Presentations

    TiO2 as a material platform for all-optical logic, at Horizons of Nanophotonics and Nanoelectronics, Harvard University (Cambridge, MA), Monday, December 20, 2010:
    As the volume of internet traffic worldwide explodes and processing demands continually increase, solutions are required to overcome the inherent speed limitations of electronic devices. In particular, there is a need for all-optical devices, with their higher bandwidth and transmission rate, to replace various electronic functions such as routing data between processors and logic operations. We identified TiO2 as a promising yet unexplored material platform for ultrafast, on-chip nonlinear optical devices. TiO2 has a high nonlinear index of refraction (n2), enabling such operations as all-... Read more about TiO2 as a material platform for all-optical logic
    Impact of sputtering parameters on titanium dioxide thin films for nonlinear nanophotonics, at Photonics West 2011 (San Francisco, CA), Monday, January 24, 2011:
    We have identified titanium dioxide (TiO2) as a promising material for on-chip nonlinear optical devices. Its high refractive index and large intrinsic nonlinearity can strongly enhance confinement and non-linear interactions. In this study we optimize our deposition process to lower the linear losses in planar waveguides. We deposit titanium oxide thin films by RF reactive sputtering titanium onto oxidized silicon wafers in an argon/oxygen environment. The oxygen partial pressure in the chamber has a large impact on the deposition rate and the film composition. We investigate the composition... Read more about Impact of sputtering parameters on titanium dioxide thin films for nonlinear nanophotonics
    Effects of annealing on optical properties of TiO2 planar waveguides, at Photonics West 2011 (San Francisco, CA), Tuesday, January 25, 2011:
    Titanium dioxide possesses a high second order nonlinear index, making it a potential material for all-optical switching. In order to exploit these properties, TiO2 thin films with high refractive indices and low losses are required. We deposit TiO2 waveguides via RF reactive sputtering onto oxidized silicon substrates. We find that film characteristics vary greatly with deposition temperature, suggesting that they may also exhibit strong sensitivity to post-deposition annealing. We annealed TiO2 thin films at various temperatures in an oxygen environment using a tube furnace. The annealed... Read more about Effects of annealing on optical properties of TiO2 planar waveguides
    Thermally managed Z-scan measurements of titanium dioxide thin films, at Photonics West (San Francisco, CA), Thursday, January 27, 2011:
    We will present measurements of the complex nonlinear response of sputtered amorphous and polycrystalline titanium dioxide (TiO2) thin films using the thermally managed z-scan technique. Using a Ti:Sapphire laser with 100-fs pulses at 800 nm, we observe ultrafast electronic effects near TiO2's half band-gap. We explore the relation between material processing parameters and observed nonlinearity. In addition, we will discuss the consequences for applications such as all-optical switching.
    TiO2 nanophotonic waveguides for on-chip nonlinear optical devices, at Photonics West 2012 (San Francisco, CA), Monday, January 23, 2012:
    Titanium dioxide (TiO2) is a promising material for nonlinear photonic applications. Its large bandgap (> 3 eV) means it is highly transparent and has minimal two photon absorption over a wide wavelength range. TiO2’s high linear and nonlinear refractive indices (> 2 and 25 × that of silica at 800 nm, respectively) allow for high optical confinement in nanophotonic structures, such as waveguides, photonic crystals and resonators, and efficient nonlinear interactions. Thus, TiO2 is a potential platform for on-chip nonlinear optical devices operating across the three traditional... Read more about TiO2 nanophotonic waveguides for on-chip nonlinear optical devices
    Simultaneous multiphoton absorption in rutile (TiO2) across the half-bandgap, at Photonics West 2012 (San Francisco, CA), Thursday, January 26, 2012:
    Future optical systems require compact, ultra-fast devices capable of switching and logic across a wide range of wavelengths. To realize this goal, ultrafast nonlinearities must be exploited while maintaining manageable linear losses and nonlinear absorption. We present TiO2 as a nonlinear material to meet these needs. TiO2 is highly transparent for wavelengths > 400 nm and possesses both high linear and nonlinear refractive indices. We measurements the nonlinear index and multiphoton absorption in bulk TiO2 (rutile) using the z-scan technique near the half bandgap (800 nm). Using... Read more about Simultaneous multiphoton absorption in rutile (TiO2) across the half-bandgap
    Reinventing the light switch: logic with photons, at Physics Colloquium, University of Massachusetts, Lowell (Lowell, MA), Wednesday, April 25, 2012:
    Future computers and communications systems will require extremely fast logic operations that cannot be achieve efficiently using electronics. By using nonlinear optical materials with nano-scale structuring, we will show how to replace these “slow” electrons with photons to achieve logic operations on an ultrafast time scale.
    Nonlinear refraction in rutile TiO2, at SPIE Photonics West: Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications XIII (San Francisco, California), Tuesday, February 4, 2014
    Titanium dioxide (TiO2) has attractive optical properties for nonlinear optical applications ranging from telecommunication to interconnect wavelengths (800–1600 nm). TiO2 demonstrates large linear and nonlinear refractive indices, wide transparency from the infrared to as low as 400 nm wavelengths, and low two-photon absorption for wavelengths longer than 800 nm. We use the Z-scan technique to investigate the nonlinear refraction and multiphoton absorption of bulk rutile TiO2 for wavelengths ranging from 800–1600 nm. Using our results, we calculate nonlinear figures of merit and discuss... Read more about Nonlinear refraction in rutile TiO2
    Zero-index nanophotonics, nonlinear optics, and quantum entanglement, at Nano-optics: Principles enabling basic research and applications, Centro Ettore Majorana (Erice), Saturday, July 22, 2017
    In these interactive lectures we explore how light can be manipulated at the nanoscale. We begin by describing optical propagation in ordinary materials and then show how materials can be engineered to achieve a refractive index of zero. These zero-index materials have remarkable properties and can be integrated in photonic circuits. We also give an introduction to nonlinear optics and discuss how zero-index materials can be used to accomplish phase matching in nonlinear optics and to obtain longer coherence times and lengths among entangled emitters or qubits.

