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  • 51.
    Shahid, Naeem
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Li, Mingyu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Naureen, Shagufta
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Swillo, Marcin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Anand, Srinivasan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Engineering mode-gaps in photonic crystal waveguides for filtering applications2011Inngår i: Conf. Lasers Electro-Opt. Europe Eur. Quantum Electron. Conf., CLEO EUROPE/EQEC, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Photonic crystal (PhC) components in InP-based materials are of practical importance not only for their unique properties but also for integration with conventional optoelectronic components on InP substrate. PhC waveguides have been investigated extensively for their unique waveguiding and dispersive properties. One such interesting property is the mode-gap which results in a transmission mini-stop band (MSB) [1] and has been investigated for applications such as coarse wavelength selection [2]. However, the optical characteristics of the MSB have to be improved significantly. Single heterojunction PhC waveguides have received much less attention [3] and in particular the internal MSB effect due to mode-coupling could bring new functions in such waveguides.

  • 52.
    Shahid, Naeem
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Naureen, Shagufta
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Anand, Srinivasan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Effect of hole shapes on the reliability of deeply-etched InP-based photonic crystal devices2012Inngår i: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 9, nr 7, s. 1670-1673Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present systematic evaluation of the optical transmission characteristics of a set of photonic crystal waveguides (PhCWs) fabricated by two schemes. An optimized hole-reshaping process to obtain cylindrical holes was applied in one scheme and a comparison is made with as-etched PhCWs. The spectral characteristics of the transmission mini- stopband (MSB) in identical waveguides show that the reliability, in terms of spectral position and shape, of fabricated PhCWs using the hole reshaping process is significantly improved in comparison to the as-etched waveguides. The obtained MSB characteristics are attractive for coarse WDM filtering and wavelength selective mirrors.

  • 53.
    Shahid, Naeem
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Naureen, Shagufta
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Li, Min Yue
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling.
    Swillo, Marcin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Kvantelektronik och -optik, QEO.
    Anand, Srinivasan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Novel postetch process to realize high quality photonic crystals in InP2011Inngår i: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 29, nr 3, s. 031202-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thermally driven reflow of material during annealing was positively used to obtain near-vertical sidewall profiles for high-aspect-ratio nanostructures in InP fabricated by dry etching. This is very promising for achieving high optical quality in photonic crystal (PhC) components. Nearly cylindrical profiles were obtained for high-aspect-ratio PhC holes with diameters as small as 200350 nm. Mini stop bands (MSBs) in line-defect PhC waveguides were experimentally investigated for both as-etched and reshaped hole geometries, and their spectral characteristics were used to assess the quality of PhC fabrication. The spectral characteristics of the MSB in PhC waveguides with reshaped holes showed significant improvement in performance with a transmission dip as deep as 35 dB with sharp edges dropping in intensity more than 30 dB for similar to 4 nm of wavelength change. These results show potential for using high extinction drop-filters in InP-based monolithic photonic integrated circuit applications. Finally, it is proposed that other nanostructure geometries may also benefit from this reshaping process.

  • 54.
    Shahid, Naeem
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Naureen, Shagufta
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Li, Mingyu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Swillo, Marcin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Anand, Srinivasan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    High quality photonic crystal waveguide filters based on mode-gap effect2011Inngår i: Conference Proceedings: International Conference on Indium Phosphide and Related Materials, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We demonstrate that the side-wall profiles of high-aspect-ratio two-dimensional (2D) photonic crystals (PhCs) in InP-based materials can be made vertical by reshaping through annealing. The annealing reduces depth and shape irregularities which are inherent to the etch-process. The efficacy of the reshaping is demonstrated by comparing the optical properties of PhC waveguides having as-etched and reshaped PhC-hole geometries. Spectral characteristics of ministop-bands (MSBs), due to coupling of third and fifth order modes with the fundamental mode, are used to qualify PhC fabrication. We demonstrate high optical quality filters based on the MSB effect (first and fifth order modes) and also use the spectral characteristics as a quality indicator of PhC fabrication. The MSBs transmission spectrum shows very sharp cut-offs for reshaped PhC waveguides. It is proposed that the reshaping process using annealing may also be beneficial for other PhC devices, nanostructure geometries and materials.

  • 55.
    Shahid, Naeem
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Speijcken, Noud
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Naureen, Shagufta
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Li, Mingyu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Swillo, Marcin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Kvantelektronik och -optik, QEO.
    Anand, Srinivasan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Ultrasharp ministop-band edge for subnanometer tuning resolution2011Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 98, nr 8, s. 081112-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We propose and demonstrate a method that enables spectral tuning with subnanometer accuracy, and is based on the transmission ministop-band (MSB) in line-defect multimode photonic crystal (PhC) waveguides. The fabricated MSB filter has ultrasharp edges which show a 30 dB drop in transmission in a 4 nm wavelength span. The use of the ultrasharp MSB edge to (optically) determine PhC fabrication accuracy is demonstrated. The wavelength position of the MSB could be tuned by temperature, with a coefficient of 0.1 nm/degrees C. The spectral characteristics of the MSB realized in this work are promising for sensing, tuning, and modulation applications.

