Laser & Photonics Reviews

Cover image for Vol. 8 Issue 4

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


  1. 1 - 31
  1. Original Papers

    1. 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

      Thumbnail image of graphical abstract

      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.

    2. 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

      Thumbnail image of graphical abstract

      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.

  2. Letter Articles

    1. Talbot holographic illumination nonscanning (THIN) fluorescence microscopy

      Yuan Luo, Vijay Raj Singh, Dipanjan Bhattacharya, Elijah Y. S. Yew, Jui-Chang Tsai, Sung-Liang Yu, Hsi-Hsun Chen, Jau-Min Wong, Paul Matsudaira, Peter T. C. So and George Barbastathis

      Article first published online: 8 AUG 2014 | DOI: 10.1002/lpor.201400053

      Thumbnail image of graphical abstract

      Optical sectioning techniques offer the ability to acquire three-dimensional information from various organ tissues by discriminating between the desired in-focus and out-of-focus (background) signals. Alternative techniques to confocal, such as active structured illumination, exist for fast optically sectioned images, but they require individual axial planes to be imaged consecutively. In this article, an imaging technique (THIN), by utilizing active Talbot illumination in 3D and multiplexed holographic Bragg filters for depth discrimination, is demonstrated for imaging in vivo 3D biopsy without mechanical or optical axial scanning.

  3. Original Papers

    1. 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

      Thumbnail image of graphical abstract

      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.

    2. 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

      Thumbnail image of graphical abstract

      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.

    3. Three-dimensional ultra-broadband integrated tapered mode multiplexers

      Simon Gross, Nicolas Riesen, John D. Love and Michael J. Withford

      Article first published online: 15 JUL 2014 | DOI: 10.1002/lpor.201400078

      Thumbnail image of graphical abstract

      The demonstration of a three-dimensional tapered mode-selective coupler in a photonic chip is reported. This waveguide-based, ultra-broadband mode multiplexer was fabricated using the femtosecond laser direct-write technique in a boro-aluminosilicate glass chip. A three-core coupler has been shown to enable the multiplexing of the LP01, LPinline image and LPinline image spatial modes of a multimode waveguide, across an extremely wide bandwidth exceeding 400 nm, with low loss, high mode extinction ratios and negligible mode crosstalk. Linear cascades of such devices on a single photonic chip have the potential to become a definitive technology in the realization of broadband mode-division multiplexing for increasing optical fiber capacity.

    4. 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

      Thumbnail image of graphical abstract

      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.

  4. Letter Articles

    1. Lasing action assisted by long-range surface plasmons

      Felix Rüting, Javier Cuerda, Jorge Bravo-Abad and Francisco J. Garcia-Vidal

      Article first published online: 1 JUL 2014 | DOI: 10.1002/lpor.201400052

      Thumbnail image of graphical abstract

      It is shown that lasing action at subwavelength scales can be achieved in realistic plasmonic systems supporting long-range surface plasmons (LRSPPs). To this end, a general numerical framework has been developed that is able to accurately account for the full spatio-temporal lasing dynamics and the vastly different length- and time-scales featured by this class of systems. Starting from a loss compensation regime for propagating LRSPPs, it is shown how the introduction of an optical feedback mechanism induces the formation of a self-sustained laser oscillation at moderate pump intensities. The simplicity of the proposed subwavelength scale laser offers significant potential as a novel class of planar light sources in complex plasmonic circuits.

