| 1. |
- Benisty, H., et al.
(author)
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Low-loss photonic-crystal and monolithic InP integration : Bands, bends, lasers, filters
- 2004
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In: Photonic Crystal Materials and Devices II. - : SPIE - International Society for Optical Engineering. - 0819452688 ; , s. 119-128
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Conference paper (peer-reviewed)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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| 2. |
- Talneau, A., et al.
(author)
-
Modal behavior of single-line photonic crystal guiding structures on InP substrate
- 2004
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In: Photonics and Nanostructures - Fundamentals and Applications. - : Elsevier BV. - 1569-4410 .- 1569-4429. ; 2:1, s. 1-10
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Journal article (peer-reviewed)abstract
- We have experimentally investigated the modal behaviour and the polarization dependence of the transmission through single-missing-row photonic crystal (PC) straight guides, bends and combiners, fabricated on InP substrate. A photonic crystal-based taper has been included to funnel light in these strongly confined structures. Two-dimensional finite-difference time-domain simulations have been performed and favorably compared with the measurements. It is found that the scattering process occurring at a bend/combiner transition plays a key role on the overall transmission.
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| 3. |
- Wessberg, Johan, 1962, et al.
(author)
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Real-time prediction of hand trajectory by ensembles of cortical neurons in primates.
- 2000
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 408:6810, s. 361-5
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Journal article (peer-reviewed)abstract
- Signals derived from the rat motor cortex can be used for controlling one-dimensional movements of a robot arm. It remains unknown, however, whether real-time processing of cortical signals can be employed to reproduce, in a robotic device, the kind of complex arm movements used by primates to reach objects in space. Here we recorded the simultaneous activity of large populations of neurons, distributed in the premotor, primary motor and posterior parietal cortical areas, as non-human primates performed two distinct motor tasks. Accurate real-time predictions of one- and three-dimensional arm movement trajectories were obtained by applying both linear and nonlinear algorithms to cortical neuronal ensemble activity recorded from each animal. In addition, cortically derived signals were successfully used for real-time control of robotic devices, both locally and through the Internet. These results suggest that long-term control of complex prosthetic robot arm movements can be achieved by simple real-time transformations of neuronal population signals derived from multiple cortical areas in primates.
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| 4. |
- Ferrini, R., et al.
(author)
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Optical study of two-dimensional InP-based photonic crystals by internal light source technique
- 2002
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In: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 38:7, s. 786-799
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Journal article (peer-reviewed)abstract
- We present the first optical study of 2-D photonic crystals (PCs) deeply etched in an InP/GaInAsP step-index waveguide. Following the same internal light source approach proposed by Labilloy and coworkers for the investigation of GaAs-based 2-D PCs, transmission measurements through simple PC slabs and 1-D Fabry-Perot (FP) cavities between PC mirrors were performed. Details are given on the experimental setup which has been implemented with respect to the original scheme and adapted to InP-based systems working at 1.5-mum. 2-D plane-wave expansion and finite difference time-domain (FDTD) methods are used to fit the experimental data. Out-of-plane losses were evaluated according to a recently introduced phenomenological model. In spite of the complex hole morphology in the measured samples, preliminary results are presented which indicate the possibility of separating different loss contributions from finite etch depth and hole shape. As for 1-D cavities, both FDTD and classical theory for planar resonators are applied in order to deduce the optical properties of the PC mirrors. The origin of an anomalously high transmission observed inside the stopgap is discussed and arguments are given to demonstrate the need for further modeling efforts when working in the bandgap regime.
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| 5. |
- Qiu, Min, et al.
(author)
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Photonic crystal optical filter based on contra-directional waveguide coupling
- 2003
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 83:25, s. 5121-5123
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Journal article (peer-reviewed)abstract
- Wavelength-selective operation of an optical filter (add/drop) based on a contra-directional photonic crystal waveguide coupler is demonstrated. The waveguides are defined as line defects in a two-dimensional triangular photonic crystal fabricated in an InP/GaInAsP heterostructure. The device is characterized using the end-fire method for the drop functionality. The experimental data are in good agreement with the theoretical results predicted by finite-difference time-domain simulations.
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| 6. |
- Talneau, A., et al.
