Laser & Photonics Reviews

Cover image for Vol. 7 Issue 6

November 2013

Volume 7, Issue 6

Pages i–ii, A47–A60, 839–1092, L67–L97

  1. Front Cover

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. You have free access to this content
      Front Cover: Chiral nanoemitter array: A launchpad for optical vortices (Laser Photonics Rev. 7(6)/2013)

      Version of Record online: 6 NOV 2013 | DOI: 10.1002/lpor.201370060

      Thumbnail image of graphical abstract

      Optical vortex light has a characteristic rotating phase, usually produced by passing a laser beam through suitable optical elements. The fluorescent emission produced by the electronic decay of excitonic states in amolecular array now offers ameans of directly emitting light with the sought vortex phase and axial singularity.

      (Picture:M.M. Coles et al. 10.1002/lpor.201300117, pp. 1087–1092, in this issue)

  2. Inside Front Cover

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. You have free access to this content
      Inside Front Cover: LED pumped polymer laser sensor for explosives (Laser Photonics Rev. 7(6)/2013)

      Version of Record online: 6 NOV 2013 | DOI: 10.1002/lpor.201370061

      Thumbnail image of graphical abstract

      Schematic drawing of an organic semiconductor laser sensor for explosive vapors. The divergent incoherent light from an InGaN lightemitting diode is converted into a coherent, directional laser beam by a nanostructured polymer laser. This compact and low-cost laser can be used to detect few-parts-per-billion concentrations of nitroaromatic explosivemolecules, exploiting a photophysical interaction between the gainmedium and surrounding vapor.

      (Picture: YueWang et al.10.1002/lpor.201300072, pp. L71–L76, in this issue)

  3. Inside Back Cover

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. You have free access to this content
      Inside Back Cover: Topological insulator as an optical modulator for pulsed solid-state lasers (Laser Photonics Rev. 7(6)/2013)

      Version of Record online: 6 NOV 2013 | DOI: 10.1002/lpor.201370062

      Thumbnail image of graphical abstract

      Topological insulators, such as Bi2Se3 have single Dirac cones on the surfaces and narrow band gaps in the bulk. Their optical absorption becomes saturated under strong excitation. Taking advantage of the saturable absorption and narrow band gap, the topological insulator can modulate the operation of a bulk solid-state laser as a pulse modulator.

      (Picture: H. Yu et al.10.1002/lpor.201300084, pp. L77–L83, in this issue)

  4. Back Cover

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. You have free access to this content
      Back Cover: Photonic-on-a-chip: a thermal actuated Mach-Zehnder interferometer and a molecular thermometer based on a single di-ureasil organic-inorganic hybrid (Laser Photonics Rev. 7(6)/2013)

      Version of Record online: 6 NOV 2013 | DOI: 10.1002/lpor.201370063

      Thumbnail image of graphical abstract

      An integrated photonic-on-a-chip device based on a single organic-inorganic di-ureasil hybrid was fabricated for optical waveguide and temperature sensing. The device, formed by a thermal-actuated Mach-Zehnder interferometer (switching power of 0.011 W) and amolecular thermometer (temperature uncertainty of 0.1ºC and spatial resolution of 13 µm), can be applied to sense temperature gradients with high resolution (10−3 ºC·µm−1).

      (Picture: R.A.S. Ferreira et al.10.1002/lpor.201300080, pp. 1027–1034, in this issue)

  5. Issue Information

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. You have free access to this content
  6. Call for Papers

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. You have free access to this content
  7. Editorial Advisory Board

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. You have free access to this content
  8. Contents

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. You have free access to this content
  9. Erratum: Photonic crystal boosted chemiluminescence reaction

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. [Laser Photonics Rev. 7, No. 4, L39–L43, (2013)]

      You have free access to this content
      Photonic crystal boosted chemiluminescence reaction : [Laser Photonics Rev. 7, No. 4, L39–L43, (2013)] (page A62)

      Xiaodi Shi, Mingzhu Li, Changqing Ye, Weizhi Shen, Yongqiang Wen, Linfeng Chen, Qiang Yang, Lei Shi, Lei Jiang and Yanlin Song

      Version of Record online: 1 OCT 2013 | DOI: 10.1002/lpor.201380031

      This article corrects:

      Photonic crystal boosted chemiluminescence reaction

      Vol. 7, Issue 4, L39–L43, Version of Record online: 29 MAY 2013

  10. Editorial

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. You have free access to this content
  11. Review Articles

