Tunable Microwave Photonic Notch Filter Research Articles

Microwave photonic notch filter based on polarisation multiplexing and cross gain modulation in a semiconductor optical amplifier

A coherent interference-free tunable microwave photonic notch filter with a pair of negative and positive coefficients generated by employing polarisation multiplexing and cross gain modulation in a semiconductor optical amplifier is proposed and demonstrated through simulation results. The negative and positive coefficients of the notch filter are realised through two orthogonal polarisation states of a single continuous wave laser diode. The free spectral range of microwave photonic filter is tuned by varying the differential group delay of a birefringent single-mode fibre. The proposed filter shows good tunability, easy implementation and is cost-effective.

Performances of Microwave Photonic Notch Filter Based on Microring Resonator With Dual-Drive Modulator

A tunable microwave photonic notch filter with ultrahigh radio frequency (RF) rejection ratio is achieved by using a dual-drive Mach-Zender modulator and a microring resonator. In addition, we dedicated to clarify the mechanisms of the microwave photonic notch filters based on a microring resonator under both overcoupled and undercoupled states and the performance differences between these two situations are investigated in detail. Furthermore, the experimental results show that the cancellation microwave photonic notch filter with ultrahigh RF rejection ratio can be achieved with both undercoupled and overcoupled microring resonators. Besides, an RF rejection ratio exceeding 50 dB was achieved for a microring resonator with an optical extinction ratio of only 4 dB, where a 46-dB enhancement from optical to RF response is obtained. Also, the bandwidth of the microwave photonic filter can tuned from 0.65 to 2.2 GHz by adjusting the coupling ratio of the ring resonator. Meanwhile, by tuning the wavelength of the optical carrier, the filtering frequency can be tuned and a tuning range of about 25 GHz was achieved. The implementation is much simpler and more economical compared with previous reports and has great potential in monolithic integration of microwave photonic filters on chip.

A widely tunable microwave photonic notch filter with adjustable bandwidth based on multi-wavelength fiber laser

A widely tunable microwave photonic notch filter with adjustable bandwidth based on multi-wavelength fiber laser is proposed and demonstrated. The multi-wavelength fiber laser generates the multi-taps of the microwave photonic filter (MPF). In order to obtain notch frequency response, a Fourier-domain optical processor (FD-OP) is introduced to control the amplitude and phase of the optical carrier and phase modulation sidebands. By adjusting the polarization controller (PC), different numbers of taps are got, such as 6, 8, 10 and 12. And the wavelength spacing of the multi-wavelength laser is 0.4 nm. The bandwidth of the notch filter is changed by adjusting the number of taps and the corresponding bandwidths are 4.41 GHz, 3.30 GHz, 2.64 GHz and 2.19 GHz, respectively. With the additional phase shift introduced by FD-OP, the notch position is continuously tuned in the whole free spectral range (FSR) of 27.94 GHz. The center frequency of the notch filter can be continuously tuned from 13.97 GHz to 41.91 GHz.

A continuously tunable microwave photonic notch filter with complex coefficient based on phase modulation

A continuously tunable microwave photonic notch filter with complex coefficient based on phase modulation is proposed and demonstrated. The complex coefficient is generated using a Fourier-domain optical processor (FD-OP) to control the amplitude and phase of the optical carrier and radio-frequency (RF) phase modulation sidebands. By controlling the FD-OP, the frequency response of the filter can be tuned in the full free spectral range (FSR) without changing the shape and the FSR of the frequency response. The results show that the center frequency of the notch filter can be continuously tuned from 17.582 GHz to 29.311 GHz with FSR of 11.729 GHz. The shape of the frequency response keeps unchanged when the phase is tuned.

Tunable megahertz bandwidth microwave photonic notch filter based on a silica microsphere cavity.

We propose and experimentally demonstrate a tunable microwave photonic notch filter with a megahertz order bandwidth based on a silica microsphere cavity coupled by an optical microfiber. The silica microsphere with a quality factor of hundreds of millions offers a full width at half-maximum bandwidth down to the order of megahertz in the transmission spectrum. Due to the coupling flexibility between the microcavity and the optical microfiber, the bandwidth and suppression ratio can be tuned and optimized to get a rejection ratio beyond 30dB. The tunability of over 15GHz is also achieved. To the best of our knowledge, this single-stopband microwave photonic filter has the narrowest bandwidth filter that has ever been experimentally demonstrated. This microwave photonic notch filter shows distinct advantages of high selectivity, compactness, flexibility, and low insertion loss.

A Widely Tunable Photonic-Assisted Microwave Notch Filter with High Linearity Using a Dual-Parallel Mach—Zehnder Modulator**Supported by the National Natural Science Foundation of China under Grant Nos 61335004 and 61275031, and the High-Tech Research and Development Program of China under Grant No 2013AA014401.

