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Ultracompact directional couplers realized in InP by utilizing feature size dependent etching
KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.ORCID iD: 0000-0002-3401-1125
KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
2008 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 33, no 17, 1927-1929 p.Article in journal (Refereed) Published
Abstract [en]

We present the design, fabrication, and measurement of an ultracompact directional coupler in InP/InGaAsP/InP. By utilizing the lag effect in the dry etching process, in one etch step, deeply etched asymmetric waveguides with a shallow groove in between are fabricated. This special property enhances the coupling efficiency for the directional coupler and thus makes the device ultracompact. We demonstrate directional couplers as short as 55 mu m, which is only 1/30th the length of the conventional design.

Place, publisher, year, edition, pages
2008. Vol. 33, no 17, 1927-1929 p.
Keyword [en]
silicon-on-insulator, cl-2-h-2, devices
National Category
URN: urn:nbn:se:kth:diva-17852DOI: 10.1364/OL.33.001927ISI: 000259653000001ScopusID: 2-s2.0-51749105202OAI: diva2:335897
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2013-11-19Bibliographically approved
In thesis
1. Design, Simulation and Characterization of Some Planar Lightwave Circuits
Open this publication in new window or tab >>Design, Simulation and Characterization of Some Planar Lightwave Circuits
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Optical devices based on planar lightwave circuit (PLC) technology have the advantages of small size, high reliability, possibility for large scale production, and potential integration with electronics. These devices are widely employed in optical telecommunications, sensing, data storage, imaging, and signal processing. This thesis focuses on some selected PLC based devices, such as power splitters, demultiplexers, triplexers and polarization beam splitters.

First, the basic principle of the waveguides and the simulation methods for PLC devices are discussed. A novel effective index method is introduced to reduce a two-dimensional structure to a one-dimensional one, and can be implemented for arbitrarily shaped waveguides. Numerical methods, such as finite-difference mode solver, beam propagation method, finite-difference time-domain method are introduced to analysis the mode profile of the waveguides, and the propagation properties of light in PLC devices.

Multimode interference (MMI) couplers are widely used in many PLCs, such as power splitters, ring lasers, optical switches, and wavelength division multiplexers/demultiplexers. In this work, concepts for improving the self-imaging quality of MMI couplers are analyzed and new designs are proposed. A significant improvement in performance together with compact sizes were obtained with taper sections at the input/output of MMI couplers based on SOI, and deeply etched ridges in MMI couplers based on SiO2. A polarization insensitive dual wavelength demultiplexer based on sandwiched MMI waveguides was presented.

Novel devices including triplexers and polarization beam splitters were realized by using photonic crystal (PhC) structures. Two stages of directional couplers based on PhC waveguides are cascaded to form an ultracompact triplexer. The special decoupling property of the PhC waveguide based directional coupler was utilized in the design. A novel polarization beam splitter was realized by combining a MMI coupler and a PhC which works as a polarization sensitive reflector.

Finally, fabrication and optical characterization of an ultra-compact directional coupler and PhC structures in InP are presented. In a single etching step, by using the lag-effect in inductively coupled plasma reactive ion etching, a compact directional coupler (55 μm) is demonstrated. Carrier life times in PhC structures etched by chemically assisted ion beam etching were investigated, for emitter and switching applications.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. xiv, 84 p.
Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2008:9
planar lightwave circuit, waveguide, coupler, multimode interference, photonic crystal waveguide, (de)multiplexer, triplexer, polarization beam splitter, dry etching, carrier life time.
National Category
urn:nbn:se:kth:diva-4760 (URN)978-91-7178-989-1 (ISBN)
Public defence
2008-06-09, sal N2, Electrum 3, Isafjordsgatan 28, Kista, Stockholm, 10:00
QC 20100909Available from: 2008-05-16 Created: 2008-05-16 Last updated: 2010-09-09Bibliographically approved

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Shi, YaochengHe, SailingAnand, Srinivasan
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Zhejiang-KTH Joint Research Center of Photonics, JORCEPElectromagnetic EngineeringMicroelectronics and Applied Physics, MAP
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