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. Editor's Choice

      Advanced optical trapping by complex beam shaping (pages 839–854)

      Mike Woerdemann, Christina Alpmann, Michael Esseling and Cornelia Denz

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/lpor.201200058

      Thumbnail image of graphical abstract

      Optical tweezers, a simple and robust implementation of optical micromanipulation technologies, have become a standard tool in biological, medical and physics research laboratories. Recently, with the utilization of holographic beam shaping techniques, more sophisticated trapping configurations have been realized to overcome current challenges in applications. Holographically generated higher-order light modes, for example, can induce highly structured and ordered three-dimensional optical potential landscapes with promising applications in optically guided assembly, transfer of orbital angular momentum, or acceleration of particles along defined trajectories. The non-diffracting property of particular light modes enables the optical manipulation in multiple planes or the creation of axially extended particle structures. Alongside with these concepts which rely on direct interaction of the light field with particles, two promising adjacent approaches tackle fundamental limitations by utilizing non-optical forces which are, however, induced by optical light fields. Optoelectronic tweezers take advantage of dielectrophoretic forces for adaptive and flexible, massively parallel trapping. Photophoretic trapping makes use of thermal forces and by this means is perfectly suited for trapping absorbing particles. Hence the possibility to tailor light fields holographically, combined with the complementary dielectrophoretic and photophoretic trapping provides a holistic approach to the majority of optical micromanipulation scenarios.

    2. Nanowire plasmonic waveguides, circuits and devices (pages 855–881)

      Xin Guo, Yaoguang Ma, Yipei Wang and Limin Tong

      Version of Record online: 11 JAN 2013 | DOI: 10.1002/lpor.201200067

      Thumbnail image of graphical abstract

      As typical one-dimensional nanostructures for waveguiding tightly confined optical fields beyond the diffraction limit, metal nanowires have been using as versatile nanoscale building blocks for functional plasmonic and photonic structures and devices. Metal nanowires, especially those fabricated by bottom-up synthesis such as Ag and Au nanowires, usually exhibit excellent diameter uniformity and surface smoothness with diameters down to tens of nanometers, which offers great opportunities for plasmonic waveguiding of optical fields with deep-subwavelength confinement, coherence maintenance and low scattering losses. Based on nanowire plasmonic waveguides, a variety of applications ranging from plasmonic couplers, interferometers, resonators to photon emitters have been reported in recent years. In this article, significant progresses in these nanowire plasmonic waveguides, circuits and devices are reviewed. Future outlook and challenges are also discussed.

    3. Coupled magnetic resonator optical waveguides (pages 882–900)

      Hui Liu and Shining Zhu

      Version of Record online: 5 MAR 2013 | DOI: 10.1002/lpor.201200069

      Thumbnail image of graphical abstract

      Optical resonators are important devices that control the properties of light and manipulate light–matter interaction. Various optical resonators are designed and fabricated using different techniques. For example, in coupled resonator optical waveguides, light energy is transported to other resonators through near-field coupling. In recent years, magnetic optical resonators based on LC resonance have been realized in several metallic microstructures. Such devices possess stronger local resonance and lower radiation loss compared with electric optical resonators. This study provides an overall introduction on the latest progress in coupled magnetic resonator optical waveguide (CMROW). Various waveguides composed of different magnetic resonators are presented and Lagrangian formalism is used to describe the CMROW. Moreover, several interesting properties of CMROWs, such as abnormal dispersions and slow-light effects, are discussed and CMROW applications in nonlinear and quantum optics are shown. Future novel nanophotonic devices can be developed using CMROWs.

    4. Silver nanowires for photonics applications (pages 901–919)

      Xiao Xiong, Chang-Ling Zou, Xi-Feng Ren, Ai-Ping Liu, Yan-Xia Ye, Fang-Wen Sun and Guang-Can Guo

      Version of Record online: 15 JAN 2013 | DOI: 10.1002/lpor.201200076

      Thumbnail image of graphical abstract

      Although silver nanowires as plasmonic components have been investigated extensively in both theoretical and experimental studies, a systematic study is still lacking. In this work, a review is given to explain some basic features of experimentally prepared nanowires and their optical properties in different situations, such as waveguides, resonators, and antennas. The review also lists several possible applications of nanowires for enhanced light-emitting, photonic device fabrication, sensors, lasers, and nonlinear optics. Combined with the merits of both nanowires and surface plasmon polaritons, silver nanowires are certain to show their potential in photonics in the near future.