  5. Original Papers

    1. 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

      Thumbnail image of graphical abstract

      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. Letter Articles

    1. High-resolution spectral characterization of two photon states via classical measurements

      Andreas Eckstein, Guillaume Boucher, Aristide Lemaître, Pascal Filloux, Ivan Favero, Giuseppe Leo, John E. Sipe, Marco Liscidini and Sara Ducci

      Article first published online: 24 JUN 2014 | DOI: 10.1002/lpor.201400057

      Thumbnail image of graphical abstract

      Quantum optics plays a central role in the study of fundamental concepts in quantum mechanics, and in the development of new technological applications. Typical experiments employ sources of photon pairs generated by parametric processes such as spontaneous parametric down-conversion and spontaneous four-wave-mixing. The standard characterization of these sources relies on detecting the pairs themselves and thus requires single photon detectors, which limit both measurement speed and accuracy. Here it is shown that the two-photon quantum state that would be generated by parametric fluorescence can be characterised with unprecedented spectral resolution by performing a classical experiment. This streamlined technique gives access to hitherto unexplored features of two-photon states and has the potential to speed up design and testing of massively parallel integrated nonlinear sources by providing a fast and reliable quality control procedure. Additionally, it allows for the engineering of quantum light states at a significantly higher level of spectral detail, powering future quantum optical applications based on time-energy photon correlations.

  7. 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

      Thumbnail image of graphical abstract

      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.

  8. Letter Articles

    1. You have full text access to this OnlineOpen article
      Few-cycle, broadband, mid-infrared optical parametric oscillator pumped by a 20-fs Ti:sapphire laser

      Suddapalli Chaitanya Kumar, Adolfo Esteban-Martin, Takuro Ideguchi, Ming Yan, Simon Holzner, Theodor W. Hänsch, Nathalie Picqué and Majid Ebrahim-Zadeh

      Article first published online: 17 JUN 2014 | DOI: 10.1002/lpor.201400091

      Thumbnail image of graphical abstract

      A few-cycle, broadband, singly-resonant optical parametric oscillator (OPO) for the mid-infrared based on MgO-doped periodically-poled LiNbO3 (MgO:PPLN), synchronously pumped by a 20-fs Ti:sapphire laser is reported. By using crystal interaction lengths as short as 250 µm, and careful dispersion management of input pump pulses and the OPO resonator, near-transform-limited, few-cycle idler pulses tunable across the mid-infrared have been generated, with as few as 3.7 optical cycles at 2682 nm. The OPO can be continuously tuned over 2179-3732 nm (4589-2680 cm-1) by cavity delay tuning, providing up to 33 mW of output power at 3723 nm. The idler spectra exhibit stable broadband profiles with bandwidths spanning over 422 nm (FWHM) recorded at 3732 nm. The effect of crystal length on spectral bandwidth and pulse duration is investigated at a fixed wavelength, confirming near-transform-limited idler pulses for all grating interaction lengths. By locking the repetition frequency of the pump laser to a radio-frequency reference, and without active stabilization of the OPO cavity length, an idler power stability better than 1.6% rms over >2.75 hours is obtained when operating at maximum output power, in excellent spatial beam quality with TEM00 mode profile.

      Photograph shows a multigrating MgO:PPLN crystal used as a nonlinear gain medium in the few-cycle femtosecond mid-IR OPO. The visible light is the result of non-phase-matched sum-frequency mixing between the interacting beams.

  9. 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

      Thumbnail image of graphical abstract

      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.

    2. You have full text access to this OnlineOpen article
      Coherent fluorescence emission by using hybrid photonic–plasmonic crystals

      Lei Shi, Xiaowen Yuan, Yafeng Zhang, Tommi Hakala, Shaoyu Yin, Dezhuan Han, Xiaolong Zhu, Bo Zhang, Xiaohan Liu, Päivi Törmä, Wei Lu and Jian Zi

      Article first published online: 17 JUN 2014 | DOI: 10.1002/lpor.201300196

      Thumbnail image of graphical abstract

      The spatial and temporal coherence of the fluorescence emission controlled by a quasi-two-dimensional hybrid photonic–plasmonic crystal structure covered with a thin fluorescent-molecular-doped dielectric film is investigated experimentally. A simple theoretical model to describe how a confined quasi-two-dimensional optical mode may induce coherent fluorescence emission is also presented. Concerning the spatial coherence, it is experimentally observed that the coherence area in the plane of the light source is in excess of 49 μm2, which results in enhanced directional fluorescence emission. Concerning temporal coherence, the obtained coherence time is 4 times longer than that of the normal fluorescence emission in vacuum. Moreover, a Young's double-slit interference experiment is performed to directly confirm the spatially coherent emission. This smoking gun proof of spatial coherence is reported here for the first time for the optical-mode-modified emission.


