Showing papers by "Philippe M. Fauchet published in 2009"
TL;DR: It is shown that the nonlinear polarization rotation induced by a pump pulse on a probe beam through cross-phase modulation inside a silicon waveguide and this phenomenon can be used to realize a fast Kerr shutter in spite of the free-carrier effects and walk-off.
Abstract: We study the nonlinear polarization rotation induced by a pump pulse on a probe beam through cross-phase modulation inside a silicon waveguide and show that this phenomenon can be used to realize a fast Kerr shutter in spite of the free-carrier effects and walk-off. We show that free carriers generated by the pump pulse through two-photon absorption affect the switching process considerably, especially with the interaction of walk-off effects. However, numerical simulations reveal that their impact is not detrimental for short pump pulses. In this case, an approximate analytical solution predicts the shape and duration of the switching window with reasonable accuracy.
51 citations
TL;DR: In this paper, multiple resonant cavities coupled to a single photonic crystal waveguide are used as a multi-channel sensor for detecting single particles in a double-channel structure.
Abstract: Photonic crystal (PhC) microcavities present multiple advantages for rapid, accurate, label-free, and sensitive detection. But their principle of operation (observation of a peak in transmission) makes their integration in serial arrays difficult. Here we report on multiple resonant cavities coupled to a single photonic crystal waveguide. The device configuration consists of a PhC waveguide with a defect line along which light is guided. Several resonant microcavities, created by modifying the radius of a hole adjacent to the defect line, are coupled to the waveguide. This PhC device, operating as a multi-channel sensor, maintains the advantages of the PhC microcavities and allows for serial arrays: Light is globally transmitted through the waveguide, except for the wavelengths corresponding to the resonant modes of the microcavities. The transmission spectrum shows as many dips as there are cavities. Simulations show that the sensitivity of such structures allows the detection of single particles -typically a virus. Preliminary results show the fabrication and characterization of a double-channel structure with small defects as a solvent sensor.
19 citations
TL;DR: In this article, a multi-channel sensor consisting of several resonant photonic crystal microcavities coupled to the same waveguide is presented for rapid and accurate label-free optical detection.
Abstract: Miniaturized and highly sensitive bio-sensors are attractive in various applications, such as medicine or food safety. Photonic crystal (PhC) microcavities present multiple advantages for rapid and accurate label-free optical detection. But their principle of operation (i.e. observation of a peak in transmission) makes their integration in serial arrays difficult. We present in this paper a multi-channel sensor consisting of several resonant PhC microcavities coupled to the same waveguide. The transmission spectrum shows as many dips as there are cavities, and each of the microcavities can act as an independent sensor. Preliminary results show the fabrication and characterization of a double-channel structure with small defects used as a solvent sensor.
6 citations
TL;DR: In this paper, a macroporous silicon diode that successfully operates in a photovoltaic mode of energy conversion is reported, which exhibits an extremely high internal surface area up to ∼6690 cm2/cm3.
Abstract: We report on the fabrication of a macroporous silicon diode that successfully operates in a photovoltaic mode of energy conversion. Typical device structures are fabricated on 4″, Cz grown, , p-type, 5 – 30 Ω-cm, Si substrates and make use of random or pre-patterned macroporous silicon films up to 100 μm thick with pores ∼1 μm in diameter and a center-to-center pore spacing of 2.5 μm. Phosphorous dopants are introduced throughout the porous silicon region with a newly adapted technique based on proximity rapid thermal diffusion. This development effort has enhanced the uniformity of dopant diffusion into the pores and subsequently improved device performance. The resulting p-n diode within the porous silicon is of a three-dimensional nature and exhibits an extremely high internal surface area up to ∼6690 cm2/cm3. To our knowledge, this is the first use of such a technique to fabricate conformal, three-dimensional p-n junctions for photovoltaic applications. The large internal surface area of this diode makes it applicable to next generation photovoltaics. Moreover, the porous silicon within this device is not simply an antireflection coating; rather it is a light trapping medium that has the ability to become a large surface area diode and can serve as a host matrix for photoactive compounds. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
6 citations
01 Jan 2009
TL;DR: In this article, the authors describe label-free optical biosensors consisting of PSi photonic bandgap structures and verify the sensitivity of these structures experimentally via the detection of a single monolayer of silane and glutaraldehyde.
