Laser & Photonics Reviews

Cover image for Vol. 7 Issue 5

September 2013

Volume 7, Issue 5

Pages i–ii, A33–A46, 605–838, L45–L65

  1. Front Cover

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    10. Focus: Biophotonics - Techniques & Applications
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      Front Cover: Advances in fluorescence diagnosis to track footprints of cancer progression in vivo (Laser Photonics Rev. 7(5)/2013

      Version of Record online: 11 SEP 2013 | DOI: 10.1002/lpor.201370050

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      Fluorescence imaging techniques have been demonstrated in preclinical and clinical studies to be very suitable for cancer diagnosis and monitoring. Future progress is speculated to move towards developing novel multimodal multifunctional probes and techniques, with potential applications in cancer diagnosis, such as noninvasive cancer diagnosis and targeted drug delivery, real-time surgical guidance and therapy monitoring.

      (Picture: M.Olivo, C. J. H. Ho, C. Y. Fu 10.1002/lpor.201200059, pp. 646–662, in this issue)

  2. Inside Front Cover

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      Inside Front Cover: Optical formation and manipulation of particle and cell patterns using a tapered optical fiber (Laser Photonics Rev. 7(5)/2013)

      Version of Record online: 11 SEP 2013 | DOI: 10.1002/lpor.201370051

      Thumbnail image of graphical abstract

      An optical method for formation and controllable manipulation of particle and cell patterns is proposed. With a laser beam at 980 nm wavelength launched into a tapered optical fiber, different sized particles and cells are formed into particle/cell chains and arrays with controllable numbers in a highly organized manner. The formed patterns can be flexibly manipulated in three dimensions.

      (Picture: H. Xin, R. Xu, and B. Li10.1002/lpor.201300028, pp. 801-809, in this issue)

  3. Inside Back Cover

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      Inside Back Cover: Tunneling-induced transparency in a chaotic microcavity (Laser Photonics Rev. 7(5)/2013)

      Version of Record online: 11 SEP 2013 | DOI: 10.1002/lpor.201370052

      Thumbnail image of graphical abstract

      A chaotic microcavity coupled with a free-space laser beam. When the probe beam is on resonance with the high-Q regular mode, it leads to the cancellation of the chaos loss due to the destructive interference of two excitation pathways, which induces a transparency in the transmitted field.

      (Picture: Y.-F. Xiao et al.10.1002/lpor.201300042, pp. L51–L54, in this issue)

  4. Back Cover

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      Back Cover: Optically active Babinet planar metamaterial film for terahertz polarization manipulation (Laser Photonics Rev. 7(5)/2013)

      Version of Record online: 11 SEP 2013 | DOI: 10.1002/lpor.201370053

      Thumbnail image of graphical abstract

      A planar Babinet-inverted dimer metamaterial in the THz frequency range. It was implemented using a new fabrication process allowing for large area (up to several cm2), freely suspended, flexible and very thin (2μm) metallic membranes. Its optical properties reveal anisotropic transmission with high optical activity. The fabrication method presented in this work has great potential for further use in the fabrication of terahertz optics.

      (Picture: M. Zalkovskij et al.10.1002/lpor.201300034, pp. 810–817, in this issue)

  5. Issue Information

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  6. Call for Papers

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  7. Editorial Advisory Board

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  8. Contents

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  9. Focus: Biophotonics - Techniques & Applications

    1. Top of page
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    3. Inside Front Cover
    4. Inside Back Cover
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    6. Issue Information
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    8. Editorial Advisory Board
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    1. Editorials

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    3. Review Articles

      You have full text access to this OnlineOpen article
      Diode laser based light sources for biomedical applications (pages 605–627)

      André Müller, Sebastian Marschall, Ole Bjarlin Jensen, Jörg Fricke, Hans Wenzel, Bernd Sumpf and Peter E. Andersen

      Version of Record online: 21 DEC 2012 | DOI: 10.1002/lpor.201200051

      Thumbnail image of graphical abstract

      Diode lasers are by far the most efficient lasers currently available. With the ever-continuing improvement in diode laser technology, this type of laser has become increasingly attractive for a wide range of biomedical applications. Compared to the characteristics of competing laser systems, diode lasers simultaneously offer tunability, high-power emission and compact size at fairly low cost. Therefore, diode lasers are increasingly preferred in important applications, such as photocoagulation, optical coherence tomography, diffuse optical imaging, fluorescence lifetime imaging, and terahertz imaging. This review provides an overview of the latest development of diode laser technology and systems and their use within selected biomedical applications.