    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

      Thumbnail image of graphical abstract

      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.

  11. Original Papers

    1. A step towards the electrophotonic nose: integrating 1D photonic crystals with organic light-emitting diodes and photodetectors

      Armin T. Exner, Ida Pavlichenko, Daniela Baierl, Morten Schmidt, Gerald Derondeau, Bettina V. Lotsch, Paolo Lugli and Giuseppe Scarpa

      Article first published online: 10 JUN 2014 | DOI: 10.1002/lpor.201300220

      Thumbnail image of graphical abstract

      An innovative integrated sensing platform for the detection of various chemical analytes via translating the photonic stop-band shift of a one-dimensional photonic crystal (PC) into an electrical current change is proposed. The miniaturized sensing platform features an organic light-emitting diode (OLED) as a light source and an organic photodetector (OPD) as a light sensor and allows for the detection of ethanol vapor concentrations down to ≈ 10 parts per million (ppm) in nitrogen, which corresponds to a stop-band shift of ≈ 27 pm. The resolution of the proposed platform exceeds the capabilities of most commercial spectrometers and by far the human eye, while, at the same time, such a sensor is less expensive and less power consuming than a spectrometer. The presented setup is generic and can detect optical changes in the transmission of PCs, which can be induced by both vapor adsorption or by a liquid analyte, as demonstrated with a microfluidic setup.

    2. Terahertz probe of individual subwavelength objects in a water environment

      Luca Masini, Sandro Meucci, Jihua Xu, Riccardo Degl'Innocenti, Fabrizio Castellano, Harvey E. Beere, David Ritchie, Donatella Balduzzi, Roberto Puglisi, Andrea Galli, Fabio Beltram, Miriam S. Vitiello, Marco Cecchini and Alessandro Tredicucci

      Article first published online: 4 JUN 2014 | DOI: 10.1002/lpor.201300224

      Thumbnail image of graphical abstract

      Terahertz (THz) spectroscopy and imaging have been heralded for some time as potentially revolutionary techniques for biomedical applications. Label-free detection of molecules and recognition of molecular events are often mentioned as the most exciting possibilities. A crucial practical goal, however, is the ability to perform such measurements on tiny amounts of biological fluids or even on individual organic structures. Living cells, for instance, have diameters at most of some tens of micrometers, i.e. at least λ/10 even for few-THz radiation. Furthermore, all analyses relevant for a biological perspective must be performed in a water environment, which presents a strong absorption across the whole THz spectral range, severely limiting the penetration of the electromagnetic field. Here, it is shown how both issues can be overcome with a lab-on-a-chip approach based on a microfluidic platform coupled to a plasmonic antenna. Using a quantum cascade laser as THz illumination source, liquid volumes down to the picoliter range are probed and direct operation on individual 10-µm diameter microparticles flowing in water is shown. The present demonstration opens the way to the development of THz biosensing of individual living cells and small probe volumes.

  12. 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

      Thumbnail image of graphical abstract

      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.

