B. Lamontagne

Publications (45)50.41 Total impact

• Conference Proceeding: Athermal silicon subwavelength grating waveguides

  M. Ibrahim, J.H. Schmid, P. Cheben, J. Lapointe, S. Janz, P.J. Bock, A. Densmore, B. Lamontagne, R. Ma, Dan-Xia Xu, W.N. Ye
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  ABSTRACT: Athermal silicon subwavelength grating waveguides are demonstrated. We report the results of numerical simulations and experiments for the waveguide thermo-optic coefficients, as well as fabrication tolerances and the thermal bandwidth.
  Group IV Photonics (GFP), 2011 8th IEEE International Conference on; 10/2011
• Article: Single-etch grating coupler for micrometric silicon rib waveguides.

  C Alonso-Ramos, A Ortega-Moñux, L Zavargo-Peche, R Halir, J de Oliva-Rubio, I Molina-Fernández, P Cheben, D-X Xu, S Janz, N Kim, B Lamontagne
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  ABSTRACT: Grating couplers are widely used as an efficient and versatile fiber-chip coupling structure in nanometric silicon wire waveguides. The implementation of efficient grating couplers in micrometric silicon-on-insulator (SOI) rib waveguides is, however, challenging, since the coupler waveguide region is multimode. Here we experimentally demonstrate grating couplers in 1.5 μm-thick SOI rib waveguides with a coupling efficiency of -2.2 dB and a 3 dB bandwidth of 40 nm. An inverse taper is used to adiabatically transform the interconnection waveguide mode to the optimum grating coupler excitation field with negligible higher order Bloch mode excitation. Couplers are fabricated in the same etch step as the waveguides using i-line stepper lithography. The benefits of wafer-scale testing and device characterization without facet preparation are thus attained at no additional cost.
  Optics Letters 07/2011; 36(14):2647-9. · 3.40 Impact Factor
• Article: Temperature-independent silicon subwavelength grating waveguides.

  J H Schmid, M Ibrahim, P Cheben, J Lapointe, S Janz, P J Bock, A Densmore, B Lamontagne, R Ma, W N Ye, D-X Xu
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  ABSTRACT: We demonstrate, by experiment and numerical calculations, temperature-independent subwavelength grating waveguides with a periodic composite core composed of alternating regions of silicon and SU-8 polymer. The polymer has a negative thermo-optic (TO) material coefficient that cancels the large positive TO effect of the silicon. Measurements and Bloch mode calculations were carried out over a range of silicon-polymer duty ratios. The lowest measured TO coefficient at a wavelength of 1550 nm is 1.8×10(-6) K(-1); 2 orders of magnitude smaller than a conventional silicon photonic wire waveguide. Calculations predict the possibility of complete cancellation of the silicon waveguide temperature dependence.
  Optics Letters 06/2011; 36(11):2110-2. · 3.40 Impact Factor
• Source

  Available from: gc.ca

  Conference Proceeding: Refractive index engineering with subwavelength gratings in silicon microphotonic waveguides

  J.H. Schmid, P. Cheben, P.J. Bock, J. Lapointe, S. Janz, A. Delâge, A. Densmore, T.J. Hall, B. Lamontagne, R. Ma, D. Xu
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  ABSTRACT: We present a method of engineering the waveguide core refractive index locally on a silicon photonic chip using subwavelength gratings. Applications such as efficient waveguide crossings, fiber-chip couplers and multiplexer circuits are discussed.
  Winter Topicals (WTM), 2011 IEEE; 02/2011
• Article: SPIE OPTO