    Outline

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    Low-loss TiO2 planar waveguides for nanophotonic applications, at IEEE Photonics Society Annual Meeting, IEEE Photonics Society (Denver, CO), Tuesday, November 9, 2010:
    We deposit TiO2 planar waveguides on oxidized silicon substrates by reactive sputtering. The films exhibit Raman spectra consistent with an amorphous or anatase phase and have losses as low as 0.4 dB/cm at 826 nm.
    Manipulating light at the nanoscale (Lectures 1 and 2), at Nano-optics: Principles enabling basic research and applications, Centro Ettore Majorana (Erice), Wednesday, July 8, 2015:
    In these interactive lectures we explore how light can be manipulated at the nanoscale. We begin by describing optical propagation in ordinary materials and then show how materials can be engineered to achieve a refractive index of zero. These zero-index materials have remarkable properties and can be integrated in photonic circuits. We also give an introduction to nonlinear optics and discuss how zero-index materials can be used to accomplish phase matching in nonlinear optics.

    Outline

     

    • Optical properties of materials
    • Dispersion of...
    Read more about Manipulating light at the nanoscale (Lectures 1 and 2)
    Manipulating light at the nanoscale (Lectures 3–5), at Nano-optics: Principles enabling basic research and applications, Centro Ettore Majorana (Erice), Thursday, July 9, 2015:
    In these interactive lectures we explore how light can be manipulated at the nanoscale. We begin by describing optical propagation in ordinary materials and then show how materials can be engineered to achieve a refractive index of zero. These zero-index materials have remarkable properties and can be integrated in photonic circuits. We also give an introduction to nonlinear optics and discuss how zero-index materials can be used to accomplish phase matching in nonlinear optics.

    Outline

     

    • Optical properties of materials
    • Dispersion of...
    Read more about Manipulating light at the nanoscale (Lectures 3–5)
    Maximizing intensity in TiO2 waveguides for nonlinear optics, at Photonics West (San Francisco, California), Wednesday, February 6, 2013:
    Titanium dioxide (TiO2) represents an attractive candidate for nonlinear optical devices due its high transparency, large refractive index, and large Kerr nonlinearity. Using electron beam lithography and a liftoff procedure, we can structure both amorphous TiO2 as well as polycrystalline anatase thin films to create photonic devices that exploit the material’s properties in order to do nonlinear optics. Nonlinear optics benefit from long interactions, necessitating large intensities along long waveguide lengths. For this reason, waveguide losses need to be minimized. We study the effects... Read more about Maximizing intensity in TiO2 waveguides for nonlinear optics
    Nonlinear Nanophotonics, at 12th International Conference on Near-field Optics, Nanophotonics and related Techniques (Donostia - San Sebastian, Spain), Sunday, September 2, 2012:
    We discuss the propagation of laser pulses in materials, the basics of nonlinear optical interactions, wave guiding and propagation of modes, fabrication of nanophotonic devices and the use of nonlinear optics at the nanoscale to fabricate optical logic gates.
    Optimizing Anatase-TiO2 Deposition for Low-loss Waveguides, at Photonics West (San Francisco, CA), Tuesday, February 5, 2013:
    Polycrystalline anatase-TiO2 thin film possesses desirable properties for on-chip photonic devices that can be used for optic computing, communication, and sensing. Low-loss anatase-TiO2 thin films are necessary for fabricating high quality optical devices. We studied anatase-TiO2 by reactively sputtering titanium metal in an oxygen environment and annealing. By correlating key deposition parameters, including oxygen flow rate, deposition pressure, RF power, and temperature to film morphology and planar waveguiding losses, we aim to understand the dominant source of propagation losses in TiO2... Read more about Optimizing Anatase-TiO2 Deposition for Low-loss Waveguides

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