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Photosensitivity of boron-codoped PECVD films in application to grating assisted WDM devices
KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.ORCID iD: 0000-0001-5967-2651
Phoxtal Communications AB.ORCID iD: 0000-0003-2136-4914
2004 (English)In: INTEGRATED OPTICS AND PHOTONIC INTEGRATED CIRCUITS / [ed] Righini, GC; Honkanen, S, BELLINGHAM: SPIE-INT SOC OPTICAL ENGINEERING , 2004, Vol. 5451, 191-198 p.Conference paper, Published paper (Refereed)
Abstract [en]

UV sensitivity of B-Ge codoped cores in PECVD silica waveguides has been investigated. Photoinduced refractive index changes have been introduced by KrF excimer laser irradiation at 248 rim, without any presensitization method. The effects of B codoping of Ge doped silica have been examined. It has been shown that B addition mildly increases glass network disorder, by broadening the O bridging angle distribution as from FTIR measurements, but on the other hand it does not produce point defects which may contribute to the absorption band at 5eV already generated by the presence of Ge doping. The fabricated channel waveguides show low optical loss even without high temperature annealing. Strong Bragg gratings imprinted into these waveguides confirm that in non thermally annealed Ge doped PECVD silica glass, where a small absorption band still exist at 5eV, B codoping supplies sufficient photosensitivity amplification to make hydrogen loading unnecessary.

Place, publisher, year, edition, pages
BELLINGHAM: SPIE-INT SOC OPTICAL ENGINEERING , 2004. Vol. 5451, 191-198 p.
Series
PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE), ISSN 0277-786X ; 5451
Keyword [en]
photosensitivity, Bragg gratings, silica-on-silicon technology, planar lightwave circuit (PLC), boron codoping, PECVD fabrication
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-4998DOI: 10.1117/12.545813ISI: 000223995500022Scopus ID: 2-s2.0-12344253989ISBN: 0-8194-5374-9 (print)OAI: oai:DiVA.org:kth-4998DiVA: diva2:7375
Conference
Conference Optics and Photonic Integrated Circuits. Strasbourg, FRANCE. APR 27-29, 2004
Note
QC 20101004 QC 20111025Available from: 2005-03-10 Created: 2005-03-10 Last updated: 2011-11-01Bibliographically approved
In thesis
1. Plasma assisted technology for Si-based photonic integrated circuits
Open this publication in new window or tab >>Plasma assisted technology for Si-based photonic integrated circuits
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The last two decades have witnessed a large increase in capacity in telecommunication systems, thanks to the development of high bandwidth, fiber optic based networks. Nevertheless the continuing growth of Internet data traffic, fuelled by the development of numerous services like on-line commerce, video on demand, large audio/video files downloads, demands for a significant increase in the ability of the network nodes to manage incoming and outcoming data streams effectively and fast. The different functionalities that are needed include add/drop channel multiplexing, routing, signal reshaping and retiming, electrical/optical and optical/electrical conversion. This has stimulated a large effort towards the investigation of technologies for opto-electronic integration at a wafer level, in order to cope with all the required operations, while limiting overall costs. Among the different approaches proposed, one of the most promising is the “Silicon optical bench”, which relies on the well established VLSI technology for the microelectronics part and on planar lightwave circuits (PLCs) made either with silica-on-silicon waveguide technology (low index contrast) of amorphous silicon technology (high index contrast) on the integrated optics side.

This thesis presents the development of new techniques and methodologies utilized in photonic device fabrication, which can be used to facilitate integration of temperature sensitive elements. The process is based on low temperature, plasma assisted, thick film deposition. First, a low temperature (300°C) deposition process based on Plasma assisted Chemical Vapour Deposition (PACVD) for the fabrication of silica based Planar Lightwave Circuits (PLC) is developed. The low thermal budget lends itself to monolithic integration with devices fabricated with different technologies. Absorption bands at around the wavelengths 1.48µm and 1.51µm caused by N-H and Si-H bonds within the material, respectively, had previously been thought to be intrinsic to the PACVD deposition method, when using N2O as oxidant gas of SiH4 and the other dopant precursors. The traditional method to eliminate these absorption bands was high temperature (>1000°C) annealing that seriously hinders device integration. An important achievement in this thesis is the improved suppression of these two absorption bands while keeping the whole fabrication temperature below 300°C and also having a high deposition rate. A complete fabrication process for silica planar lightwave circuits was also developed, by optimising the photolithography and etching step. Finally the effect of dopants like Ge and B on the optical properties of the deposited silica glass was investigated, with particular emphasis to the photosensitive properties of the material upon illumination in the near UV. UV trimming is shown to be a versatile method to selectively control polarization birefringence of devices. Transmission dips of above 50dB were achieved in photo-induced gratings in low temperature deposited B-Ge codoped waveguide cores, without the need for hydrogen loading or other sensitisation techniques. The application of a high refractive index like amorphous silicon is addressed for the realization of efficient Bragg reflectors, either as vertical cavity laser mirrors or as dispersive element for planar waveguides used in highly selective co-directional coupler filters. Applications of amorphous silicon as core material for photonic crystal devices are also shown. The investigations carried out in this thesis show that PACVD technology can provide low-loss and UV sensitive material suitable for realizing a variety of low cost integrated devices for future all optical networks.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. 34 p.
Series
Trita-MVT, ISSN 0348-4467 ; 2005:2
Keyword
Electrical engineering, silica-on-silicon technology, PACVD, plasma deposition, photonic integrated circuits, planar lightwave circuits, Elektroteknik, elektronik och fotonik
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-148 (URN)
Public defence
2005-03-21, Sal C1, KTH-Electrum, Isafjordsgatan 22, Kista, 10:00 (English)
Opponent
Supervisors
Note
QC 20101004Available from: 2005-03-10 Created: 2005-03-10 Last updated: 2010-10-04Bibliographically approved

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Wosinski, LechSwillo, Marcin

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