  P. Cheben, P. J. Bock, J. H. Schmid, J. Lapointe, S. Janz, D.-X. Xu, R. Ma, A. Densmore, A. Delâge, B. Lamontagne, T. J. Hall, R. Halir, I. Molina-Fernández, J.-M. Fédéli
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  ABSTRACT: We review recent advances in subwavelength and diffractive structures in planar waveguides. First, we present a new type of microphotonic waveguide, exploiting the subwavelength grating (SWG) effect. We demonstrate several examples of subwavelength grating waveguides and components made of silicon, operating at telecom wavelengths. The SWG technique allows for engineering of the refractive index of a waveguide core over a range as broad as 1.5-3.5 simply by lithographic patterning using only two materials, for example Si and SiO2. This circumvents an important limitation in integrated optics, which is the fixed value of the refractive indices of the constituent materials in the absence of an active tuning mechanism. A subwavelength grating fibre-chip microphotonic coupler is presented with a loss as low as 0.9 dB and with minimal wavelength dependence over a broad wavelength range exceeding 200 nm. It is shown that the SWG waveguides can be used to make efficient waveguide crossings with minimal loss and negligible crosstalk. We also present a diffractive surface grating coupler with subwavelength nanostructure, that has been implemented in a Si-wire evanescent field biological sensor. Furthermore, we discuss a new type of planar waveguide multiplexer with a SWG engineered nanostructure, yielding an operation bandwidth exceeding 170 nm for a device size of only 160 μm × 100 μm.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
  02/2011;
• Conference Proceeding: Subwavelength grating: A new type of microphotonic waveguide and implementations to fiber-chip coupling, waveguide crossing and refractive index engineering

  P.J. Bock, P. Cheben, J.H. Schmid, J. Lapointe, S. Janz, Dan-Xia Xu, A. Densmore, A. Delage, B. Lamontagne, T.J. Hall
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  ABSTRACT: We demonstrate a new microphotonic waveguide principle based on subwavelength gratings. We also present several practical implementations of subwavelength waveguides, including a microphotonic fiber-chip coupler with a coupling loss as small as -0.3 dB, a waveguide crossover with an excess loss of 0.02dB/crossing and a PDL of <;;0.1 dB, and a new type of planar waveguide multiplexer.
  Group IV Photonics (GFP), 2010 7th IEEE International Conference on; 10/2010
• Article: Integrated Optical Six-Port Reflectometer in Silicon on Insulator

  R. Halir, A. Ortega-Moux, I. Molina-Fernandez, J.G. Wanguemert-Perez, P. Cheben, Dan-Xia Xu, B. Lamontagne, S. Janz
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  ABSTRACT: The six-port reflectometer technique enables simple and accurate measurement of optical reflection coefficients in both magnitude and phase. The reflection coefficient is computed from four power measurements of linear combinations of the waves incident and reflected from the device under test. While the six-port technique is very successful at microwave frequencies and conceptually related to coherent optical phase diversity receivers, no optical implementations have been reported so far. In this paper, we present an experimental characterization of an optical six-port reflectometer composed of three multimode interference couplers, fabricated with a single etch step in silicon on insulator. Measurements are performed using a novel technique with a simple setup. The six-port combines the incident and reflected waves with magnitude and phase errors less than plusmn0.5 dB and plusmn6deg in the 1485-1575 nm band.
  Journal of Lightwave Technology 01/2010; · 2.78 Impact Factor
• Article: Compact High-Performance Multimode Interference Couplers in Silicon-on-Insulator

  R. Halir, A. Ortega-Monux, I. Molina-Fernadez, J.G. Wanguemert-Perez, P. Cheben, Dan-Xia Xu, B. Lamontagne, S. Janz
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  ABSTRACT: We demonstrate compact multimode interference (MMI) couplers on silicon-on-insulator that exhibit both high performance and relaxed tolerances. The devices are fabricated with a single shallow etch step on 1.5-mum-thick silicon, and have a footprint of 12.8 mum times 456 mum, including 100-mum-long tapers at input and output. In a Mach-Zehnder configuration, we achieve an extinction ratio larger than 22 dB for transverse-electric polarization and larger than 20 dB for transverse-magnetic polarization. This extinction ratio is maintained in the full 1520- to 1580-nm band and for MMI width variations in a range of 0.45 mu m. We also show appreciable tolerance differences between paired and general excitation MMIs.
  IEEE Photonics Technology Letters 12/2009; · 2.19 Impact Factor
• Conference Proceeding: Sub-wavelength nanostructures for engineering the effective index of silicon-on-insulator waveguides