      670 nm external cavity diode laser for Raman spectroscopy built on a 13 × 4 mm2 microbench (Copyright FBH/Schurian.com).

    4. Coherent fiber supercontinuum for biophotonics (pages 628–645)

      Haohua Tu and Stephen A. Boppart

      Version of Record online: 23 JUL 2012 | DOI: 10.1002/lpor.201200014

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      Biophotonics and nonlinear fiber optics have traditionally been two independent fields. Since the discovery of fiber-based supercontinuum generation in 1999, biophotonics applications employing incoherent light have experienced a large impact from nonlinear fiber optics, primarily because of the access to a wide range of wavelengths and a uniform spatial profile afforded by fiber supercontinuum. However, biophotonics applications employing coherent light have not benefited from the most well-known techniques of supercontinuum generation for reasons such as poor coherence (or high noise), insufficient controllability, and inadequate portability. Fortunately, a few key techniques involving nonlinear fiber optics and femtosecond laser development have emerged to overcome these critical limitations. Despite their relative independence, these techniques are the focus of this review, because they can be integrated into a low-cost portable biophotonics source platform. This platform can be shared across many different areas of research in biophotonics, enabling new applications such as point-of-care coherent optical biomedical imaging.

    5. Advances in fluorescence diagnosis to track footprints of cancer progression in vivo (pages 646–662)

      Malini Olivo, Chris Jun Hui Ho and Chit Yaw Fu

      Version of Record online: 21 FEB 2013 | DOI: 10.1002/lpor.201200059

      Thumbnail image of graphical abstract

      Fluorescence spectroscopy and imaging have been widely used for in vivo cancer diagnosis and therapy monitoring in preclinical models, as well as clinical translation. Great attempts have been made to develop novel fluorescence techniques and improve on existing ones, which can now be used in conjunction with newly developed fluorescent probes for specific cancer imaging. In this review, a broad overview of fluorescence techniques is provided, including photodynamic diagnosis, laser confocal endomicroscopy and fluorescence lifetime imaging, coupled with endogenous and exogenous fluorophores. In particular, endogenous fluorophores, such as nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD), are highlighted as they are linked to cellular metabolism in precancer growth. The use of near-infrared dyes, such as indocynanine green (ICG), for imaging deep-tissue regions is also reviewed. In addition, diagnostic algorithms used for tissue classification and cancer detection will be discussed. Lastly, emerging technologies in fluorescence diagnosis will also be included.

    6. You have full text access to this OnlineOpen article
      Upconverting nanoparticles for pre-clinical diffuse optical imaging, microscopy and sensing: Current trends and future challenges (pages 663–697)

      Can T. Xu, Qiuqiang Zhan, Haichun Liu, Gabriel Somesfalean, Jun Qian, Sailing He and Stefan Andersson-Engels

      Version of Record online: 15 JAN 2013 | DOI: 10.1002/lpor.201200052

      Thumbnail image of graphical abstract

      Upconverting nanoparticles (UCNPs) are a class of recently developed luminescent biomarkers that – in several aspects – are superior to organic dyes and quantum dots. UCNPs can emit spectrally narrow anti-Stokes shifted light with quantum yields which greatly exceed those of two-photon dyes for fluence rates relevant for deep tissue imaging. Compared with conventionally used Stokes-shifting fluorophores, UCNP-based imaging systems can acquire completely autofluorescence-free data with superb contrast. For diffuse optical imaging, the multi-photon process involved in the upconversion process can be used to obtain images with unprecedented resolution. These unique properties make UCNPs extremely attractive in the field of biophotonics. UCNPs have already been applied in microscopy, small-animal imaging, multi-modal imaging, highly sensitive bioassays, temperature sensing and photodynamic therapy. In this review, the current state-of-the-art UCNPs and their applications for diffuse imaging, microscopy and sensing targeted towards solving essential biological issues are discussed.