    5. Recent advances in monoclinic crystal optics (pages 920–937)

      Yannick Petit, Simon Joly, Patricia Segonds and Benoît Boulanger

      Version of Record online: 25 JAN 2013 | DOI: 10.1002/lpor.201200078

      Thumbnail image of graphical abstract

      This article is mainly devoted to the modeling and measurement of the absorption and fluorescence angular distributions in polarized light of monoclinic crystals. Up to now theoretical crystal optics were mostly devoted to crystals having a high crystallographic symmetry. In these crystals belonging to the cubic, hexagonal, tetragonal, trigonal or orthorhombic lattice classes, the tensor properties related to the real part of the dielectric permittivity and to its imaginary part can be described in the same frame which orientation does not vary as a function of wavelength. The situation is much more complicated in the case of monoclinic crystals because it is necessary to define a specific frame for each property and each wavelength that are considered. The main features of monoclinic crystal optics are described in detail, followed by a review of monoclinic materials and the consequence of these features on their related optical properties.

    6. You have full text access to this OnlineOpen article
      Dielectric-loaded plasmonic waveguide components: Going practical (pages 938–951)

      Ashwani Kumar, Jacek Gosciniak, Valentyn S. Volkov, Sotirios Papaioannou, Dimitrios Kalavrouziotis, Konstantinos Vyrsokinos, Jean-Claude Weeber, Karim Hassan, Laurent Markey, Alain Dereux, Tolga Tekin, Michael Waldow, Dimitrios Apostolopoulos, Hercules Avramopoulos, Nikos Pleros and Sergey I. Bozhevolnyi

      Version of Record online: 25 FEB 2013 | DOI: 10.1002/lpor.201200113

      Thumbnail image of graphical abstract

      Surface plasmon propagating modes supported by metal/dielectric interfaces in various configurations can be used for radiation guiding similarly to conventional dielectric waveguides. Plasmonic waveguides offer two attractive features: subdiffraction mode confinement and the presence of conducting elements at the mode-field maximum. The first feature can be exploited to realize ultrahigh density of nanophotonics components, whereas the second feature enables the development of dynamic components controlling the plasmon propagation with ultralow signals, minimizing heat dissipation in switching elements. While the first feature is yet to be brought close to the domain of practical applications because of high propagation losses, the second one is already being investigated for bringing down power requirements in optical communication systems. In this review, the latest application-oriented research on radiation modulation and routing using thermo-optic dielectric-loaded plasmonic waveguide components integrated with silicon-based photonic waveguides is overviewed. Their employment under conditions of real telecommunications is addressed, highlighting challenges and perspectives.

  12. Original Papers

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. Ultrafast nanoporous silica formation driven by femtosecond laser irradiation (pages 953–962)

      Matthieu Lancry, Bertrand Poumellec, John Canning, Kevin Cook, Jean-Claude Poulin and Francois Brisset

      Version of Record online: 26 JUL 2013 | DOI: 10.1002/lpor.201300043

      Thumbnail image of graphical abstract

      A type of glass modifications occurring after femto-second laser irradiation gives rise to strong (10−2). This form birefringence is thought to be related to index nanostructure (called nanogratings). Analyzing induced tracks in fused silica using scanning electron microscopy (SEM) with nm resolution shows that nanostructures are porous nanoplanes with an average index lower than typical silica (Δn ∼ –0.20). Their origin is explained as arising from fast decomposition of the glass under localized, high-intensity femtosecond laser radiation where strong nonlinear, multiphoton-induced photoionization leads to plasma generation. Mechanistic details include Coulombic explosions characteristic of strong photoionization and the production of self-trapped exciton (STE). Rapid relaxation of these STE prevents recombination and dissociated atomic oxygen instead recombines with each other to form molecular oxygen pointed out using Raman microscopy. Some of it is dissolved in the condensed glass whilst the rest is trapped within nanovoids. A chemical recombination can only occur at 1200 °C for many hours. This explains the thermal stability of such a nanostructure. Precise laser translation and control of these birefringent nanoporous structures allo arbitrarily tuning and positioning within the glass, an important tool for controlling optical properties for photonic applications, catalysts, molecular sieves, composites and more.

