We investigate the application of integrated micro-combs in RF photonic systems and demonstrate a microwave photonic intensity differentiator based on a Kerr optical comb generated by a compact integrated micro-ring resonator. The on-chip Kerr optical comb is CMOS-compatible and contains a large number of comb lines, which can serve as a high-performance multi-wavelength source for the transversal filter, thus greatly reduce the cost, size, and complexity of the system. The operation principle is theoretically analyzed, and experimental demonstrations of fractional-, first-, second-, and thirdorder differentiation functions based on the principle are presented.
An arbitrary-order intensity differentiator for high-order microwave signal differentiation is proposed and experimentally demonstrated on a versatile transversal microwave photonic signal processing platform based on integrated Kerr combs. With a CMOS-compatible nonlinear micro-ring resonator, high quality Kerr combs with broad bandwidth and large frequency spacings are generated, enabling a larger number of taps and an increased Nyquist zone. By programming and shaping individual comb lines’ power, calculated tap weights are realized, thus achieving a versatile microwave photonic signal processing platform. Arbitrary-order intensity differentiation is demonstrated on the platform. The RF responses are experimentally characterized, and systems demonstrations for Gaussian input signals are also performed.
We investigate the enhancement in the filtering quality (Q) factor of an integrated micro-ring resonator (MRR) by embedding it in an integrated Fabry-Perot (FP) cavity formed by cascaded Sagnac loop reflectors (SLRs). By using coherent interference within the FP cavity to reshape the transmission spectrum of the MRR, both the Q factor and the extinction ratio (ER) can be greatly improved. The device is theoretically analyzed, and practically fabricated on a silicon-on-insulator (SOI) platform. Experimental results show that up to 11-times improvement in Q factor and an 8-dB increase in ER can be achieved via our proposed method. The impact of varying structural parameters on the device performance is also investigated and verified.
A reconfigurable microwave photonic filter (MPF) based on an integrated Kerr comb source was proposed and
demonstrated. By employing an on-chip micro-ring resonator (MRR), a broadband Kerr comb with a large number of
comb lines was generated and used as a high-quality multi-wavelength source for the MPF, which greatly reduced the size
and cost. The enhanced performance of the MPF was theoretically analysed and systematically characterized. Due to the
large channel number and high reconfigurability of the scheme, the MPF features an improved Q factor and wideband
tunability. The experimental results matches well with theory, verifying the feasibility of our approach as a solution towards
implementing highly reconfigurable MPFs with reduced system complexity.