    7. Fiber optic probes for linear and nonlinear Raman applications – Current trends and future development (pages 698–731)

      Ines Latka, Sebastian Dochow, Christoph Krafft, Benjamin Dietzek and Jürgen Popp

      Version of Record online: 15 JAN 2013 | DOI: 10.1002/lpor.201200049

      Thumbnail image of graphical abstract

      This review focuses on fiber optic probes for linear and nonlinear Raman spectroscopy, especially for medical applications. It aims at providing an overview over contemporary technology, recent first clinical trials, and helps identifying future developments necessary to bring the emerging technology to clinical end users. After a short introduction to linear and nonlinear Raman spectroscopic modalities, general design considerations will be discussed and compared to common fiber probe setups. Subsequently, examples for medical applications of fiber optic Raman probes will be given concentrating on probes for linear Raman spectroscopy as these devices are technologically more mature compared to their counterparts based on nonlinear Raman spectroscopy. The review also includes a brief summary of first multimodal fiber optic probes and highlights their benefits for clinical applications. Finally, probes are introduced which employ either nonlinear Raman spectroscopy or surface enhanced spectroscopy.

    8. You have full text access to this OnlineOpen article
      Recent progress in tissue optical clearing (pages 732–757)

      Dan Zhu, Kirill V. Larin, Qingming Luo and Valery V. Tuchin

      Version of Record online: 31 JAN 2013 | DOI: 10.1002/lpor.201200056

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      Tissue optical clearing technique provides a prospective solution for the application of advanced optical methods in life sciences. This paper gives a review of recent developments in tissue optical clearing techniques. The physical, molecular and physiological mechanisms of tissue optical clearing are overviewed and discussed. Various methods for enhancing penetration of optical-clearing agents into tissue, such as physical methods, chemical-penetration enhancers and combination of physical and chemical methods are introduced. Combining the tissue optical clearing technique with advanced microscopy image or labeling technique, applications for 3D microstructure of whole tissues such as brain and central nervous system with unprecedented resolution are demonstrated. Moreover, the difference in diffusion and/or clearing ability of selected agents in healthy versus pathological tissues can provide a highly sensitive indicator of the tissue health/pathology condition. Finally, recent advances in optical clearing of soft or hard tissue for in vivo imaging and phototherapy are introduced.

    9. Photoacoustic microscopy (pages 758–778)

      Junjie Yao and Lihong V. Wang

      Version of Record online: 31 JAN 2013 | DOI: 10.1002/lpor.201200060

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      Photoacoustic microscopy (PAM) is a hybrid in vivo imaging technique that acoustically detects optical contrast via the photoacoustic effect. Unlike pure optical microscopic techniques, PAM takes advantage of the weak acoustic scattering in tissue and thus breaks through the optical diffusion limit (∼1 mm in soft tissue). With its excellent scalability, PAM can provide high-resolution images at desired maximum imaging depths up to a few millimeters. Compared with backscattering-based confocal microscopy and optical coherence tomography, PAM provides absorption contrast instead of scattering contrast. Furthermore, PAM can image more molecules, endogenous or exogenous, at their absorbing wavelengths than fluorescence-based methods, such as wide-field, confocal, and multi-photon microscopy. Most importantly, PAM can simultaneously image anatomical, functional, molecular, flow dynamic and metabolic contrasts in vivo. Focusing on state-of-the-art developments in PAM, this Review discusses the key features of PAM implementations and their applications in biomedical studies.