  13. Original Papers

    1. You have full text access to this OnlineOpen article
      Three-dimensional visible-light capsule enclosing perfect supersized darkness via antiresolution

      Chao Wan, Kun Huang, Tiancheng Han, Eunice S. P. Leong, Weiqiang Ding, Lei Zhang, Tat-Soon Yeo, Xia Yu, Jinghua Teng, Dang Yuan Lei, Stefan A. Maier, Boris Luk'yanchuk, Shuang Zhang and Cheng-Wei Qiu

      Article first published online: 2 JUN 2014 | DOI: 10.1002/lpor.201400006

    2. A broadband, quasi-continuous, mid-infrared supercontinuum generated in a chalcogenide glass waveguide

      Yi Yu, Xin Gai, Pan Ma, Duk-Yong Choi, Zhiyong Yang, Rongping Wang, Sukanta Debbarma, Stephen J. Madden and Barry Luther-Davies

      Article first published online: 19 MAY 2014 | DOI: 10.1002/lpor.201400034

      Thumbnail image of graphical abstract

      The production of a broadband supercontinuum spanning from 1.8 μm to >7.5 μm is reported which was created by pumping a chalcogenide glass waveguide with ≈320 fs pulses at 4 μm. The total power was ≈20 mW and the source brightness was inline image100 that of current synchrotrons. This source promises to be an excellent laboratory tool for infrared microspectroscopy.

    3. You have full text access to this OnlineOpen article
      Random lasing in an organic light-emitting crystal and its interplay with vertical cavity feedback

      Andrea Camposeo, Marco Polo, Pompilio Del Carro, Leonardo Silvestri, Silvia Tavazzi and Dario Pisignano

      Article first published online: 15 MAY 2014 | DOI: 10.1002/lpor.201400031

      Thumbnail image of graphical abstract

      The simultaneous vertical-cavity and random lasing emission properties of a blue-emitting molecular crystal are investigated. The 1,1,4,4-tetraphenyl-1,3-butadiene samples, grown by physical vapour transport, feature room-temperature stimulated emission peaked at about 430 nm. Fabry-Pérot and random resonances are primed by the interfaces of the crystal with external media and by defect scatterers, respectively. The analysis of the resulting lasing spectra evidences the existence of narrow peaks due to both the built-in vertical Fabry-Pérot cavity and random lasing in a novel, surface-emitting configuration and threshold around 500 μJ cm−2. The anti-correlation between different modes is also highlighted, due to competition for gain. Molecular crystals with optical gain candidate as promising photonic media inherently supporting multiple lasing mechanisms.

  14. Letter Articles

    1. Short-wavelength infrared defect emission as a probe of degradation processes in 980 nm single-mode diode lasers

      Martin Hempel, Jens W. Tomm, Fangyu Yue, Mauro A. Bettiati and Thomas Elsaesser

      Article first published online: 15 MAY 2014 | DOI: 10.1002/lpor.201400045

      Thumbnail image of graphical abstract

      Infrared emission from 980-nm single-mode high power diode lasers is recorded and analyzed in the wavelength range from 0.8 to 8.0 μm. A pronounced short-wavelength infrared (SWIR) emission band with a maximum at 1.3 μm originates from defect states located in the waveguide of the devices. The SWIR intensity is a measure of the non-equilibrium carrier concentration in the waveguide, allowing for a non-destructive waveguide mapping in spatially resolved detection schemes. The potential of this approach is demonstrated by measuring spatially resolved profiles of SWIR emission and correlating them with mid-wavelength infrared (MWIR) thermal emission along the cavity of devices undergoing repeated catastrophic optical damage. The enhancement of SWIR emission in the damaged parts of the cavity is due to a locally enhanced carrier density in the waveguide and allows for an analysis of the spatial damage patterns. The figure shows a side view of a diode laser during catastrophic degradation as recorded by a thermocamera within 5 successive current pulses. The geometry of the device is given in grayscale. The position of the laser chip is indicated by the dotted line. The thermal signatures of the internal degradation of the diode laser are overlaid in color. The bi-directional spread of the damage along the laser cavity is clearly visible.

