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Light manipulation in micro and nano photonic materials and structures
KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. (Ying Fu)
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Light manipulation is an important method to enhance the light-matter interactions in micro and nano photonic materials and structures by generating usefulelectric field components and increasing time and pathways of light propagationthrough the micro and nano materials and structures. For example, quantum wellinfrared photodetector (QWIP) cannot absorb normal incident radiation so thatthe generation of an electric field component which is parallel to the original incident direction is a necessity for the function of QWIP. Furthermore, the increaseof time and pathways of light propagation in the light-absorbing quantum wellregion will increase the chance of absorbing the photons.The thesis presents the theoretical studies of light manipulation and light-matter interaction in micro and nano photonic materials and structures, aiming atimproving the performance of optical communication devices, photonic integrateddevices and photovoltaic devices.To design efficient micro and nano photonic devices, it is essential to knowthe time evolution of the electromagnetic (EM) field. Two-dimensional and three-dimensional finite-difference time-domain (FDTD) methods have been adopted inthe thesis to numerically solve the Maxwell equations in micro and nano photonicmaterials and structures.Light manipulation in micro and nano material and structures studied in thisthesis includes: (1) light transport in the photonic crystal (PhC) waveguide, (2)light diffraction by the micro-scale dielectric PhC and metallic PhC structures(gratings); and (3) exciton-polaritons of semiconductor quantum dots, (4) surfaceplasmon polaritons at semiconductor-metallic material interface for subwavelengthlight control. All these aspects are found to be useful in optical devices of multiplebeam splitter, quantum well/dot infrared photodetectors, and solar cells.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , 72 p.
Series
Trita-BIO-Report, ISSN 1654-2312 ; 2012:13
Keyword [en]
Photonic crystal, quantum dot, light-matter interaction
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:kth:diva-94081ISBN: 978-91-7501-353-4OAI: oai:DiVA.org:kth-94081DiVA: diva2:525286
Public defence
2012-06-01, FD51, AlbaNova Universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20120507Available from: 2012-05-07 Created: 2012-05-07 Last updated: 2012-05-07Bibliographically approved
List of papers
1. Increased photocurrent in quantum dot infrared photodetector by subwavelength hole array in metal thin film
Open this publication in new window or tab >>Increased photocurrent in quantum dot infrared photodetector by subwavelength hole array in metal thin film
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2010 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 96, no 23, 231110- p.Article in journal (Refereed) Published
Abstract [en]

Photocurrent enhancement in quantum dot (QD) infrared photodetector (QDIP) with an optical grating of subwavelength hole array in a thin metal film has been studied by calculating the transmission and diffraction of the infrared optical field through the grating and the light-matter interaction between the transmitted optical field and electrons confined in the QD. It is shown that due to the small aspect ratio of realistic QDs in QDIPs, the light diffraction due to the surface plasmon effect at the metal-semiconductor surface and the photonic subwavelength hole array structure is dominant in increasing the photocurrent.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-27515 (URN)10.1063/1.3449117 (DOI)000278695900010 ()2-s2.0-77953508938 (ScopusID)
Note
QC 20110111Available from: 2011-01-11 Created: 2010-12-13 Last updated: 2012-05-07Bibliographically approved
2. Multiple beam splitting to free space from a V groove in a photonic crystal waveguide
Open this publication in new window or tab >>Multiple beam splitting to free space from a V groove in a photonic crystal waveguide
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2011 (English)In: Applied physics. B, Lasers and optics (Print), ISSN 0946-2171, E-ISSN 1432-0649, Vol. 102, no 4, 857-861 p.Article in journal (Refereed) Published
Abstract [en]

We present multiple-beam splitting to free space from a V groove in a two-dimensional photonic crystal waveguide (PCW) with a few additional dielectric rods at the exit of the PCW. Numerical study shows that 'one-beam-in to two-beams-out' (one-to-two, also denoted as Y-shaped), one-to-three, and one-to-five beam splittings can be easily realized over a wide bandwidth, and the split beams have remarkable properties such as symmetric energy distributions and high directional transmissions. Off-axis directional emission can also be achieved by simple displacements of the additional rods at the exit of the PCW.

