Mode-locking is an ultra-short pulse laser generation technique. The range of pulse duration may vary from picoseconds to femtoseconds. Yttrium Oxide (Y₂O₃) based saturable absorber (SA) was appropriately revealed in the mode-locked method within the 1.55-micron regime. Y₂O₃ is perfect for strength, melting point, and chemical stability and can be used as a laminated insulator due to its properties. Moreover, Y₂O₃ also owns broadband service, switching speed, and engineering features. The Y₂O₃-PVA film was produced by combining the 50 mg Y₂O₃ powder into a 50 mL polyvinyl alcohol (PVA) solution and stirring it at room temperature for about 24 h. A mode-locked pulse was recorded with the integrated Y₂O₃-PVA SA in the erbium-doped fiber laser (EDFL) cavity, and the output spectrum optical spectrum analyzer displayed was around 1560.66 nm. In addition to the sustained mode-locked pulse, a nearly constant repetition rate of 1.01 MHz at a specific pump power begins from 175.87 mW to 228.04 mW while the pulse duration is 4.15 ps. Lastly, the mode-locked pulse had been evaluated, which showed the peak power started from 4.94 kW to 6.07 kW.

As a result of the high-power output, low fuel consumption, and low emissions expected from internal combustion engines, new engine technologies continue to be developed. Laser ignition systems are a solution to these expectations with the advantages they offer. Experimental and numerical studies related to laser ignition systems are accelerating today. In this study, an internal combustion engine was simulated with the spark and laser ignition systems, and the changes in engine performance for different ignition timings were investigated comparatively. ANSYS Fluent 2021 R1 software was used in the dynamic CFD study in which the entire engine cycle was analysed. Analyses were carried out at constant engine speed with an iso-octane+air mixture. Critical parameters such as pressure, volume, and temperature changes, power, torque, IMEP, MPRR, peak pressure, HRR, CHRR, start of combustion, and combustion duration were evaluated for both ignition systems. As a result of the study, optimum performance values were obtained at 680 °CA ignition timing with laser ignition system. At this ignition timing, power, torque, IMEP, MPRR, and peak pressure values were determined as 16.4302 kW, 62.7635 Nm, 14.1743 bar, 2.4665 bar/°CA, and 61.5611 bar, respectively. The laser ignition system increased engine performance, and smoother and knock-free combustion occurred. At optimum ignition timing, combustion duration was shortened, and in-cylinder temperatures decreased. The findings show that the laser ignition system will contribute to engine development studies by positively affecting engine and combustion performance.

In this study, the gain clamping performance of Hafnia-bismuth-erbium co-doped fibre amplifier (HB-EDFA) using a lasing controlled structure with fibre Bragg grating (FBG) pair is presented. First, the gain and noise figure (NF) characteristics of a bidirectionally pumped HB-EDFA with very short lengths of heavily doped fibre are presented regarding its critical design parameters such as HB-EDF length, pump power, input signal power and signal wavelength. Then, the gain clamping performance of a bidirectionally pumped HB-EDFA having a C-band FBG pair with Bragg wavelengths of 1534 and 1542 nm is experimentally analysed. A good gain clamping capability was obtained using the proposed bidirectionally HB-EDFA design which has resulted in a dynamic signal input power range of 25 dB at 16 dB signal gain for 1.6 m HB-EDF length, and a wider dynamic signal input power range of 30 dB at 10 dB signal gain for 1.1 m HB-EDF length.

Fiber Bragg gratings (FBG) are ideal sensors for temperature, strain or vibration sensing applications with their advantages over conventional electronics sensor systems. In this paper, two different FBG sensor interrogation schemes based on broadband ASE source and tunable EDFRL source are demonstrated and compared. With both interrogator configurations, the response of the FBG sensor to temperature change is found to be linear and the sensitivities are measured as 11 pm/°C and 10.5 pm/°C, respectively. The experimental results have revealed that the optical power reflected from the FBG sensor is almost 20 dB higher with tunable EDFRL source than broadband ASE source. Thus, an interrogation method with tunable EDFRL can be suitable for remote, quasi-distributed sensor applications requiring high output power and OSNR.

Renewable energy systems, which are intermittent energy production systems, cannot always operate at high efficiency due to their nature. Since specific amounts of energy must be spent for energy production, it is essential to estimate the time intervals when the efficiency of the energy source is high. In order to actively monitor the system health, the communication traffic must be transferred to a monitoring room where the technical teams can easily observe the operating data of the equipment in the energy-generating plants. It has been assumed that the energy needs of vocational schools affiliated with the university are met by solar energy systems previously installed by the university administration in their fields. Thanks to the simulation programs, a communication network that does not violate the standards published by the International Electrotechnical Commission for solar energy systems has been designed. Contrary to the methods most preferred in wide area networks like Telecommunication Company’s tariff, we preferred wireless communication technologies. By choosing comprehensive area network technology WiMAX and local area network technology WiFi, we passed the required performance criteria under the name of related communication standards.