Wyniki wyszukiwania - BazTech

1

Generation of chirped microwave signal with any central frequency based on a nonuniformly spaced finite impulse response filter

Chen D., Wang R., Pu T., Xiang P., Fang T., Zheng J., Xiong J.

Optica Applicata

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2016

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Vol. 46, nr 3

399--408

EN

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.

2

Impact of dispersion order on optical millimetre-wave generation based on series optical external modulators without an optical filter

Singh M., Raghuwanshi S. K.

Optica Applicata

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2015

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Vol. 45, nr 2

215--226

EN

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.

3

A novel approach to photonic generation of periodic triangular radio frequency waveforms

Xiang P., Guo H., Chen D., Zhu H., Wu C.

Optica Applicata

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2015

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Vol. 45, nr 3

381--391

EN

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.

4

Development of fiber Bragg gratings technology and their complex structures for sensing, telecommunications and microwave photonics applications

Osuch T., Gąsior P., Markowski K., Jędrzejewski K.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2014

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Vol. 62, nr 4

627--633

EN

In this paper research on the development of the fiber Bragg grating (FBG) technology which has been conducted at the Institute of Electronic Systems (IES), Warsaw University of Technology (WUT) since 2004 is presented. In particular the directions in the development of advanced set-ups employing the phase mask inscription scheme are discussed and supported with the descriptions of structures designed and fabricated with the use of the laboratory stages constructed at the IES. The novelty of the presented solutions is based on the combination of numerous techniques of the external modification of the interferometric patterns (projected onto cores of photosensitive fibers to modulate their refractive index) as well as application of the modification of the internal properties of the waveguides themselves by the means of introducing strain or tapering. The development of these sophisticated set-ups resulted in the inscription of FBGs with precisely designed spectral characteristics which found application in telecommunications and sensor technology are also illustrated here. The paper is summarized with the specification of the most important achievements attained at the lab and drafting of the possible directions of further research.

5

Photonic generation of phase-coded microwave signals based on optical pulse shaping and time delay

Xiang P, Zheng X, Zhang H, Li Y, Wang R

Optica Applicata

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2012

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Vol. 42, nr 4

835--843

EN

A novel approach to photonic generation of phase-coded microwave signals based on optical pulse shaping and time delay is proposed. In the proposed approach, an optical short pulse train is inserted with a specified amount of time-delay to certain pulses, and then converted into super-Gaussian microwave pulses based on the optical pulse shaping technique. By properly adjusting the time-delay, phased-coded microwave signals with a desired code pattern can be generated. A model to describe the signal generation is developed, and the generations of phase-coded microwave signals with frequencies up to 50 GHz are demonstrated.

6

Fotonika mikrofalowa

Galwas B. A.

Elektronika : konstrukcje, technologie, zastosowania

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2007

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Vol. 48, nr 6

5-9

PL

Opisano najważniejsze procesy i układy, w których wykorzystano wzajemne oddziaływanie sygnałów pasma mikrofalowego i fal milimetrowych z sygnałami pasm optycznych. Przedstawiono podstawowe techniki transmisji sygnałów mikrofalowych łączami optycznymi oraz sposoby generacji sygnałów mikrofalowych wykorzystujące techniki fotoniki. Przedstawiono wybrane techniki wykorzystania sygnałów optycznych do sterowania układami mikrofalowymi. Artykuł kończy prezentacja wybranych systemów radiowych wykorzystujących transmisję łączami optycznymi.

EN

In this paper we present most important phenomena and systems where microwave and optical signals interact with each other. We also present elementary techniques of microwave signal transmission via optical links, optical generation of microwaves and also optical control of microwave devices. Finally a review of selected radio systems that use optical transmission is presented.

7

Modulator structures for radio-on-fiber applications

Hum S.V., Okoniewski M., Davies R. J.

Journal of Telecommunications and Information Technology

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2003

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nr 1

8-14

EN

Traditional electro-optic modulators are not optimized for bandpass applications such as radio-on-fiber delivery systems due to their limited electro-optic response. This paper presents a resonant electrode structure that can be employed in optical modulator designs to enhance the electro-optic response of the modulator over a narrow frequency band, and improve the performance of optical radio systems. A simple model of the structure is developed, and experimental results validating the model and illustrating the effectiveness of the structure are presented.