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Wyświetlanie 1-7 z 7
Tytuł:
Investigation of optical short pulse generation using intensity modulation for LiDAR and free-space communications
Autorzy:
Wang, Fei
Kang, Wen
Powiązania:
https://bibliotekanauki.pl/articles/1835768.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
intensity modulator
optical pulse generator
pulsed LiDAR
free-space communication
Opis:
A simple optical pulse generation scheme for pulsed light detection and ranging (LiDAR) and free-space communications is proposed and experimentally and numerically demonstrated, in which continuous-wave light emitted by a distributed feedback-laser diode (DFB-LD) is modulated by a lithium-niobate Mach–Zehnder intensity modulator to generate optical short pulses, and an Er-doped fiber amplifier (EDFA) is used to boost transmitting light power. Possibilities of intensity modulators for high speed communications being used to generate optical short pulses for low speed pulsed LiDAR are investigated. The influences of bias voltage of intensity modulator and bit rate of modulation signal on the generated optical pulses are discussed. The pulse width obtained by using the return to zero signal with 33% duty cycle on bit rate of 2.5 and 5 Gbit/s is respectively 128.0 and 63.2 ps, and the corresponding nominal accuracy of pulsed LiDAR is respectively 19.2 and 9.5 mm, and low repetition frequency required by pulsed LiDAR is achieved by coding to high-speed modulation signal. The system performance for free-space communications and pulsed LiDAR is evaluated, respectively. We believe that the proposed scheme is suitable for the integrated system of pulsed LiDAR and free-space communications.
Źródło:
Optica Applicata; 2021, 51, 1; 97-107
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Physical and mathematical model of the digital coherent optical spectrum analyser
Autorzy:
Kolobrodov, V. G.
Tymchyk, G. S.
Mykytenko, V. I.
Kolobrodov, M. S.
Powiązania:
https://bibliotekanauki.pl/articles/174296.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
optical spectrum analyzer
optical correlator
spatial light modulator
matrix detector
Opis:
A physical and mathematical model of digital coherent optical spectrum analyzers is discussed. In digital coherent optical spectrum analyzers the input signal is forming as a two-dimensional transparency by means of a spatial light modulator. After Fourier transformation with a lens, multiplication by a spatial filter and second Fourier transformation, the signal is captured by a matrix detector for further computer processing. A lot of digital coherent optical spectrum analyzers and their components (laser, lighting system, spatial light modulator, Fourier lens and matrix detector) models were developed to calculate the signal at the matrix detector output. They use the impulse response and transfer function to evaluate the effectiveness of digital coherent optical spectrum analyzers. The analysis of mathematical relationships shows that the use of a discrete spatial light modulator for the signal input and a matrix detector for light field registration in the spectral domain when combined with computer technology greatly extends the functionality of digital coherent optical spectrum analyzer. The formulas for impulse response and transfer function calculations were obtained, which allows to analyze and optimize the digital coherent optical spectrum analyzer basic characteristics.
Źródło:
Optica Applicata; 2017, 47, 2; 273-282
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generation of chirped microwave signal with any central frequency based on a nonuniformly spaced finite impulse response filter
Autorzy:
Chen, D.
Wang, R.
Pu, T.
Xiang, P.
Fang, T.
Zheng, J.
Xiong, J.
Powiązania:
https://bibliotekanauki.pl/articles/174334.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
microwave photonics
microwave photonic filter
chirped microwave signal
dual drive Mach–Zehnder modulator
Opis:
A novel optical approach to generating a chirped microwave signal by using a nonuniformly spaced finite impulse response filter is proposed and demonstrated. In this scheme, a narrowband Gaussian pulse is used as the original chirped-free signal, which is easy to be acquired. To eliminate the need of a wideband chirped-free signal, a mixer and a radio frequency signal are used to up-convert the spectrum of the original Gaussian signal. Therefore, the required frequency response can be calculated and reconstructed by a finite impulse response filter with nonuniformly spaced taps. Besides, a dual drive Mach–Zehnder modulator is used to realize single sideband modulation of the chirpedfree signal. Thus, the transfer function induced by the fiber dispersion is eliminated and the chirped microwave signal with any central frequency can be generated. In this paper, a design example of a filter with a central frequency of 10GHz is provided, and generation of the target chirped microwave signal is also demonstrated by numerical simulations.