    2. Editor's Choice

      Comparison between blue lasers and light-emitting diodes for future solid-state lighting (pages 963–993)

      Jonathan J. Wierer Jr., Jeffrey Y. Tsao and Dmitry S. Sizov

      Version of Record online: 1 AUG 2013 | DOI: 10.1002/lpor.201300048

      Thumbnail image of graphical abstract

      Solid-state lighting (SSL) is now the most efficient source of high color quality white light ever created. Nevertheless, the blue InGaN light-emitting diodes (LEDs) that are the light engine of SSL still have significant performance limitations. Foremost among these is the decrease in efficiency at high input current densities widely known as “efficiency droop.” Efficiency droop limits input power densities, contrary to the desire to produce more photons per unit LED chip area and to make SSL more affordable. Pending a solution to efficiency droop, an alternative device could be a blue laser diode (LD). LDs, operated in stimulated emission, can have high efficiencies at much higher input power densities than LEDs can. In this article, LEDs and LDs for future SSL are explored by comparing: their current state-of-the-art input-power-density-dependent power-conversion efficiencies; potential improvements both in their peak power-conversion efficiencies and in the input power densities at which those efficiencies peak; and their economics for practical SSL.

    3. Novel low-loss waveguide delay lines using Vernier ring resonators for on-chip multi-λ microwave photonic signal processors (pages 994–1002)

      Leimeng Zhuang, Marcel Hoekman, Willem Beeker, Arne Leinse, René Heideman, Paulus van Dijk and Chris Roeloffzen

      Version of Record online: 26 JUL 2013 | DOI: 10.1002/lpor.201300053

      Thumbnail image of graphical abstract

      In this paper, novel photonic delay lines (DLs) using Vernier/non-identical ring resonators (VRRs) are proposed and demonstrated, which are capable of simultaneous generation of multiple different delays at different wavelengths (frequencies). The simple device architectures and full reconfigurability allow the DLs to be integrated with other functional building blocks in photonic integrated circuits to realize on-chip, complex multi-λ microwave photonic signal processors with reduced system complexity. To prove the concept, DLs using VRRs in cascaded and coupled configurations have been fabricated in TriPleXTM waveguide technology, which enables a very low delay-induced loss of approximately 0.18 dB/100 ps. The fabricated DLs demonstrated simultaneous generation of four incremental delays, where a maximum incremental step of 550 ps and a corresponding top delay of 1650 ps were measured for a bandwidth up to 1 GHz. To our knowledge, this is the first report on VRRs for delay generation functionalities.

    4. Focusing surface plasmon polariton wave packets in space and time (pages 1003–1009)

      Lei-Ming Wang and Hrvoje Petek

      Version of Record online: 24 SEP 2013 | DOI: 10.1002/lpor.201300059

      Thumbnail image of graphical abstract

      The spatiotemporal focusing of surface plasmon polariton (SPP) wave packets (WPs) by planar plasmonic-lens coupling structures is described using combined femtosecond interferometric time-resolved photoemission electron microscopy (ITR-PEEM) imaging and model simulations. The focusing properties of lens structures inscribed lithographically into Ag films depend on the angle of incidence of the excitation field. Severe aberrations are introduced by the phase delay in the interaction of obliquely incident plane waves with the commonly employed circular arc-shaped lens structures. It is shown that the aberration can be corrected by accounting for propagation delays caused by the incidence angle-dependent retardation of the optical field-lens structure interaction. The focusing of SPP-WPs in both space and time is demonstrated with aberration corrected lens structures.

  13. Frontispiece

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. You have free access to this content
      Frontispiece: Organic light-emitting transistors with voltage-tunable lit area and full channel illumination (page 1010)

      Version of Record online: 6 NOV 2013 | DOI: 10.1002/lpor.201370068

      Thumbnail image of graphical abstract

      Organic light-emitting transistors (OLETs) are multifunctional optoelectronic devices that hold great promise for a variety of applications, including flat panel displays, integrated light sources for sensing and optical communication systems. The narrow illumination area within the device channel is considered intrinsic to the device architecture and is a severe technological drawback for all those applications where a controlled, wide and homogeneous emission area is required. S. Toffanin et al. (pp. 1011–1019) show that not only the position but also the extension of the emission area is voltage-tunable, and the entire channel of the transistor can be homogeneously illuminated. The modeling of the exciton distribution within the channel at the different bias conditions coupled to the modeling of the device emission profile highlights that excitons are spread through the entire channel width and across the bulk of the central emission layer of the p-channel/emitter/n-channel trilayer active heterostructure.

