Laser & Photonics Reviews

Cover image for Vol. 8 Issue 5

Early View (Online Version of Record published before inclusion in an issue)

Editor: Katja Paff

Impact Factor: 9.313

ISI Journal Citation Reports © Ranking: 2013: 3/82 (Optics); 9/67 (Physics Condensed Matter); 10/136 (Physics Applied)

Online ISSN: 1863-8899

Associated Title(s): Advanced Optical Materials, Journal of Biophotonics

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  1. 1 - 19
  1. Original Papers

    1. Generation of sub-terahertz repetition rates from a monolithic self-mode-locked laser coupled with an external Fabry-Perot cavity

      Y. F. Chen, M. T. Chang, W. Z. Zhuang, K. W. Su, K. F. Huang and H. C. Liang

      Article first published online: 29 OCT 2014 | DOI: 10.1002/lpor.201400132

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      A novel scheme to multiply the repetition rate of a monolithic self-mode-locked laser for generating sub-terahertz pulse sources is realized. A partially reflective mirror is exploited to form an external Fabry-Perot cavity. The pulse trains with the pth harmonics of the repetition rate can be flexibly obtained by adjusting the external cavity length to be a simple fraction of the crystal length.2

  2. Letter Article

    1. You have full text access to this OnlineOpen article
      High-efficiency single etch step apodized surface grating coupler using subwavelength structure

      Daniel Benedikovic, Pavel Cheben, Jens H. Schmid, Dan-Xia Xu, Jean Lapointe, Shurui Wang, Robert Halir, Alejandro Ortega-Moñux, Siegfried Janz and Milan Dado

      Article first published online: 13 OCT 2014 | DOI: 10.1002/lpor.201400113

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      It is experimentally demonstrated that a high coupling efficiency can be achieved for an arbitrary buried oxide thickness by judicious adjustment of the grating radiation angle. The measured coupling loss of a continuously apodized single etch step grating coupler is –2.16 dB with 3 dB bandwidth of 64 nm. It is also shown by simulations that coupling loss as low as –0.42 dB is predicted for a modified coupler structure with bottom mirror.

  3. Original Papers

    1. Ultrabroadband strong light absorption based on thin multilayered metamaterials

      Fei Ding, Yi Jin, Borui Li, Hao Cheng, Lei Mo and Sailing He

      Article first published online: 8 OCT 2014 | DOI: 10.1002/lpor.201400157

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      An unprecedentedly ultrabroadband light absorber is demonstrated. It is quite insensitive to the incident angle. For the fabricated 2D periodic array of 400-nm height tapers, the measured absorption is over 90% over almost the entire solar spectrum, and remains high (above 85%) even in the longer-wavelength range till 4 μm. Two mechanisms of the ultrabroadband absorption are explained.

    2. Back focal plane imaging of Tamm plasmons and their coupled emission

      Yikai Chen, Douguo Zhang, Dong Qiu, Liangfu Zhu, Sisheng Yu, Peijun Yao, Pei Wang, Hai Ming, Ramachandram Badugu and Joseph R. Lakowicz

      Article first published online: 2 OCT 2014 | DOI: 10.1002/lpor.201400117

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      The unique optical properties of Tamm plasmons (TPs) – such as flexible wavevector matching conditions including inplane wavevector within the light line, and existing both S- and P-polarized TPs − facilitate them for direct optical excitation. The Tamm plasmon-coupled emission (TPCE) from a combined photonic–plasmonic structure sustaining both surface plasmons (SPs) and TPs is described in this paper. The sensitivity of TPCE to the emission wavelength and polarization is examined with back focal plane imaging and verified with the numerical calculations. The results reveal that the excited probe can couple with both TPs and SPs, resulting in surface plasmon-coupled emission (SPCE) and TPCE, respectively. The TPCE angle is strongly dependent on the wavelength allowing for spectral resolution using different observation angles. These Tamm structures provide a new tool to control the optical emission from dye molecules and have many potential applications in fluorescence-based sensing and imaging.

