Search

Sub-wavelength grating (SWG) metamaterials have been considered to provide promising solutions in the development of next-generation photonic integrated circuits. In recent years, increasied interest has been paid to silicon photonic planar biosensors based on SWG geometries for performance enhancement. In this work, we demonstrate a highly sensitive label-free phase-shifted Bragg grating (PSBG) sensing configuration, which consists of sub-wavelength block arrays in both propagation and transverse directions. By introducing salt serial dilutions and electrostatic polymers assays, bulk and surface sensitivities of the proposed sensor are characterized, obtaining measured results up to 579.2 nm/RIU and 1914 pm/nm, respectively. Moreover, the proposed multi-box PSBG sensor presents an improved quality factor as high as ∼ 8000 , roughly 3-fold of the microring-based counterpart, which further improves the detection limit. At last, by employing a biotin-streptavidin affinity assay, the capability for small molecule monitoring is exemplified with a minimum detectable concentration of biotin down to 2.28 × 10 - 8 M ., Competing Interests: The authors declare that there are no conflicts of interest related to this article., (© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.)

We propose and demonstrate broadband, entirely mode-evolution-based, polarization splitter-rotators (PSR) using sub-wavelength grating (SWG) assisted adiabatic waveguides for two SOI platforms. Our PSRs are more compact than previously demonstrated entirely mode-evolution-based designs. The devices were fabricated using two fabrication processes and, in both cases, the measured spectra show close matches to the simulation results. One of the processes uses standard optical lithography and, hence, this is the first time that an SWG-based PSR has been experimentally implemented using such a process. Finally, measurements for arbitrary input polarizations on an active, automated polarization receiver, that uses one of our PSRs, are also presented.

A ring resonator based 4 channel wavelength division multiplexing (WDM) receiver with polarization diversity is demonstrated at 10 Gb/s per channel. By forming a waveguide loop between the two output ports of a polarization splitter-rotator (PSR), the input signals in the quasi-transverse-electric (quasi-TE) and the quasi-transverse-magnetic (quasi-TM) polarizations can be demultiplexed by the same set of ring resonator filters, thus reducing the number of required channel control circuits by half compared to methods which process the two polarizations individually. Large signal measurement results indicate that the design can tolerate a signal delay of up to 30% of the unit interval (UI) between the two polarizations, which implies that compensating for manufacturing variability with optical delay lines on chip is not necessary for a robust operation. The inter-channel crosstalk is found negligible down to 0.4nm (50 GHz) spacing, at which point the adjacent channel isolation is 17 dB, proving the design's compatibility for dense WDM application.

In this work, we present optical add/drop multiplexer (OADM) filters for coarse wavelength-division-multiplexing (CWDM) systems with high sidelobe suppressions that result in high adjacent channel isolations (A i ). The filters are realized by using a compact, series-cascaded configuration of apodized, contradirectional-coupling-based filters. We experimentally demonstrate a device with a measured A i of 53 dB (these devices hold the promise of achieving even higher A i s). While having large A i s, our devices have the wide bandwidths and low insertion losses required for CWDM applications. In addition, our demonstrated OADM has a nearly constant group delay, which results in low dispersion in the passband.