    10. Gas in scattering media absorption spectroscopy – from basic studies to biomedical applications (pages 779–796)

      Sune Svanberg

      Version of Record online: 25 FEB 2013 | DOI: 10.1002/lpor.201200073

      Thumbnail image of graphical abstract

      The recently introduced Gas in Scattering Media Absorption Spectroscopy (GASMAS) technique provides novel possibilities for analysis in biophotonics. Free gas in pores or cavities is monitored with narrow-band laser radiation, which can discern the gas absorptive imprints which are typically several orders of magnitude more narrow than the features of the surrounding tissue through which the diffusely scattered light emerges to the detector. Important gases monitored are oxygen and water vapour. Applications include diagnosis of human sinus cavities and surveillance of neonatal children, but also characterization of food-stuffs, food packages and pharmaceutical preparations. Non-biological applications include the study of construction materials such as wood, polystyrene foams and ceramics. For nano-porous materials, information on the pore sizes can be obtained from observed line broadening. Apart from concentration measurements, the GASMAS technique also allows the study of gas transport and diffusion, and pressure and temperature information can also be obtained.

  10. Regular Content

    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
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    9. Contents
    10. Focus: Biophotonics - Techniques & Applications
    11. Regular Content
    12. Frontispiece
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    1. Original Papers

      Imaging of subcutaneous microcirculation vascular network by double correlation Optical Coherence Tomography (pages 797–800)

      Alexander Doronin and Igor Meglinski

      Version of Record online: 10 MAY 2013 | DOI: 10.1002/lpor.201200108

      Thumbnail image of graphical abstract

      Spatial distribution of superficial blood vessels in human skin in vivo has been observed by using the double correlation Optical Coherence Tomography (OCT). To remove background noise, reduce the artifacts associated with patient motions and to increase the overall quality of the experimental OCT images an adaptive Wiener filtering technique has been employed. Fourier domain correlation has been subsequently applied to enhance spatial resolution of images of vascular network in human skin in vivo. Image processing has been performed on Graphics Processing Units (GPUs) utilizing Compute Unified Device Architecture (CUDA) framework in the frequency-domain. This approach allows carrying out image processing in parallel significantly speeding up the computations. The presented results show that the double correlation method permits obtaining 2D/3D OCT images of subcutaneous microcirculation vascular network and its spatial distribution within the human skin with higher spatial resolution compare to the other OCT correlation-based techniques developed earlier.

    2. Optical formation and manipulation of particle and cell patterns using a tapered optical fiber (pages 801–809)

      Hongbao Xin, Rui Xu and Baojun Li

      Version of Record online: 19 JUL 2013 | DOI: 10.1002/lpor.201300028

      Thumbnail image of graphical abstract

      A method for optical formation and controllable manipulation of particle and cell patterns using a tapered optical fiber is demonstrated. With a laser beam at 980-nm wavelength launched into the fiber, different sized silica particles were formed into particle patterns (both one-dimensional chains and two-dimensional arrays) with different particle numbers by optical binding. The formed particle patterns can be controllably manipulated in three dimensions. Using yeast cells as an example, it was demonstrated that the method is applicable for the formation of biological cell patterns, without damage to the yeast cell viability. This method provides a new facile way for biophotonic and biological researches with particles and cells in a highly organized manner.

    3. Optically active Babinet planar metamaterial film for terahertz polarization manipulation (pages 810–817)

      Maksim Zalkovskij, Radu Malureanu, Christian Kremers, Dmitry N. Chigrin, Andey Novitsky, Sergei Zhukovsky, Peter T. Tang, Peter U. Jepsen and Andrei V. Lavrinenko

      Version of Record online: 10 JUN 2013 | DOI: 10.1002/lpor.201300034

      Thumbnail image of graphical abstract

      A planar Babinet-inverted dimer metamaterial possessing strong optical activity is proposed and characterized. An original fabrication method to produce large area (up to several cm2) freely suspended flexible metallic membranes is implemented to fabricate the metamaterial. Its optical properties are characterized by terahertz time-domain spectroscopy, revealing anisotropic transmission with high optical activity. A simple coupled resonator model is applied to explain the principal optical features of the dimers, with predictive power of positions and number of resonances through a parametrical model. The model is validated for correct polarization-dependent quantitative results on the optical activity in transmission spectra. The fabrication method presented in this work as well as the slit dimer design has great potential for exploitation in terahertz optics.