  4. Review Articles

    1. You have full text access to this OnlineOpen article
      Waveguide sub-wavelength structures: a review of principles and applications

      Robert Halir, Przemek J. Bock, Pavel Cheben, Alejandro Ortega-Moñux, Carlos Alonso-Ramos, Jens H. Schmid, Jean Lapointe, Dan-Xia Xu, J. Gonzalo Wangüemert-Pérez, Íñigo Molina-Fernández and Siegfried Janz

      Article first published online: 30 SEP 2014 | DOI: 10.1002/lpor.201400083

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      Periodic structures with a sub-wavelength pitch have been known since Hertz conducted his first experiments on the polarization of electromagnetic waves. While the use of these structures in waveguide optics was proposed in the 1990s, it has been with the more recent developments of silicon photonics and high-precision lithography techniques that sub-wavelength structures have found widespread application in the field of photonics. This review first provides an introduction to the physics of sub-wavelength structures. An overview of the applications of sub-wavelength structures is then given including: anti-reflective coatings, polarization rotators, high-efficiency fiber–chip couplers, spectrometers, high-reflectivity mirrors, athermal waveguides, multimode interference couplers, and dispersion engineered, ultra-broadband waveguide couplers among others. Particular attention is paid to providing insight into the design strategies for these devices. The concluding remarks provide an outlook on the future development of sub-wavelength structures and their impact in photonics.

    2. You have full text access to this OnlineOpen article
      Fiber optical parametric amplifiers in optical communication systems

      Michel E. Marhic (†), Peter A. Andrekson, Periklis Petropoulos, Stojan Radic, Christophe Peucheret and Mahmoud Jazayerifar

      Article first published online: 30 SEP 2014 | DOI: 10.1002/lpor.201400087

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      The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase-insensitive amplifiers (PIAs) and phase-sensitive amplifiers (PSAs) are considered. Low-penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength- and time-division multiplexed formats. High-quality mid-span spectral inversion has been demonstrated at 0.64 Tb/s, avoiding electronic dispersion compensation. All-optical amplitude regeneration of amplitude-modulated signals has been performed, while PSAs have been used to demonstrate phase regeneration of phase-modulated signals. A PSA with 1.1-dB noise figure has been demonstrated, and preliminary wavelength-division multiplexing experiments have been performed with PSAs. 512 Gb/s have been transmitted over 6,000 km by periodic phase conjugation. Simulations indicate that PIAs could reach data rate x reach products in excess of 14,000 Tb/s × km in realistic wavelength-division multiplexed long-haul networks. Technical challenges remaining to be addressed in order for fiber OPAs to become useful for long-haul communication networks are discussed.

  5. Original Papers

    1. Polarization independent broadband terahertz antireflection by deep-subwavelength thin metallic mesh

      Lu Ding, Qing Yang Steve Wu and Jing Hua Teng

      Article first published online: 22 SEP 2014 | DOI: 10.1002/lpor.201400135

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      Broadband antireflection coatings for passive terahertz (THz) components are extremely important in the application of THz technology. Metallic nano-films are commonly used for this purpose. Here a new approach to realize polarization independent broadband antireflection in THz range, based on a meta-surface design is experimentally demonstrated. The internal reflection of a broadband THz pulse (spectral bandwidth of 0.06 – 4 THz) at a Si/air interface can be fully suppressed with a Cr square mesh with deep-subwavelength dimensions. Small nonuniformity of the meta-surface structure can enhance the tolerance on structural parameters for achieving the AR condition. The design concept is applicable to other metals and frequency ranges as well, which opens a new window for future AR coatings.

