Bandpass Microwave Photonic Filter Research Articles

Tunable and Reconfigurable Bandpass Microwave Photonic Filters Utilizing Integrated Optical Processor on Silicon-on-Insulator Substrate

A tunable and reconfigurable bandpass microwave photonic filter based on an integrated optical processor is proposed and experimentally demonstrated on a silicon-on-insulator substrate. The optical processor based on microrings, Mach-Zehnder interferometer, and Y-branches is utilized to produce two bandpass responses for separately processing optical carrier and sideband. Moreover, the microwave responses can be varied by thermal tuning the resonance of microrings. According to the experimental results, the operating frequency and -3-dB bandwidth can be tuned from 18 to 40 GHz and from 5 to 15 GHz, respectively.

New equivalent continuously tunable high‐resolution microwave photonic bandpass filter

AbstractA new technique for implementing an equivalent continuously tunable high‐resolution microwave photonic bandpass filter is presented.It is based on applying frequency conversion to the RF signal before and after high‐resolution bandpass filtering. Experimental results are presented, which demonstrate the continuously tuning of a high‐resolution microwave photonic bandpass filter. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2584–2587, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27142

Widely Tunable Single Bandpass Microwave Photonic Filter Based on Phase Modulation and Stimulated Brillouin Scattering

We propose and demonstrate a widely tunable single bandpass microwave photonic filter (MPF) based on phase modulation (PM) and stimulated Brillouin scattering (SBS). The operation principle of the filter is based on the concept of using the Brillouin selective sideband amplification to achieve effective PM to amplitude modulation (AM) conversion. Only when one of the phase modulated sidebands lies in the SBS gain spectrum, can PM-to-AM conversion occur and the corresponding PM frequency be detected. Whereas the phase modulated sidebands lie out of the SBS gain spectrum, there is no RF signal obtained due to the -phase difference. As a result, a bandpass filter centered at a special frequency can be achieved. By adjustment of the Brillouin pump wavelength, tunable single bandpass MPF can be obtained. In the experiment, a microwave photonic filter with narrow bandwidth of about 35 MHz and a tuning range of 20 GHz has been obtained.

A Wideband Frequency Tunable Optoelectronic Oscillator Incorporating a Tunable Microwave Photonic Filter Based on Phase-Modulation to Intensity-Modulation Conversion Using a Phase-Shifted Fiber Bragg Grating

An optically tunable optoelectronic oscillator (OEO) with a wide frequency tunable range incorporating a tunable microwave photonic filter implemented based on phase-modulation to intensity-modulation conversion using a phase-shifted fiber Bragg grating (PS-FBG) is proposed and experimentally demonstrated. The PS-FBG in conjunction with two optical phase modulators in the OEO loop form a high-Q, wideband and frequency-tunable microwave photonic bandpass filter, to achieve simultaneously single-frequency selection and frequency tuning. Since the tuning of the microwave filter is achieved by tuning the wavelength of the incident light wave, the tunability can be easily realized at a high speed. A theoretical analysis is performed, which is verified by an experiment. A microwave signal with a frequency tunable from 3 GHz to 28 GHz is generated. To the best of our knowledge, this is the widest frequency tunable range ever achieved by an OEO. The phase noise performance of the OEO is also investigated.

Chaotic ultra-wideband radio generator based on an optoelectronic oscillator with a built-in microwave photonic filter

We induce a microwave photonic bandpass filter into an optoelectronic oscillator to generate a chaotic ultra-wideband signal in both the optical and electrical domain. The theoretical analysis and numerical simulation indicate that this system is capable of generating band-limited high-dimensional chaos. Experimental results coincide well with the theoretical prediction and show that the power spectrum of the generated chaotic signal basically meets the Federal Communications Commission indoor mask. The generated chaotic carrier is further intensity modulated by a 10 MHz square wave, and the waveform of the output ultra-wideband signal is measured for demonstrating the chaotic on-off keying modulation.

Optically Tunable Frequency-Multiplying Optoelectronic Oscillator

An optically tunable frequency-multiplying optoelectronic oscillator (OEO) incorporating a tunable microwave photonic bandpass filter is proposed and experimentally demonstrated. The microwave photonic filter is implemented employing a phase-shifted fiber Bragg grating, a polarization modulator, and a phase modulator. The frequency tuning is realized by changing the wavelength of the light wave to the OEO loop. The frequency-doubling and frequency-quadrupling operations with large frequency tunability are experimentally demonstrated. The phase noise performance of the generated microwave signals is also investigated.

Overcoming Tap-Delay-Variation Induced Distortion in Microwave Photonic Filters

A new technique to realize a multiple-tap microwave photonic Alter that is free of the limitations of tap-delay-variation induced Alter distortion, which enables it to operate at high microwave frequencies, is presented. It is based on a technique using a wideband high-order dispersion compensator to cancel the group delay variations of the primary optical fiber dispersive delay line. The compensator, implemented using a programmable Fourier-domain dynamic wavelength processor incorporating liquid crystal on silicon pixels, provides a tailored optical phase profile to effectively cancel out the tap-delay variations originating from the primary fiber delay line. Experimental results verify the new technique and demonstrate a 20-tap microwave photonic bandpass filter obtained using a multi-frequency laser source with equally spaced lines, which operates to 20 GHz without any radio frequency distortion.

