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Publications (10 of 124) Show all publications
Vasileva, E., Baitenov, A., Chen, H., Li, Y., Sychugov, I., Yan, M., . . . Popov, S. (2019). Effect of transparent wood on the polarization degree of light. Optics Letters, 44(12), 2962-2965
Open this publication in new window or tab >>Effect of transparent wood on the polarization degree of light
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2019 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 44, no 12, p. 2962-2965Article in journal (Refereed) Published
Abstract [en]

We report on the study of polarization properties of light propagating through transparent wood (TW), which is an anisotropically scattering medium, and consider two cases: completely polarized and totally unpolarized light. It was demonstrated that scattered light distribution is affected by the polarization state of incident light. Scattering is the most efficient for light polarized parallel to cellulose fibers. Furthermore, unpolarized light becomes partially polarized (with a polarization degree of 50%) after propagating through the TW. In the case of totally polarized incident light, however, the degree of polarization of transmitted light is decreased, in an extreme case to a few percent, and reveals an unusual angular dependence on the material orientation. The internal hierarchical complex structure of the material, in particular cellulose fibrils organized in lamellae, is believed to be responsible for the change of the light polarization degree. It was demonstrated that the depolarization properties are determined by the angle between the polarization of light and the wood fibers, emphasizing the impact of their internal structure, unique for different wood species.

Place, publisher, year, edition, pages
OPTICAL SOC AMER, 2019
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-255191 (URN)10.1364/OL.44.002962 (DOI)000471636700005 ()31199356 (PubMedID)2-s2.0-85067943575 (Scopus ID)
Funder
EU, European Research Council, 742733
Note

QC 20190904

Available from: 2019-09-04 Created: 2019-09-04 Last updated: 2020-05-23Bibliographically approved
Zhang, Y., Ren, X., Liu, D., Yan, M. & Zhang, M. (2019). Inverse design of compact digital nanophotonic power dividers with arbitrary power ratios using modified adjoint method. In: 2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2019: . Paper presented at 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC). Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>Inverse design of compact digital nanophotonic power dividers with arbitrary power ratios using modified adjoint method
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2019 (English)In: 2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2019, Institute of Electrical and Electronics Engineers Inc. , 2019Conference paper, Published paper (Refereed)
Abstract [en]

Inverse-designed digital nanophotonic devices have been widely and successfully used due to their simple brute-force design methods, compact footprint, flexibly-designed functions and high performance in various applications. Unfortunately, the number of 3D FDTD simulations in brute-force methods will increase exponentially with the 'pixel' number in a digital pattern, which may drastically limit the inverse design capability of digital nanophotonic devices. In this work, we propose and demonstrate a modified adjoint method for efficient inverse design of compact digital nanophotonic power dividers with arbitrary power ratios.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2019
National Category
Computer Sciences
Identifiers
urn:nbn:se:kth:diva-272373 (URN)10.1109/CLEOE-EQEC.2019.8873169 (DOI)2-s2.0-85074657334 (Scopus ID)9781728104690 (ISBN)
Conference
2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)
Note

QC 20200513

Available from: 2020-05-13 Created: 2020-05-13 Last updated: 2020-05-13Bibliographically approved
Medina, L., Nishiyama, Y., Daicho, K., Saito, T., Yan, M. & Berglund, L. (2019). Nanostructure and Properties of Nacre-Inspired Clay/Cellulose Nanocomposites—Synchrotron X-ray Scattering Analysis. Macromolecules, 52(8), 3131-3140
Open this publication in new window or tab >>Nanostructure and Properties of Nacre-Inspired Clay/Cellulose Nanocomposites—Synchrotron X-ray Scattering Analysis
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2019 (English)In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, no 8, p. 3131-3140Article in journal (Refereed) Published
Abstract [en]

