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ABSTRACT: We present a new synchronized design for flattening the passband of an arrayed-waveguide grating (AWG) over a broad wavelength range of 90 nm. A wavelength-insensitive 3-dB balanced coupler is designed to be used in duplicate in a Mach-Zehnder interferometer (MZI); the phase deviation created by one of the balanced couplers is cancelled by flipping the other coupler around. This MZI is arranged in tandem with the AWG such that the output signal of the MZI is the input signal of the AWG. We demonstrate a 5-channel, 18-nm-spacing AWG with a 0.5-dB bandwidth of 12 nm over a 90-nm spectral range. A low-loss cascaded AWG system is demonstrated by using the MZI-synchronized flat-top AWG as a primary filter.
Optics Express 07/2012; 20(16):18313-8. · 3.59 Impact Factor
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ABSTRACT: The paper presents a simple coupled mode model to describe near band-edge phenomena in the spectral response of waveguides
with a section containing a rectangular grating. It is shown that nearly all relevant parameters can be determined in reasonable
approximation from only the dispersion curve and one adjustable, proportionality constant. The theory is compared with results
from numerical calculations and experiments.
Optical and Quantum Electronics 04/2012; 38(9):799-813. · 0.82 Impact Factor
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ABSTRACT: We report the fabrication and characterization of a dual-wavelength distributed-feedback channel waveguide laser in ytterbium-doped aluminum oxide. Operation of the device is based on the optical resonances that are induced by two local phase shifts in the distributed-feedback structure. A stable microwave signal at ~15 GHz with a -3 dB width of 9 kHz was subsequently created via the heterodyne photodetection of the two laser wavelengths. The long-term frequency stability of the microwave signal produced by the free-running laser is better than ±2.5 MHz, while the power of the microwave signal is stable within ±0.35 dB.
Optics Letters 01/2012; 37(2):181-3. · 3.40 Impact Factor
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ABSTRACT: An integrated arrayed-waveguide grating fabricated in silicon-oxynitride technology is applied to Raman spectroscopy. After its validation by reproducing the well-known spectrum of cyclohexane, polarized Raman spectra are measured of extracted human teeth containing localized initial carious lesions. Excellent agreement is obtained between the spectra of healthy and carious tooth enamel measured with our integrated device and spectra recorded using a conventional Raman spectrometer. Our results represent a step toward the realization of compact, hand-held, integrated spectrometers, e.g. for the detection of dental caries at an early stage.
Optics Letters 12/2011; 36(23):4629-31. · 3.40 Impact Factor
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ABSTRACT: This paper presents the fabrication technology for a novel class of photonic devices which integrates silicon 2D photonic crystal (PhC) waveguides and electrostatically actuated microelectromechanical systems. Bimorph cantilevers equipped with tips that are self-aligned relative to the holes of the PhC modulate the propagation properties of the slab PhC depending on the proximity of the tips to the holes. The integrated devices have been successfully fabricated by surface micromachining techniques. Preliminary experiments with these devices have shown 80% throughput modulation using a square-wave drive signal of 0–8 V at 1 kHz.
Journal of Micromechanics and Microengineering 11/2011; 21(12):125010. · 2.11 Impact Factor
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ABSTRACT: We investigate a way to externally generate the local oscillator (LO) signal used for downconversion of the K<sub>u</sub>-band (10.7-12.75 GHz) RF signal received from a phased array antenna (PAA). The signal is then translated to an intermediate frequency (950-2150 MHz) at the output of the mixer of standard LNBs (Low Noise Block) of a DVB-S (Digital Video Broadcasting-Satellite) reception system. The LO is generated optically by heterodyning of two lasers. We analyze the impact of the laser parameters (optical power and linewidth) on the quality of the generated LO (i.e. phase stability and carrier-to-noise ratio). In addition, a complete system analysis is presented for a 25×64 elements PAA system. We also report the progress on the development of the distributed feedback (DFB) lasers to be used in the heterodyne process. We analyze and experimentally demonstrate that, in order to have an optically-generated LO with equivalent performance to the one of an electronic LO, the laser linewidth should be in the order of tens of Hz, with a maximum relative intensity noise (RIN) of -123 dB/Hz and a minimum optical power of 0.125 mW.
