Photonic-Based Multiformat Signal Generator With Dispersion Immunity for Multichannel Transmission

In this article, a photonic multiformat microwave signal generator with immunity to chromatic dispersion-induced power (CDIP) fading is proposed and demonstrated. A dual-parallel Mach–Zehnder modulator (DPMZM) is driven by a baseband signal to perform a multiformat modulation optical signal. An active demultiplexer based on optical injection locking serves as the filter and amplifier to select individual comb lines from the optical frequency comb (OFC). Beating the selected comb line and the modulated optical signal at a photodetector (PD) after fiber transmission, the microwave signal can be generated. The system features an ultra-wideband (UWB) frequency tuning range, eliminating the need for a broadband modulator and radio frequency (RF) synthesizer. The created equivalent single-sideband (SSB) modulation is used to eliminate the CDIP over fiber transmission. Excellent frequency reconfiguration and multiformat switch ability are achieved by adjusting the wavelength of the main laser (ML) and the format of baseband signals while keeping at the normal bias point. A proof-of-concept experiment demonstrates that the multiformat waveforms, including switchable chirped signals, polyphase-coded signals, and ternary amplitude-shift keying (ASK) signals, have been successfully generated. The long-range transmission experiment verifies that the CDIP can be successfully eliminated.