  P. Cheben, J.H. Schmid, P. Bock, Dan-Xia Xu, S. Janz, A. Delage, J. Lapointe, B. Lamontagne, A. Densmore, T. Hall
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  ABSTRACT: Silicon-on-insulator (SOI) is considered the most promising high-index-contrast waveguide platform for fabricating microphotonic devices with high integration density. However, there are fundamental challenges with this waveguide system related to the fixed values of the refractive indices of the constituent materials (Si and SiO₂). In this paper, we present a method that can potentially circumvent this limitation by using the sub-wavelength grating effect in SOI waveguides to effectively engineer materials with intermediate refractive indices by standard lithographic patterning. The first implementations of the SWG effect in SOI waveguides are discussed, including our latest results in fiber-chip couplers, anti-reflective and high-reflectivity waveguide facets, mode transformers between waveguides of different geometries, and microphotonic waveguide crossings.
  Transparent Optical Networks, 2009. ICTON '09. 11th International Conference on; 08/2009
• Chapter: Silicon Photonic Wire Waveguide Sensors

  S. Janz, A. Densmore, D.-X. Xu, P. Waldron, J. Lapointe, J. H. Schmid, T. Mischki, G. Lopinski, A. Delâge, R. McKinnon, P. Cheben, B. Lamontagne
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  ABSTRACT: Silicon photonic wire evanescent field (PWEF) waveguide sensors have a very high intrinsic response to molecular adsorption. This response arises from the high refractive index contrast and small size of these waveguides, which in combination cause much of the electric field to be localized to a thin layer adjacent to the waveguide surface. We describe the basic theory of PWEF waveguide sensors and compare the predicted PWEF sensor performance with that of surface plasmon resonance (SPR) and other waveguide systems. Finally, we present experimental results for PWEF sensors incorporated into integrated optical circuits employing Mach–Zehnder interferometers (MZIs), ring resonators, and folded waveguide structures that both amplify and facilitate the interrogation of the PWEF sensor response.
  12/2008: pages 229-264;
• Source

  Available from: Dan-Xia Xu

  Conference Proceeding: Cancellation of the temperature dependence in SOI photonic wire ring resonator sensors

  D.-X. Xu, E. Post, A. Densmore, P. Waldron, S. Janz, J. Lapointe, A. Delage, P. Cheben, J.H. Schmid, B. Lamontagne
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  ABSTRACT: We demonstrate a method of canceling the temperature dependence of ring resonator sensors using a double ring configuration. Temperature calibration curves are provided for SOI photonic wire ring sensors with air and SU8 polymer cladding.
  Group IV Photonics, 2008 5th IEEE International Conference on; 10/2008
• Article: Interference effect in scattering loss of high-index-contrast planar waveguides caused by boundary reflections.

  J H Schmid, A Delâge, B Lamontagne, J Lapointe, S Janz, P Cheben, A Densmore, P Waldron, D-X Xu, K P Yap
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  ABSTRACT: We present theoretical and experimental results on an interference effect caused by boundary reflections on the optical scattering loss in high-index-contrast planar waveguides. Analytical expressions for the polarization-dependent scattering loss are derived using a surface Green's function. For high-index-contrast waveguides of submicrometer dimensions a significant deviation from accepted theory arises, including scattering loss suppression owing to a thin-film interference effect. Our theoretical predictions are confirmed by loss measurements on silicon-on-insulator channel waveguides.
  Optics Letters 08/2008; 33(13):1479-81. · 3.40 Impact Factor
• Conference Proceeding: Densely folded silicon photonic wire biosensors in ring resonator and Mach-Zehnder configurations