Abstract: Because of its large internal surface area, porous silicon (PSi) is an attractive material for chemical and biological sensing applications. This chapter describes label-free optical biosensors consisting of PSi photonic bandgap structures. After a brief review of the material science and key properties of PSi, the design, fabrication, and sensitivity of various PSi photonic bandgap structures is discussed. The properties of one type of these structures, namely PSi microcavities, are discussed in detail. The sensitivity of these structures is then verified experimentally via the detection of a single monolayer of silane and glutaraldehyde. Examples of biosensing are then discussed. They include the detection of DNA segments, Gram negative bacteria, IgG, and pathogenic E. coli.
4 citations
02 Jun 2009
TL;DR: In this article, a conformal pn junction was proposed to reduce the switching energy of resonant devices to below 100 aJ, which is the minimum switching energy required for a resonant device.
Abstract: We show that a conformal pn junction can reduce the switching energy of resonant devices to below 100 aJ.
2 citations
TL;DR: In this article, a novel capacitive-type chemical sensor structure that uses recently discovered porous nanocrystalline silicon (pnc-Si) membranes covered with metal as the capacitor plates while a polymer layer sandwiched between them serves as the sensing layer for solvent vapor detection is discussed.
Abstract: Here we discuss a novel capacitive-type chemical sensor structure that uses recently discovered porous nanocrystalline silicon (pnc-Si) membranes [1] covered with metal as the capacitor plates while a polymer layer sandwiched between them serves as the sensing layer for solvent vapor detection. Pnc-Si is new ultrathin (15 nm) membrane material with pore sizes ranging from 5 to 50 nm and porosities from < 0.1 to 15 % that is fabricated using standard silicon semiconductor processing techniques. We present a study of pnc-Si membranes as a platform for such a sensor. The degree of swelling and the reversibility of the polymer/pnc-Si membrane system immersed in analyte-containing vapors are observed using optical and electrical techniques.
2 citations
17 Nov 2009
TL;DR: In this paper, a Kerr switch based on nonlinear polarization rotation induced by cross-phase modulation in a silicon strip waveguide was demonstrated and the potential of sub-picosecond switching was revealed.
Abstract: We experimentally demonstrate a Kerr switch based on nonlinear polarization rotation induced by cross-phase modulation in a silicon strip waveguide. Our numerical simulations agree with the experimental measurements and reveal the potential of sub-picosecond switching.
1 citations
TL;DR: In this paper, cross-phase modulation induced nonlinear polarization rotation was used to realize sub-picosecond Kerr switching in a silicon waveguide using only a few watts of pump peak power.
Abstract: We demonstrate that cross-phase modulation induced nonlinear polarization-rotation can be used to realize sub-picosecond Kerr switching in a silicon waveguide using only a few watts of pump peak power. Our experimental results agree with theory.
1 citations
TL;DR: SiMPore as mentioned in this paper is a new class of porous membrane that is unique in its combination of nanoscale thickness (<50 nm) with macroscopic, yet robust, millimeter-scale lateral dimensions and tunable pore size in the range of ˜5nm to ˜100nm.