(author)
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High-bandwidth transmission of an efficient photonic-crystal mode converter
- 2004
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In: Optics Letters. - 0146-9592 .- 1539-4794. ; 29:15, s. 1745-1747
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Journal article (peer-reviewed)abstract
- We have investigated both theoretically and experimentally the spectral behavior and the transmission and reflection performance of a photonic-crystal (PhC) mode converter upon an InP substrate. This taper exhibits 70% transmission efficiency on an 80-nm bandwidth when it couples a ridge access guide to a strongly confined single-missing-row PhC guide. Such a taper design included in a PhC bend contributes a large benefit to the overall transmission budget of the PhC-based link.
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| 7. |
- Anand, Srinivasan, et al.
(author)
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Towards realization of high quality 2D-photonic crystals in InP/GaInAsP/InP
- 2004
-
In: 2004 International Conference on Indium Phosphide and Related Materials, Conference Proceedings. - 0780385950 ; , s. 311-313
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Conference paper (peer-reviewed)abstract
- Two-dimensional photonic crystals (PhCs) were etched into InP/GaInAsP/InP planar waveguides using chlorine based chemical assisted ion beam etching (CAIBE). Etching mechanisms and process parameters crucial for high quality PhC definition are discussed, with special attention to the lag-effect. The processed PhCs were optically characterized by measuring transmission through simple slabs and one-dimensional cavities. The optical properties inside the photonic bandgap are much better compared to both previously reported CAME results and results obtained with other etching methods. In particular, we measured a record quality factor of 310 for one-dimensional cavities fabricated in this material system.
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| 8. |
- Carmody, C., et al.
(author)
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Structural, electrical, and optical analysis of ion implanted semi-insulating InP
- 2004
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 95:2, s. 477-482
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Journal article (peer-reviewed)abstract
- Semi-insulating InP was implanted with MeV P, As, Ga, and In ions, and the resulting evolution of structural properties with increased annealing temperature was analyzed using double crystal x-ray diffractometry and cross sectional transmission electron microscopy. The types of damage identified are correlated with scanning spreading resistance and scanning capacitance measurements, as well as with previously measured Hall effect and time resolved photoluminescence results. We have identified multiple layers of conductivity in the samples which occur due to the nonuniform damage profile of a single implant. Our structural studies have shown that the amount and type of damage caused by implantation does not scale with implant ion atomic mass.
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| 9. |
- Happ, T. D., et al.
(author)
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Single-mode operation of coupled-cavity lasers based on two-dimensional photonic crystals
- 2001
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 79:25, s. 4091-4093
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Journal article (peer-reviewed)abstract
- We report the fabrication of short-cavity lasers with highly reflective two-dimensional photonic crystal mirrors on an InGaAsP/InP laser structure emitting at 1.57 mum. An intracavity photonic crystal mirror creates two coupled cavities, which provide additional longitudinal mode selection for stable single-mode operation with side-mode suppression ratios exceeding 35 dB. The shortest lasers with l=100 mum overall length have a threshold current of 13 mA and provide more than 4 mW power under continuous wave operation. Longer devices with l=200 mum deliver up to 9 mW. A maximum modulation bandwidth of 7.9 GHz was determined by relative intensity noise measurements.
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| 10. |
- Kamp, M., et al.
(author)
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Semiconductor photonic crystals for optoelectronics
- 2004
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In: Physica. E, Low-Dimensional systems and nanostructures. - : Elsevier BV. - 1386-9477 .- 1873-1759. ; 21:2-4, s. 802-808
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Journal article (peer-reviewed)abstract
- We present a number of designs for the integration of photonic crystals (PC) with active semiconductor devices. As a first step, the use of PC blocks as laser mirrors is demonstrated. Ridge-waveguide lasers with a length of 100 mum and two PC mirrors achieve threshold currents below 8 mA. In order to obtain single-mode operation, an intracavity PC mirror can be used, which effectively separates the laser into two coupled cavities. Lasing occurs where two modes of the cavities coincide, leading to single-mode operation with a side-mode suppression ratio (SMSR) of over 35 dB. We also present two full PC devices: a single-mode laser with a coupled resonant cavity waveguide (CROW) and a tunable laser. The CROW device consists of a chain of 40 hexagonal cavities formed in a block of PC, with a total length of 140 mum. Low threshold, single-mode operation with over 40 dB SMSR is demonstrated. Coupled cavities are used for the tunable PC laser, which covers a tuning range of over 30 nm.
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