A widely tunable microwave photonic (MWP) notch filter with high linearity based on a dual-parallel Mach—Zehnder modulator (DPMZM) is proposed and experimentally demonstrated. The motivation of this work lies in the fact that the MWP notch filter previously reported has nonlinear distortions generally induced by the nonlinear property of electro-optic devices. In this scheme, even-order modulated sidebands at the DPMZM output are effectively suppressed by properly adjusting bias voltages of the DPMZM, which are the dominant factor to induce the nonlinear distortions into the MWP notch filter. The proposed scheme is theoretically analyzed and experimentally verified.

Tunable microwave photonic notch filter based on sliced broadband optical source.

A microwave photonic filter is demonstrated with both tunable center frequency and bandwidth. This filter is switchable from all-pass, bandpass to notch filter, and the notch filter is a result of the subtraction of a bandpass filter from an all-pass filter based on a balanced photodetector. The all-pass filter is achieved based on a single wavelength radio over fiber link, and the bandpass one is acquired by using the spectrum-sliced broadband optical source. Theoretical analysis and experimental results show that both the center frequency and the bandwidth of the notch filter can be widely tuned.

The study of an ultrawide tunable range single passband microwave photonic notch filter

A single passband tunable microwave photonic notch filter with ultrawide tunable range is presented. It is based on dual-drive Mach-Zehnder modulator and stimulated Brillouin scattering. By introducing two pump signals whose frequency interval equals twice of the Brillouin frequency shift, the available filter tuning range can reach 4fB. With the increase of the number of pump light the tuning range of the filter will grow proportionally. The amplitude of the output signal of the notch filter changes with the half-wave voltage and a DC bias voltage of DDMZM.

All-Optical Continuously Tunable Flat-Passband Microwave Photonic Notch Filter

A new all-optical microwave photonic notch filter (MPNF) is presented. It is based on controlling the amplitude and phase of the optical carriers and RF phase modulation sidebands via a diffraction-based Fourier-domain optical processor. It has the ability of realizing a flat-passband, narrow-notch, and large-free-spectral-range amplitude response and a group delay response with very few ripples. The carrier and sideband optical phase controls enable a continuous notch frequency tuning operation to be realized without altering the response shape. The filter has a simple structure and a wide bandwidth as it only involves optical components. Experimental results demonstrate an MPNF that exhibits a flat passband with <; 1 dB ripples, a deep notch of > 35 dB, and low group delay ripples of <; ±25 ps, together with the continuous notch frequency tunability and excellent long-term stability and repeatability.

Continuously Tunable Flat-Passband Microwave Photonic Notch Filter Based on Primary and Secondary Tap Distribution Impulse Response

Abstract: A new microwave photonic signal processor that has the ability to realize a continuously tunable high-resolution notch filter response is presented. It is based on designing the filter impulse response to have a primary and secondary tap distribution. With a proper design on the tap amplitudes, the notch filter passband can be flattened. The filter notch frequency can be also continuously tuned by controlling the phase shift of the secondary taps via a diffraction-based Fourier-domain optical processor. The notch filter has a robust response and high signal-to-noise-ratio (SNR) performance. Experimental results demonstrate that the new microwave photonic notch filter can simultaneously realize a flat passband of only a 1-dB ripple, a large free spectral range of 4.7 GHz, and a notch depth of over 40 dB while tuning the notch frequency.

Tunable negative coefficient microwave photonic filter based on a polarization modulator and a polarization beam interferometer

A new tunable microwave photonic notch filter with negative coefficients is presented. It is based on a polarization modulator and a polarization beam interferometer. Experimental results are presented that embody the new concept.

High-speed tunable microwave photonic notch filter based on phase modulator incorporated Lyot filter.

A high-speed tunable microwave photonic notch filter with ultrahigh rejection ratio is presented, which is achieved by semiconductor optical amplifier (SOA)-based single-sideband modulation and optical spectral filtering with a phase modulator-incorporated Lyot (PM-Lyot) filter. By varying the birefringence of the phase modulator through electro-optic effect, electrically tuning of the microwave photonic notch filter is experimentally achieved at tens of gigahertz speed. The use of SOA-polarizer based single-sideband modulation scheme provides good sideband suppression over a wide frequency range, resulting in an ultrahigh rejection ratio of the microwave photonic notch filter. Stable filter spectrum with bandstop rejection ratio over 60dB is observed over a frequency tuning range from 1.8 to 10GHz. Compare with standard interferometric notch filter, narrower bandwidth and sharper notch profile are achieved with the unique PM-Lyot filter, resulting in better filter selectivity. Moreover, bandwidth tuning is also achieved through polarization adjustment inside the PM-Lyot filter, that the 10-dB filter bandwidth is tuned from 0.81 to 1.85GHz.