    2. Orthorhombic YAlO3 – a novel many-phonon SRS-active crystal

      Alexander A. Kaminskii, Oliver Lux, Jerzy Hanuza, Hanjo Rhee, Hans Joachim Eichler, Hitoki Yoneda, Jian Zhang, Dingyuan Tang and Akira Shirakawa

      Article first published online: 14 AUG 2014 | DOI: 10.1002/lpor.201400058

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      In single crystals of orthorhombic YAlO3, widely known as a host-matrix for Ln3+-lasant ions, many-phonon stimulated Raman scattering interactions as well as different manifestations of cascaded and cross-cascaded nonlinear χ(3)[LEFT RIGHT ARROW]χ(3) processes are initiated by picosecond laser pulses. The scientific and applicative potential of YAlO3 crystals is considerably expanded by the demonstration of its SRS properties. In particular, the studies revealed the manifestation of eight χ(3)-active vibrational modes. The corresponding Stokes and anti-Stokes lines have been assigned and the steady-state Raman gain coefficients related to the strongest phonon mode have been estimated. In addition, a short review presents the stimulated emission channels of its Ln3+-ions together with some χ(3)-nonlinear laser properties of crystals belonging to the binary Y2O3-Al2O3 system.

    3. Ultrasensitive terahertz/infrared waveguide modulators based on multilayer graphene metamaterials

      Irina Khromova, Andrei Andryieuski and Andrei Lavrinenko

      Article first published online: 11 AUG 2014 | DOI: 10.1002/lpor.201400075

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      This paper studies and classifies the electromagnetic regimes of multilayer graphene-dielectric artificial metamaterials in the terahertz/infrared range. The employment of such composites for waveguide-integrated modulators is analysed and three examples of novel tunable devices are presented. The first one is a modulator with excellent ON-state transmission and very high modulation depth: >38 dB at 70 meV graphene's electrochemical potential (Fermi energy) change. The second one is a modulator with extreme sensitivity towards graphene's Fermi energy - a minute 1 meV variation of the latter leads to >13.2 dB modulation depth. The third one is a tunable waveguide-based passband filter. The narrow-band cut-off conditions around the ON-state allow the latter to shift its central frequency by 1.25% per every meV graphene's Fermi energy change.

    4. Thick junction broadband organic photodiodes

      Ardalan Armin, Mike Hambsch, Il Ku Kim, Paul L Burn, Paul Meredith and Ebinazar B Namdas

      Article first published online: 31 JUL 2014 | DOI: 10.1002/lpor.201400081

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      Inorganic semiconductor-based broadband photodetectors are ubiquitous in imaging technologies such as digital cameras and photometers. Herein a broadband organic photodiode (OPD) that has performance metrics comparable or superior to inorganic photodiodes over the same spectral range is reported. The photodiode with an active layer comprised of a poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)]:[6,6]-phenyl-C71-butyric acid methyl ester bulk heterojunction blend had a dark current < 1 nA/cm2, specific detectivity of ∼1013 Jones, reverse bias −3 dB frequency response of 100 kHz to 1 MHz, and state-of-the-art Linear Dynamic Range for organic photodiodes of nine orders of magnitude (180 dB). The key to these performance metrics was the use of a thick junction (700 nm), which flattened the spectral response, reduced the dark current and decreased performance variations. The strategy also provides a route to large area defect free “monolithic” structures for low noise integrated photo-sensing, position determination, or contact, non-focal imaging.

    5. Versatile Raman fiber laser for sodium laser guide star

      Lei Zhang, Huawei Jiang, Shuzhen Cui, Jinmeng Hu and Yan Feng

      Article first published online: 28 JUL 2014 | DOI: 10.1002/lpor.201400055

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      Robust high-power narrow-linewidth lasers at 589 nm are required for sodium laser guide star adaptive optics in astronomy. A high-power 589 nm laser based on Raman fiber amplifier is reported here, which works in both continuous-wave and pulsed formats. In the continuous-wave case, the laser produces more than 50 W output. In the pulsed case, the same laser produces square-shaped pulses with tunable repetition rate (500 Hz to 10 kHz) and duration (1 ms to 30 μs). The peak power is as high as 84 W and remains constant during the tuning. The laser also emits an adjustable sideband at 1.71 GHz away from the main laser frequency for better sodium excitation. The versatility of the laser offers much flexibility in laser guide star application.

