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The benefits of photonics over electronics in the application of optical transceivers and both classical and quantum computing have been demonstrated over the past decades, especially in the ability to achieve high bandwidth, high interconnectivity, and low latency. Due to the high maturity of silicon photonics foundries, research on photonics devices such as silicon micro ring resonators (MRRs), Mach-Zehnder modulators (MZM), and photonic crystal (PC) resonators has attracted plenty of attention. Among these photonic devices, silicon MRRs using carrier depletion effects in p-n junctions represent optical switches manufacturable in the most compact magnitude at high volume with demonstrated switching energies ~5.2fJ/bit. In matrix multiplication demonstrated with integrated photonics, one approach is to couple one bus straight waveguide to several MRRs with different resonant wavelengths to transport signals in different channels, corresponding to a matrix row or column. However, such architectures are potentially limited to ~30 MRRs in series, by the limited free-spectral range (FSR) of an individual MRR. We show that PC switches with sub-micron optical mode confinements can have a FSR >300nm, which can potentially enable energy efficient computing with larger matrices of ~200 resonators by multiplexing. In this paper, we present designs for an oxide-clad bus-coupled PC switch with 1dB insertion loss, 5dB extinction, and ~260aJ/bit switching energy by careful control of the cavity geometry as well as p-n junction doping. We also demonstrate that air-clad bus-coupled PC switches can operate with 1dB insertion loss, 3dB extinction, and ~80aJ/bit switching energy. 

Diverse chip-based sensors utilizing integrated silicon photonics have been demonstrated in resonator and phase shifter/interferometer configurations. Till date, interferometric techniques with the Mach-Zehnder Interferometer (MZI) and Young’s interferometer have shown the lowest mass detection limits (in pg/mm2). Slow light in photonic crystal waveguides integrated with MZIs enables compact geometries due to enhanced optical path lengths as light propagates with high group index. In a typical MZI, light propagating in the signal arm overlaps with analytes and undergo a relative phase change with respect to the light in the reference arm which leads to measured output intensity changes. In this paper, using integrated photonic methods, we demonstrate a slow light enhanced Michelson interferometer (MI) biosensor, wherein the reference and signal arms are traversed twice by the propagating optical mode. As a result, the analyte interaction length is effectively doubled since the propagating optical mode undergoes twice the phase shift as would be observed in a MZI. In an asymmetric MI configuration, the resultant doubling of the phase shift is observed as a doubling of the resonance wavelength shift for a fixed change in the analyte concentration. The device sensitivity is thus doubled with respect to a conventional MZI while also effectively halving the geometric length compared to the MZI sensor 

Periodic arrays of resonant dielectric nano- or microstructures provide perfect reflection across spectral bands whose extent is controllable by design. At resonance, the array yields this result even in a single subwavelength layer fashioned as a membrane or residing on a substrate. The resonance effect, known as guided-mode resonance, is basic to modulated films that are periodic in one dimension (1D) or in two dimensions (2D). It has been known for 40 years that these remarkable effects arise as incident light couples to leaky Bloch-type waveguide modes that propagate laterally while radiating energy. Perfect reflection by periodic lattices derives from the particle assembly and not from constituent particle resonance. We show that perfect reflection is independent of lattice particle shape in the sense that it arises for all particle shapes. The resonance wavelength of the Bloch-mode-mediated zero-order reflectance is primarily controlled by the period for a given lattice. This is because the period has direct, dominant impact on the homogenized effective-medium refractive index of the lattice that controls the effective mode index experienced by the mode generating the resonance. In recent years, the field of metamaterials has blossomed with a flood of attendant publications. A significant fraction of this output is focused on reflectors with claims that local Fabry-Perot or Mie resonance causes perfect reflection with the leaky Bloch-mode viewpoint ignored. In this paper, we advance key points showing the essentiality of lateral leaky Bloch modes while laying bare the shortcomings of the local mode explanations. The state of attendant technology with related applications is summarized. The take-home message is that it is the assembly of particles that delivers all the important effects including perfect reflection. 

We present principles of leaky-mode photonic lattices explaining key properties enabling potential device applications. The one-dimensional grating-type canonical model is rich in properties and conceptually transparent encompassing all essential attributes applicable to two-dimensional metasurfaces and periodic photonic slabs. We address the operative physical mechanisms grounded in lateral leaky Bloch mode resonance emphasizing the significant influence imparted by the periodicity and the waveguide characteristics of the lattice. The effects discussed are not explainable in terms of local Fabry-Perot or Mie resonances. In particular, herein, we summarize the band dynamics of the leaky stopband revealing principal Bragg diffraction processes responsible for band-gap size and band closure conditions. We review Bloch wave vector control of spectral characteristics in terms of distinct evanescent diffraction channels driving designated Bloch modes in the lattice.