  A. Densmore, D.X. Xu, P. Waldron, S. Janz, T. Mischki, G. Lopinski, J. Lapointe, A. Delage, E. Post, C. Storey, P. Cheben, B. Lamontagne, J.H. Schmid
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  ABSTRACT: We demonstrate silicon photonic wire evanescent field sensors formed by folding long photonic wire waveguides into dense spiral paths that occupy spot sizes less than 150 mum in diameter, and are hence suitable for biochip array formats. These sensors are incorporated into both ring resonator and Mach-Zehnder interferometer (MZI) interrogation circuits, and tested by monitoring streptavidin protein adsorption. The level of detection is less than 1% of a monolayer in either configuration. Using a balanced MZI design, we show that the sensors can be insensitive to temperature and wavelength, while retaining a very high sensitivity to molecular adsorption.
  Lasers and Electro-Optics, 2008 and 2008 Conference on Quantum Electronics and Laser Science. CLEO/QELS 2008. Conference on; 06/2008
• Article: Spiral-path high-sensitivity silicon photonic wire molecular sensor with temperature-independent response.

  A Densmore, D-X Xu, S Janz, P Waldron, T Mischki, G Lopinski, A Delâge, J Lapointe, P Cheben, B Lamontagne, J H Schmid
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  ABSTRACT: We demonstrate a new silicon photonic wire waveguide evanescent field (PWEF) sensor that exploits the strong evanescent field of the transverse magnetic mode of this high-index-contrast, submicrometer-dimension waveguide. High sensitivity is achieved by using a 2 mm long double-spiral waveguide structure that fits within a compact circular area of 150 microm diameter, facilitating compatibility with commercial spotting apparatus and the fabrication of densely spaced sensor arrays. By incorporating the PWEF sensor element into a balanced waveguide Mach-Zehnder interferometer circuit, a minimum detectable mass of approximately 10 fg of streptavidin protein is demonstrated with near temperature-independent response.
  Optics Letters 04/2008; 33(6):596-8. · 3.40 Impact Factor
• Article: Microelectronics, MEMS, and Nanotechnology

  K. P. Yap, J. Lapointe, B. Lamontagne, A. Delâge, A. Bogdanov, S. Janz, B. Syrett
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  ABSTRACT: We show that integrated optical star couplers can be useful characterization devices to measure the sidewall roughness-induced scattering losses of planar waveguides. We describe the detailed fabrication processes of these star couplers on the silicon-on-insulator (SOI) platform and the process improvements implemented to reduce the waveguide sidewall roughness and scattering loss. We report the main process challenges, particularly to assure a clear gap between any adjacent waveguides of the dense and closely spaced output waveguide array. These challenges are addressed by optimizing the exposure dose of the resist and adding an oxygen ashing treatment to eliminate waveguide footings. We demonstrate further improvement on the waveguide profile and sidewall roughness through the use of a thin Cr hardmask for the dry plasma etching. This optimized fabrication process is capable of producing approximately a 3 nm root-mean-square sidewall roughness, measured using both scanning electron microscopy (SEM) and atomic force microscopy (AFM). Using the fabricated star couplers, we manage to measure the relative scattering losses of various waveguides with the width varying from 0.2 to 2.0 μm in a single measurement, and show that the measured losses agree with the measured sidewall roughness.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
  12/2007;
• Conference Proceeding: Silicon Photonic Arrayed Waveguide Grating Devices and Sub-Wavelength Structures

  P. Cheben, A. Delage, A. Densmore, M. Florjanczyk, S. Janz, B. Lamontagne, J. Lapointe, E. Post, I. Powell, J. Schmid, P. Waldron, Dan-Xia Xu
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  ABSTRACT: We review recent advances in silicon photonic arrayed waveguide grating and sub-wavelength grating devices developed at the NRC Canada. We present three original microspectrometer concepts, namely a compact 50 channel AWG microspectrometer with a spectral resolution of 1 A and a total chip size of 8 x 8 mm", a Fourier- transform AWG with a markedly increased light gathering capability compared to conventional AWG devices, and an AWG with a resolution significantly increased by inserting a triangular photonic crystal waveguide region in the phased array. Various new sub-wavelength grating waveguide structures will also be presented, including monolithic fibre-chip couplers, anti-reflective waveguide facets and mirrors.
  Transparent Optical Networks, 2007. ICTON '07. 9th International Conference on; 08/2007
• Article: Mode Converters for Coupling to High Aspect Ratio Silicon-on-Insulator Channel Waveguides

