A single sideband (SSB) phase-modulated link with an improved spurious-free dynamic range (SFDR) is proposed and experimentally demonstrated. By generating a single-sideband phase-modulated signal containing a specific spectrum for demodulation, the third-order intermodulation distortion (IMD3) is effectively suppressed. The theoretical analysis is presented, and the experimental results show that a carrier-to-interference ratio of 62.45 dB is achieved. The improved SFDR is 120.25 dB · Hz4/5, which is 14.47 dB higher than that of a conventional SSB phase-modulated link.
We propose and experimentally demonstrate a pulse radar signal generation based on the Fourier domain mode-locked optoelectronic oscillator (FDML-OEO). In this method, two low-frequency control signals generated by a direct digital synthesizer (DDS) are adopted to control the tunable laser source (TLS) and the bias voltage of Mach-Zehnder modulators (MZM) respectively. The broadband pulse signals are generated by directly truncating the broadband signals on the basis of a FDML-OEO by controlling the frequency and amplitude of the bias voltage of the MZM. In the experiment, the broadband radar pulse signals with tunable duty cycle and the center frequency are demonstrated. In particular, the center frequency of signals are tuned by changing the initial phase of pulse driving signal and the triangular wave or the wavelength of TLS, which have greatly potential in improving the detection capability of the radar system.
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 single sideband phase modulated radio over fiber link with improved spurious-free dynamic range is propsed, in which an optical processor is used for IMD3 suppression. A theoretical analysis is presented and the simulation experiment results indicate that the SFDR is up to 126.3 dB·Hz4/5.
We propose a fiber Bragg grating sensor interrogation system based on a Fourier domain mode-locked optoelectronic oscillator (FDML-OEO). The FDML is achieved by synchronizing the period of the driving current of the laser with the round-trip time of the OEO loop. By employing a narrow band electrical filter with the central frequency located within the sweeping frequency of the FDML-OEO, pulsed microwave output can be obtained. The wavelength shift of the phase-shift fiber Bragg grating (PS-FBG) can be interrogated by measuring the pulse interval variation. The experimental results indicate that the pulse interval of the generated signal has a linear relationship with the axial strain applied to the PS-FBG and a sensitivity as high as 0.42 μs/με is achieved.
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