KEYWORDS: Microwave photonics, Signal attenuation, Image processing, Scattering, Signal processing, Optical modulators, Optical amplifiers, Electrooptic modulators, Signal generators, Signal detection
The electrical mixer is limited by operation bandwidth and parallel processing capacity, and is suffering from increasingly serious electro-magnetic interference. By introducing photonic properties, microwave photonic technology has many advantages compared to the traditional microwave technology, such as low loss, large bandwidth, high parallel processing capacity, anti-electromagnetic interference and so on. In this work, a Stimulated Brillouin Scattering (SBS) based microwave photonic mixer with high image rejection capacity is proposed. Due to the high wavelength-selectivity and wideband tenability of the SBS process, the image rejection ratio of the mixer exceeds 40dB over the IF range of 80 MHz to 2 GHz and the RF range of 2 to 40 GHz.
KEYWORDS: Microwave photonics, Electromagnetism, Telecommunications, Signal generators, Signal processing, Frequency combs, Modulation frequency, Channel projecting optics, Signal detection, Sensing systems
As the electromagnetic environment becomes more and more complex and strong electromagnetic interference becomes normal, in order to improve the ability of ultra-wideband(UWB) communication under strong resistance and complex electromagnetic environment, the wideband communication anti-interference technology has been applied more and more widely in electronic information systems. Based on the advantages of microwave photonic technology such as ultra-wideband and anti-interference, this paper constructed an ultra-wideband adaptive anti-interference communication system by combining microwave photonic spectrum sensing and high-speed frequency hopping signal generation. In the ultra-wideband adaptive anti-jamming communication system, the spectrum sensing module carries out high-speed real-time sensing of electromagnetic environment, the intelligent processor decides the safe spectrum information according to the spectrum sensing information, and the frequency-hopping signal generation module generates high-speed frequency-hopping signals according to the decision information, which can realize the adaptive anti-jamming of ultra-wideband communication. In the simulation, the 2~18GHz frequency spectrum is perceived at a high speed by using a coherent optical comb, and a frequency hopping pattern is determined according to the perceived information. The frequency hopping signal generation module generates a frequency hopping signal of 20000 hops /s according to the frequency hopping pattern, which improves the adaptive recognition ability of the communication system in the UWB range.
An optical true-time delay generation scheme based on WSS for adaptive null steering is proposed. The system is based on optically-switched fiber TTD technology. Take the advantages of the LCoS-based programmable WSS, arbitrary multiple true-time delays to generate multiple nulls can simultaneously be synthesized by control the routing of the optical radio frequency signal between the wavelength selective switches. We simulate the scheme with Optisystem and Matlab, the results confirm the scheme is able to achieve null depth over 50dB.
The precision of frequency signal is constantly improving, and the application of high-precision frequency signals requires an equally high-precision transmission method. So in this paper, we demonstrate an optical carrier radiofrequency phase stabilization transfer system based on a phase lock loop (PLL), applied to a 20 km spooled fiber link. The phase noise induced by optical fiber is suppressed by the PLL, and the transfer stability improved from 7.2×10-13@1 s to 8.9×10-15@1 s. In addition, the phase difference of peak-to-peak with compensation is less than 10 ps in a measurement of about 1 day. The phase study in antenna is with the compensation mode, so this work will lay the foundation for the phase synchronization of distributed coherent antenna system.
The increasing demands for enhance information security in the national defense and military applications such as satellite communication and integrated RF front end, have led to a critical requirement for high-speed frequency-hopping systems. However, the traditional frequency-hopping systems which is based on electrical domain is limited by its own electronic bottleneck. For example, the bandwidth is generally limited to several GHz, and the speed is generally limited to ms. Therefore, this paper innovatively propose a frequency-hopping system which has wide hopping-frequency bandwidth and frequency-hopping speed by using microwave photonics. The system has a frequency hopping bandwidth of more than 70GHz, a hopping speed of up to ns, and a maximum support of 35 frequency points, which can greatly expand the application prospect of secure communication.
Concerning future ultra wideband (UWB) real-time measurement of electromagnetic spectrum demand in electromagnetic battlefield, this paper proposes a frequency-time mapping measurement method based on microwave photonics. Frequency-time mapping, or real-time Fourier transform, maps the input ultra-wideband electromagnetic spectrum information to the output time-domain waveform. The electromagnetic spectrum signal is modulated to light by CS-SSB modulation, and frequency-time mapping is formed by using electrically modulated micro-ring. Through simulation verification, the method can achieve frequency measurement of panoramic bandwidth signal from100MHz to 30GHz.The frequency resolution can reach 80 MHZ, whose scanning time is less than 20us. The method can achieve ultra-high speed, high-precision, broadband measurement of wideband complex electromagnetic spectrum situation, providing technical support for future electromagnetic spectrum operations.
