Photonic generation of phase-coded linearly frequency modulation signals with increased TBWP

Abstract

As a new pulse compression signal, the phase-coded linearly frequency modulated (LFM) signal is proposed to faciliate multi-purpose radars. Here, we propose and demonstrate a phase-coded LFM signal generator, whose center frequency and bandwidth can be both adjusted. The phase-coded LFM signal generator is realized by feeding a phase-modulated optical signal into an optoelectronic oscillator (OEO). When the Fourier domain mode-locking is achieved, a phasecoded LFM signal is successfully generated. The center frequency and bandwidth of the generated microwave signal can be adjusted by changing the wavelength of the tunable laser source (TLS) and the peak-to-peak voltage of the driving signal, respectively. Experiment results show that a phase-coded LFM microwave signal with a center frequency of 9.5 GHz and a bandwidth of 5 GHz is successfully generated, whose TBWP is 5.6×10⁵. To demonstrate the flexibility of the proposed scheme, the center frequency and bandwidth of the generated phase-coded LFM signal are adjusted to 12.4 and 2.6 GHz, respectively. The signal generator can be used in pulse compression radar in the future.