  15. Original Papers

    1. All-optical modulation based on silicon quantum dot doped SiOx:Si-QD waveguide

      Chung-Lun Wu, Sheng-Pin Su and Gong-Ru Lin

      Article first published online: 15 MAY 2014 | DOI: 10.1002/lpor.201400024

      Thumbnail image of graphical abstract

      All-optical modulation based on silicon quantum dot doped SiOx:Si-QD waveguide is demonstrated. By shrinking the Si-QD size from 4.3 nm to 1.7 nm in SiOx matrix (SiOx:Si-QD) waveguide, the free-carrier absorption (FCA) cross section of the Si-QD is decreased to 8 × 10−18 cm2 by enlarging the electron/hole effective masses, which shortens the PL and Auger lifetime to 83 ns and 16.5 ps, respectively. The FCA loss is conversely increased from 0.03 cm−1 to 1.5 cm−1 with the Si-QD size enlarged from 1.7 nm to 4.3 nm due to the enhanced FCA cross section and the increased free-carrier density in large Si-QDs. Both the FCA and free-carrier relaxation processes of Si-QDs are shortened as the radiative recombination rate is enlarged by electron–hole momentum overlapping under strong quantum confinement effect. The all-optical return-to-zero on-off keying (RZ-OOK) modulation is performed by using the SiOx:Si-QD waveguides, providing the transmission bit rate of the inversed RZ-OOK data stream conversion from 0.2 to 2 Mbit/s by shrinking the Si-QD size from 4.3 to 1.7 nm.

    2. Frequency comb expansion in a monolithic self-mode-locked laser concurrent with stimulated Raman scattering

      C. Y. Lee, C. C. Chang, H. C. Liang and Y. F. Chen

      Article first published online: 15 MAY 2014 | DOI: 10.1002/lpor.201400017

      Thumbnail image of graphical abstract

      The discovery of a novel phase-locked frequency comb generated from a monolithic laser with the concurrent processes of self-mode locking (SML) and stimulated Raman scattering (SRS) is reported. It is experimentally shown that the width of the Raman gain can be exploited to considerably expand the frequency comb of a monolithic SML crystal laser via the SRS process. At a pump power of 6.5 W, an output power of 140 mW in the Stokes wave with a pulse width as narrow as 2.9 ps at a pulse repetition rate of 6.615 GHz is obtained. The present finding not only provides useful insights into the monolithic intracavity SRS process but also paves the way for generating mode-locked pulses based on monolithic self-Raman crystals.

    3. Switchable surface plasmon dichroic splitter modulated by optical polarization

      Seung-Yeol Lee, Hansik Yun, Yohan Lee and Byoungho Lee

      Article first published online: 16 APR 2014 | DOI: 10.1002/lpor.201400025

      Thumbnail image of graphical abstract

      For the miniaturization of optical devices, surface plasmon polaritons (SPPs) have been widely utilized due to their outstanding confinement and field-enhancement characteristics. Analyzing a spectrum of optical signals and splitting certain regions of the spectrum range within a submicrometer-scale structure are demanded for optical integrated systems. In this paper, a novel type of dichroic surface plasmon launcher that can switch the launching direction according to incident polarization states is demonstrated. Compared to the previously reported plasmonic dichroic splitters, the proposed schemes do not use any asymmetric geometry for directional launching. Hence, the direction of guided SPPs can be interchanged according to the polarization state. Such characteristics will be helpful to design switchable plasmonic devices that can be applied to active plasmonic integrated circuits.

    4. Planar bifunctional Luneburg-fisheye lens made of an anisotropic metasurface

      Xiang Wan, Xiaopeng Shen, Yu Luo and Tie Jun Cui

      Article first published online: 4 APR 2014 | DOI: 10.1002/lpor.201400023

      Thumbnail image of graphical abstract

      Luneburg lens and Maxwell-fisheye lens are well-known microwave and optical devices with distinct focusing properties. Here, a planar bifunctional Luneburg-fisheye lens made of an anisotropic metasurface is presented, which features as a Luneburg along the horizontal optical axis, while as a fisheye along the vertical optical axis. A method to control the inhomogeneous indices of refraction along the two optical axes independently is proposed by designing an anisotropic and nonuniform metasurface, which can provide the required distributions of refractive indices approximately for Luneburg and fisheye lenses viewing from the two optical axes. Experiments in the microwave frequency range demonstrate very good performance of the planar bifunctional Luneburg-fisheye lens. The proposed method opens up an avenue to design other kinds of bifunctional devices using metasurfaces in the microwave, terahertz, and even optical ranges.