    4. Optimization of direct modulation rate for circular microlasers by adjusting mode Q factor (pages 818–829)

      Xiao-Meng Lv, Yong-Zhen Huang, Ling-Xiu Zou, Heng Long and Yun Du

      Version of Record online: 15 JUL 2013 | DOI: 10.1002/lpor.201300036

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      Semiconductor microcircular lasers have been investigated as potential light sources for photonic integrated circuits and optical interconnections for more than two decades. However, the direct modulation bandwidths of the circular microlasers remain a challenge, especially when being compared with other microlasers, such as photonic crystal lasers. In this paper, microcircular lasers connected to an output waveguide are investigated for high-speed direct modulation with optimized mode Q factors. Small signal modulation with a resonance frequency of fR = 12.5 GHz is realized for a AlGaInAs/InP circular microlaser with a radius of 10 µm at 290 K. Furthermore, clear eye diagrams are observed at 12.5 Gbit/s for a 15-µm radius circular microlaser with fR = 6.9 GHz.

  11. Frontispiece

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      Frontispiece: 4H-SiC: a new nonlinear material for midinfrared lasers (page 830)

      Version of Record online: 11 SEP 2013 | DOI: 10.1002/lpor.201370058

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      Nonlinear optical (NLO) frequency conversion is commonly used for generating midinfrared (MIR) lasers that offer light sources for a variety of applications. However, the low laser damage thresholds of NLO crystals used so far seriously limit the output power of MIR lasers. Shunchong Wang et al. (pp. 831–838) demonstrate a new nonlinear material 4H-SiC for producing midinfrared laser. Broadband midinfrared laser ranging from 3.90 to 5.60 μm is generated in 4H-SiC by phasematched difference-frequency generation for the first time. The results may open a door to practically utilize wide bandgap semiconductors with high laser damage thresholds as nonlinear optical materials for high power output of midinfrared lasers.

  12. Regular Content

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    1. Original Papers

      4H-SiC: a new nonlinear material for midinfrared lasers (pages 831–838)

      Shunchong Wang, Minjie Zhan, Gang Wang, Hongwen Xuan, Wei Zhang, Chunjun Liu, Chunhua Xu, Yu Liu, Zhiyi Wei and Xiaolong Chen

      Version of Record online: 19 JUL 2013 | DOI: 10.1002/lpor.201300068

      Thumbnail image of graphical abstract

      Nonlinear optical (NLO) frequency conversion is commonly used for generating midinfrared (MIR) lasers that offer light sources for a variety of applications. However, the low laser damage thresholds of NLO crystals used so far seriously limit the output power of MIR lasers. Here, a new nonlinear material 4H-SiC is demonstrated for producing MIR laser. Broadband MIR radiation ranging from 3.90 to 5.60 μm is generated in 4H-SiC by phase-matched difference-frequency generation for the first time. The results may open a door to practically utilize wide-bandgap semiconductors with high laser damage thresholds as NLO materials for high power output of MIR lasers.

    2. Editor's Choice

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      Continuous-wave vertically emitting photonic crystal terahertz laser (pages L45–L50)

      Zhaolu Diao, Christopher Bonzon, Giacomo Scalari, Mattias Beck, Jérôme Faist and Romuald Houdré

      Version of Record online: 22 JUL 2013 | DOI: 10.1002/lpor.201300035

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      Compact semiconductor light sources with high performance continuous-wave (CW) and single mode operation are highly demanded for many applications in the terahertz (THz) frequency range. Distributed feedback (DFB) and photonic crystal (PhC) quantum cascade (QC) lasers are amongst the leading candidates in this field. Absorbing boundary condition is a commonly used method to control the optical performance of a laser in double-metal confinement. However, this approach increases the total loss in the device and results in a large threshold current density, limiting the CW maximum output power and operating temperature. In this letter, a robust surface emitting continuous-wave terahertz QC laser is realized in a two-dimensional PhC structure by a second order Bragg grating extractor that simultaneously provides the boundary condition necessary for mode selection. This results in a 3.12 THz single mode CW operation with a 3 mW output power and a maximum operation temperature (Tmax) of 100 K. Also, a highly collimated far-field pattern is demonstrated, which is an important step towards real world applications.

