Abstract-Out-of-plane losses are the major issue in the integration of two-dimensional photonic crystal devices in photonic integrated circuits. In this paper, we show that the out-of-plane losses of pillar-based photonic crystal waveguides can be vastly reduced, even for pillars with a low vertical index contrast, such as in InP/InGaAsP/InP technology. These low losses are obtained by creating confinement between the pillars with a polymer layer stack. We show that the spatial frequency component of the Bloch mode in the first Brillouin zone (i.e., the component inside the light cone), is significantly suppressed by the optimized polymer layer stack.Index Terms-Bloch modes, out-of-plane loss, pillar-based photonic crystals.

Abstract-The strong polarization dependence of twodimensional photonic crystals is exploited for polarization filtering. The device with a length of 3.9 m is integrated in a photonic integrated circuit based on InP waveguide technology. The average transmissions in the wavelength range from 1530 to 1570 nm are 08.7 dB for transverse-magnetic polarization and 026.5 dB for transverse-electric polarization.

The development of integrated polarization manipulating devices opens the perspective on the use of polarization as a new design dimension in InP-based integrated optics. Examples will be given of how this results in additional functionalities.

To]", R. Notzel P.J. van Veldhoven"' and H.W.M. Saleminka.b7" b We have investigated ICP-etching of deep photonic crystal holes in InP using solely Clz as supplied etching gas. The influence of process parameters on hole geometry is discussed and optical test results are reported.InP based two-dimensional (2D) deeply etched holetype photonic crystals are likely to be present in many of the hture optical devices involving the telecommunication wavelength of 1550 nm. For operation around 1550 nm a triangular lattice of etched holes with a lattice constant a of -400 nm and a diameter d of-250 nm can be used. To fulfill the requirement of low optical loss, the holes should be etched through an InP/lnGaAsP/InP planar waveguide structure with a depth of -2.5 pm and with smooth and vertical sidewalls. (1) Deep photonic crystal holes in InP have been successfully etched using chemically assisted ion beam etching and electron cyclotron resonance reactive ion etching, all based on Cl?-chemistry. (2,3,4) A versatile etching technique for largescale fabrication is inductively coupled plasma (ICP) etching, however, so far only one ICP process has been reported for deep hole etching, based on SIC4. ( 5 ) ICP etching of InP using Clz as main etch gas has been used in other photonic crystal applications such as pillars and shallow holes for membranes. (6, 7) In this work we investigate ICP-etching for fabrication of deeply etched hole-type photonic crystals in the InP-based material system using gas flow consisting solely of Ch.All experiments were performed on (100) n-type Sndoped InP substrates with a size of approximately 8x8 mm'. For optical experiments a waveguide structure consisting of 500 nm InGaAsP (h=1.25 pm) with a 500 nm InP upper cladding on top, grown lattice matched to the KnP by metal organic vapour phase epitaxy, was used. The photonic crystal pattern is defined into a layer of ZEP520A (positive e-beam resist) with e-beam lithography. This pattern is then transferred into a 400 nm thick, PECVD deposited Si,N,-masking layer with a CHF3-based RIE process. The ICP etch experiments were carried out in a load-locked Oxford Plasmalab IO0 system. Since the main etch-product, Inch, is not enough volatile at room temperature the etching was performed at elevated temperature. Sample temperature control in ICP etching can be difficult due to significant heating by the ion bombardment. (8) To keep the sample temperature as close to the preset value as possible the 0-7&03-8891-7105/$20.00 02005 lEEE following measures were taken. The samples were glued with heat conducting paste onto a 4 in. silicon carrier wafer. The table temperature was regulated by resistive heating in combination with short sequenced processing (etch steps of 30 s). The stage temperature was measured with a thermocouple. The ion energy was controlled by the negative DC-bias voltage, which is induced by capacitive coupling of additional rf-power to the plasma. Hereby, the relatively low plasma potential is neglected. The chlorine flow was kept const...

Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publicationCitation for published version (APA): Pozo, J., Bente, E. A. J. M., Heck, M. J. R., Docter, B., Karouta, F., Kok, A. A. M., ... Lenstra, D. (2008). InPbased lasers and photonic crystals devices for integrated photonics. In 10th Anniversary International Conference on Transparent Optical Networks, ICTON 2008, Athens, Greece, 22-26 June 2008 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. ABSTRACTIn this paper, some of the activities towards the fabrication of Photonic Integrated Circuits at the COBRA Research Institute are summarized. Firstly, rate equations are used for the understanding of instability and dynamics in multilongitudinal mode semiconductor lasers. Secondly, we report the results of our investigation on broad-bandwidth frequency comb generators based on novel mode-locked InAs/InGaAsP/InP quantum dot laser diodes. In addition, we will show the integration of two-dimensional pillar-based photonic crystal waveguides in an InGaAsP/InP photonic integrated circuit. Keywords: nonlinear dynamics, InP, photonic crystals, modelocking, integrated optics laser, DBR gratings. INTRODUCTIONThe COBRA Research Institute at the University of Technology Eindhoven is active in research in semiconductor materials and semiconductor optical devices. The fabrication of Photonic Integrated Circuits (PICs) in which semiconductor lasers and photonic crystals structures can be built-in, allows photonic systems to be more compact and capable of providing higher performance than with the use of discrete optical components. In addition, they...