Keyword
DIRECTIONAL EMISSION; ENHANCEMENT; EMITTER
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-32034 (URN)10.1007/s00340-010-4285-2 (DOI)000288447300022 ()2-s2.0-79955920066 (ScopusID)
Note
QC 20110404Available from: 2011-04-04 Created: 2011-04-04 Last updated: 2012-05-07Bibliographically approved
3. Exciton Polariton Contribution to the Stokes Shift in Colloidal Quantum Dots
Open this publication in new window or tab >>Exciton Polariton Contribution to the Stokes Shift in Colloidal Quantum Dots
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2011 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 115, no 13, 5286-5293 p.Article in journal (Refereed) Published
Abstract [en]

We study the exciton polariton contribution to the Stokes shift in colloidal quantum dots (QDs). By detailed quantum mechanical description of light-matter interaction and temporal analysis of incident electromagnetic field across the QD using the finite-difference time-domain method, we have shown that the optical excitation of an exciton in the QD and its coupling with the excitation radiation (i.e., exciton polariton) induce strong variations in the dielectric constant of the QD which contribute significantly to the Stokes shift and cause modifications 50 in the absorption spectrum that agrees well with experiments.

Keyword
CDS NANOCRYSTALS, DEPOSITION, ENERGY, FILMS, DARK
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-32622 (URN)10.1021/jp109608t (DOI)000288885900014 ()2-s2.0-79953677832 (ScopusID)
Note
QC 20110419Available from: 2011-04-19 Created: 2011-04-18 Last updated: 2012-05-07Bibliographically approved
4. Time-resolved photocurrents in quantum well/dot infrared photodetectors with different optical coupling structures
Open this publication in new window or tab >>Time-resolved photocurrents in quantum well/dot infrared photodetectors with different optical coupling structures
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2012 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, no 4, 043502- p.Article in journal (Refereed) Published
Abstract [en]

Temporal developments of photocurrents excited by an infrared radiation pulse in quantum well/dot infrared photodetectors with different optical coupling structures have been theoretically studied. It is shown that the light diffraction in a conventional reflective grating structure is a near-field effect containing severe crosstalk from neighboring pixels. A concave reflector not only eliminates the crosstalk but also strongly diffracts and focuses the incident electric field into deep active layers, which significantly increases the photocurrents in the photodetectors.

National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-91623 (URN)10.1063/1.3678637 (DOI)000300064500067 ()2-s2.0-84863018238 (ScopusID)
Note
QC 20120323Available from: 2012-03-23 Created: 2012-03-19 Last updated: 2012-05-07Bibliographically approved
5. Comb-shaped photonic crystal structure for efficient broadband light diffraction and funnelling in solar cells
Open this publication in new window or tab >>Comb-shaped photonic crystal structure for efficient broadband light diffraction and funnelling in solar cells
2012 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, Vol. 99, 316-320 p.Article in journal (Refereed) Published
Abstract [en]

We present a comb-shaped photonic-crystal (PhC) rods-lattice structure of broadband light diffraction and funnelling for solar cell applications. It is shown that the photonic band of this PhC structure is very dispersive over a broad bandwidth so that light will be efficiently diffracted in the wavelength region of solar radiation. The PhC structure also creates resonance modes leading to further diffraction and funnelling of light so that the light propagates in many pathways in the whole PhC lattice region, which will greatly facilitate light-matter interaction when light-absorbing elements are embedded in the PhC structure. The proposed structure is also valid for photodetection applications.

Keyword
Light diffraction and funnelling, Photovoltaic, Photonic crystal, Solar cell
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-92990 (URN)10.1016/j.solmat.2011.12.020 (DOI)000301167200044 ()2-s2.0-84862801322 (ScopusID)
Note
QC 20120411Available from: 2012-04-11 Created: 2012-04-10 Last updated: 2012-05-07Bibliographically approved
6. Improving efficiency of quantum dot infrared photodetector by using photonic crystal framework in the active layer
Open this publication in new window or tab >>Improving efficiency of quantum dot infrared photodetector by using photonic crystal framework in the active layer
2011 (English)Conference paper (Refereed)
Abstract [en]

Photonic crystal structure as a framework in both substrate and active layer in quantum dot infrared photodetector is used to improve the interaction between photons and QDs.

National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-94106 (URN)10.1109/CLEOE.2011.5942866 (DOI)2-s2.0-80052289144 (ScopusID)978-145770533-5 (ISBN)
Conference
2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference, CLEO EUROPE/EQEC 2011; Munich; Germany; 22-26 May 2011
Note

QC 20140916

Available from: 2012-05-07 Created: 2012-05-07 Last updated: 2014-09-16Bibliographically approved

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