Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Electromagnetic simulation and design of etched diffraction grating demultiplexers
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Among various planar lightwave circuits for multiplexing/demultiplexing in an optical communication system, etched diffraction gratings (EDGs) have shown great potential due to their compactness and high spectral finesse. Conventional numerical methods for grating simulation cannot be used to simulate an EDG demultiplexer of large size (in terms of the wavelength). In the present thesis, the polarization-dependent characteristics of an EDG demultiplexer are analyzed with a boundary element method (BEM) for both an echelle grating coated with a metal and a dielectric grating with total internal reflection (TIR) facets. For EDGs with metal-coated facets, we use a more effective method, namely, method of moments (MoM). Futhermore, a fast simulation method for EDGs with TIR facets is presented based on the Kirchhoff–Huygens principle and the Goos-Hänchen shift. This simple method has a good agreement with a BEM over a wide range of practical parameters of the device.

Several novel designs are presented in order to improve the performances of EDGs. (1) By making some appropriate roughness on the surface of the shaded facets, the PDL of the demultiplexer can be effectively reduced over a large bandwith. (2) For EDGs based on Si nanowire structures, we compensate the polarization-dependent wavelength dispersion (PDλ) in the whole operational spectrum by introducing a polarization compensation area in its free propagation region. (3) An EDG demultiplexer with suppressed sidelobe is designed. The designed EDG demultiplexer can give a crosstalk as small as 50 dB in theory. (4) By chirping the diffraction order for each facet, we minimize the envelope intensity for the other adjacent diffraction orders to achieve a negligible return loss in a large spectral width. (5) A design for EDG demultiplexers is presented to obtain both large grating facets and a larger free spectral range (FSR) using the optimal chirped diffraction orders for different facets.

The influences of the fabrication errors (e.g., rounded effect, surface roughness and point defect in the waveguide) on the performance (such as the insertion loss, the polarization dependent loss and the chromatic dispersion) of an EDG demultiplexer are also analyzed in detail.

Silicon nanowire waveguides and related EDGs are studied. An EDG demultiplexer with 10 nm spacing is finally fabricated and characterized.

Place, publisher, year, edition, pages
Stockholm: KTH , 2008. , X, 113 p.
Series
Trita-EE, ISSN 1653-5146 ; 2008:078
Keyword [en]
etched diffraction grating, wavelength division multiplexing, passive devices, diffraction grating, planar waveguide devices, DWDM, optical communication.
National Category
Telecommunications
Identifiers
URN: urn:nbn:se:kth:diva-4791OAI: oai:DiVA.org:kth-4791DiVA: diva2:13981
Public defence
2008-06-11, Entreplan D3, Lindstedtsv 5, main campus of KTH, 10:00
Opponent
Supervisors
Note
QC 20100910Available from: 2008-06-02 Created: 2008-06-02 Last updated: 2010-09-10Bibliographically approved
List of papers
1. Fast analysis method for polarization-dependent performance of a concave diffraction grating with total-internal-reflection facets
Open this publication in new window or tab >>Fast analysis method for polarization-dependent performance of a concave diffraction grating with total-internal-reflection facets
2005 (English)In: Journal of the Optical Society of America A: Optics and Image Science, and Vision, ISSN 1084-7529, Vol. 22, no 9, 1947-1951 p.Article in journal (Refereed) Published
Abstract [en]

A fast simulation method for a waveguide-based concave grating with total-internal-reflection (TIR) facets is presented using the Kirchhoff-Huygens principle. Unlike the conventional scalar method, modifications are made to take into account the influence of the Goos-Hanchen (GH) shift. The simple method is in good agreement with a numerical method based on rigorous coupled-wave analysis for a wide range of practical device parameters and can provide an insightful physical explanation for the numerical results. It is shown that the GH shift is a main contributing factor for the loss and the polarization-dependent loss of an etched diffraction grating demultiplexer with TIR facets.

Keyword
Computer simulation, Light polarization, Light reflection, Mathematical models, Numerical methods, Optical communication, Optical waveguides, Refractive index, Wavelength division multiplexing, Arrayed waveguide gratings, Etched diffraction gratings (EDGs), Goos-Hanchen (GH) shift, Hybrid diffraction method (HBD), Kirchoff-Huygens principle, Total-internal-reflection (TIR)
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-8607 (URN)10.1364/JOSAA.22.001947 (DOI)000231544400027 ()2-s2.0-25444439301 (Scopus ID)
Note
QC 20100910Available from: 2008-06-02 Created: 2008-06-02 Last updated: 2013-11-19Bibliographically approved
2. Effects of surface roughness on the performance of an etched diffraction grating demultiplexer
Open this publication in new window or tab >>Effects of surface roughness on the performance of an etched diffraction grating demultiplexer
2006 (English)In: Journal of the Optical Society of America A: Optics and Image Science, and Vision, ISSN 1084-7529, Vol. 23, no 3, 646-650 p.Article in journal (Refereed) Published
Abstract [en]

The fabrication tolerance of surface roughness on the performance [such as the insertion loss, the polarization-dependent loss (PDL), and the chromatic dispersion] of an etched diffraction grating demultiplexer is analyzed by using an accurate method of moments. The results show that both the insertion loss and the chromatic dispersion rapidly increase as the roughness of the grating facets increases. Appropriate residual roughness of the shaded facets can reduce the PDL of the demultiplexer, and the mechanism for the existence of an optimal residual roughness is explained.

