Resonantly enhanced lumped-element O-band Mach-Zehnder modulator with an ultra-wide operating wavelength range.

We demonstrate an O-band resonantly enhanced Mach-Zehnder modulator utilizing highly overcoupled resonators with staggered resonance wavelengths that achieves an operating range of 6.6 nm (7.1 nm) with a 1 dB (3 dB) optical modulation amplitude penalty.

Multi-color flow cytometer with PIC-based structured illumination.

We demonstrate a flow cytometer in which structured light illumination is used to attribute fluorescent and scattering signals to their excitation wavelength. A suitable multi-color light source emitting structured illumination patterns at 405, 488, 561 and 640 nm is developed based on a silicon nitride photonic integrated circuit and cytometry experiments are conducted with calibration beads. Performance metrics of the novel cytometer are compared with those of a mature, commercial device.

Sub-wavelength tunneling barrier in rib waveguide microring modulators with vanishing bending losses.

Silicon photonics ring resonators in rib waveguide configuration are among the most important components for wavelength-division-multiplexed communication networks. While the rib waveguide enables simple electrical connectivity in microring modulators and add-drop multiplexers, it also results in unacceptable bending losses once the circumference is shrunk below a few micrometers, limiting achievable free spectral ranges and resonant enhancements. We introduce a sub-wavelength tunneling barrier at the critical radius at which the conformally mapped effective index of the slab exceeds that of the waveguide in order to suppress these bending losses, while increasing the resonator's resistance only slightly.

Activity-induced targeting of profilin and stabilization of dendritic spine morphology.

Morphological changes in dendritic spines have been implicated in connective plasticity in brain circuitry, but the underlying pathway leading from synaptic transmission to structural change is unknown. Using primary neurons expressing GFP-tagged proteins, we found that profilin, a regulator of actin polymerization, is targeted to spine heads when postsynaptic NMDA receptors are activated and that actin-based changes in spine shape are concomitantly blocked. Profilin targeting was triggered by electrical stimulation patterns known to induce the long-term changes in synaptic responsiveness associated with memory formation.