  J. H. Schmid, B. Lamontagne, P. Cheben, A. Delage, S. Janz, A. Densmore, J. Lapointe, E. Post, P. Waldron, D.-X. Xu
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  ABSTRACT: The design, simulation, and experimental performance of mode converters for coupling from single-mode silicon-on-insulator ridge waveguides to high aspect ratio channel waveguides are described. The converters consist of a two-level adiabatic taper structure. The final channel waveguide is 1.5 mum high by 0.8 mum wide. Simulations predict that for total coupler lengths longer than 20 mum, the coupling loss from the fundamental ridge mode to the slit mode is better than -0.2 dB. The couplers and waveguides were fabricated using a two-step self-aligned process. The measured coupling loss for fabricated mode converters is -0.4 dB
  IEEE Photonics Technology Letters 07/2007; · 2.19 Impact Factor
• Article: A high-resolution silicon-on-insulator arrayed waveguide grating microspectrometer with sub-micrometer aperture waveguides.

  P Cheben, J H Schmid, A Delâge, A Densmore, S Janz, B Lamontagne, J Lapointe, E Post, P Waldron, D-X Xu
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  ABSTRACT: We demonstrate a 50-channel high-resolution arrayed waveguide grating microspectrometer with a 0.2 nm channel spacing on a silicon-on-insulator (SOI) platform. The chip size is 8 mm x 8 mm. High channel density and spectral resolution are achieved using high aspect ratio 0.6 mum x 1.5 mum waveguide apertures to inject the light into the input combiner and to intercept different spectral channels at the output combiner focal region. The measured crosstalk is <-10 dB, the 3 dB channel bandwidth is 0.15 nm, and the insertion loss is -17 dB near the central wavelength of lambda = 1.545 mum.
  Optics Express 04/2007; 15(5):2299-306. · 3.59 Impact Factor
• Article: A Silicon-on-Insulator Photonic Wire Based Evanescent Field Sensor

  A. Densmore, D.-X. Xu, P. Waldron, S. Janz, P. Cheben, J. Lapointe, A. Delage, B. Lamontagne, J.H. Schmid, E. Post
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  ABSTRACT: We demonstrate a new, highly sensitive evanescent field sensor using silicon-on-insulator (SOI) photonic wire waveguides. Theoretical analysis shows that thin SOI waveguides can provide higher sensitivity over devices based in all other common planar waveguide material systems for the probing of both thin adsorbed biomolecular layers and bulk homogeneous solutions. A Si photonic wire waveguide was incorporated into a Mach-Zehnder interferometer based sensor, configured to monitor the index change of a homogeneous solution. High effective index change of 0.31 per refractive index unit (RIU) change of the solution was measured, confirming theoretical predictions
  IEEE Photonics Technology Letters 01/2007; · 2.19 Impact Factor
• Article: Microphotonic Elements for Integration on the Silicon-on-Insulator Waveguide Platform

  S. Janz, P Cheben, D. Dalacu, A. Delge, A Densmore, B. Lamontagne, M-J Picard, E. Post, J H Schmid, P. Waldron, D-X Xu, Yap, W. N. Ye
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  ABSTRACT: This paper presents an overview of our recent work on several fundamental optical elements and their integration on the silicon-on-insulator (SOI) waveguide platform. Theory, design and experimental results are presented for monolithically integrated asymmetric graded-index waveguide couplers, as well as output couplers based on total internal reflection mirrors. Design strategies for dispersive elements on SOI, for example, ring resonators and arrayed waveguide gratings, are discussed with special emphasis on methods to eliminate the polarization sensitivity. Finally, the properties and applications of evanescent fields in SOI waveguides are reviewed.
  IEEE Journal of Selected Topics in Quantum Electronics 12/2006; 12(6):1402-1415. · 3.78 Impact Factor