Microwave photonic signal generation using a quadratic FBG based optoelectronic oscillator

We proposed an optoelectronic oscillator (OEO), incorporating a dual parallel Mach–Zehnder modulator (DP-MZM) and quadratic fiber Bragg grating (Q-FBG) for microwave photonic (MWP) applications. The suggested system combines the unique dispersive and reflective properties of the Q-FBG to achieve enhanced frequency stability and spectral purity. The Q-FBG facilitates precise control over the oscillation frequency by introducing quadratic phase modulation, effectively suppressing spurious modes and improving phase noise performance. Experimental results demonstrate the capability of the OEO-QFBG system to generate low-phase-noise microwave signals with superior stability compared to conventional OEO designs. A 20 GHz microwave signal with low phase noise of –134.93 dBc Hz−1 at 10 kHz offset was generated. This work underscores the potential of integrating advanced photonic components, such as Q-FBGs, for advanced microwave photonics applications, including radar systems, communications, and high-precision instrumentation.