  14. Original Papers

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. Organic light-emitting transistors with voltage-tunable lit area and full channel illumination (pages 1011–1019)

      Stefano Toffanin, Raffaella Capelli, Wouter Koopman, Gianluca Generali, Susanna Cavallini, Andrea Stefani, Davide Saguatti, Giampiero Ruani and Michele Muccini

      Version of Record online: 29 JUL 2013 | DOI: 10.1002/lpor.201300066

      Thumbnail image of graphical abstract

      Organic light-emitting transistors (OLETs) are multifunctional optoelectronic devices that hold great promise for a variety of applications, including flat panel displays, integrated light sources for sensing and optical communication systems. The narrow illumination area within the device channel is considered intrinsic to the device architecture and is a severe technological drawback for all those applications where a controlled, wide and homogeneous emission area is required. Here it is shown that not only the position but also the extension of the emission area is voltage-tunable, and the entire channel of the transistor can be homogeneously illuminated. The modeling of the exciton distribution within the channel at the different bias conditions coupled to the modeling of the device emission profile highlights that excitons are spread through the entire channel width and across the bulk of the central emission layer of the p-channel/emitter/n-channel trilayer active heterostructure.

    2. Nanocomposite-based stretchable optics (pages 1020–1026)

      Cristian Ghisleri, Mirko Siano, Luca Ravagnan, Marco Alberto Carlo Potenza and Paolo Milani

      Version of Record online: 6 SEP 2013 | DOI: 10.1002/lpor.201300078

      Thumbnail image of graphical abstract

      Stretchable and conformable optical devices open up very exciting perspectives for the fabrication of systems incorporating diffracting and optical power in a single element. Supersonic cluster beam implantation of silver nanoparticles in an elastomeric substrate grooved by molding allows effective fabrication of cheap and simple stretchable optical elements able to withstand thousands of deformations and stretching cycles without any degradation of their optical properties. The nanocomposite-based reflective optical devices were characterized both morphologically and optically showing excellent performances and stability compared to similar devices fabricated with standard techniques. The nanocomposite-based devices can therefore be applied to arbitrary curved nonoptical grade surfaces in order to achieve optical power and to minimize aberrations like astigmatism. The high resilience of the nanocomposite material on which the devices are based allows them to be peeled and reused multiple times.

    3. Photonic-on-a-chip: a thermal actuated Mach-Zehnder interferometer and a molecular thermometer based on a single di-ureasil organic-inorganic hybrid (pages 1027–1035)

      Rute A. S. Ferreira, Carlos D S. Brites, Carlos M. S. Vicente, Patrícia P. Lima, Ana R. N. Bastos, Paulo G. Marques, Marianne Hiltunen, Luis D. Carlos and Paulo S. André

      Version of Record online: 24 SEP 2013 | DOI: 10.1002/lpor.201300080

      Thumbnail image of graphical abstract

      An integrated photonic-on-a-chip device based on a single organic-inorganic di-ureasil hybrid was fabricated for optical waveguide and temperature sensing. The device is composed by a thermal actuated Mach-Zehnder (MZ) interferometer operating with a switching power of 0.011 W and a maximum temperature difference between branches of 0.89 ºC. The MZ interferometer is covered by a Eu3+/Tb3+ co-doped di-ureasil luminescent molecular thermometer with a temperature uncertainty of 0.1ºC and a spatial resolution of 13 µm. This is an uncommon example in which the same material (an organic-inorganic hybrid) that is used to fabricate a particular device (a thermal-actuated MZ interferometer) is also used to measure one of the device intrinsic properties (the operating temperature). The photonic-on-a-chip example discussed here can be applied to sense temperature gradients with high resolution (10−3 ºC·µm−1) in chip-scale heat engines or refrigerators, magnetic nanocontacts and energy-harvesting machines.

    4. Nanoimprinted distributed feedback lasers comprising TiO2 thin films: Design guidelines for high performance sensing (pages 1036–1042)

      Christoph Vannahme, Michael C. Leung, Frank Richter, Cameron L. C. Smith, Pétur G. Hermannsson and Anders Kristensen

      Version of Record online: 9 SEP 2013 | DOI: 10.1002/lpor.201300083

      Thumbnail image of graphical abstract

      Design guidelines for optimizing the sensing performance of nanoimprinted second order distributed feedback dye lasers are presented. The guidelines are verified by experiments and simulations. The lasers, fabricated by UV-nanoimprint lithography into Pyrromethene doped Ormocomp thin films on glass, have their sensor sensitivity enhanced by a factor of up to five via the evaporation of a titanium dioxide (TiO2) waveguiding layer. The influence of the TiO2 layer thickness on the device sensitivity is analyzed with a simple model that accurately predicts experimentally measured wavelength shifts induced by varied superstrate refractive indices. The superstrate refractive index is additionally shown to determine which of the possible waveguiding modes dominates for lasing, indicating a method to flexibly select the polarization of the laser. The detection limit of the sensor system is further discussed, finding an optimum at 7.5· 10−6 RIU. Wavelength changes caused by dye bleaching must be taken into account for long-term measurements.

