1,728,918 research outputs found
AMOL
No full textThesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 91-94).In this thesis, the concept of absorbance-modulation optical lithography (AMOL) is described, and the feasibility experimentally verified. AMOL is an implementation of nodal lithography, which is not bounded by the diffraction limit of incident lights. Experimental results showed promising capability of AMOL and matched well with simulation. Several key elements of the AMOL system are discussed: the material systems of AMOL, limitations on the material and optical systems presented, and the design and fabrication of spiral phase elements that generate ring-shaped beams required by AMOL.by Hsin-Yu Sidney Tsai.S.M
Modern traumas
No full textModern traumas is an evocative collection of poetry that explores some of the most troubling and disturbing issues of our time. In its sweep, universality and poignancy the work has been hailed as a unique achievement in contemporary literature by the author, Amol Titus, whose previous works darkness at Bamiyan and A Summit at Jungfraujoch have resonated with a diverse cross section of readers.Jakarta106 halaman : ilustrasi ; 30 c
Opportunities and Challenges in Twisted Bilayer Graphene: A Review
No full textTwo-dimensional (2D) materials exhibit enhanced physical, chemical, electronic, and optical properties when compared to those of bulk materials. Graphene demands significant attention due to its superior physical and electronic characteristics among different types of 2D materials. The bilayer graphene is fabricated by the stacking of the two monolayers of graphene. The twisted bilayer graphene (tBLG) superlattice is formed when these layers are twisted at a small angle. The presence of disorders and interlayer interactions in tBLG enhances several characteristics, including the optical and electrical properties. The studies on twisted bilayer graphene have been exciting and challenging thus far, especially after superconductivity was reported in tBLG at the magic angle. This article reviews the current progress in the fabrication techniques of twisted bilayer graphene and its twisting angle-dependent properties. © 2020, The Author(s).1
Compact, high-repetition-rate sources
No full textIn this talk, I will give a brief overview of the state of the art high-repetition-rate, mode-locked sources and will outline their relevance in many applications. I will then focus on our research on waveguide lasers, quantum-dot-doped glasses and recent demonstrations of mode-locked waveguide laser sources
Application of Geographical Information system (GIS) in urban water of Amol in Iran at time of natural disaster
No full textFor the management of urban disaster risk, periodic updating of geo- databases of urban water is crucial, particularly in developing countries where urbanisation rates are very high. However, collecting information on the characteristics of buildings and lifelines through full ground surveys can be very costly and time-consuming. this article has done operationally in Amol city which is located in Mazandaran Province of Iran and it tries to represent by using rules and data of collected from different maps, urban designing and capabilities of Geographical Information system (GIS) in urban water management at the time of natural disasters. Structure of this article is like that in first we established a comprehensive data base related to water utilities by collecting, entering, saving and data management, then by modeling water utilities we had practically considered its operational aspects related to water utilities problems in urban regions
Low Carbon Strategies for the Indian Electricity Sector: Opportunities for Leapfrogging
No full textAmol Phadke research focuses on low carbon pathways for the electricity sector and policy and program innovation to achieve the same. He currently leads LBNL’s support to the U.S. Department of Energy on the Super Efficient Appliance Deployment Initiative (SEAD), a multi- country collaboration to accelerate appliance and equipment efficiency. He also co-leads LBNL’s collaboration with the Regulatory Assistance Project as a Global Best Practice Network on Power where most of LBNL’s efforts are focused on clean energy policies and programs in India. Amol routinely advises national and state governments in India and the U.S. on clean energy policies and programs. Amol has a Bachelor of Engineering degree from Government College of Engineering, Pune, India and a M.S. and Ph.D. from the Energy and Resources Group, UC Berkeley.Lecture delivered at Humboldt State University on October 20, 2011 by Amol Phadke, Principle Scientific Engineering Associate at the International Energy Studies Group. Part of the Sustainable futures speaker series sponsored by the Schatz Energy Research Center and the Environment and Community Program
Ultrafast waveguide lasers
No full textMode-locked lasers with repetition-rates in excess of 1 GHz have many applications in areas such as optical sampling, non-linear microscopy, and optical frequency metrology. To date there have been very few demonstrations of such high repetition-rate lasers with sub-picosecond operation and high average power. This thesis deals with the realisation of such compact sources using an integrated-optics platform. Waveguides offer certain key advantages, including a low threshold power, high slope efficiency, compatibility with monolithic devices, and a low mode-locking threshold, making them very promising candidates for such devices. Ultrafast multi-GHz waveguide lasers are described in this thesis, which are compact, mass-producible and low-cost making them very exciting candidates for industrial applications. Mode-locking was demonstrated in an ion-exchanged Yb:phosphate glass waveguide laser with integrated saturable absorber elements. An average output power as high as 80 mW was achieved at a pulse repetition frequency (PRF) of 4.9 GHz, at a wavelength around 1 µm and with pulse durations as short as 740 fs. Using shorter cavity lengths, waveguide lasers with PRFs of 10.4 GHz, 12 GHz and 15.2 GHz were achieved with pulse durations between 757 fs and 824 fs. A Gires Tournois Interferometer (GTI) effect was used to facilitate soliton mode-locking in the waveguides via accurate control of the gap between the waveguide and the output coupling mirror. This is a convenient technique to control the dispersion without introducing any extra elements in the laser cavity. Two further Yb-doped ultrafast laser hosts, RbTiOPO4 and KY(WO4)2, were investigated for their potential as ultrafast waveguide laser sources, having both been previously demonstrated as good bulk ultrafast systems. Laser action was demonstrated for the first time in an (Yb,Nb):RbTiOPO4 planar waveguide laser, fabricated by liquid-phase epitaxy. Ion-beam milling was then used to fabricate the first ever single-mode rib waveguides in (Yb,Nb):RbTiOPO4 fabricated by dry etching techniques but laser action was not possible due to propagation losses of ~3dB/cm. A systematic study of the reactive ion etching of RbTiOPO4 was then carried out to minimise the surface roughness, in an attempt to reduce the propagation losses. The first ever demonstration of single-mode waveguiding in (Yb,Nb):RbTiOPO4 fabricated by reactive ion etching was demonstrated but the propagation losses remained high. Using (Yb,Gd,Lu):KY(WO4)2 as a gain media, efficient laser action was demonstrated in an "inverted-rib" waveguide laser structure fabricated by ion-beam milling. This laser was found to have a threshold power as low as 13 mW and a maximum slope efficiency of 58% and showed characteristics of a pure 3-level laser by lasing at 981 nm. However, further loss reduction is again required in order for efficient ultrafast operation to be obtained in the future. Mode-locked waveguide laser operation was extended to the 1.5µm spectral region based on an ion-exchanged Er,Yb:phosphate glass waveguide laser using a novel SESAM based on a quantum dot in well (DWELL) structure. 2.5 ps pulses at a PRF of 4.8 GHz and an average output power of 9 mW were achieved. With a shorter waveguide sample, a PRF of 6.8 GHz with an average output power of 30 mW and pulse duration of 5.4 ps was achieved. The repetition-rate of the laser was finely tuned by controlling the pump power offering an attractive technique for enabling future frequency-comb stabilisation. This is the highest reported repetition-rate from a mode-locked waveguide laser at 1.5 µm and is also the first ever waveguide laser mode-locked by a quantum dot SESAM. Finally, as an initial step towards further extension to the 2µm spectral region, laser action was demonstrated, for the first time, in an ion-exchanged Tm:glass waveguide laser with a threshold power as low as 44 mW and a maximum slope efficiency of 6.8% around 1.9 µm. Designs for power-scaling of such sources have also been discussed in this thesis
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