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. While the experimental device still features a slightly higher sensitivity floor than the commercial one, all but the most weakly stained beads can be categorized. These promising results validate the feasibility of the proposed concept.
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. The fundamental working principle is explained and illustrated with a design study based on the finite difference eigenmode method. Three-dimensional finite difference time domain simulations verify the design and a proof-of-concept microring modulator is modeled based on the novel geometry.
We report on glass-molded micro-optical interposers for single-mode fiber-to-PIC coupling fabricated in parallel by isothermal molding of 1-inch glass plates yielding over 100 arrays of 8 lenses each. Excess losses between PIC and singlemode fiber are below 1 dB. In addition to allowing a narrow package footprint, beam transformation maps mode profiles between fibers and surface couplers, and, in case of grating couplers, can adapt the light incidence angle on a wavelengthspecific basis, facilitating packaging of PICs in CWDM and LAN-WDM modules. The interposers can be further extended to support polarization management and isolation by coating with polarization selective thin film stacks in MacNeille configuration, as well as wavelength multiplexing by coating with dichroic stacks. Using this technique, over 256 bidirectional transceiver channels can be packaged in the footprint of a single reticle.
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