Źródło:
Optica Applicata; 2016, 46, 3; 399-408
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of dispersion order on optical millimetre-wave generation based on series optical external modulators without an optical filter
Autorzy:
Singh, M.
Raghuwanshi, S. K.
Powiązania:
https://bibliotekanauki.pl/articles/174512.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
fiber chromatic dispersion
microwave photonics
radio-over-fiber
dual-drive Mach–Zehnder modulator
Opis:
The influence of higher order fiber dispersions (like chromatic dispersion and dispersion slope) on the optical millimeter-wave generation is studied. Optical sideband suppression ratio and radio frequency spurious suppression ratio are given and discussed. Moreover, the mathematical results of the proposed model are verified by experiments and numerical simulations.
Źródło:
Optica Applicata; 2015, 45, 2; 215-226
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wavelength-adjustable all-optical wavelength conversion using a tunable fiber laser and an electroabsorption modulator
Autorzy:
Tseng, C.-L.
Lin, Y.-W.
Ching, P.-J.
Cheng, Y.-T.
Jou, J.-J.
Liu, C.-K.
Powiązania:
https://bibliotekanauki.pl/articles/174311.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
wavelength conversion
fiber ring laser
erbium-doped fiber
electroabsorption modulator
wavelength division multiplexing (WDM) network
Opis:
A wavelength conversion scheme is presented experimentally using a wavelength tunable erbium-doped fiber laser as a probe light source and an electroabsorption modulator with a DC bias only.For the input wavelength of 1557nm with a 10-Gb/s non-return to zero signal, the Q value is 10.6and the power penalty is less than 1.5dB at a bit error rate of 10–9 at the probe wavelength of1560nm. Given a fixed Q value of 6, probe wavelengths cover a range of 25nm. Furthermore,the relationship between the range of probe wavelength and the amount of power penalty is alsoinvestigated.
Źródło:
Optica Applicata; 2016, 46, 3; 347-352
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A novel approach to photonic generation of periodic triangular radio frequency waveforms
Autorzy:
Xiang, P.
Guo, H.
Chen, D.
Zhu, H.
Wu, C.
Powiązania:
https://bibliotekanauki.pl/articles/174643.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
microwave photonics
triangular waveform
polarization modulator (PolM)
microwave photonic filter (MPF)
radio frequency (RF) waveform generation
Opis:
A novel approach to photonic generation of triangular radio frequency waveforms with a tunable repetition rate is proposed and analyzed. In the proposed system, a continuous-wave light is modulated by a reference microwave signal through a polarization modulator, and then its output optical sidebands are manipulated by a microwave photonic filter with a negative tap. By properly adjusting the system parameters, full-duty-cycle triangular radio frequency waveforms can be generated after optical-to-electrical conversion, and its repetition rate (frequency) can be tuned in a wide range. A model describing the proposed system is derived, which is verified via computer simulations.
Źródło:
Optica Applicata; 2015, 45, 3; 381-391
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial light modulator design and generation of structured electromagnetic waves using digital light processors
Autorzy:
Yalcinkaya, F.
Koc, T.
Pala, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2172826.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
spatial light modulator
digital micro-mirror device
digital light processing
structured electromagnetic wave
orbital angular momentum
hologram
Opis:
Spatial light modulators (SLMs) are versatile devices used for optical studies. These instruments have a wide area of application in photonics. Additionally, SLMs have potential utility in different applications, such as biomedical applications, laser based surgery for precise cutting and as optical tweezers to separate cells in a petri container. However, the high cost of SLM devices prevents their widespread use in many areas, including industrial areas and scientific research laboratories. This paper demonstrates how to design a digital light processor (DLP) based low-cost SLM and describes how to obtain structured electromagnetic waves with the designed SLM. Therefore, this research was undertaken to design and produce a low-cost SLM device for optical applications. For this purpose, two prerequisites had to be fulfilled, the first was to use suitable components of a projection device with DLP-based digital micro-mirror device (DMD), and the second was to eliminate unnecessary SLM components from the system. Finally, holographic images reflected on the SLM screen were created by using Mathematica software program to change the amplitude and phase of the electromagnetic waves in order to obtain the structured electromagnetic waves.
Źródło:
Optica Applicata; 2022, 52, 3; 461--479
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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