We propose a compact 1-mm-radius microring resonator sensor based on a hybrid plasmonic waveguide on a silicon-on-insulator substrate. The hybrid waveguide is composed of a metal-gap-silicon structure, where the optical energy is greatly enhanced in the narrow gap. We use the finite element method to numerically analyze the device optical characteristics as a biochemical sensor. As the optical field in the hybrid micoring resonator has a large overlap with the upper-cladding sensing medium, the sensitivity is very high compared to other dielectric microring resonator sensors. The compactness of the hybrid microring resonator is resulted from the balance between bending radiation loss and metal absorption loss. The proposed hybrid microring resonator sensors have the main advantages of small footprint and high sensitivity and can be potentially integrated in an array form on a chip for highly-efficient lab-on-chip biochemical sensing applications.

We investigate the photocurrent generation with surface-state absorption effect in a silicon waveguide integrated with periodically interleaved p-n junctions. Due to the high electric field (~5 × 10 ⁵ V/cm) and large depletion area coverage in the waveguide, our device can collect more photocurrent than regular p-i-n and p-n structures. The responsivity of our device is optical power dependent with a higher value at a lower power level. The measured 3-dB bandwidth of the frequency response is 11.5 GHz. Although its responsivity is low compared to that of III-V and Ge photodiodes, its simple fabrication and compatibility with all-silicon photonic devices makes it suitable as on-chip optical power monitors.

The coupling characteristics of conical micro/nano fibers (CMNFs) are investigated using numerical simulations and experiments. Distinct from uniform micro/nano fibers (UMNFs), the coupling efficiency not only depends on the overlapping length between two CMNFs but also the tapering angle of the CMNFs. With the increase of overlapping length, the coupling efficiency gradually converges to a stable value, with its convergence speed determined by the angle of the CMNFs. Experimental result shows the convergent coupling efficiency can be >90%. The spectral response of the coupler shows a “box-shape” profile with a 3-dB bandwidth of 2 nm, resembling a flat-top bandpass filter. And experimental results also show the coupling characteristics of CMNFs are overlapping length and taper angle dependent, which verify the simulation conclusions.

We investigate the influence of coupling strength on self-coupled optical waveguide (SCOW) resonators. Experimental results reveal that the SCOW resonator transmission spectrum can exhibit single-channel or dual-channel stopbands with the band splitting level determined by the two coupling coefficients. Electrically tunable SCOW resonators comprising 2×2 Mach-Zehnder interferometer couplers are also demonstrated, which shows a similar change trend upon coupling tuning.

A new kind of 3ⁿ feed-forward programmable optical fiber true delay line was proposed. Theoretical analysis was presented on its delay performance and expandability. Experimental demonstration was given to show the implementation of such delay lines using SOAs and Farady rotation mirrors. Delay step as small as 0.5 ps with precision of about 0.03 ps was achieved. Measurement was performed to verify the feasibility and results are given.