  • 56. Sudhakar, S.
    et al.
    Nagarajan, Mony
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Baskar, K.
    Irradiation induced nanotrack and property modification in Zn 3P 22012Inngår i: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 9, nr 7, s. 1636-1639Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Zn 3P 2 epilayers were grown on InP (100) substrates by liquid phase epitaxy (LPE) using In solvent. Zinc composition in the epilayers was varied by changing the zinc mole fraction in the growth melt and was confirmed by energy dispersive X-ray analysis (EDAX). Stoichiometric Zn 3P 2 epilayers were subjected to 100 MeV Ni ion irradiation with various ion fluences of 1 × 10 10 to 1 × 10 13 ions/cm 2 at 77 K. From the high resolution X-ray diffraction (HRXRD) of 100 MeV Ni ion irradiated epilayers, the decrease in the peak intensities and increase in the FWHM values were observed. AFM analysis revealed the formation of nanotracks in the irradiated Zn 3P 2 epilayers. Hall measurements showed the decrease in carrier mobility with the increase of ion fluence. The absorption band edge of Zn 3P 2 gradually decreased from 1.49 eV to 1.42 eV upon increasing the ion fluence.

  • 57. Suresh, S.
    et al.
    Lourdudoss, Sebastian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Landgren, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Baskar, K.
    Studies on the effect of ammonia flow rate induced defects in gallium nitride grown by MOCVD2010Inngår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 312, nr 21, s. 3151-3155Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gallium nitride (GaN) epitaxial layers were grown with different V/III ratios by varying the ammonia (NH3) flow rate, keeping the flow rate of the other precursor, trimethylgallium (TMG), constant, in an MOCVD system. X-ray rocking curve widths of a (1 0 2) reflection increase with an increase in V/III ratio while the (0 0 2) rocking curve widths decrease. The dislocation density was found to increase with an increase in ammonia flow rate, as determined by hot-wet chemical etching and atomic force microscopy. 77K photoluminescence studies show near band emission at 3.49 eV and yellow luminescence peaking at 2.2 eV. The yellow luminescence (YL) intensity decreases with an increase in V/III ratio. Positron annihilation spectroscopy studies show that the concentration of Ga-like vacancies increases with an increase in ammonia flow rate. This study confirms that the yellow luminescence in the GaN arises due to deep levels formed by gallium vacancies decorated with oxygen atoms.

  • 58.
    Swillo, Marcin
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Ivarsson, M.
    Neubeck, A.
    Holm, N. G.
    Broman, C.
    Björk, Gunnar G.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101), Kvantelektronik och -optik, QEO (flyttad till SCI 2011-07-01).
    Laser ablation in selected minerals for extracting fluid in inclusions2011Inngår i: Conf. Lasers Electro-Opt. Europe Eur. Quantum Electron. Conf., CLEO EUROPE/EQEC, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Fluid inclusions are naturally formed micro-containers in minerals that have been sealed since the mineral was formed. Analysis of inorganic and organic fluids from various inclusions is of particular interest for geologists, who are investigating environmental information and sometimes organic content. The inclusions are to a large extent prevented from contamination and many temporal changes as they are embedded within minerals. However, an essential part of the investigation procedure is the method of extracting fluids from such minerals. Since mechanical drilling or polishing involves a high risk for contamination of the sample, it is suggested to use a laser ablation technique to isolate the samples. In order to assess the potential of this technique, we have studied the parameters for laser ablation in quartz, calcite and apatite (the most common minerals containing fluid inclusions).

  • 59.
    Swillo, Marcin
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvantelektronik och -optik, QEO.
    Sanatinia, Reza
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Halvledarmaterial, HMA.
    Anand, Srinivasan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Halvledarmaterial, HMA.
    Surface Optical Nonlinearity in GaP Nanopillar Waveguides2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Second harmonic generation in GaP nanopillars is investigated by polarization measurements and light confinement analysis. Effective thickness of the nonlinear surface region is ~ 10nm and the corresponding nonlinear coefficient 20 times larger than in bulk.

