Silicon micro-ring resonators (MRRs) are compact and versatile devices whose periodic frequency response can be exploited for a wide range of applications, the most straightforward being periodic filters, add-drop multiplexers or wavelength selective switches [1]. Recently, we have exploited the design flexibility of MRRs in order to demonstrate spectral and temporal signal shaping. In particular, MRRs can be used for optical modulation format conversion from return-to-zero (RZ) on-off keying (OOK) to non-return-to-zero (NRZ) OOK [2]. This technique has been used for multi-channel format conversion, but also for the first ever demonstration of NRZ signal generation at 640 Gb/s by conversion of an optical time division multiplexed (OTDM) signal [3]. It has also been extended to format conversion from RZ differential phase-shift keying (DPSK) to NRZ-DPSK [4]. Another application ofMRRs is for the demodulation of DPSK signals [5]. Other temporal shaping demonstrations include the generation of ultra-widebandmonocycle pulses [6] as well as the enhancement of the modulation speed of directly modulated lasers [7]. Even though silicon MRRs are promising devices, they suffer from inherent polarization sensitivity, which is a critical impediment to their practical use. We will show how polarization diversity circuits based on polarization splitters and rotators can be engineered to significantly reduce their polarization sensitivity and illustrate the benefit of such circuits with the example of an MRR-based DPSK demodulator [8].