    3. Letters

      Tunneling-induced transparency in a chaotic microcavity (pages L51–L54)

      Yun-Feng Xiao, Xue-Feng Jiang, Qi-Fan Yang, Li Wang, Kebin Shi, Yan Li and Qihuang Gong

      Version of Record online: 21 JUN 2013 | DOI: 10.1002/lpor.201300042

      Thumbnail image of graphical abstract

      A new form of induced transparency enabled by dynamical tunneling coupling of continuous chaos and discrete regular modes in a slightly deformed optical microcavity is demonstrated experimentally. An optical beam is focused on the cavity boundary and tuned on resonance with a high-Q mode, which leads to destructive interference for the excitation of chaotic field and induces a transparency in the transmission. The experimental results are in excellent agreement with a model based on quantum scattering theory. This tunneling-induced transparency is accompanied by extremely steep normal dispersion, and holds great potential in slow light and enhanced nonlinear interactions.

    4. Self-phase-locked degenerate femtosecond optical parametric oscillator based on BiB3O6 (pages L55–L60)

      Venkata Ramaiah-Badarla, Adolfo Esteban-Martin and Majid Ebrahim-Zadeh

      Version of Record online: 22 JUL 2013 | DOI: 10.1002/lpor.201300058

      Thumbnail image of graphical abstract

      A self-phase-locked degenerate femtosecond optical parametric oscillator (OPO) based on the birefringent nonlinear material, bismuth triborate, BiB3O6, synchronously-pumped by a Kerr-lens-mode-locked Ti:sapphire laser at 800 nm is described. By exploiting versatile phase-matching properties of BiB3O6, including large spectral and angular acceptance for parametric generation and low group velocity dispersion in the optical xz plane, stable self-phase-locked degenerate OPO operation centered at 1600 nm is demonstrated using collinear type I (e [RIGHTWARDS ARROW] oo) interaction in a 1.5-mm crystal at room temperature.

      The degenerate OPO output spectrum extends over 46 nm (∼5.4 THz) with 190 fs pulse duration for input pump pulses of 155 fs with a bandwidth of 7 nm. Phase coherence between the pump and degenerate output is verified using f-2f interferometry, and discrete frequency beats caused by different carrier-envelope-offset frequencies are measured using radio frequency measurements.

      Photo shows a 1.5-mm BiB3O6 crystal used as a nonlinear gain medium in a degenerate self-phase-locked femtosecond OPO operating at room temperature. The green beam is the result of non-phase-matched sum-frequency mixing between the pump light and the sub-harmonic OPO field at degeneracy.

    5. Bottom-up engineering of diamond micro- and nano-structures (pages L61–L65)

      Igor Aharonovich, Jonathan C. Lee, Andrew P. Magyar, David O. Bracher and Evelyn L. Hu

      Version of Record online: 9 JUL 2013 | DOI: 10.1002/lpor.201300065

      Thumbnail image of graphical abstract

      Engineering nanostructures from the bottom up enables the creation of carefully sculpted complex structures that are not accessible via top down fabrication techniques, in particular, complex periodic structures for applications in photonics and sensing. In this work a proof of principle that bottom up approach can be adopted and utilized for sculpting devices from diamond is proposed and demonstrated. A realization of periodic structures is achieved by growing nanoscale single crystal diamond through a defined pattern. Optical wave-guiding of a narrow band emission attributed to the SiV defects in diamond is demonstrated by overgrowth on a thin diamond membrane. In addition, an array of hexagonal microdisks with diameter sizes ranging from 1 to 4 μm is demonstrated. The bottom up approach for diamond opens up new avenues for devices fabrication and sculpting three dimensional structures.

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