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Microwave photonics (MWP) harnesses optical devices and techniques to generate, process, and transport microwave and millimeter-wave signals. By combining ultra-wideband optoelectronic devices, low-loss fiber distribution, strong immunity to electromagnetic interference, and compatibility with large-scale photonic integration, MWP provides an effective route to overcome bottlenecks in purely electronic systems. These capabilities support applications including 5G/6G mobile fronthaul/backhaul, distributed coherent radar, true-time-delay beamforming, broadband instantaneous frequency measurement, reconfigurable microwave signal processing, low-phase-noise microwave generation, and photonic AI accelerators. In this thesis, we explore how broadband optical sources (BOS), including coherent optical frequency combs (OFCs) and non-coherent amplified spontaneous emission (ASE), can expand the performance and application potential of MWP, with a focus on microwave signal processing and generation.

The first part of this thesis investigates BOS-enabled microwave photonic filters (MPFs) and signal processors based on a finite-impulse-response (FIR) framework. In these architectures, chromatic dispersion introduces wavelength-dependent delays between adjacent optical carriers, forming a tapped-delay-line filter closely related to FIR filtering in digital signal processing. Based on this principle, we develop and experimentally validate a versatile MWP signal processor reconfigurable for integral and fractional Hilbert transforms, differentiation, and integration, using OFCs generated by a quantum-dash mode-locked laser as a coherent BOS. We then address a related challenge in dispersion-based FIR implementations: in real fiber links, third-order dispersion (TOD) distorts the designed tap delays and degrades the processor/filter response. To solve this issue, we propose and experimentally demonstrate, in an ASE-based architecture, a chirp-like spectral slicing technique that effectively removes TOD-induced impairment.

The second part further investigates ASE-driven optoelectronic oscillators (OEOs) for high-quality and reconfigurable microwave generation by amplifying the MPF output and feeding it back to form a closed optoelectronic loop. We demonstrate a single-cavity OEO that can switch among single-frequency, dual-frequency, and mode-locked regimes. However, this OEO is inherently prone to multimode oscillation because the MPF passband is relatively broad while the long cavity has a small free spectral range (FSR), allowing multiple cavity modes to oscillate. This reflects a long-standing OEO trade-off: a long cavity improves phase noise but reduces FSR, making single-mode oscillation difficult. To overcome this trade-off, we propose cascaded zero-dispersion recirculating loops (ZD-RLs) as auxiliary FIR filters in an ASE-driven OEO to enhance the MPF Q-factor. Experiments show that progressively cascading ZD-RLs improves the sidemode suppression ratio (SMSR) without compromising phase-noise performance, providing the first experimental demonstration of overcoming this trade-off. Building on the strength of ZD-RLs, we further extend the approach to a broader family of OEO regimes, including a mode-locked OEO for microwave frequency-comb generation with record-high harmonic mode-locking order, a dual-frequency OEO with independently tunable tones while maintaining single-mode oscillation, and a dispersion-tuned OEO that experimentally demonstrates dispersion-enabled frequency tuning in an OEO for the first time.

Overall, this thesis establishes BOS as a versatile and scalable enabler for MWP, advancing both reconfigurable microwave signal processing and high-quality microwave generation. By addressing key practical bottlenecks, including dispersion-induced impairments in FIR-based processors and the long-standing mode-purity–phase-noise trade-off in long-loop OEOs, we push MWP signal processors and OEOs toward real-world deployment.