In this paper, a new photonic approach for frequency-doubled triangular and square waveforms generation is proposed and experimentally demonstrated. The scheme is based on two single-drive ...Mach-Zehnder modulators (MZMs) and one of them is located in a Sagnac loop. By properly setting the working points of the two MZMs and the polarization angle of the light injected into the Sagnac loop, two orthogonal-polarization optical signals with tunable amplitudes can be obtained. One of them is the carrier-suppressed first-order optical sidebands and the other is the carrier-suppressed third-order optical sidebands. After the photoelectric conversion, we can get frequency-doubled and frequency-sextupled microwave harmonics with tunable amplitudes and the desired waveforms can be obtained. In addition, the phase relationship and the amplitude of the generated second- and sixth-order electrical harmonics will remain unchanged during fiber transmission. Thus, the scheme is suitable for fiber transmission in future centralized radio-over-fiber systems.
Nonlinear distortion and chromatic dispersion are two long-standing limiting factors of radio-over-fiber (ROF) links. Here, we proposed an ROF link with both the two problems mitigated ...simultaneously. Furthermore, a tunable optical carrier-to-sideband ratio (CSR) can also be implemented in this simple system to improve the gain and the noise figure (NF) of the link. All these three factors are optimized in a simple ROF link which shows increased performance of the system. The scheme is based on a single dual-polarization Mach-Zehnder modulator (DPol-MZM). One bias voltage of the Dpol-MZM is employed to mitigate the nonlinear distortion. The polarization direction and the phase relationship of the modulated polarization multiplexed signal are used to adjust the CSR and suppress the dispersion, respectively, by adjusting a polarization controller (PC). In the experiment, 3-30-GHz RF signal is transmitted without power fading. A two-tone signal with the frequencies of 12.5 and 12.505 GHz is employed to verify the optimization of three main parameters of the ROF link link gain, NF, and spurious-free dynamic range (SFDR) where the link gain, NF, and SFDR are improved by 11.9, 5.8, and 14.5 dB, respectively, compared with conventional quadrature biased link based on one Mach-Zehnder modulator for 50-km single-mode fiber (SMF) transmission. Meanwhile, 100-Mbaud 16 quadrature amplitude modulation (QAM) signals centered at 12.5 and 14.7 GHz are used to verify the transmission performance. After dispersion compensation, nonlinear optimization, and CSR optimization, error vector magnitude (EVM) is improved from 17.03% to 2.97%.
A novel analog photonic down-conversion link based on a polarization modulator and a phase modulator with simultaneous linear optimization and chromatic dispersion-induced power fading compensation ...is proposed and experimentally demonstrated. By introducing an appropriate phase shift to the optical sidebands, chromatic dispersion-induced power fading is compensated, and third-order intermodulation distortion terms are eliminated in the same time. The scheme exhibits wide operating frequency range due to its no use of filters and frequency-dependent electrical or optical devices. The scheme is robust, as the operation of the polarization modulator and the phase modulator are independent of signal amplitude and bias voltage. Experimental results show that, for a 25-km transmission link, an improvement of more than 15.5 dB in spurious-free dynamic range is achieved and the dispersion-induced power fading is compensated at the same time. In addition, benefiting from the power compensation and significant suppression of IMD3, a 16QAM vector signal is demonstrated to have a good demodulation performance.
A novel photonic microwave and millimeter-wave (mm-wave) mixer with simultaneous third-order intermodulation distortion (IMD3) suppression and dispersion-induced power fading compensation is proposed ...and experimentally demonstrated. In our proposed scheme, a dual-polarization quadrature phase shift-keying (DP-QPSK) modulator is used to modulate RF/IF and LO signals. The bias voltages of the main modulators are adjusted to compensate dispersion-induced power fading. When the polarization state of the modulated signal and the attenuation of the RF signal are properly adjusted, IMD3 distortion can be suppressed. In the experiment, relatively flat microwave and mm-wave signals from 11 to 35 GHz are obtained through 4- and 50-km fiber transmission, while the measured spurious free dynamic range (SFDR) is <inline-formula> <tex-math notation="LaTeX">112.9~{\mathrm {dB}} \cdot \text{Hz} ^{4/5} </tex-math></inline-formula>. In addition, an up-converted 16 quadrature amplitude modulation (16 QAM) vector signal with a carrier frequency of 19.3 GHz is obtained and the measured constellation diagrams and error vector magnitudes are given after transmission over different fiber lengths (back to back, 4 and 50 km).
We propose and experimentally demonstrate an ultraefficient broadband photonic channelizer. By polarization-division multiplexing the received signal and using dual-output Hartley image-reject ...receiving topology, <inline-formula> <tex-math notation="LaTeX">4N </tex-math></inline-formula> channels can be generated with only (<inline-formula> <tex-math notation="LaTeX">N +1 </tex-math></inline-formula>)-line signal optical frequency comb (OFC) and <inline-formula> <tex-math notation="LaTeX">N </tex-math></inline-formula>-line local oscillator (LO) OFC, and the frequency interval of the OFC is reduced to half of the typical value. With the use of the integrated dual-polarization coherent detection receiver (DP-CDR), the required quadrature optical hybrid (QOH) and the balanced photodetectors (BPDs) are reduced to half. The system size is reduced and stability is improved. Besides, assisted with a digital signal processor (DSP) algorithm, the IQ imbalance can be compensated, and approximately, ideal image rejection can be realized. A proof-of-concept experiment is carried out. A 2-14-GHz wideband signal is successfully divided into 12 channels with 1-GHz bandwidth by applying four-line signal OFC and three-line LO OFC. The image rejection ratio (IRR), channel isolation (CI), and spurious-free dynamic range (SFDR) are also measured and discussed.