    6. Dynamic laser prototyping for biomimetic nanofabrication

      Dong-Xu Liu, Yun-Lu Sun, Wen-Fei Dong, Rui-Zhu Yang, Qi-Dai Chen and Hong-Bo Sun

      Article first published online: 15 JUL 2014 | DOI: 10.1002/lpor.201400043

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      Micronanofabrication technologies developed so far pursue faithful conversion from digital models to matter structures. This is vital for microdevices in optics, mechanics, and electronics, where device shape and size matter. However, biotissues grow under rich environmental factor interactions, as demands novel manufacturing approaches for biomimetic and biological fabrication. Here, a concept of dynamic laser prototyping is reported, which is based on a new finding of a multilayered three-dimensional (3D) wrinkling phenomenon. The 3D wrinkling started with formation of a photocrosslinked hydrogel sheet by femtosecond laser direct writing. It was followed by spontaneous self-bending of the sheet, caused by a purposely designed sheet–substrate stress mismatch. The flower blooming process has been successfully mimicked, indicating broader usages of the technology in biotissue-growth-related manufacturing.

    7. Development of a Joule-class Yb:YAG amplifier and its implementation in a CPA system generating 1 TW pulses

      Christoph Wandt, Sandro Klingebiel, Sebastian Keppler, Marco Hornung, Markus Loeser, Mathias Siebold, Christoph Skrobol, Alexander Kessel, Sergei A. Trushin, Zsuzsanna Major, Joachim Hein, Malte C. Kaluza, Ferenc Krausz and Stefan Karsch

      Article first published online: 25 JUN 2014 | DOI: 10.1002/lpor.201400040

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      In this paper the development and implementation of a novel amplifier setup as an additional stage for the CPA pump laser of the Petawatt Field Synthesizer, currently developed at the Max-Planck-Institute of Quantum Optics, is presented. This amplifier design comprises 20 relay-imaged passes through the active medium which are arranged in rotational symmetry. As the gain material, an in-house-developed Yb:YAG active-mirror is used. With this setup, stretched 4 ns seed pulses are amplified to output energies exceeding 1 J with repetition rates of up to 2 Hz. Furthermore, a spectral bandwidth of 3.5 nm (FWHM) is maintained during amplification and the compression of the pulses down to their Fourier-limit of 740 fs is achieved. To the best of our knowledge, this is the first demonstration of 1 TW pulses generated via CPA in diode-pumped Yb:YAG.

  6. Review Articles

    1. Intracavity phase interferometry: frequency combs sensor inside a laser cavity

      Ladan Arissian and Jean-Claude Diels

      Article first published online: 24 JUN 2014 | DOI: 10.1002/lpor.201300179

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      In traditional interferometric measurements, a physical quantity that changes the phase of a resonator is monitored through a change of its transmission. Interferometry inside a laser exploits the ultimate Q-factor of that resonator, and converts the phase to be measured into a frequency. A mode-locked laser with two intracavity pulses emits two frequency combs of the same repetition rate. The quantity to be measured (a sub-nano displacement, a nonlinear index, an acceleration or rotation, a magnetic or electric field) produces a minute phase change (inline image rad) in one of the two intracavity pulses, which is converted into a frequency, measured by beating the two pulse trains emitted by the laser. This paper presents methods of operating mode-locked lasers in which two independent pulses circulate, producing two frequency combs of the same repetition rate. Various examples of physical quantities that can be measured through this technique are presented.

  7. Original Papers

    1. Use of tunable second-harmonic signal from KNbO3 nanoneedles to find optimal wavelength for deep-tissue imaging

      Fuhong Cai, Jiaxin Yu, Jun Qian, Ye Wang, Zhong Chen, Jingyun Huang, Zhizhen Ye and Sailing He

      Article first published online: 17 JUN 2014 | DOI: 10.1002/lpor.201400009

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      Nonlinear optical (NLO) responses of perovskite-type nanostructures have a variety of potential applications owing to the highly efficient frequency conversion guaranteed by both the material itself and the nanometer-scale configuration. KNbO3 (KN) nanoneedles have been identified as a promising NLO material because of the superior broadband frequency conversion efficiency, and if incident light is propagating in a direction perpendicular to the axis of a nanoneedle, then the phase-matching constraint can be relaxed. Here, the second-harmonic generation (SHG) and third-harmonic generation (THG) responses of both individual and clustered KN nanoneedles are reported. Based on these results, a novel method is proposed for determining the optimal excitation wavelength for NLO imaging of several biological samples, with KN nanoneedles acting as NLO agents. The method is shown to provide the optical features in the focal plane and a more reliable estimation of the optimal excitation wavelength for deep-tissue imaging.