  • 60.
    Usman, Muhammad
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Nazir, Aftab
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Aggerstam, Thomas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Linnarsson, Margareta
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hallén, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Electrical and structural characterization of ion implanted GaN2009Inngår i: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 267, nr 8-9, s. 1561-1563Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ion implantation induced defects and their consequent electrical impact have been investigated. Unintentionally doped n-type gallium nitride was implanted with 100 keV Si+ and 300 keV Ar+ ions in a fluence range of 10(14)-10(15) ions/cm(2). The samples were characterized with Rutherford backscattering/Channeling method for damage buildup. Time of flight elastic recoil detection analysis was implied on the Si implanted samples to see the ion depth distribution. At implanted GaN samples were studied electrically with scanning spreading resistance microscopy. Our results show that an At fluence of 5 x 10(14) cm(-2) increases the resistance by five orders of magnitude to a maximum value. For the highest fluence, 6 x 10(15) cm(-2), the resistivity decreases by two orders of magnitude.

  • 61.
    Wang, Zhechao
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Junesand, Carl
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Metaferia, Wondwosen
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Hu, Chen
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Lourdudoss, Sebastian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101), Fotonik (Stängd 20120101).
    A monolithic integration platform for silicon photonics2011Inngår i: 2011 ICO International Conference on Information Photonics, IP 20112011 ICO International Conference on Information Photonics, IP 2011, IEEE Communications Society, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A novel epitaxial lateral overgrowth (ELOG) technology-based monolithic integration platform for silicon photonics is demonstrated. High quality, defect-free InP ELOG mesa has been experimentally obtained on silicon by using hydride vapor phase epitaxy (HVPE). The proposed platform provides unique advantages for the realization of active devices on silicon

  • 62.
    Westerberg, Staffan
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101). University of California Berkeley, United States.
    Wang, C.
    Somorjai, G. A.
    Heat of adsorption of CO on Pt(1 1 1) obtained by sum frequency generation vibrational spectroscopy: A new technique to measure adsorption isotherms2005Inngår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 582, nr 1-3, s. 137-144Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    CO adsorption on Pt(1 1 1) was studied at temperatures between 373 K and 463 K in a pressure range of 1 × 10-8-3 × 10-5 Torr. Adsorption isotherms were obtained using sum frequency generation, (SFG). By correlating the normalized SFG signal to the surface coverage, the obtained isotherms are in satisfactory agreement with Langmuir adsorption, which is suitable for coverages up to a monolayer. Close to saturation coverage the heat of adsorption was determined to 113(±15) kJ/mol, which is in close agreement to values obtained by single crystal adsorption calorimetry, low energy electron diffraction (LEED) and temperature programmed desorption (TPD) [Y.Y. Yeo, L. Vattuone, D.A. King, J. Chem. Phys. 106 (1997) 392; G. Ertl, M. Neumann, K.M. Streit, Surf. Sci. 64 (1977) 393].

  • 63.
    Wosinski, Lech
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik.
    Wang, Zhechao
    Lou, Fei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik.
    Dai, Daoxin
    Lourdudoss, Sebastian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Thylén, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik.
    Advanced silicon device technologies for optical interconnects2012Inngår i: Optoelectronic Integrated Circuits XIV / [ed] Louay A. Eldada, El-Hang Lee, SPIE - International Society for Optical Engineering, 2012, s. 826506-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Silicon photonics is an emerging technology offering novel solutions in different areas requiring highly integrated communication systems for optical networking, sensing, bio-applications and computer interconnects. Silicon photonicsbased communication has many advantages over electric wires for multiprocessor and multicore macro-chip architectures including high bandwidth data transmission, high speed and low power consumption. Following the INTEL's concept to "siliconize" photonics, silicon device technologies should be able to solve the fabrication problems for six main building blocks for realization of optical interconnects: light generation, guiding of light including wavelength selectivity, light modulation for signal encoding, detection, low cost assembly including optical connecting of the devices to the real world and finally the electronic control systems.

  • 64. Zhou, X. P.
    et al.
    Soares, F. M.
    Fontaine, N. K.
    Baek, J. H.
    Cheung, S.
    Shearn, M.
    Scherer, A.
    Olsson, Fredrik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Lourdudoss, Sebastian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Liu, K. Y.
    Tsang, W. T.
    Yoo, S. J. B.
    16-channel × 100-GHz monolithically integrated O-CDMA transmitter with SPECTS encoder and seven 10-GHz mode-locked lasers2010Inngår i: 2010 Conference on Optical Fiber Communication, Collocated National Fiber Optic Engineers Conference, OFC/NFOEC 2010, New York: IEEE , 2010, s. 5465650-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We demonstrate a fully-integrated O-CDMA transmitter by monolithically integrating 7 collidingpulse mode-locked lasers with two arrayed waveguide gratings and 16 phase modulators in InP technology.

12 51 - 64 of 64
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