    5. You have full text access to this OnlineOpen article
      A monolithic resonant terahertz sensor element comprising a metamaterial absorber and micro-bolometer (pages 1043–1048)

      James Grant, Ivonne Escorcia-Carranza, Chong Li, Iain J. H. McCrindle, John Gough and David R. S. Cumming

      Version of Record online: 6 SEP 2013 | DOI: 10.1002/lpor.201300087

      Thumbnail image of graphical abstract

      In this article a monolithic resonant terahertz sensor element with a noise equivalent power superior to that of typical commercial room temperature single pixel terahertz detectors and capable of close to real time read-out rates is presented. The detector is constructed via the integration of a metamaterial absorber and a micro-bolometer sensor. An absorption magnitude of 57% at 2.5 THz, a minimum NEP of inline image and a thermal time constant of 68 ms for the sensor are measured. As a demonstration of detector capability, it is employed in a practical Nipkow terahertz imaging system. The monolithic resonant terahertz detector is readily scaled to focal plane array formats by adding standard read-out and addressing circuitry enabling compact, low-cost terahertz imaging.

    6. Control of surface charge for high-fidelity nanostructuring of materials (pages 1049–1053)

      Gediminas Gervinskas, Gediminas Seniutinas and Saulius Juodkazis

      Version of Record online: 17 SEP 2013 | DOI: 10.1002/lpor.201300093

      Thumbnail image of graphical abstract

      The universal problem of surface charging during focused ion milling has been fully resolved using a flood-gun approach based on simultaneous co-illumination with a UV light-emitting diode (LED). Non-distorted as-designed nano-patterns were milled using Ga+ ions on dielectric materials which charge up strongly. Deep-UV (250–280 nm) LED co-illumination during the ion beam milling fully discharges optically the surface under standard Ga+ ion-milling conditions. Photo-ionization of electrons trapped at the sub-surface defects to the free vacuum state is a key to the phenomenon (inline image nm corresponds to a photon energy inline image eV). The method is applicable as a solution to other charging problems where electrons (primary or secondary) and their spatial redistribution affect nanofabrication or imaging.

    7. Nonlinear absorption and refraction in crystalline silicon in the mid-infrared (pages 1054–1064)

      Xin Gai, Yi Yu, Bart Kuyken, Pan Ma, Steve J. Madden, Joris Van Campenhout, Peter Verheyen, Gunther Roelkens, Roel Baets and Barry Luther-Davies

      Version of Record online: 11 OCT 2013 | DOI: 10.1002/lpor.201300103

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      The wavelength dependence of the nonlinear absorption and the third order nonlinear refraction of crystalline silicon between 2.75 μm and 5.5 μm as well as at 1.55 μm have been measured. It was found that at all wavelengths multi-photon and free carrier absorption can be significant. In particular nonlinear absorption can affect silicon devices designed for the mid-infrared that require strong nonlinear response, such as for the generation of a supercontinuum.

    8. You have full text access to this OnlineOpen article
      Micro-LED pumped polymer laser: A discussion of future pump sources for organic lasers (pages 1065–1078)

      Johannes Herrnsdorf, Yue Wang, Jonathan J. D. McKendry, Zheng Gong, David Massoubre, Benoit Guilhabert, Georgios Tsiminis, Graham A. Turnbull, Ifor D. W. Samuel, Nicolas Laurand, Erdan Gu and Martin D. Dawson

      Version of Record online: 17 SEP 2013 | DOI: 10.1002/lpor.201300110

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      Optical pumping conditions for organic solid-state lasers (OSLs) are discussed with particular emphasis on the use of gallium nitride based light-emitting diodes (LEDs) as pump sources. LEDs operate in a regime where the pump should be optimized for a short rise time and high peak intensity, whereas fall time and overall pulse duration are less important. Lasers pumped with this approach need to have very low thresholds which can now be routinely created using (one-dimensional) distributed feedback lasers. In this particular case stripe-shaped excitation with linearly polarized light is beneficial. Arrays of micron-sized flip-chip LEDs have been arranged in an appropriate stripe shape and the array dimensions were chosen such that the divergence of LED emission does not cause a loss in peak intensity. These micro-LED arrays have successfully been used to pump OSLs with thresholds near 300 W/cm2 (∼9 ns rise time, 35 ns pulse duration), paving the way for compact arrays of indirectly electrically pumped OSLs.