  16. Review Articles

    1. 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

      Thumbnail image of graphical abstract

      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.

    2. Ultra-low loss waveguide platform and its integration with silicon photonics

      Martijn J. R. Heck, Jared F. Bauters, Michael L. Davenport, Daryl T. Spencer and John E. Bowers

      Article first published online: 5 MAR 2014 | DOI: 10.1002/lpor.201300183

      Thumbnail image of graphical abstract

      Planar waveguides with ultra-low optical propagation loss enable a plethora of passive photonic integrated circuits, such as splitters and combiners, filters, delay lines, and components for advanced modulation formats. An overview is presented of the status of the field of ultra-low loss waveguides and circuits, including the design, the trade-off between bend radius and loss, and fabrication rationale. The characterization methods to accurately measure such waveguides are discussed. Some typical examples of device and circuit applications are presented. An even wider range of applications becomes possible with the integration of active devices, such as lasers, amplifiers, modulators and photodetectors, on such an ultra-low loss waveguide platform. A summary of efforts to integrate silicon nitride and silica-based low-loss waveguides with silicon and III/V based photonics, either hybridly or heterogeneously, will be presented. The approach to combine these integration technologies heterogeneously on a single silicon substrate is discussed and an application example of a high-bandwidth receiver is shown.

    3. Functional organic single crystals for solid-state laser applications

      Hong-Hua Fang, Jie Yang, Jing Feng, Takeshi Yamao, Shu Hotta and Hong-Bo Sun

      Article first published online: 2 MAR 2014 | DOI: 10.1002/lpor.201300222

      Thumbnail image of graphical abstract

      Because of long-range order and high chemical purity, organic crystals have exhibit unique properties and attracted a lot of interest for application in solid-state lasers. As optical gain materials, they exhibit high stimulated emission cross section and broad tunable wavelength emission as similar to their amorphous counterpart; moreover, high purity and high order give them superior properties such as low scattering trap densities, high thermal stability, as well as highly polarized emission. As electronic materials, they are potentially able to support high current densities, thus making it possible to realize current driven lasers. This paper mainly describes recent research progress in organic semiconductor laser crystals. The building molecules, crystal growth methods, as well as their stimulated emission characteristics related with crystal structures are introduced; in addition, the current state-of-the-art in the field of crystal laser devices is reviewed. Furthermore, recent advances of crystal lasers at the nanoscale and single crystal light-emitting transistors (LETs) are presented. Finally, an outlook and personal view is provided on the further developments of laser crystals and their applications.

    4. On-chip stimulated Brillouin Scattering for microwave signal processing and generation

      Ravi Pant, David Marpaung, Irina V. Kabakova, Blair Morrison, Christopher G. Poulton and Benjamin J. Eggleton

      Article first published online: 10 FEB 2014 | DOI: 10.1002/lpor.201300154

      Thumbnail image of graphical abstract

      Demonstration of continuously tunable delay, low-noise lasers, dynamically controlled gratings, and optical phase shifting using the stimulated Brillouin scattering (SBS) process has lead to the emergence of SBS as a promising technology for microwave photonics. On-chip realization of SBS enables photonic integration of microwave photonic signal processing and offers significantly enhanced performance and improved efficiency. On-chip stimulated Brillouin scattering is reviewed in the context of slow-light based tunable delay, low-noise narrow linewidth lasers and filtering for integrated microwave photonics. A discussion on key material and device properties, necessary to enable on-chip Brillouin scattering using both the single-pass and resonator geometry, is presented along with an outlook for photonic integration of microwave signal processing and generation in other platforms.

  17. 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


  1. 1 - 31