A phase-coded microwave signal generation method based on parallel Mach-Zehnder modulator (MZM) with tunable frequency multiplication factor is proposed and demonstrated. By controlling the modulation index and the optical power ratio of the parallel MZMs, phase-coded microwave signals with frequency multiplication factors of 1, 3 and 5 are obtained. The feasibility of this approach is demonstrated by theoretical analysis and simulation, in which binary phase-coded signals with carrier frequency of 1GHz, 3GHz or 5GHz are respectively generated under 1GHz radio frequency (RF) signal input.
Complex electromagnetic environment in the future battlefield requires spectrum sensing equipment to have broadband and high-resolution measurement capabilities. This paper proposes a microwave photonic frequency measurement method based on optical spectrum operation and stimulated Brillouin scattering. The use of optical spectrum operation is to realize generating pump light in a large range, so as to realize the excitation of stimulated Brillouin scattering in a wide spectrum range, and further the stimulated Brillouin scattering is employed to realize high-resolution frequency sensing. The principle of this method is given and the feasibility of the method is verified experimentally. Experiment results show the measurement capability of the proposed method covers a frequency range of 0.03–40 GHz with a resolution of 25 MHz. The proposed method can effectively support high-resolution frequency sensing in complex electromagnetic environments.
A photonic approach to generate triangular frequency modulated microwave waveform (TFMMW) using frequency-scanning (FS) laser and dual-output dual-parallel Mach-Zehnder modulator (DO-DPMZM) is proposed and demonstrated. In the scheme, a DO-DPMZM followed by a time delayer and a polarization beam combiner is utilized to generate orthogonally polarized -1rst-order sideband and +1rst-order sideband with time delay. After that, a TFMMW with large time-bandwidth product (TBWP) can be generated by photoelectric balanced detection. In the simulation experiments, Ka band TFMMW with TBWP of 9830.4 is generated and its ambiguity function is investigated
A simple single sideband (SSB) analog optical link with enhancement spurious free dynamic range (SFDR) is proposed. By coupling the independent optical carrier and +1st, +2nd order phase-modulated optical sidebands to be demodulation, the suppression of IMD3 is achieved. An theoretical model is established and the simulation results show that the carrier-to-interference ratio (CIR) presents a 32dB improvement and the corresponding improved SFDR is 123.5 dB·HZ2/3 , which is 18.6 dB larger than that of conventional single sideband phase-modulated link. In particular, the proposed SSB link can avoid the periodic power attenuation caused by dispersion, presenting great potential usage in modern radar system.
Detecting targets with long distance and high resolution is the goal of radar techniques. Traditional electrical radar which has a long working distance always work at low frequency and thus has a limited bandwidth. We demonstrate a microwave photonic radar system which can realize larger bandwidth at low-frequency band based on optical-domain frequency operation. P-band and C-band radio-frequency (RF) signals with 700-MHz and 4-GHz bandwidths, respectively are generated, while the latter is adopted to detect space-separated corner reflectors to demonstrate the effectiveness of the proposed system.
An approach for photonic generation dual-chirp microwave waveform (DCMW) with frequency and bandwidth multiplication without filtering is proposed and demonstrated. A continuous-wave (CW) optical signal is sent to a polarization division multiplexing modulator. In the modulator, one part of the CW optical signal is modulated by the radio-frequency (RF) driving signals to generate ±2 nd-order single-frequency sidebands, while another one is modulated by the baseband chirped signals to generate ±2 nd-order chirped sidebands. After that, a frequency-doubled and bandwidth-quadrupled DCMW can be generated by photoelectric balanced detection. In the simulation experiments, by using a RF driving signal at 5GHz and a baseband single-chirp signal with bandwidth of 0.5GHz as the input electrical signals, a DCMW with central frequency of 10GHz and bandwidth of 2GHz is generated.
An optical length measuring method exploiting microwave interrogated cascaded fiber Mach-Zehnder interferometer (MZI) is proposed. The frequency response of the filter with respect to the fiber length change of MZI is studied and an length measuring sensitivity of 2.580 GHz/mm is obtained. The proposed sensing configuration is with high sensitivity, easy to implement and shows the capability for other parameters measurement such as temperature, strain, and vibration.
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