Nacre-inspired clay nanocomposites have excellent mechanical properties, combined with optical transmittance, gas barrier properties, and fire retardancy, but the mechanical properties are still below predictions from composite micromechanics. The properties of montmorillonite clay/nanocellulose nanocomposite hybrids are investigated as a function of clay content and show a maximum Young’s modulus as high as 28 GPa. Ultimate strength, however, decreases from 280 to 125 MPa between 0 and 80 wt % clay. Small-angle and wide-angle X-ray scattering data from synchrotron radiation are analyzed to suggest nanostructural and phase interaction factors responsible for these observations. Parameters discussed include effective platelet modulus, platelet out-of-plane orientation distribution, nanoporosity, and platelet agglomeration state.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Composite Science and Engineering Paper, Pulp and Fiber Technology Nano Technology
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-249608 (URN)10.1021/acs.macromol.9b00333 (DOI)000466053200022 ()2-s2.0-85064838487 (Scopus ID)
Funder
Knut and Alice Wallenberg FoundationSwedish Foundation for Strategic Research , RMA11-0065
Note

QC 20190521

Available from: 2019-04-12 Created: 2019-04-12 Last updated: 2020-03-09Bibliographically approved
Lu, L., Liu, D., Yan, M. & Zhang, M. (2019). Subwavelength adiabatic multimode Y-junctions. Optics Letters, 44(19), 4729-4732
Open this publication in new window or tab >>Subwavelength adiabatic multimode Y-junctions
2019 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 44, no 19, p. 4729-4732Article in journal (Refereed) Published
Abstract [en]

Adiabatic multimode Y-junctions are extensively used for the design of multimode silicon photonics devices due to their straightforward principle in achieving mode splitting and manipulation. However, experimentally, the limited feature size achievable by lithography can greatly deteriorate the adiabatic branching property and result in large excess loss and crosstalk. Here, we propose a branch structure consisting of a circular-hole-based chirped subwavelength slot. By optimizing the holes' radii and positions under our fabrication constraint, we designed and experimentally demonstrated both symmetric and asymmetric approximately adiabatic four-mode Y-junctions with excellent performance close to ideal Y-junctions over a broad wavelength span. Such junctions are compact, CMOS-compatible, exhibit a relatively large fabrication tolerance, and could be extended for more modes; hence they can be potentially deployed for mode-division multiplexing silicon-photonic systems.

Place, publisher, year, edition, pages
OPTICAL SOC AMER, 2019
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-262962 (URN)10.1364/OL.44.004729 (DOI)000488503500027 ()31568428 (PubMedID)2-s2.0-85072760891 (Scopus ID)
Note

QC 20191205

Available from: 2019-12-05 Created: 2019-12-05 Last updated: 2020-03-09Bibliographically approved
Chen, H., Baitenov, A., Li, Y., Vasileva, E., Popov, S., Sychugov, I., . . . Berglund, L. (2019). Thickness Dependence of Optical Transmittance of Transparent Wood: Chemical Modification Effects. ACS Applied Materials and Interfaces, 11(38), 35451-35457
Open this publication in new window or tab >>Thickness Dependence of Optical Transmittance of Transparent Wood: Chemical Modification Effects
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2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 38, p. 35451-35457Article in journal (Refereed) Published
Abstract [en]

Transparent wood (TW) is an emerging optical material combining high optical transmittance and haze for structural applications. Unlike nonscattering absorbing media, the thickness dependence of light transmittance for TW is complicated because optical losses are also related to increased photon path length from multiple scattering. In the present study, starting from photon diffusion equation, it is found that the angle-integrated total light transmittance of TW has an exponentially decaying dependence on sample thickness. The expression reveals an attenuation coefficient which depends not only on the absorption coefficient but also on the diffusion coefficient. The total transmittance and thickness were measured for a range of TW samples, from both acetylated and nonacetylated balsa wood templates, and were fitted according to the derived relationship. The fitting gives a lower attenuation coefficient for the acetylated TW compared to the nonacetylated one. The lower attenuation coefficient for the acetylated TW is attributed to its lower scattering coefficient or correspondingly lower haze. The attenuation constant resulted from our model hence can serve as a singular material parameter that facilitates cross-comparison of different sample types, at even different thicknesses, when total optical transmittance is concerned. The model was verified with two other TWs (ash and birch) and is in general applicable to other scattering media.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
transparent wood, transmittance, photon diffusion equation, attenuation coefficient, anisotropic scattering
National Category
Physical Sciences
Research subject
Physics, Material and Nano Physics; Physics, Material and Nano Physics
Identifiers
urn:nbn:se:kth:diva-262791 (URN)10.1021/acsami.9b11816 (DOI)000488322900100 ()31483595 (PubMedID)2-s2.0-85072687041 (Scopus ID)
Funder
EU, European Research Council, 742733
Note

