Nanofluidic tuning of photonic crystal circuits

Abstract

By integrating soft-lithography-based nanofluidics with silicon nanophotonics, we demonstrate dynamic, liquid-based addressing and high ⌬n / n͑ϳ0.1͒ refractive index modulation of individual features within photonic structures at subwavelength length scales. We show ultracompact tunable spectral filtering through nanofluidic targeting of a single row of holes within a planar photonic crystal. We accomplished this with an optofluidic integration architecture comprising a nanophotonic layer, a nanofluidic delivery structure, and a microfluidic control engine. Variants of this technique could enable dynamic reconfiguration of photonic circuits, selective introduction of optical nonlinearities, or delivery of single molecules into resonant cavities for biodetection.

Enhancement of Refractive Index Sensitivity in Photonic Crystal Waveguide-Based Sensors by Selective Infiltration

“…Such a structure can be used as a sensor, whose principle of operation is based on the cut-o wavelength shift caused by the in ltration of the holes. In ltration can be performed by various selective in ltration techniques, which have been experimentally demonstrated, such as using an integrated micro uidic circuit [24], an actuated microtip [25] or micropipette [26] with a high precision and good reproducibility.…”

Silicon photonic crystal nanostructures for refractive index sensing

“…Other groups used evanescent coupling from ridge waveguides ͑WGs͒ to a silicon PhC nanocavity in a serial geometry, achieving sensitivities of ⌬n / n = 0.002. 9,10 Sensors based on measuring the transmission properties of PhC-WGs were investigated by Erickson et al 11 and Skivesen et al 12 Cunningham et al 13 utilized an alternative approach based on detecting the RI from a two-dimensional Bragg grating. However, as for SPR and interferometric methods this approach is nonlocal and requires a large analyte volume.…”

Microfluidic photonic crystal double heterostructures

“…8 However, the nanometer-scale precision required to realize sophisticated and optimized geometries eventually becomes a limiting factor in achieving high-Q cavities, as pointed out by Asano et al 9 Recently, several groups have reported demonstrations of postprocessed PCS structures, granting them the flexibility to tune or reconfigure device properties to suit various applications at any time after the PCS is fabricated. [10][11][12][13] In particular, Intonti et al introduced a "pixel by pixel" approach for writing and rewriting PCS defect structures via fluid infiltration. 12 Theoretical results of Tomljenovic-Hanic et al showed that high Q-factor cavities could be achieved in PCSs from fluid infiltration 14 by forming doubleheterostructured geometries, providing an integrated optofluidic sensing architecture.…”