Abstract
A photonics-assisted dual-chirp microwave signal generation scheme is proposed based on electro-optic modulation and heterodyne detection. The dual-chirp microwave signal is generated by heterodyne beating between a dual-chirp optical waveform and a frequency-shifted optical carrier, where the dual-chirp optical waveform is obtained by applying a baseband symmetric-triangle linear frequency modulated signal to a Mach-Zehnder modulator biased at the minimum transmission point, and the frequency-shifted optical carrier is obtained by carrier-suppressed single-sideband modulation in a dual-parallel Mach-Zehnder modulator (DPMZM) with the assistance of an electronic 90° hybrid. The bandwidth of the generated dual-chirp microwave signal is twice of that of the input baseband signal, and the central frequency can be tuned by varying the frequency of the single-tone microwave signal applied to the DPMZM. Both numerical simulation and experiment are carried out to demonstrate the proposed scheme. In the simulation, a dual-chirp microwave signal with a center frequency of 15 GHz and a bandwidth of 6 GHz is generated. In the proof-of-concept experiment, dual-chirp microwave signals centered at 1.5 GHz and with bandwidth of 100 MHz and 200 MHz are generated, which verifies the feasibility of the proposed scheme.
Highlights
In modern radar systems, linearly chirped microwave signals are widely employed to enhance the range resolution through pulse compression technology [1], [2]
The dual-chirp microwave signal is generated by heterodyne beating between a dual-chirp optical waveform and a frequency-shifted optical carrier, where the dual-chirp optical waveform is obtained by applying a baseband symmetric-triangle linear frequency modulated signal to a MachZehnder modulator biased at the minimum transmission point, and the frequency-shifted optical carrier is obtained by carrier-suppressed single-sideband modulation in a dualparallel Mach-Zehnder modulator (DPMZM) with the assistance of an electronic 90° hybrid
After heterodyne beating with a frequency-shifted optical carrier from a DPMZM driven by a tunable single-tone RF signal via an electrical 90° hybrid, a dual-chirp microwave signal with double-bandwidth of the input baseband single-chirp waveform is generated, whose central frequency is equal to the input single-tone RF signal
Summary
Linearly chirped microwave signals are widely employed to enhance the range resolution through pulse compression technology [1], [2]. After heterodyne beating with a frequency-shifted optical carrier from a DPMZM driven by a tunable single-tone RF signal via an electrical 90° hybrid, a dual-chirp microwave signal with double-bandwidth of the input baseband single-chirp waveform is generated, whose central frequency is equal to the input single-tone RF signal. Both simulation and experiment are carried out to demonstrate the feasibility of the proposed scheme.
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