| 1. |
- Angulo Barrios, Carlos, 1974-
(författare)
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Gallium arsenide based buried heterostructure laser diodes with aluminium-free semi-insulating materials regrowth
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Semiconductor lasers based on gallium arsenide and relatedmaterials are widely used in applications such as opticalcommunication systems, sensing, compact disc players, distancemeasurement, etc. The performance of these lasers can beimproved using a buried heterostructure offering lateralcarrier and optical confinement. In particular, if theconfinement (burying) layer is implemented by epitaxialregrowth of an appropriate aluminium-free semi-insulating (SI)material, passivation of etched surfaces, reduced tendency tooxidation, low capacitance and integration feasibility areadditional advantages.The major impediment in the fabrication of GaAs/AlGaAsburied-heterostructure lasers is the spontaneous oxidation ofaluminium on the etched walls of the structure. Al-oxide actsas a mask and makes the regrowth process extremely challenging.In this work, a HCl gas-basedin-situcleaning technique is employed successfully toremove Al-oxide prior to regrowth of SI-GaInP:Fe and SI-GaAs:Fearound Al-containing laser mesas by Hydride Vapour PhaseEpitaxy. Excellent regrowth interfaces, without voids, areobtained, even around AlAs layers. Consequences of usinginadequate cleaning treatments are also presented. Regrowthmorphology aspects are discussed in terms of different growthmechanisms.Time-resolved photoluminescence characterisation indicates auniform Fe trap distribution throughout the regrown GaInP:Fe.Scanning capacitance microscopy measurements demonstrate thesemi-insulating nature of the regrown GaInP:Fe layer. Thepresence of EL2 defects in regrown GaAs:Fe makes more difficultthe interpretation of the characterisation results in the nearvicinity of the laser mesa.GaAs/AlGaAs buried-heterostructure lasers, both in-planelasers and vertical-cavity surface-emitting lasers, withGaInP:Fe as burying layer are demonstrated for the first time.The lasers exhibit good performance demonstrating thatSI-GaInP:Fe is an appropriate material to be used for thispurpose and the suitability of our cleaning and regrowth methodfor the fabrication of this type of semiconductor lasers.Device characterisation indicates negligible leakage currentalong the etched mesa sidewalls confirming a smooth regrowthinterface. Nevertheless, experimental and simulation resultsreveal that a significant part of the injected current is lostas leakage through the burying material. This is attributed todouble carrier injection into the SI-GaInP:Fe layer.Simulations also predict that the function of GaInP:Fe ascurrent blocking layer should be markedly improved in the caseof GaAs-based longer wavelength lasers.Keywords:semiconductor lasers, in-plane lasers, VCSELs,GaAs, GaInP, semi-insulating materials, hydride vapour phaseepitaxy, regrowth, buried heterostructure, leakage current,simulation.
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| 2. |
- Aparicio, Francisco, et al.
(författare)
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Incorporation of luminescent nanometric films in photonic crystals and devices for the development of photonic sensors
- 2010
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Konferensbidrag (refereegranskat)abstract
- Dye molecules embedded in different matrices in the form of thin films are the basis of specific materials used for laser cavities, optical filters, optical gas sensors, etc. In the present communication we discuss a new methodology based on the remote microwave plasma assisted deposition of dye containing thin films that circumvent the above mentioned problems. It permits a tailored synthesis of optically active nanometric thin films containing dye molecules which are active as fluorescence emitters (i.e., coloured and fluorescent films). The principle of this new procedure is the partial polymerization of dye molecules that are evaporated over a substrate while exposed to a remote microwave Ar plasma. As a result of this process a polymeric thin film is produced in one step where some dye molecules keep intact their optical activity (although eventually, their optical response can be slightly modified by matrix effects). This methodology has been recently used for the deposition of novel plasma nanocomposites containing non-aggregated laser dyes to maximize the fluorescent emission of the materials and for the fabrication of optical NO2 sensing nanocomposites. To illustrate the possibilities of the technique we present here results for different fluorescent dye molecules, as perylene dyes, and several xanthene and oxazine derivative cationic dyes which are typically used as gain media in tuneable laser dyes. The luminescent, optical and sensing properties of these dye containing nanocomposites will be presented. These active optical layers are being developed for the fabrication of photonic sensor devices, optical filters and photonic chips (PHODYE EU Project). This is due to the full compatibility of the synthetic methodology with the present integrated microelectronic and optoelectronic technology. The possibilities for the fabrication of photonic devices integrating these active optical layers will be demonstrated. Especial attention will be paid to recent results about the incorporation of the luminescent films in photonic crystals and about the conformal growth of luminescent planar defects within artificial opals.
