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The development of facile and efficient polymerizations toward functional polymers with unique structures and attractive properties is of great academic and industrial significance. Here we develop a straightforward C–H-activated polyspiroannulation route to in situ generate photoresponsive spiro-polymers with complex structures. The palladium(II)-catalyzed stepwise polyspiroannulations of free naphthols and internal diynes proceed efficiently in dimethylsulfoxide at 120 °C without the constraint of apparent stoichiometric balance in monomers. A series of functional polymers with multisubstituted spiro-segments and absolute molecular weights of up to 39,000 are produced in high yields (up to 99%). The obtained spiro-polymers can be readily fabricated into different well-resolved fluorescent photopatterns with both turn-off and turn-on modes based on their photoinduced fluorescence change. Taking advantage of their photoresponsive refractive index, we successfully apply the polymer thin films in integrated silicon photonics techniques and achieve the permanent modification of resonance wavelengths of microring resonators by UV irradiation., Photoresponsive polymers are receiving great attention due to the increasing demands on smart optical and biological materials. Here, the authors report a C–H-activated polyspiroannulation route to in situ generate photoresponsive spiro-polymers with potential applications in photopatterning and silicon photonics techniques.

We demonstrate an on-chip optical cell stretcher using optical lattices generated from SU8-filled vertically embedded multimode-interference waveguides in a silicon substrate. We extract the shear modulus of ∼2 μN/m from swollen rabbit red blood cells.

In this paper, we report our recent progress in silicon-nitride-based optofluidic label-free biosensors using a surfacefunctionalized coupled-resonator optical waveguide (CROW) in the visible wavelengths. The working principle is based on far-field imaging of the CROW mode-field intensity distributions at a fixed probe wavelength. The imaged pattern variation reflects real-time analyte-binding information on the CROW surfaces. Our surface-functionalized 16- microring CROW reveals six eigenstates with distinctive mode-field intensity distributions. Our proof-of-concept sensing experiment at an arbitrarily chosen probe wavelength within the CROW transmission band shows a detection of streptavidin concentration down to 40 ng/ml.

We report on-chip optical lattice generation using SU8-filled vertically embedded multimode-interference waveguides in a silicon substrate. We show stretching of rabbit red blood cells using the generated optical lattices in a fluidic channel.

Silicon photonics is becoming the leading technology for photonic integrated circuits (PICs) due to large-scale integration, low cost, and high-volume productions enabled by complementary metal-oxide-semiconductor (CMOS) fabrication process. Thanks to various material and optical characteristics of crystalline silicon, the silicon-on-insulator platform has become the dominant material platform for silicon photonics. Meanwhile, monolithic or heterogeneous integration of other materials on silicon photonic chips, including the silicon nitride (SiN)-on-insulator platform and the III–V-on-silicon platform, are under rapid developments to enhance the functionalities of silicon photonics. Among the myriad of silicon photonic structures for passive and active components, integrated microresonators are promising for a broad range of applications due to their strong resonance field enhancement, narrowband wavelength selectivity, and compact footprints. In this paper, we review the state of the art and our perspectives on emerging technologies based on integrated silicon photonic microresonators in the technology domains of intradatacenter optical interconnects, integrated nonlinear and quantum photonics, and lab-on-a-chip optical biosensing. We specifically review recent progress and our original work in SOI microring-based crossbar switch fabrics; III–V-on-silicon microresonator lasers; silicon-based microresonator nonlinear and quantum sources; and SiN microresonator-based optical biosensors.

We illustrate a 2×2 quantum photonic switch fabric using two-photon quantum interference in an integrated silicon microring resonator array. Our modeling demonstrates phase- or wavelength-selective routing of single photons at different output states.

Chip-scale, optical microcavity-based biosensors typically employ an ultra-high-quality microcavity and require a precision wavelength-tunable laser for exciting the cavity resonance. For point-of-care applications, however, such a system based on measurements in the spectral domain is prone to equipment noise and not portable. An alternative microcavity-based biosensor that enables a high sensitivity in an equipment-noise-tolerant and potentially portable system is desirable. Here, we demonstrate the proof-of-concept of such a biosensor using a coupled-resonator optical-waveguide (CROW) on a silicon-on-insulator chip. The sensing scheme is based on measurements in the spatial domain, and only requires exciting the CROW at a fixed wavelength and imaging the out-of-plane elastic light-scattering intensity patterns of the CROW. Based on correlating the light-scattering intensity pattern at a probe wavelength with the light-scattering intensity patterns at the CROW eigenstates, we devise a pattern-recognition algorithm that enables the extraction of a refractive index change, Δn, applied upon the CROW upper-cladding from a calibrated set of correlation coefficients. Our experiments using an 8-microring CROW covered by NaCl solutions of different concentrations reveal a Δn of ~1.5 × 10(-4) refractive index unit (RIU) and a sensitivity of ~752 RIU(-1), with a noise-equivalent detection limit of ~6 × 10(-6) RIU.