KEYWORDS: Channel projecting optics, Frequency combs, Modulators, Signal detection, Mirrors, Control systems, Single mode fibers, Oscillators, Microwave photonics, Modulation
For the urgent demand of the broadband, high efficient, parallel processing and anti-jamming capability in the field of ultra-wideband measurement control and communication. This paper puts forward a kind of channelized receive technology based on microwave photonic technology. The coherent optical comb generation module generates the signal optical comb and the local oscillator optical comb. The coherent optical comb with high repetition frequency is obtained by using cascade modulator and nonlinear technique. In order to satisfy the 10 comb tooth designed for the system, the FSR of coherent optical frequency comb is greater than 100GHz and 99.4GHz respectively, and the channel bandwidth is 600MHz. The channel division module receives the broadband RF signal from the RF front-end and modulates it to the optical frequency comb. By DPMZM single sideband modulation, 10 optical combs can be used to shift the frequency of the oscillator frequency comb. At the same time, according to the position of the 6GHz signal, the frequency comb is accurate controlled. After the WDM multiplexing device, it is selected by the high-speed optical switch controlled by the control unit. The photoelectric detection and mirror frequency suppression are realized by coherent demodulation, which consists of an optical mixer, a balance detector and a bridge. Which realizes channelized reception and cross-frequency conversion of any 6GHz wideband signal from the DC to 40 GHz band. Achieve 3dB channel consistency and mirror frequency suppression above 30dB. The results are verified by simulation and experiment. This method can also be extended to receive ultra-high speed frequency hopping signals. Which can provides technical support for ultra-wideband measurement control and communication, integrated RF front-end and electromagnetic space integration system.
Vector beam lasers are highly desirable for wide applications ranging from manipulation to communications. In this paper, we report the first directly modulated vector beam laser with azimuthally polarized emission. It’s a microcylinder cavity added with proper second order grating on the top, which enables single-mode lasing and efficient surface emission. Through theoretically and numerically analysis, the lasers are designed in detail. With optimized top grating, the emission is azimuthally polarized vector beam.
In the fields of ultra-wideband satellite communication, integrated radio frequency, radar and other national defense and military at present, it is necessary to realize the interconversion between baseband signals and radio frequency signals in Ka or even U band and L band to meet the processing requirements of RF front-end. Traditional electronic technology usually uses multistage local vibration mixing to realize frequency conversion, which is complicated and accompanied by serious nonlinearity and noise accumulation. As a kind of multi-wavelength light source, optical frequency beam can provide stable multiple local oscillations in the optical domain, and move the baseband/RF signals to the optical domain to achieve flexible mixing processing. In this paper, an UWB microwave photonic mixing technology based on optical frequency comb is innovatively proposed. UWB octave-spanning up-conversion from 10MHz to 60.01 GHz and down-conversion can be achieved by using only 20 GHz microwave driver, which effectively improves the RF preprocessing capability of UWB transmitter in the field of national defense and military.
A differentiator-based photonic approach for the instantaneous microwave frequency measurement (IFM) using a phase modulator and an optical Gaussian filter is proposed and experimentally demonstrated. A microwave frequency measurement with high resolution is achieved by a monotonous frequency-to-power mapping obtained by differential operation in optical domain. A proof-of-concept experiment has been performed, in which a measurement error less than ±0.1 GHz over the frequency range 0.1-10 GHz with input power of 0 dBm is demonstrated. The measurement error of the IFM system is still less than ±0.24 GHz, even though input signal power decreases to -30 dBm. The approach suggests a potential capacity for integrated IFM by using all-optical computing.
Photonic generation and processing of high-frequency and large-bandwidth microwave arbitrary waveforms have become an increasingly important area that can find numerous applications, such as in ultrawide-band (UWB) communication systems, radar, and other warfare systems, and the quality directly decides the system performance. Based on the microwave photonic channelization, arbitrary waveforms were generated through dual optical frequency combs (OFCs) with different free spectrum ranges (FSR). Due to the multiple optical channels with tunable amplitude and phase, the fundamental and higher harmonics are generated simultaneously and used to synthesize into the required waveforms. Combining the advantages of low-loss broadband photonics and microwave with fine narrowband control, the proposed channelized synthesis arbitrary waveform overcomes the electronic bottleneck of ultra-wideband analog processing and opens up a whole new solution to microwave signal generation. The simulation experiment system based on Optisystem software is conducted, the results confirm that an arbitrary wave, such as triangular, square, and sawtooth will be generated by adjusting the channel parameters, and the accuracy of the generated waveforms can be improved by introducing the fifth Fourier component. Compared to the waveform synthesized by the third-order harmonic, the root mean square error (RMSE) of the fifth-order harmonic is increased by 17%-20%.
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