Browsing by Author "Baets, Roel"

Now showing 1 - 4 of 4
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    PublicationOpen Access
    Absorption spectroscopy of xylene with a PDMS gas concentrating layer on SOI waveguides
    (2013) Santesteban López, Andrea; López-Amo Sáinz, Manuel; Yebo, Nebiyu A.; Baets, Roel; Escuela Técnica Superior de Ingenieros Industriales y de Telecomunicación; Telekomunikazio eta Industria Ingeniarien Goi Mailako Eskola Teknikoa; Ghent University (Bélgica); Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    The presence of chemical substances on the environment, such as xylene, has harmful effects on human health. Exposure to xylene to humans causes symptoms in a range from dizziness to death, being crucial to monitor it. Silicon-on-insulator (SOI) waveguides and absorption spectroscopic technique for gas sensing presents an interesting alternative due to its high potential of provide miniaturized, compact and high sensitivity devices. Moreover, the use of gas pre-concentrating chemical films is presented as an alternative approach for enhanced gas detection using optical waveguides. In this work, we investigate gaseous xylene absorption in the near-infra-red region (NIR), exploiting evanescent field absorption (EFA) on SOI waveguides covered by a preconcentrating polydimethylsiloxane (PDMS) film. Estimations of absorption cross section and the PDMS enhancement factor have been made. It has been experimentally observed that 5000 times gas density enhancement is achievable with the PDMS films. The potential benefit of gluing fibers on the grating couplers has been studied and 5 times improvement in the measurement stability with glued fibers has been observed. However, in order to maintain a better overlap between the grating transmission spectrum and the absorption band of xylene, most experiments were run without gluing the fibers. By using a 350nm PDMS film on a 1.2 cm long SOI waveguide, an expected absorption behavior has been observed at a concentration of ∼ 4000ppm gaseous xylene; which is in a close agreement with an estimate taken with approximately 5000 times PDMS enhancement factor. A rising absorption trend has been observed in the region beyond 1665nm agreeing with the theoretical xylene absorption band. An absorption measurement for a drop of liquid xylene on a PDMS coated waveguide has been also carried out which gave a further confirmation on the absorption trend observed at ∼4000ppm xylene vapor. It is, however, observed that ensuring measurement and environmental stability can be critical in absorption experiments. For instance, in one experiment, the measured absorption appeared to extend outside the expected region likely due various factors such as mechanical stability and temperature contributing to the system noise. Future studies may focus on minimizing the measurement noise and lowering the gas detection limits.
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    PublicationOpen Access
    Compact and highly-efficient polarization independent vertical resonant couplers for active-passive monolithic integration
    (Optical Society of America, 2008) Galarza Galarza, Marko; Thourhout, Dries Van; Baets, Roel; López-Amo Sáinz, Manuel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    Compact low-loss polarization independent vertical coupling between a 1.55 μm InGaAsP bulk active waveguide and a passive waveguide based on bimodal interference is presented. Simulation results show low coupling loss (<0.1 dB) over coupler lengths more than 5 times shorter than using the adiabatic design. The concept avoids submicron photolithographic features and shows acceptable fabrication tolerances.
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    PublicationOpen Access
    Vertically coupled InP/InGaAsP microring lasers using a single epitaxial growth and singleside lithography
    (IEEE, 2020) García López, Óscar; Thourhout, Dries Van; Verstuyft, Steven; López-Amo Sáinz, Manuel; Baets, Roel; Galarza Galarza, Marko; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
    The experimental demonstration of vertical microring lasers requiring only one single epitaxial growth and two single-side lithographic steps is presented, in what is the simplest fabrication scheme for such devices published to date. The fabricated lasers show series resistance of around 20 Ω at forward bias, threshold currents at room temperature between 35 and 58 mA, and single-mode emission with a side-lobe suppression ratio higher than 30 dB. The measured optic output power level is of tens of microwatts. The approach allows the improvement of the optical features maintaining the simplicity of the manufacturing procedure.
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    PublicationOpen Access
    Vertically coupled microring resonators using one epitaxial growth step and single-side lithography
    (Optical Society of America, 2015) García López, Óscar; Thourhout, Dries Van; Lasaosa Medarde, Daniel; López-Amo Sáinz, Manuel; Baets, Roel; Galarza Galarza, Marko; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
    A new concept for the fabrication of integrated microring resonators, requiring only one single epitaxial growth and two single-side lithographic steps, is proposed in what is the simplest fabrication scheme for vertical microrings published to date. The approach is based on two vertically stacked phase matched core layers. The effect of bus waveguide, coupling region and ring structure parameters is theoretically analyzed. Numerical calculations predict high performance devices with quality factors of over 10000. The scheme can feature both active and passive regions, allowing the fabrication of microring lasers.