A tunable photonic microwave notch filter with a negative coefficient using nonlinear behavior of a reflective semiconductor optical amplifier

ABSTRACTWe propose and experimentally demonstrate a simple tunable photonic microwave notch filter with positive and negative coefficients. The negative coefficient is obtained from a single input signal (positive coefficient) using cross gain modulation (XGM) in a reflective semiconductor optical amplifier (RSOA). When the RSOA is operated in the saturated region, the signal carried on the pump wavelength is inversely copied to the probe wavelength by the XGM effect, showing a negative coefficient. This probe wavelength is easily generated by self‐injection locking the RSOA through a wavelength‐selective filter. Further, variable time delay for filter tuning is achieved using wavelength‐dependent time delay in a fiber medium by changing the Bragg wavelength of the fiber Bragg grating. The proposed microwave notch filter shows notch dips of more than 33 dB and has a tuning range from 828 to 905 MHz in a free spectral range with a wavelength change of 0.6 nm. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1328–1331, 2014

Tunable microwave photonic notch filter using on-chip stimulated Brillouin scattering

We report the first demonstration of a tunable microwave photonic notch filter based on stimulated Brillouin scattering (SBS) in a photonic chip. Single-sideband with carrier modulation (SSB+C) scheme was used to map the SBS loss spectrum into a frequency notch in the RF domain. The notch frequency can be tuned by modulating the SSB+C signal onto a tunable carrier, which was generated by means of SSB suppressed-carrier (SSB-SC) modulation. The notch filter has a high-resolution with 3-dB and 6-dB bandwidths of 126MHz and 78MHz, respectively. The filter has a notch depth of 20dB, and the notch frequency can be continuously tuned over a range of 2-8GHz, which is limited only by the current measurement setup.

Tunable Microwave Photonic Notch Filter and Bandpass Filter Based on High-Birefringence Fiber-Bragg-Grating-Based Fabry–Pérot Cavity

We propose and successfully demonstrate a microwave photonic filter based on phase modulation (PM) and a fiber-Bragg-grating-based Fabry-Perot (FBG-FP) cavity etched in a high-birefringence fiber. It can switch between continuously tunable single notch filter and bandpass filter operation. The principle of the tunable notch filter is based on the reflection response of the FBG-FP to break the phase balance of PM sidebands and achieve effective phase modulation to amplitude modulation conversion, while the principle of the bandpass filter is based on the transmission response of the FBG-FP to break the amplitude balance of the PM sidebands. Both filters have narrow bandwidth and high side-mode suppression ratio.

Ultrawide Tunable Microwave Photonic Notch Filter Based on Stimulated Brillouin Scattering

A new ultrawide tunable microwave photonic notch filter that exhibits a very high resolution is presented. It is based on a stimulated Brillouin scattering technique, which processes the modulation sidebands generated by a dual-drive Mach-Zehnder modulator. Tuning is realized by changing the drive frequency to an electro-optic intensity modulator. Experimental results demonstrate a high-resolution notch filter with a 3-dB bandwidth of 82 MHz, a notch depth of over 40 dB, a flat passband from near DC to 20 GHz with very low ripples, and a notch frequency that can be continuously tuned with shape invariance over an ultrawide frequency range from 2 to 20 GHz.

Continuously Tunable Microwave Photonic Notch Filter With a Complex Coefficient

This paper presents a continuously tunable microwave photonic notch filter with a complex coefficient. The complex coefficient is generated using a radio-frequency (RF) phase shifter that consists of a dual-parallel Mach-Zehnder modulator (DPMZM) and a tunable optical bandpass filter (TBPF). By simply controlling the bias voltage of the DPMZM, the frequency response of the filter can be continuously tuned over a full free spectral range (FSR) without changing the shape of the frequency response.

Tunable Microwave Photonic Notch Filter Based on a high-birefringence linearly chirped fiber Bragg grating

In this paper, a continuously tunable microwave photonic notch filter is proposed and experimentally demonstrated. This filter is based on the differential group delay generated by a high-birefringence linearly chirped fiber Bragg grating. This microwave photonic filter belongs to the orthogonal polarization approach, polarization maintaining structure ensures the filter free from the random optical interference problem. Its response is induced by the differential group delay (DGD) of the Hi-Bi LCFBG and it can be varied by tuning the grating through adding gradient strength to the grating. Free spectral range tuning by 9.27 GHz with more than 35 dB notch rejection is achieved.

Continuously tunable microwave photonic notch filter based on the differential group delay

AbstractA continuously tunable microwave photonic notch filter is proposed and experimentally demonstrated. This filter is based on the differential group delay generated by a high‐birefringence linearly chirped fiber Bragg grating. The tunability is realized by applying gradient tension to the grating. Free spectral range tuning by 9.27 GHz with more than 35 dB notch rejection is achieved. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:121–123, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25679

Photonic Technique for the Measurement of Frequency and Power of Multiple Microwave Signals

An optical approach to simultaneously measure the frequency and power of several microwave signals is presented and demonstrated. The system is based on the processing of an interferogram generated by integrating the microwave power over the measurement band at the output of a tunable photonic microwave notch filter. Experimental results to demonstrate the principle of operation are provided showing a resolution of 15 MHz.