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| 3. |
- Barrios, Carlos Angulo, et al.
(författare)
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Demonstration of slot-waveguide structures on silicon nitride / silicon oxide platform
- 2007
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Ingår i: Optics Express. - 1094-4087. ; 15:11, s. 6846-6856
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first demonstration of guiding light in vertical slot-waveguides on silicon nitride/silicon oxide material system. Integrated ring resonators and Fabry-Perot cavities have been fabricated and characterized in order to determine optical features of the slot-waveguides. Group index behavior evidences guiding and confinement in the low-index slot region at O-band (1260-1370nm) telecommunication wavelengths. Propagation losses of < 20 dB/cm have been measured for the transverse-electric mode of the slot-waveguides.
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| 4. |
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| 5. |
- Barrios, Carlos Angulo, et al.
(författare)
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Label-free optical biosensing with slot-waveguides
- 2008
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 33:7, s. 708-710
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate label-free molecule detection by using an integrated biosensor based on a Si3N4/SiO2 Slot-waveguide microring resonator. Bovine serum albumin (BSA) and anti-BSA molecular binding events on the sensor surface are monitored through the measurement of resonant wavelength shifts with varying biomolecule concentrations. The biosensor exhibited sensitivities of 1.8 and 3.2 nm/(ng/mm(2)) for the detection of anti-BSA and BSA, respectively. The estimated detection limits are 28 and 16 pg/mm(2) for anti-BSA and BSA, respectively, limited by wavelength resolution.
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| 6. |
- Barrios, Carlos Angulo, et al.
(författare)
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Slot-waveguide biochemical sensor
- 2007
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 32:21, s. 3080-3082
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Tidskriftsartikel (refereegranskat)abstract
- We report an experimental demonstration of an integrated biochemical sensor based on a slot-waveguidemicroring resonator. The microresonator is fabricated on a Si3N4-SiO2 platform and operates at a wavelength of 1.3 mu m. The transmission spectrum of the sensor is measured with different ambient refractive indices ranging from n = 1. 33 to 1.42. A linear shift of the resonant wavelength with increasing ambient refractive index of 212 nm/refractive index units (RIU) is observed. The sensor detects a minimal refractive index variation of 2 X 10(-4) RIU.
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| 7. |
- Carlborg, Carl Fredrik, et al.
(författare)
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A packaged optical slot-waveguide ring resonator sensor array for multiplex label-free assays in labs-on-chips
- 2010
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Ingår i: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0197 .- 1473-0189. ; 10:3, s. 281-290
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Tidskriftsartikel (refereegranskat)abstract
- We present the design, fabrication, and characterisation of an array of optical slot-waveguide ring resonator sensors, integrated with microfluidic sample handling in a compact cartridge, for multiplexed real-time label-free biosensing. Multiplexing not only enables high throughput, but also provides reference channels for drift compensation and control experiments. Our use of alignment tolerant surface gratings to couple light into the optical chip enables quick replacement of cartridges in the read-out instrument. Furthermore, our novel use of a dual surface-energy adhesive film to bond a hard plastic shell directly to the PDMS microfluidic network allows for fast and leak-tight assembly of compact cartridges with tightly spaced fluidic interconnects. The high sensitivity of the slot-waveguide resonators, combined with on-chip referencing and physical modelling, yields a volume refractive index detection limit of 5 x 10(-6) refractive index units (RIUs) and a surface mass density detection limit of 0.9 pg mm(-2), to our knowledge the best reported values for integrated planar ring resonators.
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| 8. |
- Gylfason, Kristinn, 1978-, et al.
(författare)
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On-chip temperature compensation in an integrated slot-waveguide ring resonator refractive index sensor array
- 2010
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Ingår i: Optics Express. - 1094-4087. ; 18:4, s. 3226-3237
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Tidskriftsartikel (refereegranskat)abstract
- We present an experimental study of an integrated slot-waveguide refractive index sensor array fabricated in silicon nitride on silica. We study the temperature dependence of the slot-waveguide ring resonator sensors and find that they show a low temperature dependence of -16.6 pm/K, while at the same time a large refractive index sensitivity of 240 nm per refractive index unit. Furthermore, by using on-chip temperature referencing, a differential temperature sensitivity of only 0.3 pm/K is obtained, without individual sensor calibration. This low value indicates good sensor-to-sensor repeatability, thus enabling use in highly parallel chemical assays. We demonstrate refractive index measurements during temperature drift and show a detection limit of 8.8 x 10(-6) refractive index units in a 7 K temperature operating window, without external temperature control. Finally, we suggest the possibility of athermal slot-waveguide sensor design.
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| 9. |
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