QC 20191022

Available from: 2019-10-22 Created: 2019-10-22 Last updated: 2020-05-14Bibliographically approved
Li, Y., Yang, X., Fu, Q., Rojas, R., Yan, M. & Berglund, L. (2018). Towards centimeter thick transparent wood through interface manipulation. Journal of Materials Chemistry A, 6(3), 1094-1101
Open this publication in new window or tab >>Towards centimeter thick transparent wood through interface manipulation
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2018 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, no 3, p. 1094-1101Article in journal (Refereed) Published
Abstract [en]

Transparent wood is an attractive structural material for energy-saving buildings due to its high optical transmittance, good thermal insulation, and high toughness. However, thick highly transparent wood is challenging to realize. In the current work, highly transparent wood (1.5 mm) with a transmittance of 92%, close to that of pure PMMA (95%), is demonstrated. The high transmittance was realized by interface manipulation through acetylation of wood template. Both experiments and electromagnetic modeling support that the improved transmittance is mainly due to elimination of interface debonding gap. By applying this method, a centimeter-thick transparent wood structure was obtained. The transparent wood could be used as a substrate for an optically tunable window by laminating a polymer dispersed liquid crystal (PDLC) film on top. The techniques demonstrated are a step towards the replacement of glass in smart windows and smart buildings.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2018
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-222182 (URN)10.1039/c7ta09973h (DOI)000422949700040 ()2-s2.0-85040915327 (Scopus ID)
Note

QC 20180206

Available from: 2018-02-06 Created: 2018-02-06 Last updated: 2018-02-06Bibliographically approved
Li, Y., Yang, X., Fu, Q., Rojas, R., Yan, M. & Berglund, L. (2018). Towards centimeter thick transparent wood through interface manipulation. International Journal of Materials and Chemistry, 6, 1094-1101
Open this publication in new window or tab >>Towards centimeter thick transparent wood through interface manipulation
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2018 (English)In: International Journal of Materials and Chemistry, ISSN 2166-5346, E-ISSN 2166-5354, Vol. 6, p. 1094-1101Article in journal (Refereed) Published
Abstract [en]

Transparent wood is an attractive structural material for energy-saving buildings due to its high optical transmittance, good thermal insulation, and high toughness. However, thick highly transparent wood is challenging to realize. In the current work, highly transparent wood (1.5 mm) with a transmittance of 92%, close to that of pure PMMA (95%), is demonstrated. The high transmittance was realized by interface manipulation through acetylation of wood template. Both experiments and electromagnetic modeling support that the improved transmittance is mainly due to elimination of interface debonding gap. By applying this method, a centimeter-thick transparent wood structure was obtained. The transparent wood could be used as a substrate for an optically tunable window by laminating a polymer dispersed liquid crystal (PDLC) film on top. The techniques demonstrated are a step towards the replacement of glass in smart windows and smart buildings.

National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-273235 (URN)10.1039/c7ta09973h (DOI)000422949700040 ()2-s2.0-85040915327 (Scopus ID)
Funder
EU, European Research Council, 742733
Note

QC 20200515

Available from: 2020-05-12 Created: 2020-05-12 Last updated: 2020-05-15Bibliographically approved
Fu, Q., Yan, M., Jungstedt, E., Yang, X., Li, Y. & Berglund, L. A. (2018). Transparent plywood as a load-bearing and luminescent biocomposite. Composites Science And Technology, 164, 296-303
Open this publication in new window or tab >>Transparent plywood as a load-bearing and luminescent biocomposite
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2018 (English)In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 164, p. 296-303Article in journal (Refereed) Published
Abstract [en]

