SA) for the first time, to the best of our knowledge. The investigated SA was prepared using a simple, low-cost and straightforward technique, whereby the CuPc powder was embedded into polyvinyl alcohol (PVA) to form a thin film. The thin film acted as a mode-locker when it was incorporated into the EDFL cavity to produce output pulses at a repetition rate of 1.8 MHz with a pulse duration of 1.98 ps. The frequency spectrum showed a signal-to-noise ratio as high as 55 dB, which indicates the stability of the mode-locking operation. To the best of our knowledge, this is the first work to report using CuPc as a mode-locker.

On Reliable and Efficient Data Gathering Based Routing in Underwater Wireless Sensor Networks.

This paper presents cooperative routing scheme to improve data reliability. The proposed protocol achieves its objective, however, at the cost of surplus energy consumption. Thus sink mobility is introduced to minimize the energy consumption cost of nodes as it directly collects data from the network nodes at minimized communication distance. We also present delay and energy optimized versions of our proposed RE-AEDG to further enhance its performance. Simulation results prove the effectiveness of our proposed RE-AEDG in terms of the selected performance matrics.