General Assembly and Scientific Symposium, 2011 XXXth URSI; 09/2011
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ABSTRACT: The principle, fabrication and characterization of a dielectric MEMS cantilever located a few 100 nm above a racetrack ring resonator are presented. After fabrication of the resonators on silicon-on-insulator (SOI) wafers in a foundry process, the cantilevers were integrated by surface micromachining techniques. Off-state deflections of the cantilevers have been optimized to appropriately position them near the evanescent field of the resonator. Using electrostatic actuation, moving the cantilevers into this evanescent field, the propagation properties of the ring waveguide are modulated. We demonstrate 122 pm tuning of the resonance wavelength of the optical ring resonator (in the optical C-band) without change of the optical quality factor, on application of 9 V to a 40 µm long cantilever. This compact integrated device can be used for tuning/switching a specific wavelength, with very little energy for operation and negligible cross talk with surrounding devices.
Optics Express 08/2011; 19(17):15864-78. · 3.59 Impact Factor
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ABSTRACT: The Bragg grating technology was used to fabricate a DBR waveguide laser with two 3.75-mm long Bragg reflectors, which were separated by 2.5 mm, in ytterbium-doped Al<sub>2</sub>O<sub>3</sub>. The laser was pumped at 976 nm and had a threshold of 10 mW launched pump power. It produced a maximum output power of 47 mW at a launched pump power of 91.5 mW, which resulted in a slope efficiency of 67% (Fig. la). No saturation of the output power was observed and further power scaling was only limited by the available pump power. The laser operated at the Bragg wavelength of 1021.2 nm (TE polarized) and the laser emission peak had a signal-to noise ratio of more than 45 dB. The measured optical linewidth was limited by the 0.1 nm resolution of the optical spectrum analyzer. This is, to our knowledge, the first Al<sub>2</sub>O<sub>3</sub> DBR waveguide laser and also the highest efficiency of any rare-earth-ion-doped waveguide laser on a silicon chip.
Lasers and Electro-Optics Europe (CLEO EUROPE/EQEC), 2011 Conference on and 12th European Quantum Electronics Conference; 06/2011
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ABSTRACT: A technology to monolithically integrate micro-bimorph cantilevers equipped with tips that are self-aligned with respect to the holes of a 2D photonic crystal cavity-based channel-drop filter is presented. On electrostatic actuation, the tips move into the holes and provide electromechano-optical modulation of light. The technology allows the fabrication of tips on specific photonic crystal holes by controlling the hole diameter and the sacrificial layer thickness. The integrated device is both mechanically and optically characterized. A 180 pm wavelength shift at the first band edge of the photonic crystal cavity-based channel-drop filter is measured on the application of a 2 V dc voltage to the cantilever. This CMOS-compatible device is designed to operate in the C-band of the telecommunication wavelengths and constitutes a promising candidate for future integrated all-optical devices.
Journal of Micromechanics and Microengineering 06/2011; 21(7):074004. · 2.11 Impact Factor
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ABSTRACT: We present two arrayed waveguide gratings fabricated in silicon-oxynitride for near infrared Raman spectroscopy. Our devices exhibit very low losses and polarization insensitivity over a large spectral range of 156 nm and 214 nm, respectively.
Lasers and Electro-Optics (CLEO), 2011 Conference on; 06/2011
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ABSTRACT: We investigate excitation and light collection from a scattering medium by an integrated waveguide probe. A probe with one excitation and eight collector waveguides is fabricated in silicon oxynitride technology. Experiments are performed on light collection from a highly scattering water suspension of latex nanospheres. By use of a Monte Carlo model, the propagation of light through highly scattering media is simulated and good agreement with the experimental data is found.
IEEE Photonics Technology Letters 04/2011; · 2.19 Impact Factor
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ABSTRACT: We present results related to the fabrication of a novel and potentially highly sensitive mechano-optical sensor for hydrogen gas, based on microcantilevers, provided with a selectively gas-absorbing palladium layer, suspended above a Si<sub>3</sub>N<sub>4</sub> grated waveguide (GWG). Integrated microcantilever-GWG devices have been fabricated successfully using microelectromechanical systems (MEMS) techniques. Several technical problems encountered during the preparation of such integrated devices (i.e., grating production, surface roughness, facet quality) will be discussed, and solutions to address these issues will be given as well. We also present preliminary experimental results, showing the sensing of cantilever nano-displacements, and so the feasibility of proposed read-out principle.