Single Passband Microwave Photonic Filter With Continuous Wideband Tunability Based on Electro-Optic Phase Modulator and Fabry–Pérot Semiconductor Optical Amplifier

We propose and experimentally demonstrate a microwave photonic filter based on an electro-optic phase modulator (EOPM) and a Fabry-Perot semiconductor optical amplifier (FP-SOA). A microwave photonic filter with a single passband between 0 and 40 GHz is obtained. In the single passband microwave photonic filter, the microwave subtraction effect is introduced in optical domain to improve the performance. A theoretical model is established to describe the operation principle of the microwave photonic filter, and the predicted results show good agreement with the experimental results. In the experiment, the center frequency and the 3-dB bandwidth are 18.3 GHz and 99.5 MHz, respectively, with the corresponding Q factor of 184, and the rejection ratio and shape factor are 34.3 dB and 5, respectively. The continuous wideband tunability of the microwave photonic filter is also demonstrated by adjusting the bias current of FP-SOA.

Tunable Multi-Tap Bandpass Microwave Photonic Filter Using a Windowed Fabry-Pérot Filter-Based Multi-Wavelength Tunable Laser

A center frequency-tunable multi-tap bandpass microwave photonic filter (MPF) is proposed and experimentally demonstrated. A specially designed multi-wavelength fiber ring laser, in which a windowed Fabry-Perot (FP) filter is used as the wavelength selection and power control component, has been developed to serve as the optical source for the MPF. By adjusting the windowed FP filter, both the wavelength spacing and power profile of the multi-wavelength laser can be changed. The output of the optical source is phase modulated by a microwave signal. 25 km of single-mode fiber (SMF) is then used to act as a dispersive medium to introduce time delays between taps. Thus, a tunable bandpass response is obtained at the output of a high-speed photodetector (PD). In addition, the passband centered at DC is removed due to the use of phase modulation. The experimental results show that more than 45 wavelengths can be generated in the multi-wavelength ring laser. With the electronic tuning of the wavelength spacing, tuning of the passband center frequency of the MPF by 3 GHz is achieved.

IR-UWB-Over-Fiber Systems Compatible With WDM-PON Networks

Integrating an ultrawideband-over-fiber (UWBoF) system into a wavelength division multiplexing passive optical network (WDM-PON) is of great interest due to the high potential to provide high data-rate and flexible wired and wireless services with a favorable cost. In this paper, we perform a comprehensive study on an impulse radio UWBoF system compatible with the WDM-PON architecture implemented based on a photonic microwave bandpass filter. The bandpass filter is a two-tap delay-line filter implemented using either a polarization modulator (PolM) or a phase modulator (PM), which is used to simultaneously shape an electrical Gaussian-like pulse to an optical UWB pulse and reduce the out-band noise and interference. The features of the photonic microwave bandpass filters are theoretically studied. The photonic microwave bandpass filter based on a PolM would produce a chirp-free UWB signal, while the one based on a PM would generate a UWB signal that is insensitive to fiber dispersion. A single-channel UWBoF system with ON-OFF keying, biphase modulation, and pulse-position modulation without and with time hopping are experimentally studied. The experimental results agree well with the theoretical predictions. A four-channel UWBoF broadcasting network as well as a hybrid WDM-PON network to provide both wireless and wired services is also experimentally investigated. Results show that a conventional WDM-PON network could be easily upgraded to provide UWB services by incorporating the proposed photonic microwave bandpass filter.

Single passband microwave photonic filter using continuous-time impulse response

A single passband microwave photonic signal processor based on continuous time impulse response that has high resolution, multiple-taps and baseband-free response as well as exhibiting a square-top passband and tunability, is presented. The design and synthesis of the frequency response are based on a full systematic model for single passband microwave photonic filters to account for arbitrary spectrum slice shapes, which for the first time investigates the combined effects from both the dispersion-induced carrier suppression effect and the RF decay effect due to the spectrum slice width, to enable the optimum design to be realized by utilizing the carrier suppression effect to improve the filter performance. Experimental results demonstrate a high order microwave filter showing high resolution single passband filtering as well as exhibiting reconfiguration, square-top passband and tunability, for the first time to our best knowledge.

Microwave photonic bandpass filter based on spectrumslicing and phase modulator

A tunable microwave photonic bandpass filter with high mainlobe-to-sidelobe ratio (MSR) based on a phase modulator and a dispersive device is proposed. The multi-tap characteristics of the filter are realized by slicing a broadband source using a Mach-Zehnder interferometer (MZI) which results in a high MSR of 25 dB. The tunability of the filter is realized by an optical variable delay line (OVDL) in one arm of the MZI, which changes the wavelength spacing of the sliced broadband source and results in a tunable free spectrum range (FSR) of the filter. The central frequency of the bandpass filter is tunable from 10.7 GHz to 27 GHz by changing the wavelength spacing from 0.145 nm to 0.054 nm.