  8. ORIGINAL PAPERS

    1. Highly directional spaser array for the red wavelength region

      Xiangeng Meng, Jingjing Liu, Alexander V. Kildishev and Vladimir M. Shalaev

      Article first published online: 16 JUN 2014 | DOI: 10.1002/lpor.201400056

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      The spaser offers an opportunity to achieve coherent optical sources at nanometer scales due to the extreme confinement of optical fields. However, achievement of spasers with directional propagation in the visible wavelength region remains a challenge thus far, owing to the unique optical feedback mechanism and large dissipative losses of the metal cavity. Here, we experimentally demonstrate for the first time a spaser showing highly directional emission in the visible by using a periodic subwavelength hole array perforated in a metal film, which function as plasmonic nanocavities, along with an organic laser dye to supply gain. The lasing occurs in the red wavelength region and shows a single mode. It is suggested that the optical feedback for spasing is provided by the SPP–Bloch wave, which is supported by the fact that no spasing was attained in aperiodic holes as well as in periodic holes that do not support the SPP–Bloch wave at the spasing wavelength.

  9. Review Articles

    1. You have full text access to this OnlineOpen article
      Ultrafast laser inscription: perspectives on future integrated applications

      Debaditya Choudhury, John R. Macdonald and Ajoy K. Kar

      Article first published online: 2 JUN 2014 | DOI: 10.1002/lpor.201300195

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      This paper reviews the recent advancements achieved using ultrafast laser inscription (ULI) that highlight the cross-disciplinary potential of the technology. An overview of waveguide fabrication is provided and the three distinct types of waveguide cross-section architectures that have so far been fabricated in transparent dielectric materials are discussed. The paper focuses on two key emergent technologies driven by ULI processes. First, the recently developed photonic devices, such as compact mode-locked waveguide sources and novel mid-infrared waveguide lasers are discussed. Secondly, the phenomenon and applications of selective etching in developing ultrafast laser inscribed structures for compact lab-on-chip devices are elaborated. The review further discusses the conceivable future of ULI in impacting the aforementioned fields.

    2. Advances in vanadate laser crystals at a lasing wavelength of 1 micrometer

      Haohai Yu, Junhai Liu, Huaijin Zhang, Alexander A. Kaminskii, Zhengping Wang and Jiyang Wang

      Article first published online: 27 MAR 2014 | DOI: 10.1002/lpor.201400022

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      Sapphire, garnet and vanadate crystals are the most prominent optical materials, and vanadates play important roles in optics, especially in lasers and nonlinear optics. Neodymium-doped yttrium vanadate (Nd:YVO4) is representative and available commercially. Based on Nd:YVO4, several vanadate crystals are being developed with the goal of fulfilling the need for differential applications and improvement of certain operational aspects, such as with pulsed lasers or high-power continuous-wave lasers. In recent years, some important effects, including energy enhancement, bistability of output performance, self-Raman frequency shifting, etc., and some novel applications, such as quantum optics, pulsed lasers modulated by the two-dimensional crystals, etc., have been discovered with vanadates as gain materials. In this paper, the preparation, characterization and laser applications of vanadate laser crystals at the lasing wavelength of 1 micrometer, including YVO4, GdVO4, LuVO4, GdxY1–xVO4 and LuxGd1–xVO4 (0<x<1) doped with Nd3+ and ytterbium (Yb3+) are systematically reviewed by highlighting the most recent research progress. Their specific properties are presented, generation mechanisms of novel physical effects are discussed, new applications are given and possible future applications proposed by focusing on some potential strengths.

  10. Errata

    1. Recent advances in bioluminescence tomography: methodology and system as well as application

      C. Qin, J. Feng, S. Zhu, X. Ma, J. Zhong, P. Wu, Z. Jin and J. Tian

      Article first published online: 1 OCT 2012 | DOI: 10.1002/lpor.201270011

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