Satellite communication is moving toward multi-band, large bandwidth communication and high data rate space networking, which requires more processing, switching, and high-speed transmission ...capability of satellite communication payload. The electronic bottleneck of traditional microwave systems in processing speed and transmission bandwidth makes it difficult to adapt to the future demands of satellite communications. Aiming at the limitations of satellite communication based on traditional microwave technology, this article discusses the potential benefits of satellite communication payload based on microwave photonic (SCP-MP) to space information communication networks (SICN). Then it proposes the architecture of SCP-MP, along with its main components and functional structure. We also review the key technologies, such as low spurious frequency conversion, channelization, optical switching, chip, and integration, and discuss challenges. An outlook on the prospects of SCP-MP is also included.
An all-optical radio-over-fiber (RoF) link with double spectral-efficient transmission and compensation of chromatic dispersion-induced power fading is proposed and experimentally demonstrated. At ...the central office, a commercial dual-polarization quadrature phase-shift keying modulator is utilized to produce a polarization-multiplexed signal composed of two modulated microwave vector signals and an unmodulated optical carrier. At the remote node, by adjusting the polarization controller to introduce a proper phase shift to the unmodulated optical carrier, the two vector signals can be demodulated respectively and dispersion-induced power fading can be compensated simultaneously. The link performance is evaluated by error vector magnitude and bit error rate.
An all-optical, image-reject, and fundamental/sub-harmonic downconverted radio-over-fiber (RoF) link using a polarization-division multiplexing Mach–Zehnder modulator (PDM-MZM) and fiber-dispersion ...effect is proposed. At the remote antenna unit, the receiving radio frequency (RF) signal and the local oscillator (LO) signal are used to drive two sub-MZMs of the PDM-MZM. After a length of optical fiber transmission, at the central office, by using the fiber-dispersion effect and controlling the polarization controller to introduce an appropriate phase shift between the RF and LO sidebands, image rejection is achieved and power fading is avoided simultaneously. Because the scheme is a simple and all-optical system without electrical frequency-dependent devices or filters, it has a good image-reject capability over a large working frequency range. Besides, the downconverter in sub-harmonic mode can decrease frequency requirement of the LO signal. Experimental results indicate that in the fundamental and sub-harmonic downconverters, for a single-tone signal, IRRs are over 47 dB. Image rejection for the 100-Mbaud 16-QAM signal and demodulated desired IF signal with a good EVM of less than 7% are realized. The proposed structure can be applied in RoF systems and microwave and millimeter-wave receivers.
•In image-reject RoF link, if the fiber-dispersion effect is used to implement image rejection, the link can be effectively simplified. Here, an image-reject fundamental/sub-harmonic downconverted RoF link using fiber-dispersion effect is proposed.•The scheme is a simple all-optical system without any filters or electrical frequency-dependent devices and the subharmonic downconverter can decrease the LO frequency requirement.•The scheme can be applied in RoF systems, microwave and millimeter-wave receivers.
A photonics-based radar jamming signal generator is proposed in this paper. By adjusting a polarization controller, interrupted-sampling repeater jamming (ISRJ), comb spectrum modulation jamming ...(CSMJ), ISRJ and CSMJ composite jamming can be respectively generated after photoelectric conversion. We have experimentally verified the generation of ISRJ signals with duty cycles of 50% and 25%, the generation of CSMJ signals with comb spectrum frequency intervals of 5 MHz and 10 MHz, and the generation of their composite jamming signals in the Ku band. Additionally, the ISRJ and CSMJ composite jamming effect of radar signals in the Ka band has been tested. After matched filtering processing, multiple false targets are produced and the total number of jamming targets can be up to 25, demonstrating significant jamming effects. The proposed structure can generate multi-format jamming signals without using digital radio frequency memory, which is suitable for producing high-frequency and large-bandwidth jamming signals. It can be applied in electronic countermeasure systems.
•The scheme can generate multi-format jamming signals for LFM signal, namely interrupted-sampling repeater jamming (ISRJ), comb spectrum modulation jamming (CSMJ), ISRJ and CSMJ composite jamming.•The scheme does not use digital radio frequency memory, which is easy to generate high frequency and large bandwidth jamming signals. The experimental results show that the LFM signal with 1-GHz bandwidth in Ku band and the LFM signal with 1.2-GHz bandwidth in Ka band have good jamming effects.•After matched filtering processing, multiple false targets are generated and the total number of jamming targets can be up to 25, demonstrating significant jamming effects. The scheme has good application value in electronic countermeasure system.
A novel linearized analog photonic down-conversion link based on an integrated dual-polarization quadrature phase-shift keying (DP-QPSK) modulator is proposed and experimentally verified. Radio ...frequency and local oscillator signals are fed into the DP-QPSK modulator via an electrical attenuator, respectively. By adjusting the ratio of the two attenuators, the third-order intermodulation distortion can be eliminated based on balanced detection. The scheme is simple and compact and it achieves full spectrum utilization because of using no filter. Experimental results show that the spurious free dynamic range is improved by 16.43 dB for a two-tone signal and the error vector magnitude is improved by 6.16% for a 100-MSym/s 16-quadrature-amplitude-modulation signal.
•About 16-dB improvement of SFDR and 6% improvement of EVM.•Very compact structure mainly consisting of an integrated DP-QPSK modulator and a balanced photodiode.•Full spectrum utilization and using no filter.
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