    9. Bi-directional organic light-emitting diodes with nanoparticle-enhanced light outcoupling (pages 1079–1087)

      Hong-Wei Chang, Jonghee Lee, Tae-Wook Koh, Simone Hofmann, Björn Lüssem, Seunghyup Yoo, Chung-Chih Wu, Karl Leo and Malte C. Gather

      Version of Record online: 8 OCT 2013 | DOI: 10.1002/lpor.201300111

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      An effective method is presented for enhancing the outcoupling efficiency of translucent/bi-directional organic light-emitting diodes (TL/BD-OLEDs) with a bottom indium tin oxide (ITO) anode and a top cathode comprised of a thin Ag layer covered with an organic capping layer. Upon insertion of a nanoparticle (NP)-based scattering layer (NPSL) between the substrate and the ITO anode, the TL/BD-OLEDs exhibit significantly enhanced external quantum efficiency (EQE) in both emission directions. Furthermore, the NPSL improves the color stability of the TL/BD-OLEDs over a wide range of viewing angles. Simulations based on geometrical and statistical optics are performed to elucidate the mechanism by which the efficiency is enhanced and to establish strategies for further optimization. Simulations performed on the scattering layers with varying NP volume percentage reveal that the bottom-side emission is governed by competition between waveguide-mode extraction and backward scattering by NPs in the film, while the top-side emission is largely dominated by the latter. Optimized bi-directional OLEDs achieve a 1.64-fold enhanced EQE compared to reference devices without NPSL.

    10. You have full text access to this OnlineOpen article
      Chiral nanoemitter array: A launchpad for optical vortices (pages 1088–1092)

      Matt M. Coles, Mathew D. Williams, Kamel Saadi, David S. Bradshaw and David L. Andrews

      Version of Record online: 11 OCT 2013 | DOI: 10.1002/lpor.201300117

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      A chiral arrangement of molecular nanoemitters is shown to support delocalised exciton states whose spontaneous decay can generate optical vortex radiation. In contrast to techniques in which phase modification is imposed upon conventional optical beams, this exciton method enables radiation with a helical wave-front to be produced directly. To achieve this end, a number of important polarisation and symmetry-based criteria need to be satisfied. It emerges that the phase structure of the optical field produced by degenerate excitons in a propeller-shaped array can exhibit precisely the sought character of an optical vortex – one with unit topological charge. Practical considerations for the further development of this technique are discussed, and potential new applications are identified.

  15. Letters

    1. Top of page
    2. Front Cover
    3. Inside Front Cover
    4. Inside Back Cover
    5. Back Cover
    6. Issue Information
    7. Call for Papers
    8. Editorial Advisory Board
    9. Contents
    10. Erratum: Photonic crystal boosted chemiluminescence reaction
    11. Editorial
    12. Review Articles
    13. Original Papers
    14. Frontispiece
    15. Original Papers
    16. Letters
    1. Subwavelength grating Fourier-transform interferometer array in silicon-on-insulator (pages L67–L70)

      Przemek J. Bock, Pavel Cheben, Aitor V. Velasco, Jens H. Schmid, André Delâge, Mirosław Florjańczyk, Jean Lapointe, Dan-Xia Xu, Martin Vachon, Siegfried Janz and María L. Calvo

      Version of Record online: 22 AUG 2013 | DOI: 10.1002/lpor.201300063

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      A planar waveguide Fourier-transform spectrometer with densely arrayed Mach-Zehnder interferometers is demonstrated. Subwavelength gratings are used to produce an optical path difference without waveguide bends. The fabricated device comprises of an array of 32 Mach-Zehnder interferometers, which produce a spatial interferogram without any moving parts, yielding a spectral resolution of 50 pm and a free-spectral range of 0.78 nm. As a result of similar propagation losses in subwavelength grating waveguides and conventional strip waveguides, loss imbalance is minimized and high interferometic extinction ratio of −25 to −30 dB is obtained. Furthermore, phase and amplitude errors arising from normal fabrication variation are compensated by the spectral retrieval process using calibration measurements.