Keyword
Demultiplexing, Diffraction, Insertion losses, Light polarization, Optical communication, Optical waveguides, Surface roughness, Wavelength division multiplexing, Chromatic dispersion, Diffraction grating demultiplexer, Polarization dependent loss (PDL)
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-8608 (URN)10.1364/JOSAA.23.000646 (DOI)000235747900017 ()2-s2.0-33645416558 (Scopus ID)
Note
QC 20100910Available from: 2008-06-02 Created: 2008-06-02 Last updated: 2013-11-19Bibliographically approved
3. Sidelobe suppression design of etched diffraction grating demultiplexers using optimized air trenches in front of each output waveguide
Open this publication in new window or tab >>Sidelobe suppression design of etched diffraction grating demultiplexers using optimized air trenches in front of each output waveguide
2006 (English)In: Journal of the Optical Society of America A: Optics and Image Science, and Vision, ISSN 1084-7529, Vol. 23, no 10, 2645-2649 p.Article in journal (Refereed) Published
Abstract [en]

An etched diffraction grating (EDG) demultiplexer with high sidelobe suppression is designed. Sidelobes resulting from two adjacent wavelengths are suppressed by etching two optimized rectangular air trenches in front of each output waveguide that can induce large resonance loss in the adjacent wavelength but have little influence on the operational wavelength. The designed EDG demultiplexer can suppress crosstalk to less than 50 dB in theory.

Keyword
Crosstalk, Demultiplexing, Interference suppression, Optical communication equipment, Adjacent wavelength, Etched diffraction grating demultiplexers, Output waveguide, Sidelobe suppression
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-8609 (URN)10.1364/JOSAA.23.002645 (DOI)000240858500028 ()2-s2.0-33751238787 (Scopus ID)
Note
QC 20100910Available from: 2008-06-02 Created: 2008-06-02 Last updated: 2013-11-19Bibliographically approved
4. Echelle grating demultiplexers with reduced return loss by using chirped diffraction order design
Open this publication in new window or tab >>Echelle grating demultiplexers with reduced return loss by using chirped diffraction order design
2006 (English)In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 18, no 14, 1506-1508 p.Article in journal (Refereed) Published
Abstract [en]

A design for echelle grating demultiplexers is presented to reduce the return loss. The input waveguide is placed on the minimal intensity position of the diffraction envelope. Then, by further chirping the diffraction order for each facet, we minimize the envelope intensity for other adjacent diffraction orders, which can contribute to a negligible return loss for a large spectral width. The present design is appropriate for multifrequency laser or multistage demultiplexer applications.

Keyword
demultiplexing, gratings, optical planar waveguide components, return loss, wavelength division multiplexing (WDM)
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-8610 (URN)10.1109/LPT.2006.877573 (DOI)000240417800036 ()2-s2.0-33745635728 (Scopus ID)
Note
QC 20100909Available from: 2008-06-02 Created: 2008-06-02 Last updated: 2013-11-19Bibliographically approved
5. Etched diffraction grating demultiplexers with large free-spectral range and large grating facets
Open this publication in new window or tab >>Etched diffraction grating demultiplexers with large free-spectral range and large grating facets
2006 (English)In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 18, no 24, 2695-2697 p.Article in journal (Refereed) Published
Abstract [en]

A design for etched diffraction grating demultiplexers is presented to obtain both large grating facets and a larger free-spectral range (FSR) using the optimal chirped diffraction orders for different facets. The large grating facets by using a large diffraction order contribute to lowering the manufacturing difficulty, and can provide lower polarization-dependent loss. However, usually the large diffraction order must lower the FSR of the device by all means. Based on the present design, the FSR can overlay the whole diffraction envelop for a special order, but avoid the influence of the adjacent diffraction envelops. Calculations indicate that the extinction ratio between the operated order and adjacent orders can attain a 35 dB or so, which makes the crosstalk from channels in adjacent envelops to those in the operated diffraction envelop acceptable.

Keyword
Demultiplexing, diffraction order, free-spectral range (FSR), gratings, optical planar waveguide components, wavelength-division multiplexing (WDM)
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-24176 (URN)10.1109/LPT.2006.888046 (DOI)000243173300166 ()2-s2.0-33845863719 (Scopus ID)
Note
QC 20100819Available from: 2010-08-19 Created: 2010-08-19 Last updated: 2013-11-19Bibliographically approved
6. Design of a polarization-insensitive echelle grating demultiplexer based on silicon nanophotonic wires
Open this publication in new window or tab >>Design of a polarization-insensitive echelle grating demultiplexer based on silicon nanophotonic wires
2008 (English)In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 20, no 9-12, 860-862 p.Article in journal (Refereed) Published
Abstract [en]

A polarization-insensitive design of an echelle grating (or etched diffraction grating) demultiplexer based on silicon nanowires is proposed in the present letter, by introducing a polarization compensation area in its free propagation region. The polarization-dependent wavelength shift of the present device has been compensated at the whole spectral range. For a design with nine channels and 10-nm channel spacing, when the wavelength shift at the central channel 1550 nm is. completely compensated, the wavelength shifts of the two edge channels are only 0.14 and 0.15 nm, which are acceptable.

Keyword
arrayed waveguide grating (AWG), etched diffraction grating (EDG), polarization compensation, silicon-on-insulator (SOI) nanowire, wavelength-division multiplexing (WDM), photonic wires, wave-guides
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-17628 (URN)10.1109/lpt.2008.921839 (DOI)000256966100065 ()2-s2.0-67149142269 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2013-11-19Bibliographically approved

Open Access in DiVA

fulltext(1984 kB)942 downloads
File information
File name FULLTEXT01.pdfFile size 1984 kBChecksum MD5
183accfa490c0b7795034d305efdef2de0ff7abd9d98eacb425cc1583456b9a1de32a3e5
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Song, Jun
By organisation
Electromagnetic Engineering
Telecommunications

Search outside of DiVA

GoogleGoogle Scholar
Total: 942 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

urn-nbn

Altmetric score

urn-nbn
Total: 566 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf