| 1. |
- Anand, Srinivasan, et al.
(författare)
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High aspect ratio etching and characterization of 2D-photonic crystals in InP/InGaAsP/InP heterostructures
- 2004
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Ingår i: Photonics. - : SPIE - International Society for Optical Engineering. - 0819451703 ; , s. 78-89
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Konferensbidrag (refereegranskat)abstract
- We report on the fabrication and characterization of 2D photonic crystals (PhCs) in InP/InGaAsP/InP heterostructures. It is demonstrated that Ar/C12 based chemically assisted ion beam etching (CAIBE) is a very promising method to obtain high aspect ratio etching of PhCs in the InP-based materials. With this process, it is possible to obtain PC-holes as deep as 3 microns even for feature (PhC-hole) sizes as small as 200-250 nm. The optical characteristics of the fabricated PhC-based elements/devices such as line-defect waveguides, in-plane resonant cavities and drop-filter based on contra-directional coupling will be reported. The devices were measured using end-fire coupling and the obtained results were simulated using the 2D finite difference time domain (FDTD) method including an effective loss-approximation. The etched PhC-waveguides show low transmission losses, less than 1 dB/100 mum. A quality factor of 400 for a 6 micron long cavity with 6-hole mirrors is obtained. Finally, drop-functionality in a PhC-based filter using contra-directional coupling is demonstrated.
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| 2. |
- Benisty, H., et al.
(författare)
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Low-loss photonic-crystal and monolithic InP integration : Bands, bends, lasers, filters
- 2004
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Ingår i: Photonic Crystal Materials and Devices II. - : SPIE - International Society for Optical Engineering. - 0819452688 ; , s. 119-128
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Konferensbidrag (refereegranskat)abstract
- Practical realizations of 2D (planar) photonics crystal (PhC) are either on a membrane or etched through a conventional heterostructure. While fascinating objects can emerge from the first approach, only the latter approach lends itself to a progressive integration of more compact PhC's towards monolithic PICs based on InP. We describe in this talk the various aspects from technology to functions and devices, as emerged from the European collaboration "PCIC". The main technology tour de force is deep-etching with aspect ratio of about 10 and vertical sidewall, achieved by three techniques (CAIBE, ICP-RIE, ECR-RIE). The basic functions explored are bends, splitters/combiners, mirrors, tapers, and the devices are filters and lasers. At the end of the talk, I will emphasize some positive aspects of "broad" multimode PhC waveguides, in view of compact add-drop filtering action, notably.
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| 3. |
- Benisty, H., et al.
(författare)
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Models and measurements for the transmission of submicron-width waveguide bends defined in two-dimensional photonic crystals
- 2002
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Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 38:7, s. 770-785
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Tidskriftsartikel (refereegranskat)abstract
- One of the essential building-blocks of miniature photonic crystal (PC)-based photonic integrated circuits (PICs) is the sharp bend. Our group has focused on the 2-D photonic crystal based on a triangular lattice of holes perforating a standard heterostructure. The latter, GaAlAs-based or InP-based, is vertically a monomode waveguide. We consider essentially one or two 60 bends defined by one to five missing rows, spanning both cases of monomode and multimode channel waveguides. From intensive modeling and various experimental measurements (both on GaAs and InP), we point out the origin of the present level of bend insertion losses and discuss the merits of the many roads open for improved design.
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| 4. |
- Berrier, Audrey, et al.
(författare)
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Negative Refraction at Infrared Wavelengths in a Two-Dimensional Photonic Crystal
- 2004
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 93:073902
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first experimental evidence of negative refraction at telecommunication wavelengths by a two-dimensional photonic crystal field. Samples were fabricated by chemically assisted ion beam etching in the InP-based low-index constrast system. Experiments of beam imaging and light collection show light focusing by the photonic crystal field. Finite-difference time-domain simulations confirm that the observed focusing is due to negative refraction in the photonic crystal area.
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| 5. |
- Dainese, Matteo, et al.
(författare)
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Narrow band coupler based on one-dimensional Bragg reflection waveguide
- 2003
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Ingår i: 2003 Optical Fiber Communication Conference. - 1557527466 ; , s. 44-46
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Konferensbidrag (refereegranskat)abstract
- A new configuration based on the coupling between a conventional low loss, weakly guiding channel waveguide and a Bragg reflection waveguide (BRW) was discussed. The strong difference between the dispersion of a Bragg reflection waveguide and a channel waveguide was used to create a narrow band coupler. The two-dimensional analysis of the BRW was generally based on the transfer matrix method. The structure consisted of a weakly guiding conventional Ge-doped silica waveguide on the top of which a BRW was stacked. The number of periods in the mirror between the BRW and the silica waveguide affected the coupling length and ultimately the bandwidth.
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| 6. |
- Dainese, Matteo, et al.
(författare)
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Photosensitivity of boron-codoped PECVD films in application to grating assisted WDM devices
- 2004
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Ingår i: INTEGRATED OPTICS AND PHOTONIC INTEGRATED CIRCUITS. - BELLINGHAM : SPIE-INT SOC OPTICAL ENGINEERING. - 0819453749 ; , s. 191-198
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Konferensbidrag (refereegranskat)abstract
- UV sensitivity of B-Ge codoped cores in PECVD silica waveguides has been investigated. Photoinduced refractive index changes have been introduced by KrF excimer laser irradiation at 248 rim, without any presensitization method. The effects of B codoping of Ge doped silica have been examined. It has been shown that B addition mildly increases glass network disorder, by broadening the O bridging angle distribution as from FTIR measurements, but on the other hand it does not produce point defects which may contribute to the absorption band at 5eV already generated by the presence of Ge doping. The fabricated channel waveguides show low optical loss even without high temperature annealing. Strong Bragg gratings imprinted into these waveguides confirm that in non thermally annealed Ge doped PECVD silica glass, where a small absorption band still exist at 5eV, B codoping supplies sufficient photosensitivity amplification to make hydrogen loading unnecessary.
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| 7. |
- Jaskorzynska, Bozena, et al.
(författare)
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Nonlinear upconversion-rate in Er-doped fibers
- 2001
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Ingår i: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 99:1, s. 147-153
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Tidskriftsartikel (refereegranskat)abstract
- Energy transfer between excited rare-earth ions has been widely used for realizing upconversion lasers and also recognized as a gain limiting factor in high-concentration Er-doped amplifiers. The energy transfer leads to upconversion of the excitation which for randomly distributed (not clustered) ions is called homogeneous upconversion. It was commonly assumed that the rate of homogeneous upconversion is a linear function of the population inversion N-2. However, recently published Monte Carlo simulations predict that the homogeneous upconversion rate is a nonlinear function of N-2 and that it, moreover, depends on the pump and signals rates. In this paper we review some of our experimental results confirming those predictions. We also propose a statistical, analytical model describing the observed homogeneous upconversion behavior in Er-doped fibers.
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| 8. |
- Mulot, M., et al.
(författare)
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Dry etching of photonic crystals in InP based materials
- 2002
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Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T101, s. 106-109
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Tidskriftsartikel (refereegranskat)abstract
- Photonic crystal (PC) etching in InP/GaInAsP using two different processes, namely Ar/CH4/H-2 based Reactive Ion Etching (RIE) and Ar/Cl-2 based Chemically Assisted Ion Beam Etching (CAIBE), is investigated in detail and the results are compared. Our goal was to identify the limits of the processes and to optimize process parameters for PC etching. With Ar/CH4/H-2 RIE, we obtained PC holes with smooth profiles. However, the etch depth depends strongly on the hole diameter; the smaller the hole diameter, the smaller is the obtained hole depth. This together with the obtained hole profiles indicates the presence of an etch-limiting mechanism and is attributed to inefficient removal of etch-products. In the case of Ar/Cl-2 CAME, we find that both shape and depth of the holes, depend on sample temperature, Cl-2 flow and etching duration. By optimizing the process parameters, we show that it is possible to balance the physical and chemical components in the etch process. We demonstrate that Ar/Cl-2 CAME is a promising process for PC etching in InP. With this process, we can obtain sufficiently deep holes (2.3-2.5 mum) even for hole diameters as small as 220nm.
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| 9. |
- Mulot, Mikael, et al.
(författare)
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Fabry-Perot cavities based on two-dimensional photonic crystals fabricated in InP membranes
- 2004
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 95:10, s. 5928-5930
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Tidskriftsartikel (refereegranskat)abstract
- We measured the transmission and analyzed out-of-plane loss in Fabry-Perot filters based on photonic crystals etched in a suspended InP membrane. The resonant cavity of the Fabry-Perot filter is based on a single row line defect introduced in a triangular lattice of air holes. The transmission spectrum of these structures is measured by using the end-fire method. We measured a cavity quality factor of 3200 for a resonance wavelength in the 1.5 mum wavelength range. We identify that radiation through the holes at both extremities of the resonant cavity largely contributes to the loss in the device.
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| 10. |
- Mulot, M., et al.
(författare)
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In-plane resonant cavities with photonic crystal boundaries etched in InP-based heterostructure
- 2003
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 83:6, s. 1095-1097
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Tidskriftsartikel (refereegranskat)abstract
- The optical properties of in-plane cavities with photonic crystal boundaries fabricated into an InP/GaInAsP/InP slab waveguide structure are presented. The investigated cavities are realized as segments of different lengths bounded by V-shaped double or single mirrors in straight photonic crystal waveguides and were designed to have resonance in the 1.55 mum wavelength range. High aspect ratio etching of the photonic crystal is achieved using Ar/Cl-2-based chemically assisted ion beam etching. The optical loss inside the photonic crystal waveguide was determined by fitting the measured transmission spectra with two-dimensional finite-difference time-domain simulations. The experimental results, combined with the simulations, indicate that major sources of loss in these cavities are radiation through the cavity mirrors and out-of-plane scattering of the third-order mode inside of the cavity. The best results were obtained for a 6.2 mum long resonant cavity with double mirrors that had an appreciably high-quality factor of 460.
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