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Investigation of a selectable multi-passband microwave photonic filter based on cascaded optical comb filters

Wang F., Peng M. M.

Optica Applicata

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2021

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Vol. 51, nr 3

457--467

EN

A multi-passband microwave photonic filter (MPF) with selectable passband frequency, spanning 0-20 GHz frequency range, is proposed, and experimentally demonstrated, in which passband frequency can be flexibly selected within a maximum passband number to four. The scheme is based on the generation of tunable optical comb lines using a broadband optical source sliced by cascaded optical comb filters, achieved by connecting an in-line birefringence fiber filter and a reconfigurable Lyot filter in series, such that various filter tap spacing and spectral combinations are obtained for the configuration of the MPF. The proposed MPF can operate with four different passband states, namely, single-, dual-, triple-, and quadruple-passband, only by adjusting polarization states of the cascaded optical comb filters. All these passbands are with a 3-dB bandwidth varying from 200 to 460 MHz and more than 20-dB sidelobe suppression.

2

Reconfigurable and tunable multi-tap bandpass microwave photonic filter based on a hybrid-gain-assisted multi-wavelength fiber ring laser

Peng Mengmeng, Wang Fei, Shi Lun, Huang Jingxin, Kang Wen

Optica Applicata

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2019

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Vol. 49, nr 3

499--507

EN

A reconfigurable and tunable multi-tap bandpass microwave photonic filter based on a hybrid-gain-assisted multi-wavelength fiber ring laser (HMFRL) is proposed and experimentally demonstrated. The HMFRL containing a hybrid gain medium and a high birefringence fiber loop mirror serves as the multiple taps generator for the microwave photonic filter. In order to realize a bandpass filter, the multiple taps are phase modulated, then the modulated signal is launched into a coil of dispersion compensating fiber to introduce different time delays for each tap. As a result, a bandpass response is obtained at the output of a high speeding photodetector. By adjusting the bias of the semiconductor optical amplifier from 344 to 450 mA, the number of multiple taps can be increased without optical signal-to-noise ratio degradation. Thus, a multi-tap bandpass microwave photonic filter with bandwidth reconfiguring from 449 to 274 MHz is achieved. In addition, by changing the length of polarization maintaining fiber in the high birefringence fiber loop mirror, the wavelength spacing of the multiple taps can be adjusted, making the bandpass microwave photonic filter’s free spectral range tunable.

3

Polarization dependence of stimulated Brillouin scattering-based switchable microwave photonic filter

Gu Jun, Wang Fei, Lu Youxi, Peng Mengmeng, Shi Lun, Kang Wen, Huang Jingxin

Optica Applicata

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2019

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Vol. 49, nr 1

5--11

EN

We propose and experimentally demonstrate a switchable microwave photonic filter based on polarization dependence of stimulated Brillouin scattering (SBS). The continuous optical wave from a tunable laser source is split into two branches. One branch serves as the SBS pump source and another branch serves as the signal source which are interactional to generate the SBS effect in the dispersion-shifted fiber. Only by adjusting the polarization direction of pump light and signal light, a frequency response switched between bandpass and notch filtering shape can be obtained.

4

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.