Integrated optofluidic microsystem based on vertical high-order one-dimensional silicon photonic crystals

In this work, fabrication and testing of an optofluidic microsystem exploiting high aspect-ratio, vertical, silicon/air one-dimensional (1D) photonic crystals (PhC) are reported. The microsystem is composed of an electrochemically micromachined silicon substrate integrating a 1D PhC featuring high-order bandgaps in the near-infrared region, bonded to a glass cover provided with inlet/outlet holes for liquid injection/extraction in/out the PhC-itself. Wavelength shifts of the reflectivity spectrum of the photonic crystal, in the range 1.0–1.7 μm, induced by flow of different liquids through the PhC air gaps are successfully measured using an in-plane all-fibre setup, thanks to the PhC high aspect-ratio value. Experimental results well agree with theoretical predictions and highlight the good linearity and high sensitivity of such an optofluidic microsystem in measuring refractive index changes. The sensitivity value is estimated to be 1,049 nm/RIU around 1.55 μm, which is among the highest reported in the literature for integrated refractive index sensors, and explained in terms of enhanced interaction between light and liquid within the PhC.

[1]  Seung-Man Yang,et al.  Holographic fabrication of photonic nanostructures for optofluidic integration. , 2008, Lab on a chip.

[2]  Jean-Michel Lourtioz,et al.  Fabrication of 2-D and 3-D silicon photonic crystals by deep etching , 2002 .

[3]  V. Lehmann.  The Physics of Macropore Formation in Low Doped n‐Type Silicon , 1993 .

[4]  S. Merlo,et al.  Optical Quality-Assessment of High-Order One-Dimensional Silicon Photonic Crystals With a Reflectivity Notch at $\lambda \sim 1.55\ \mu\hbox{m}$ , 2010, IEEE Photonics Journal.

[5]  Two-dimensional infrared photonic crystal based on macroporous silicon , 1996 .

[6]  Benjamin J. Eggleton,et al.  Reconfigurable photonic crystal circuits , 2010 .

[7]  A. Lipson,et al.  A 1-D Photonic Band Gap Tunable Optical Filter in (110) Silicon , 2007, Journal of Microelectromechanical Systems.

[8]  M. Kubota,et al.  Free-Space Tunable and Drop Optical Filters Using Vertical Bragg Mirrors on Silicon , 2006, IEEE Journal of Selected Topics in Quantum Electronics.

[9]  S. Merlo,et al.  Optical characterization of alcohol-infiltrated one-dimensional silicon photonic crystals. , 2009, Optics letters.

[10]  Vladimir A. Tolmachev,et al.  One-dimensional photonic crystal obtained by vertical anisotropic etching of silicon , 2002 .

[11]  H. Föll,et al.  Formation Mechanism and Properties of Electrochemically Etched Trenches in n‐Type Silicon , 1990 .

[12]  Giuseppe Barillaro,et al.  Dimensional Constraints on High Aspect Ratio Silicon Microstructures Fabricated by HF Photoelectrochemical Etching , 2002 .

[13]  Christelle Monat,et al.  Integrated optofluidics: A new river of light , 2007 .

[14]  Silicon micromachined periodic structures for optical applications at λ=1.55μm , 2006 .

[15]  S. Merlo,et al.  Optical Quality-Assessment of High-Order One-Dimensional Silicon Photonic Crystals With a Reflectivity Notch at ! ! 1 : 55 " m , 2010 .

[16]  Bandgap Tuning of Silicon Micromachined 1-D Photonic Crystals by Thermal Oxidation , 2008, IEEE Journal of Selected Topics in Quantum Electronics.

[17]  Kazuaki Sakoda,et al.  Optical Properties of Photonic Crystals , 2001 .

[18]  Annette Grot,et al.  Ultra compact biochemical sensor built with two dimensional photonic crystal microcavity , 2004 .

[19]  N A Mortensen,et al.  Photonic crystal resonator integrated in a microfluidic system. , 2008, Optics letters.

[20]  B. J. Eggleton,et al.  Optofluidics: a novel generation of reconfigurable and adaptive compact architectures , 2008 .

[21]  David Erickson,et al.  A multiplexed optofluidic biomolecular sensor for low mass detection. , 2009, Lab on a chip.

[22]  Bandgap Tuning of Silicon Micromachined , 2008 .

[23]  S. Merlo,et al.  Optical Characterization of High-Order 1-D Silicon Photonic Crystals , 2009, IEEE Journal of Selected Topics in Quantum Electronics.

[24]  Xudong Fan,et al.  On the performance quantification of resonant refractive index sensors. , 2008, Optics express.

[25]  Jörg P Kutter,et al.  Optical detection in microfluidic systems , 2009, Electrophoresis.

[26]  G. Barillaro,et al.  Electrochemical etching in HF solution for silicon micromachining , 2002 .