Romain Blanchard

Publications (22) View all

• Article: Vanadium dioxide as a natural disordered metamaterial: perfect thermal emission and large broadband negative differential thermal emittance

  Mikhail A. Kats, Romain Blanchard, Shuyan Zhang, Patrice Genevet, Changhyun Ko, Shriram Ramanathan, Federico Capasso
  [show abstract] [hide abstract]
  ABSTRACT: We experimentally demonstrate that a thin (~150 nm) film of vanadium dioxide (VO2) deposited on sapphire has an anomalous thermal emittance profile when heated, which arises due to the optical interaction between the film and the substrate when the VO2 is at an intermediate state of its insulator-metal transition (IMT). Within the IMT region, the VO2 film comprises nanoscale islands of metal- and dielectric-phase, and can thus be viewed as a natural, disordered metamaterial. This structure displays "perfect" blackbody-like thermal emissivity over a narrow wavelength range (~40 cm-1), surpassing the emissivity of our black soot reference. We observed large broadband negative differential thermal emittance over a >10 {\deg}C range: upon heating, the VO2/sapphire structure emitted less thermal radiation and appeared colder on an infrared camera. We anticipate that emissivity engineering with thin film geometries comprising VO2 will find applications in infrared camouflage, thermal regulation, infrared tagging and labeling.
  04/2013;
• Source

  Available from: Patrice Genevet

  Article: Generation of two-dimensional plasmonic bottle beams

  Patrice Genevet, Jean Dellinger, Romain Blanchard, Alan She, Marlene Petit, Benoit Cluzel, Mikhail A. Kats, Frederique de Fornel, Federico Capasso
  [show abstract] [hide abstract]
  ABSTRACT: By analogy to the three dimensional optical bottle beam, we introduce the plasmonic bottle beam: a two dimensional surface wave which features a lattice of plasmonic bottles, i.e. alternating regions of bright focii surrounded by low intensities. The two-dimensional bottle beam is created by the interference of a non-diffracting beam, a cosine-Gaussian beam, and a plane wave, thus giving rise to a non-diffracting complex intensity distribution. By controlling the propagation constant of the cosine- Gauss beam, the size and number of plasmonic bottles can be engineered. The two dimensional lattice of hot spots formed by this new plasmonic wave could have applications in plasmonic trapping.
  Optics Express 04/2013; 21(8):10295-10300. · 3.59 Impact Factor
• Article: External ring-cavity quantum cascade lasers

  Pietro Malara, Romain Blanchard, Tobias S. Mansuripur, Aleksander K. Wojcik, Alexey Belyanin, Kazuue Fujita, Tadataka Edamura, Shinichi Furuta, Masamichi Yamanishi, Paolo de Natale, Federico Capasso
  [show abstract] [hide abstract]
  ABSTRACT: An external ring-cavity quantum cascade laser (QCL) is demonstrated. Gain competition between the clockwise and anticlockwise ring-cavity modes results in a transition from bidirectional to directional emission as current is increased. In the directional regime, spatial hole burning (SHB) is suppressed, and the spectrum evolves to a single longitudinal mode, in contrast with the multimode spectrum of a comparable Fabry-Pérot QCL. The absence of SHB and the long path-length of the external cavity make this laser an excellent candidate for active mode-locking and high-sensitivity spectroscopic applications in the mid-infrared. A proof-of-principle intracavity absorption spectroscopic detection of water vapor is demonstrated.
  Applied Physics Letters 04/2013; 102(14):141105. · 3.84 Impact Factor
• Source

  Available from: Romain Blanchard

  Article: High-brightness tapered quantum cascade lasers

  Burc Gokden, Tobias S. Mansuripur, Romain Blanchard, Christine Wang, Anish Goyal, Antonio Sanchez-Rubio, George Turner, Federico Capasso
  [show abstract] [hide abstract]
  ABSTRACT: An index-guided tapered quantum cascade laser emitting near 9.5 μm with sloped sidewalls and no anti-reflection coating is presented, and the performance for devices with taper half-angles of 1° and 2° is investigated. The 1° device delivers up to 2.5 W of peak optical power at room temperature with beam quality-factor M2 = 2.08, while the two-degree device outputs 3.8 W with M2 = 2.25 for a maximum brightness of 1.87 MW cm−2 sr−1.
  Applied Physics Letters 02/2013; 102(5):053503. · 3.84 Impact Factor
• Source

  Available from: Romain Blanchard

  Article: Thermal tuning of mid-infrared plasmonic antenna arrays using a phase change material.

  Mikhail A Kats, Romain Blanchard, Patrice Genevet, Zheng Yang, M Mumtaz Qazilbash, D N Basov, Shriram Ramanathan, Federico Capasso
  [show abstract] [hide abstract]
  ABSTRACT: We demonstrate that the resonances of infrared plasmonic antennas can be tuned or switched on/off by taking advantage of the thermally driven insulator-to-metal phase transition in vanadium dioxide (VO₂). Y-shaped antennas were fabricated on a 180 nm film of VO₂ deposited on a sapphire substrate, and their resonances were shown to depend on the temperature of the VO₂ film in proximity of its phase transition, in good agreement with full-wave simulations. We achieved tunability of the resonance wavelength of approximately 10% (>1 μm at λ∼10 μm).
  Optics Letters 02/2013; 38(3):368-70. · 3.40 Impact Factor