All-fiber all-normal-dispersion passively mode-locked neodymium-doped fiber laser operation at 1064 nm

In this work, we report an all-fiber Nd-doped passively mode-locked fiber laser based on nonlinear polarization rotation mechanism operating in the 1.06 μm region. When the pump power was 300 mW, a pulse with a maximum average output power of 0.63 mW, a narrowest pulse duration of 1.22 ps and a pulse repetition rate of 14.25 MHz was obtained.

The Yb3+:LuAlO3 crystal as an active medium for picosecond mode-locked lasers

Herein, we report on the mathematical modelling and experimental study of the regime of nonsoliton mode locking in a laser based on the Yb3+:LuAlO3 (Yb:LuAP) crystal with longitudinal pumping by laser diode radiation. Simulation based on the Haus master equation permitted to determine the requirements for the parameters of a saturable absorber (SA), the level of the average output power, the size of the TEM00 mode of the cavity in the active element and on the gate to obtain a stable regime of generation of picosecond laser pulses. Laser experiments were carried out in a fourmirror X-shaped resonator using a semiconductor saturable mirror (SESAM) as a passive modulator and a laser diode with a fiber output of a maximum power up to 30 W at a wavelength of 978.5 nm as a pump source. We obtained a stable passive mode locking with a maximum average output power of up to 12 W and an ultrashort pulse duration of about 2 ps at an optical conversion efficiency of pump radiation into lasing radiation of about 38 %. Laser pulses were obtained at a central wavelength of about 999 nm with a minimum Stokes shift (about 2 %) with respect to the pump radiation, which significantly reduced the thermal load on the active element. Additionally, the preliminary results on the second harmonic generation and synchronous pumping of a parametric light generator using a Yb3+ : LuAlO3 crystal laser as a pump source are presented.

Evaluating OADM network simulation and an overview based metropolitan application

Using optical add–drop multiplexer/remover multiplexer (OADM), it is possible to add or remove wavelengths and change or route them through the various nodes and networks. At this moment, key problems in add–drop multiplexer (ADM) are the bandwidth, modulation format, and reuse wavelength. In this article, the Optisystem software simulation is used as a platform to design, test, and verify the method applied to the current work; the OADM is proposed based on the metro network to get distribution between nodes over a transmission link; OADM analysis was presented with four channels (193.1, 193.2, 193.3, and 193.4 THz) at total bandwidth of 1.6 Tb/s, none-return-to-zero (NRZ), and return to zero coding types. Experiment one shows that the average output power is −17.997 dBm, the average drop power is −17.997 dBm, and the average add power is −18.338 dBm, the average gain is −0.0429 dB, the average noise figure is 0 dB, the average power input signal is 10.679 dBm, the average of power output signal is 10.633 dBm, and the average output optical signal-to-noise ratio (OSNR) is 0 dB, However, the second experiment shows that the average output power is −24.238 dBm, the average drop power is −24.288 dBm, and the average add power is −24.753 dBm, the average gain is −0.0417 dB, the average noise figure is 0 dB, average power input signal is 7.691 dBm, average of power output signal is 7.677 dBm, and the average output OSNR 0 dB. The system supports four input channels, four add channels, four output channels, and four drop channels. The results are acceptable after three spans of Solitons fiber with 600 km length, 200 km for each span. Nonetheless, it is believed that it is well justified to adopt these schemes in the current optical network with a low cost for overall expenditure.

Mechanism, theory and application research of a rotating electromagnetic energy harvester suitable for multi-directional excitation

Energy harvesting in multi-directional excitation for human wearable devices is a challenge. A rotating electromagnetic energy harvester(REMEH) based on an eccentric rotor structure is proposed in this paper. Two poles of the magnets in REMEH are alternately arranged in a ring. The electrical output characteristics of the energy harvester are analyzed through theoretical, numerical simulation and experimental testing methods based on the establishment of magnetic flux density models, the coil induced voltage, and the excitation direction of the eccentric rotor structure. Theoretical analysis and experimental results show that the design of the eccentric rotor structure is well adapted to multi-directional and irregular excitation. The circular staggered arrangement of the magnets effectively increases the output voltage and output power. The results show that the average output power increases slowly when the walking speed increases from 1km/h to 3km/h, and the average output power increases substantially when the walking speed increases from 3km/h to 5km/h. When the walking speed is 1km/h and 3km/h, the average output power is 0.439mW and 0.638mW, respectively. At a walking speed of 5 km/h, the average output power increases rapidly to 1.68mW, corresponding to a power density of 16.59μW/g. This high-performance energy harvester can provide effective power supply for wearable devices or low-powered sensors.

Automatic Cleaning System Design to Increase PV Panel Output Power

The existence of the Township Housing, which is currently near the coal mine site, precisely in Tanjung Enim, South Sumatra, with a relatively open area (41 Ha) and a relatively high elevation of approximately 100 meters over the sea level, has the potential to be installed with PV panels as a solar power plant. Installation of PV panels in residential areas close to coal mining activities has the potential to indirectly generate a lot of mine dust which can reduce the amount of light received by the PV panels, which in turn can affect the output power of the PV panels. The purpose of this study is to analyze the use of an automatic cleaning system to increase the output power of PV panels by comparing the output power of PV panels produced between PV panels with an automatic cleaning system in the form of a water sprayer with PV panels that are not equipped with a water sprayer (standard PV installation). The use of an automatic cleaning system shows an increase in the average output power of 44.56 Watt. The difference between Isc PV water sprayer and normal PV is 0.5513 A. Iload measurement on PV water sprayer is 0.1973 A higher than normal PV, while for VOC PV panel water sprayer is smaller than normal PV is about 0.45 V. For PV water sprayer Vload is 0.431 V is more significant than normal PV panels. Meanwhile, for the generated load power or Pload, the PV water sprayer is 9.47 watts higher than normal PV. From all these values, the average efficiency produced by PV water sprayer is 1.81% greater than the efficiency produced by normal PV. This study shows that PV using a water sprayer produces an average output power of 44.56 watts

A Dual-Mode InGaP/GaAs HBT Power Amplifier Using a Low-Loss Parallel Power-Combining Transformer with IMD3 Cancellation Method

A dual mode InGaP/GaAs heterojunction bipolar transistor (HBT) power amplifier (PA) using a parallel power-combining transformer (PCT) is presented herein. A low loss transformer is implemented on a printed circuit board (PCB) to improve the passive efficiency of a PCT. Dual-mode operation is applied to reduce the current consumption at a low power level. In the low-power (LP) mode, one of the individual amplifiers is turned off to reduce the current consumption. Additionally, a third-order intermodulation distortion (IMD3) cancellation method using a PCT combiner is proposed to improve linearity performance. Nonlinear IMD3 components from each amplifier cancel each other out through magnetic coupling in the secondary winding of the PCT. The implemented PA achieves a saturated output power of 33.8 dBm and a peak power-added efficiency (PAE) of 54.5% at 0.91 GHz with a 5-V power supply. An average output power of 25.2 dBm with an adjacent channel leakage ratio (ACLR) of −42 dBc is delivered when the PA is tested with an orthogonal frequency division multiplexing (OFDM) 64-quadrature amplitude modulated (64-QAM) signal with a bandwidth of 10 MHz and peak-to-average power ratio (PAPR) of 7.8 dB. When compared with the high-power (HP) mode operation, the LP mode operation could save 48% of the current consumption at an average output power of 10.4 dBm.