IEEE Photonics Technology Letters 03/2011; · 2.19 Impact Factor
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ABSTRACT: We report the fabrication and performance of a highly efficient, monolithic distributed-Bragg-reflector channel waveguide laser in ytterbium-doped aluminum oxide. The 1 cm long device was fabricated on a standard thermally oxidized silicon substrate and was optically pumped with a 976 nm laser diode. Single-longitudinal-mode and single-polarization operation was achieved at a wavelength of 1021.2 nm. Continuous-wave output powers of up to 47 mW and a launched pump power threshold of 10 mW resulted in a slope efficiency of 67%.
Optics Letters 03/2011; 36(5):603-5. · 3.40 Impact Factor
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ABSTRACT: A photonic crystal slab waveguide (PhC-WG) with an integrated MEMS bimorph cantilever actuator has been successfully fabricated using deep UV lithography and surface micromaching techniques. The cantilever is equipped with tips that are self-aligned with respect to the holes of the PhC-WG such that on electrostatic actuation, with modest voltages of less than 10 V, these tips move into the holes. This provides electro-opto-mechanical modulation of light-transmission, up to 80%, for interaction lengths as short as 10 μm. The device is monolithically integrated and designed to operate in the C-band of the telecommunication wavelengths.
Micro Electro Mechanical Systems (MEMS), 2011 IEEE 24th International Conference on; 02/2011
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ABSTRACT: A semianalytical model for light collection by integrated waveguide probes is developed by extending previous models used to describe fiber probes. The efficiency of waveguide probes is compared to that of different types of fiber probes for different thicknesses of a weakly scattering sample. The simulation results show that integrated probes have a collection efficiency that is higher than that of small-core fiber probes, and, in the particular case of thin samples, also exceeds the collection efficiency of large-core highly multimode fiber probes. An integrated waveguide probe with one excitation and eight collector waveguides is fabricated and applied to excite and collect luminescence from a ruby rod. The experimental results are in good agreement with the simulation and validate the semianalytical model.
Applied Optics 02/2011; · 1.41 Impact Factor
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ABSTRACT: The use of integrated optics for Optical Coherence Tomography (OCT) can offer significant cost reductions and new applications. We designed, fabricated, and characterized Silicon oxynitride (SiON) elliptic couplers that are used to focus light from a chip into the off-chip environment. Fizeau-based OCT measurements are performed and compared to calculations.
Journal of Lightwave Technology 11/2010; · 2.78 Impact Factor
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ABSTRACT: We present an on-chip arrayed waveguide grating (AWG) sensor based on the confocal arrangement of two AWGs, one acting as focusing illuminator and one as signal collector. The chip can be close to, or in direct contact with, a sample, e.g., biological tissue, without the need of external optics. The collection efficiency of our device can be more than 1 order of magnitude higher than that of a standard AWG, in which light is collected by one input channel. Experimental results on the collection efficiency and volume are presented, together with a demonstration of multiwavelength imaging.
Optics Letters 08/2010; · 3.40 Impact Factor
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ABSTRACT: We report the realization and performance of a distributed feedback channel waveguide laser in erbium-doped aluminum oxide on a standard thermally oxidized silicon substrate. The diode-pumped continuous-wave laser demonstrated a threshold of 2.2 mW absorbed pump power and a maximum output power of more than 3 mW with a slope efficiency of 41.3% versus absorbed pump power. Single-longitudinal-mode and single-polarization operation was achieved with an emission linewidth of 1.70+/-0.58 kHz (corresponding to a Q factor of 1.14 x 10(11)), which was centered at a wavelength of 1545.2 nm.
Optics Letters 07/2010; 35(14):2394-6. · 3.40 Impact Factor
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ABSTRACT: We propose a novel and highly sensitive mechano-optical device for gas-sensing through nano-displacements, based on micro-cantilevers, supplied with a selective gas absorbing layer (Pd), suspended above a Si 3 N 4 grated waveguide (GWG). We present the simulation and preliminary experimental results, which indicate the sensing of nanodisplacements, an important intermediate step for the gas-sensing purpose.
05/2010;
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ABSTRACT: Reflection gratings on Al<sub>2</sub>O<sub>3</sub> channel waveguides were defined by focused ion beam milling. Fabry-Perot microcavities were fabricated and improved performance upon annealing was demonstrated, making them viable candidates as resonators for on-chip waveguide lasers.
LEOS Annual Meeting Conference Proceedings, 2009. LEOS '09. IEEE; 11/2009
