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21.
Multimedia Tools and Applications - When trying to identify a printed forged document, examining digital evidence can prove to be a challenge. In this study, microscopic images are used for printed... 相似文献
22.
Al-Sayed Samar Reda Samad Fatma Abdel Mohamed Tarek Youssef Doaa 《Metallurgical and Materials Transactions A》2022,53(10):3807-3807
Metallurgical and Materials Transactions A - 相似文献
23.
A new model of inductively coupled high frequency radio frequency identification (HF RFID) reader antennas is presented in this paper based on the idea of using the self resonance frequency (SRF) of a small multi turn coil. The introduced multi turn small self resonant coil (MT SSRC) antenna is mathematically analyzed in terms of SRF, number of turns, dimensions and dielectric characteristics of the insulation, where present. Based on the analysis, a compact planar version of MT SSRC antennas having two turns, the two turn planar SSRC (TTP SSRC), is investigated and the dependency of the SRF to the antenna dimension is observed. A TTP SSRC antenna operating at 13.56 MHz is fabricated and is compared with an old model of HF RFID antennas; an optimized Q factor and a more uniform near field pattern is obtained for the new antenna. The benefits of the obtained optimized Q factor and uniform near pattern is explained for smart shelf application. Also, a number of TTP SSRC antennas operating at a distinct frequency, 13.56 MHz here, are fabricated on different substrates and it is shown that the Q factor and dimension of the TTP SSRC antenna could be controlled and adjusted based on the dielectric characteristics of the substrate. The new antenna prototype has a beneficial application to smart shelf applications in HF RFID. 相似文献
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MUSTAFA MOHAMMED NAJM MOHAMMED NAJM ABDULLAH AYA A. ALMUKHTAR BELAL AHMED HAMIDA MOH YASIN SULAIMAN WADI HARUN 《光电子快报》2023,19(11):681-685
This paper demonstrated a Q-switched erbium-doped fiber laser (EDFL) using an organic saturable absorber (SA) based on 8-HQCdCl2H2O material. The organic thin film was prepared using the casting process. The proposed Q-switched EDFL has a maximum repetition rate of 143 kHz, minimum pulse duration of 1.85 µs and the highest pulse energy of 167 nJ. The Q-switched peak laser was at a central wavelength of 1 531 nm with a 3 dB bandwidth of 3.52 nm and power intensity of 2.64 dBm. 相似文献
26.
A. Yasim 《Journal of Modern Optics》2020,67(4):367-373
ABSTRACTBased on monolayer MoTe2 film, we have proposed a mode-locked fibre laser delivering single-wavelength and dual-wavelength solitons at the telecommunication band. The saturable absorber (SA) is synthesized by coating monolayer MoTe2 film on the pinhole of fibre pigtail. The experimental results show that our soliton lasers can work at the single- and dual-wavelength states, respectively, by appropriately adjusting the polarization controller. The proposed laser can work stably at the mode-locking state for several hours, indicating that monolayer MoTe2 film is an excellent SA material for ultrafast optics. 相似文献
27.
An Er/Yb co-doped fiber/Raman hybrid amplifier (HA) is proposed and studied theoretically and analytically to improve the gain and noise figure of optical amplifiers. The calculations are performed under a uniform dopant and steady-state conditions. The initial energy transfer efficiency for Er/Yb co-doped fiber amplifier (EYDFA) is introduced, while the amplified spontaneous emission (ASE) is neglected. The glass fiber used for both Er/Yb and Raman amplifiers is phosphate. Different pump powers are used for both EYDFA and RA with 1 μW input signal power, 1 m length of Er/Yb amplifier and 25 km length of Raman amplifier (RA). The proposed model is validated for Er/Yb co-doped amplifier and Raman amplifier separately by comparing the calculating results with the experimental data. A high gain and low noise figure at 200 mW Raman pump power and 500 mW Er/Yb pump power are obtained for the proposed HA as compared with the experimental results of EYDFA, Raman amplifier and the EDFA/Raman hybrid amplifier. 相似文献
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《Ceramics International》2015,41(7):8650-8654
In this paper, an integrated passively Q-switched DBR laser made in glass integrated optics technology is designed, fabricated and investigated. The laser, operating at 1030 nm wavelength, is formed by an ion-exchanged single mode waveguide realized in an Ytterbium doped phosphate glass. The feedback is provided by a DBR structure made of a Fiber Bragg Grating and a dielectric mirror. The Q-switched behavior is obtained by hybridizing the saturable absorber on the waveguides, so that it interacts with the evanescent part of the guided field. The saturable absorber we use is a bis(4-dimethylaminodithiobenzil)nickel (BDN) dye incorporated in a polymeric film. Using this structure, we were able to demonstrate a Q-switched operation for several BDN concentrations, allowing to vary the pulse duration and the repetition rate of the device. Moreover, we report a very narrow 372 MHz wide emission spectrum while in Q-switched regime. 相似文献
30.
《Optical Fiber Technology》2013,19(4):304-308
We propose a wavelength-tunable thulium-doped single mode fiber laser with a digitally controlled micro-mirror array device. The fast and flexible lasing wavelength switching property was achieved by the pixelated spatial modulation of the micro-mirror array. The proposed laser provides a maximum output power of 160 mW with 24% slope efficiency and a narrow output linewidth of less than 0.03 nm. The operating wavelength is continuously tunable from 1863 nm to 1937 nm with a wavelength selectivity accuracy of less than 0.4 nm and a fast switching time of ∼75 μs. 相似文献