    2. Editor's Choice

      You have full text access to this OnlineOpen article
      LED pumped polymer laser sensor for explosives (pages L71–L76)

      Yue Wang, Paulina O. Morawska, Alexander L. Kanibolotsky, Peter J. Skabara, Graham A. Turnbull and Ifor D. W. Samuel

      Version of Record online: 8 OCT 2013 | DOI: 10.1002/lpor.201300072

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      A very compact explosive vapor sensor is demonstrated based on a distributed feedback polymer laser pumped by a commercial InGaN light-emitting diode. The laser shows a two-stage turn on of the laser emission, for pulsed drive currents above 15.7 A. The ‘double-threshold’ phenomenon is attributed to the slow rise of the ∼30 ns duration LED pump pulses. The laser emits a 533 nm pulsed output beam of ∼10 ns duration perpendicular to the polymer film. When exposed to nitroaromatic model explosive vapors at ∼8 ppb concentration, the laser shows a 46% change in the surface-emitted output under optimized LED excitation.

    3. Topological insulator as an optical modulator for pulsed solid-state lasers (pages L77–L83)

      Haohai Yu, Han Zhang, Yicheng Wang, Chujun Zhao, Baolin Wang, Shuangchun Wen, Huaijin Zhang and Jiyang Wang

      Version of Record online: 8 OCT 2013 | DOI: 10.1002/lpor.201300084

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      Topological insulators are states of quantum matter that have narrow topological nontrivial energy gaps and a large third-order nonlinear optical response. The optical absorption of topological insulators can become saturated under strong excitation. In this work, with Bi2Se3 as an example, it was demonstrated that a topological insulator can modulate the operation of a bulk solid-state laser by taking advantage of its saturable absorption. The result suggests that topological insulators are potentially attractive as broadband pulsed modulators for the generation of short and ultrashort pulses in bulk solid-state lasers, in addition to other promising applications in physics and computing.

    4. Electro-optic polymer/titanium dioxide hybrid core ring resonator modulators (pages L84–L88)

      Feng Qiu, Andrew M. Spring, Feng Yu, Isao Aoki, Akira Otomo and Shiyoshi Yokoyama

      Version of Record online: 6 SEP 2013 | DOI: 10.1002/lpor.201300089

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      Compact electro-optic (EO) modulators are desirable for a number of applications. In this study, a ring modulator has been fabricated in the titanium dioxide (TiO2) core and EO polymer cladding waveguide structure. A 250-nm thick TiO2 core was utilized to minimize the ring radius down to 100 μm, to avoid using the top cladding between the EO polymer and the electrode, and to improve the poling efficiency. The resonance obtained by the ring modulator was observed to shift by 0.02 nm/V due to the enhanced in-device EO coefficient of 105 pm/V. A modulation depth of 3 dB was observed at the frequency response function at 20 kHz using 2-V Vp–p clock signal.

    5. High-energy optical parametric oscillator for the 6 μm spectral range based on HgGa2S4 pumped at 1064 nm (pages L89–L92)

      Adolfo Esteban-Martin, Georgi Marchev, Valeriy Badikov, Vladimir Panyutin, Valentin Petrov, Galina Shevyrdyaeva, Dmitrii Badikov, Marina Starikova, Svetlana Sheina, Anna Fintisova and Aleksey Tyazhev

      Version of Record online: 8 OCT 2013 | DOI: 10.1002/lpor.201300102

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      The defect chalcopyrite crystal HgGa2S4 has been employed in a 1064-nm pumped optical parametric oscillator to generate <7 ns long idler pulses near 6.3 μm with energies as high as 3 mJ, tunable in a broad spectral range from 4.5 to 9 μm.

    6. Five-cycle pulses near λ = 3 μm produced in a subharmonic optical parametric oscillator via fine dispersion management (pages L93–L97)

      Magnus W. Haakestad, Alireza Marandi, Nick Leindecker and Konstantin L. Vodopyanov

      Version of Record online: 8 OCT 2013 | DOI: 10.1002/lpor.201300112

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      Five-cycle (50 fs) mid-IR pulses at 80-MHz repetition rate are produced using a degenerate (subharmonic) optical parametric oscillator (OPO), synchronously pumped by an ultrafast 1560-nm fiber laser. The effects of cavity dispersion and the length of a periodically poled lithium niobate (PPLN) gain element on the output spectrum and pulse duration are investigated by taking advantage of a very broad (∼ 1000 cm−1) gain bandwidth near the 3.1-μm OPO degeneracy point. A new method of assessing the total OPO group delay dispersion across its entire spectrum is proposed, based on measuring spectral signatures of trace amounts of molecular gases injected into the OPO cavity.

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