Transparent wood (TW) structures in research studies were either thin and highly anisotropic or thick and isotropic but weak. Here, transparent plywood (TPW) laminates are investigated as load-bearing biocomposites with tunable mechanical and optical performances. Structure-property relationships are analyzed. The plies of TPW were laminated with controlled fiber directions and predetermined stacking sequence in order to control the directional dependence of modulus and strength, which would give improved properties in the weakest direction. Also, the angular dependent light scattering intensities were investigated and showed more uniform distribution. Luminescent TPW was prepared by incorporation of quantum dots (QDs) for potential lighting applications. TPW can be designed for large-scale use where multiaxial load-bearing performance is combined with new optical functionalities.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Transparent Wood, Nanotechnology, Biocomposite, Photonics
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-233274 (URN)10.1016/j.compscitech.2018.06.001 (DOI)000440121700036 ()2-s2.0-85048381154 (Scopus ID)
Funder
EU, European Research Council, 742733
Note

QC 20180821

Available from: 2018-08-21 Created: 2018-08-21 Last updated: 2020-05-15Bibliographically approved
Li, Y., Fu, Q., Rojas, R., Yan, M., Lawoko, M. & Berglund, L. (2017). Lignin-Retaining Transparent Wood. ChemSusChem, 10(17), 3445-3451
Open this publication in new window or tab >>Lignin-Retaining Transparent Wood
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2017 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, no 17, p. 3445-3451Article in journal (Refereed) Published
Abstract [en]

Optically transparent wood, combining optical and mechanical performance, is an emerging new material for light-transmitting structures in buildings with the aim of reducing energy consumption. One of the main obstacles for transparent wood fabrication is delignification, where around 30wt% of wood tissue is removed to reduce light absorption and refractive index mismatch. This step is time consuming and not environmentally benign. Moreover, lignin removal weakens the wood structure, limiting the fabrication of large structures. A green and industrially feasible method has now been developed to prepare transparent wood. Up to 80wt% of lignin is preserved, leading to a stronger wood template compared to the delignified alternative. After polymer infiltration, a high-lignin-content transparent wood with transmittance of 83%, haze of 75%, thermal conductivity of 0.23WmK(-1), and work-tofracture of 1.2MJm(-3) (a magnitude higher than glass) was obtained. This transparent wood preparation method is efficient and applicable to various wood species. The transparent wood obtained shows potential for application in energy-saving buildings.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2017
Keywords
building materials, delignification, energy saving, lignin, wood
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-214873 (URN)10.1002/cssc.201701089 (DOI)000410136800018 ()28719095 (PubMedID)2-s2.0-85029175474 (Scopus ID)
Funder
EU, European Research Council, 742733
Note

QC 20171024

Available from: 2017-10-24 Created: 2017-10-24 Last updated: 2020-05-15Bibliographically approved
Li, Y., Fu, Q., Rojas, R., Yan, M., Lawoko, M. & Berglund, L. (2017). Lignin-Retaining Transparent Wood. ChemSusChem, 10(17), 3445-3451
Open this publication in new window or tab >>Lignin-Retaining Transparent Wood
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2017 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, no 17, p. 3445-3451Article in journal (Refereed) Published
Abstract [en]

Optically transparent wood, combining optical and mechanical performance, is an emerging new material for light-transmitting structures in buildings with the aim of reducing energy consumption. One of the main obstacles for transparent wood fabrication is delignification, where around 30wt% of wood tissue is removed to reduce light absorption and refractive index mismatch. This step is time consuming and not environmentally benign. Moreover, lignin removal weakens the wood structure, limiting the fabrication of large structures. A green and industrially feasible method has now been developed to prepare transparent wood. Up to 80wt% of lignin is preserved, leading to a stronger wood template compared to the delignified alternative. After polymer infiltration, a high-lignin-content transparent wood with transmittance of 83%, haze of 75%, thermal conductivity of 0.23WmK(-1), and work-tofracture of 1.2MJm(-3) (a magnitude higher than glass) was obtained. This transparent wood preparation method is efficient and applicable to various wood species. The transparent wood obtained shows potential for application in energy-saving buildings.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2017
Keywords
building materials, delignification, energy saving, lignin, wood
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-273382 (URN)
Funder
EU, European Research Council, 742733
Note

QC 20171024

Available from: 2020-05-15 Created: 2020-05-15 Last updated: 2020-05-15Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3368-9786

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