Abstract: A new class of porous membrane has been fabricated that is unique in its combination of nanoscale thickness (<50 nm) with macroscopic, yet robust, millimeter-scale lateral dimensions and tunable pore size in the range of ˜5nm to ˜100nm. The membrane material is porous nanocrystalline Si (pnc-Si)1, and is being scaled-up to commercial volumes by a startup company, SiMPore, Inc. Standard commercial separation membranes with pores in this size regime are polymeric materials (poly ether sulphone, cellulose, etc.), microns in thickness, leading to pore morphologies that resemble long narrow tubes or tortuous-path 3-D matrices. As pnc-Si membrane thickness approaches the pore diameters, a simplified structure of holes in a thin sheet results, greatly enhancing both diffusive and forced flow transport through the membrane, as predicted by classical transport theories2. Pnc-Si has confirmed these theoretical predictions, demonstrating record-breaking transport rates, in addition to precise size-separation of nanoparticles, viruses, proteins, and nucleic acids. Applications for this highly precise silicon-based membrane range from highly efficient separations and purification of biomolecules, complexes, and nanoparticles, to substrates for microscopy to cell culture and co-culture. SiMPore is focused on navigating this application space with the goal of quickly introducing products that will allow the company to become self-sustaining and profitable though direct sales or partnerships with market leaders. Key product development drivers include potential competitive performance advantages and perceived value to a particular market, the IP landscape, development costs of the membrane and the device package/interface, and alignment with existing in-house capabilities.
02 Jun 2009
TL;DR: In this paper, multiple resonant cavities coupled to a single photonic crystal waveguide operating as a multi-channel sensor were investigated and good reproducibility was observed between the spectrum of double-channel devices and those of single cavities.
Abstract: We report on multiple resonant cavities coupled to a single photonic crystal waveguide operating as a multi-channel sensor. This device is characterized by as many dips in its transmission spectrum as there are cavities. Good reproducibility is observed between the spectrum of double-channel device and those of the single cavities. Infiltration of isopropanol in the holes leads to a red shift of the resonance wavelengths.
17 Nov 2009
TL;DR: In this paper, the authors investigated the scattering losses due to multiple interfaces in a multi-slot waveguide and showed the significant advantages of slot waveguide structures, including the very high photon confinement in the lower index material, which could make this structure ideal for a laser structures in which electrical pumping takes place in thin Si layers and light is emitted, after energy transfer, from Er atoms located in the thin SiO 2 layers.
Abstract: Ever since slot waveguide was first proposed [1][2], its unique photon confinement characteristic has attracted a lot of interest. Its applications in several areas such as silicon light emission device, nonlinear optical device, and optical bio detection have been proposed and experimentally verified [3][4][5]. Different merit functions for device design have also been proposed for some specific applications [6]. We have recently demonstrated the significant advantages of multi-slot waveguide structures, including the very high photon confinement in the lower index material [7], which could make this structure ideal for a laser structures in which electrical pumping takes place in thin Si layers and light is emitted, after energy transfer, from Er atoms located in the thin SiO 2 layers. However, scattering losses due to multiple interfaces has not yet been investigated. While low loss single-slot waveguides have been reported [8], no information on loss is available for multi-slot waveguide.
06 Nov 2009
TL;DR: In this article, a reversible donor species such as protons or fluorine was introduced for the selective formation of islands of crystalline silicon surrounded by porous silicon, which is reversible as the fluorine outdiffuses during higher temperature annealing.
Abstract: The oxidation of electrochemically etched porous silicon (PSi) has demonstrated success in the formation of device quality localized SOI for CMOS applications [1,2]. A primary advantage with a localized SOI formation is the ability to integrate novel device structures and optoelectronics (i.e. optical switches, waveguides) with bulk silicon CMOS. The formation of PSi can be done selectively by controlling the Fermi level in areas to be etched or not etched, which is typically done by adjusting the level of doping [1]. An alternative method is to introduce a reversible donor species such as protons [2] or fluorine (this work) for the selective formation of islands of crystalline silicon surrounded by porous silicon. Implanted fluorine in silicon has demonstrated a donor effect upon annealing at low temperature (600°C), which is reversible as the fluorine outdiffuses during higher temperature annealing (1000°C). Crystalline silicon islands that were fabricated with this technique have a thickness of about 300nm and are completely surrounded by oxidized porous silicon. Further study will investigate the device quality of the localized SOI structures for microelectronic and optoelectronic applications.