Low-loss optical channel drop filters based on high-contrast Si–air photonic crystals by wet anisotropic etching

On the performance of label-free biosensors based on vertical one-dimensional photonic crystal resonant cavities

“…The resonant cavity of Fig. 1(a) is representative of 1DPhC FP resonant cavities that have been reported in the literature so far [17,20]. Fig.…”

“…They inherently feature independent fluidic (through the air-gaps) and optical (perpendicularly to the air-gaps) paths that enable the realization of integrated "flow-through" biosensors with higher sensitivity and lower limit of detection with respect to standard "flow-over" approaches, on the one hand, as well as the integration of biosensors together with on-chip microfluidic and optical networks for the realization of miniaturized biosensing platforms, on the other hand [16]. Fabry-Perot (FP) resonant cavities obtained by breaking the periodicity of vertical silicon/air 1DPhCs with a half-wave defect have been also successfully reported for tunable filter fabrication [17][18][19], though their use for sensing applications has been limited to refractometry [20].…”

Vertical One-Dimensional Photonic Crystal Platforms for Label-Free (Bio)Sensing: Towards Drop-and-Measure Applications

“…This enables the integration of both fluidic and optical paths on the same chip as the PhC structure and envisages, in turn, the effective possibility of developing 1D PhC platforms with on-chip fluidic and optical networks. Several cases of 1D PhC platforms making use of vertical 1D PhCs fabricated by dry etching technology, namely deep reactive ion etching, or wet etching technology, namely chemical etching, have been reported for optical applications [7][8][9]. A few examples have also been reported for sensing applications [10][11][12].…”

An all-silicon optical platform based on linear array of vertical high-aspect-ratio silicon/air photonic crystals

“…together with vertical PhC-based blocks has been reported, allowing coupling/positioning/alignment of optical fibers with PhCs to be easily and safely performed. [15][16][17][18][19] Most of these works deal with silicon-on-insulator (SOI) wafers, for which the limited thickness of the top silicon layer reduces the etching depth and, in turn, the microstructure height to tens of microns. 18,19 The use of standard and cheaper bulk silicon wafers that allow, at least in principle, etching depth of hundreds microns, therefore compatible to the diameter of standard optical fibers, to be achieved has been overlooked so far, mainly because of technological constraints of state-of-theart HAR etching technologies.…”

“…[15][16][17] Renilkumar and Nair proposed an interesting approach based on wet anisotropic etching, specifically Potassium Hydroxide (KOH), of (110)-oriented silicon wafers to fabricate vertical silicon/air 1D-PhCs-based Fabry-Perot filters together with U-grooves for optical fiber. 15 Chen et al demonstrated the feasibility of a fiber-groove photonic crystal integrated system in which vertical silicon/air 1D-PhCs are etched by high-density chloridebased plasma process on a silicon substrate after preliminary fabrication of macroscopic fiber grooves by standard dry reactive ion etching (DRIE) process. 16 Hosomi et al integrated vertical silicon/air 1D-PhCs by using cryogenic plasma etching on (100)-silicon substrate together with both input and output V-grooves, these latter obtained by wet anisotropic etching before PhC fabrication.…”