Tunable microwave photonic bandpass filter with high-resolution, coherence-free operation

Two new structures that can realise both tunable and high-resolution filter operation simultaneously, together with low-noise, are presented. Experimental results demonstrate a wide tuning range for high-resolution low-noise bandpass filters with a Q value of 200.

Arbitrary response design for incoherent microwave photonic filters based on basic filtering cell combination

An arbitrary response designing method for incoherent microwave photonic filter (MPF) is proposed and experimentally verified. By decomposing the response function of incoherent MPFs into basic filtering cells, arbitrary responses can be designed by simply choosing and recombining proper filtering cells. With the proposed method, required implementing parameters for arbitrary responses can be determined easily, which will bring great convenience for realistic MPF implementation based on existing structures. A simple band-pass MPF is designed as an example and a verification experiment is set up to testify the designing results. Good accordance between the theoretical and the experimental results are obtained.

Analysis of tunable photonic microwave bandpass filter with negative coefficient

Analysis of tunable photonic microwave bandpass filter with negative coefficient based on an electro-optic phase modulator (EOPM) followed by a fiber Michelson interferometer with orthogonally polarized arms is presented. The Michelson interferometer is made by connecting two fibers to the output ports of a polarization beamsplitter (PBS) and attaching high reflecting Bragg gratings at the other end of the fibers. The negative coefficient is generated from the optical interference of the two phase modulated optical carriers when recombined at the PBS. A two-tap microwave bandpass filter with one negative coefficient is presented. The chromatic dispersion is expected to have no effect on this filter. The filter is tunable over a wide frequency bandwidth using short fiber lengths.

Photonic microwave bandpass filter with negative coefficients based on flat‐top

AbstractIn this article, a novel microwave photonic filter with negative coefficient using semiconductor optical amplifiers and Fiber Bragg Gratings is proposed. Three major factors, including input current, grating coefficients and the input signal power are analyzed and compared respectively with scrutinize their affects to the filter response. Through the simulation, a better performance of the flat‐top microwave photonic filter can be achieved. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 9–13, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24824

Microwave photonic bandpass filter using a multi‐wavelength laser with a bell‐shaped power profile

AbstractA low cost sidelobe suppressed tunable microwave photonic bandpass filter is proposed and experimentally demonstrated. The filter is based on a multi‐wavelength ring laser and a segment of single mode fiber as a dispersive element. Through adjustment of the power profile of the multi‐wavelength laser to a bell shape, a filter frequency response without sidelobes is achieved. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1329–1332, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24316

Single Passband, Discretely Tunable, Photonic Microwave Bandpass Filter Based on Highly Birefringent Fiber-Based Comb Filter

By experiment, we demonstrate a photonic microwave finite impulse response (FIR) filter scheme that exhibits both the features of flexible frequency tuning and single passband. The proposed filter is constructed by the combined use of a broadband Gaussian-shaped supercontinuum (SC) and a wavelength spacing tunable, highly birefringent (Hi-Bi) fiber-based comb filter. By incorporating a three-segment, Hi-Bi fiber-based, Lyot-type, comb filter into a spectrum slicing-based photonic microwave FIR filter scheme, we achieve both novel features of single passband and passband RF frequency tuning at the same time. It is shown that the discrete tuning of passband RF frequency can be obtained simply by rotating beam polarization. Our experimental demonstration shows a flexible passband RF frequency tuning over a range of 7.3 GHz.

Photonic microwave bandpass filter with improved dynamic range

A technique to improve the dynamic range of a photonic microwave bandpass filter is proposed and experimentally demonstrated. The filter is implemented based on phase modulation to intensity modulation conversion using fiber Bragg gratings (FBGs) serving as frequency discriminators, with the optical carriers located at the left or right slopes of the FBGs, to generate positive or negative tap coefficients. The dynamic range of the photonic microwave bandpass filter is increased by reducing the optical-carrier-induced shot noise and relative intensity noise at the photodetector, which is realized by placing the optical carriers at the lower slopes of the FBG reflection spectra. A photonic microwave bandpass filter with an improvement in dynamic range of about 10 dB is demonstrated.

High- Q, tunable, photonic microwave single passband filter based on stimulated Brillouin scattering and fiber Bragg grating filtering

We experimentally demonstrate a single passband, photonic microwave bandpass filter scheme based on stimulated Brillouin scattering (SBS) in optical fiber. A single side band (SSB)-modulated probe and a single frequency, tunable pump beam that have been produced by the combination of conventional Mach–Zehnder modulators and fiber Bragg grating filters, are used for the generation of SBS phenomenon in a 1-km long highly nonlinear dispersion-shifted optical fiber. Using the proposed scheme a single microwave passband with a ∼26 MHz bandwidth is readily achieved over a radio frequency tuning range from 1.3 to 9.3 GHz. The maximum Q-factor is measured to be ∼360.