In this paper we achieve non-reciprocity in a silicon optical ring resonator, by introducing two small time-modulated perturbations into the ring. Isolators are designed using this time-perturbed ring, side-coupled to waveguides. The underlying operation of the time-modulated ring and isolator is analyzed using Temporal Coupled Mode Theory (TCMT). The TCMT is used to find the angular distance, phase difference and thickness of the two time-modulated points on the ring resonator and also to find and justify the optimum values for the modulation frequency and amplitude, which yields maximum isolation in the isolator arrangements. Insight into the major players that determine isolation are also presented, with the aid of TCMT. Our proposed structure is much simpler to implement compared to other ring-based optical isolators, as it does not require spatio-temporal modulation, or large regions with modulation, but only two point perturbations on the ring. All results are obtained using realistic values of modulation and validated using an in-house full-wave solver. We achieve 21 dB isolation and −0.25 dB insertion loss at the telecommunication wavelengths.

Near field scanning optical microscopy exploiting differential interference contrast enhancement is demonstrated. Beam splitting in the near field region is implemented using a dual color probe based on plasmonic color sorter idea. This provides the ability to illuminate two neighboring points on the sample simultaneously. It is shown that by modulating the two wavelengths employed in exciting such a probe, phase difference information can be retrieved through measuring the near field photoinduced force at the difference of the two modulation frequencies. This difference in frequency is engineered to correspond to the first resonant frequency of the cantilever, resulting in improved SNR, and sensitivity. The effect of both topographical and material changes in the proposed near field differential interference (NFDIC) technique are investigated for CNT and silica samples. This method is a promising technique for high contrast and high spatial resolution microscopy.

Sampling is the primary functional step of an analogue to digital conversion, required for sensing, measurement, signal processing, metrology, and various data communication applications. Here we present, for the first time, to the best of our knowledge, the optical sampling of different microwave signals with sinc-pulse sequences with a very compact integrated silicon photonics ring modulator. By a simple time interleaving with three branches, the employed ring modulator enables ultra-compact photonic integrated analog to digital converters with a sampling rate of three times the RF bandwidth of itself and of the used photodetector and electronic devices. Therefore, its analogue bandwidth is 50% higher than the RF bandwidth of the incorporated electronics and photonics. Thus, the method might enable high-bandwidth analogue to digital converters with ultracompact footprint and lower power consumption for future communication systems, sensors, and measurement devices.

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Resonance-splitting is measured in active silicon micro-ring resonators, resulting from the coupling between counter-rotating modes. Parameters of the model, using Temporal Coupled Mode Theory (TCMT), are obtained by fitting the model to the experimental results.