| 1. |
- Anand, Srinivasan, et al.
(författare)
-
Towards realization of high quality 2D-photonic crystals in InP/GaInAsP/InP
- 2004
-
Ingår i: 2004 International Conference on Indium Phosphide and Related Materials, Conference Proceedings. - 0780385950 ; , s. 311-313
-
Konferensbidrag (refereegranskat)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.
|
|
| 2. |
- Benisty, H., et al.
(författare)
-
Low-loss photonic-crystal and monolithic InP integration : Bands, bends, lasers, filters
- 2004
-
Ingår i: Photonic Crystal Materials and Devices II. - : SPIE - International Society for Optical Engineering. - 0819452688 ; , s. 119-128
-
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.
|
|
| 3. |
- Ferrini, R., et al.
(författare)
-
Minimization of out-of-plane losses in planar photonic crystals by optimizing the vertical waveguide
- 2004
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 85:18, s. 3998-4000
-
Tidskriftsartikel (refereegranskat)abstract
- A two-dimensional phenomenological approach previously developed for the modeling of out-of-plane losses in low refractive index contrast planar photonic crystals (PPhCs) is used to study the dependence of the different loss terms on the planar waveguide parameters. It is demonstrated that: (i) Losses can be minimized by designing vertical heterostructures optimized for a given technological process and/or for a given hole shape; and (ii) any small reduction of the loss value has a strong impact on the optical performances of PPhC structures.
|
|
| 4. |
- Ferrini, R., et al.
(författare)
-
Optical study of two-dimensional InP-based photonic crystals by internal light source technique
- 2002
-
Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 38:7, s. 786-799
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 5. |
|
|
| 6. |
- Moosburger, J., et al.
(författare)
-
Nanofabrication of high quality photonic crystals for integrated optics circuits
- 2002
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 13:3, s. 341-345
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we report on the fabrication and characterization of two-dimensional photonic crystals. They are realized as a hexagonal array of air holes etched in GaAs or InP based slab waveguide heterostructures. The fabrication steps are discussed, with a focus on the development of suitable dry etching processes. Holes with a depth of I mum on GaAs and 4 Mm on InP were fabricated, which results in a good overlap of the guided mode with the photonic crystal patterns and low losses. The optical quality of the structures is assessed by transmission spectroscopy of photonic crystal blocks and photonic crystal-based waveguides.
|
|
| 7. |
- Mulot, Mikael, et al.
(författare)
-
Fabrication of two-dimensional InP-based photonic crystals by chlorine based chemically assisted ion beam etching
- 2004
-
Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; 22:2, s. 707-709
-
Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional photonic crystals (PhCs) were etched into InP/(Ga,In)(As,P) planar waveguides using chlorine-based chemical assisted ion beam etching (CAIBE). The processed PhCs were optically characterized by measuring transmission through simple slabs and one-dimensional cavities. The optical performances inside the photonic band gap are much better compared to both previously reported CAIBE 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.
|
|
| 8. |
- Wild, B., et al.
(författare)
-
Temperature tuning of the optical properties of planar photonic crystal microcavities
- 2004
-
Ingår i: Proc SPIE Int Soc Opt Eng. - : SPIE. ; , s. 311-317
-
Konferensbidrag (refereegranskat)abstract
- We report on the temperature tuning of the optical properties of planar Photonic Crystal (PhC) microcavities. Studies were made on one and two dimensional PhCs that were etched in InP and GaAs vertical waveguides. Two dimensional (hexagonal) and one-dimensional (Fabry-Pérot) cavities were optically investigated by an internal light source technique. The samples were mounted on a Peltier-stage which allowed temperature variation from T = 20 °C up to T = 76 °C. A linear dependence of the resonance wavelengths with respect to temperature is observed. A gradient of dλ/dT = 0.09 nm/°C and 0.1 nm/°C for the GaAs and InP based cavities was observed, respectively. These results are in agreement with the theoretical calculations based on the thermal dependence of the refractive index of the PhC semiconductor component.
|
|
| 9. |
- Wild, B., et al.
(författare)
-
Temperature tuning of the optical properties of planar photonic crystal microcavities
- 2004
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 84:6, s. 846-848
-
Tidskriftsartikel (refereegranskat)abstract
- We report on the temperature tuning of the optical properties of photonic crystal (PhC) microcavities. Planar and one-dimensional cavities were made from two-dimensional PhCs etched in GaAs and InP based vertical waveguides. These systems were optically characterized by an internal light source technique. The samples were mounted on a Peltier stage in order to vary the temperature from 20 to 76degreesC. Linear dependence of the resonance wavelengths with respect to the temperature is observed with gradients dlambda/dT=0.09 and 0.1 nm/degreesC for GaAs and InP based cavities, respectively. These results are in agreement with theoretical calculations based on the thermal dependence of the refractive index of the PhC semiconductor component.
|
|
| 10. |
- Anand, K J S, et al.
(författare)
-
Effects of morphine analgesia in ventilated preterm neonates : primary outcomes from the NEOPAIN randomised trial
- 2004
-
Ingår i: The Lancet. - 0140-6736 .- 1474-547X. ; 363:9422, s. 1673-82
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Opioid analgesia is commonly used during neonatal intensive care. We undertook the Neurologic Outcomes and Pre-emptive Analgesia in Neonates (NEOPAIN) trial to investigate whether pre-emptive morphine analgesia decreases the rate of a composite primary outcome of neonatal death, severe intraventricular haemorrhage (IVH), and periventricular leucomalacia (PVL) in preterm neonates.METHODS: Ventilated preterm neonates (n=898) from 16 centres were randomly assigned masked placebo (n=449) or morphine (n=449) infusions. After a loading dose (100 microg/kg), morphine infusions (23-26 weeks of gestation 10 microg kg(-1) h(-1); 27-29 weeks 20 microg kg(-1) h(-1); 30-32 weeks 30 microg kg(-1) h(-1)) were continued as long as clinically justified (maximum 14 days). Open-label morphine could be given on clinical judgment (placebo group 242/443 [54.6%], morphine group 202/446 [45.3%]). Analyses were by intention to treat.FINDINGS: Baseline variables were similar in the randomised groups. The placebo and morphine groups had similar rates of the composite outcome (105/408 [26%] vs 115/419 [27%]), neonatal death (47/449 [11%] vs 58/449 [13%]), severe IVH (46/429 [11%] vs 55/411 [13%]), and PVL (34/367 [9%] vs 27/367 [7%]). For neonates who were not given open-label morphine, rates of the composite outcome (53/225 [24%] vs 27/179 [15%], p=0.0338) and severe IVH (19/219 [9%] vs 6/189 [3%], p=0.0209) were higher in the morphine group than the placebo group. Placebo-group neonates receiving open-label morphine had worse rates of the composite outcome than those not receiving open-label morphine (78/228 [34%] vs 27/179 [15%], p<0.0001). Morphine-group neonates receiving open-label morphine were more likely to develop severe IVH (36/190 [19%] vs 19/219 [9%], p=0.0024).INTERPRETATION: Pre-emptive morphine infusions did not reduce the frequency of severe IVH, PVL, or death in ventilated preterm neonates, but intermittent boluses of open-label morphine were associated with an increased rate of the composite outcome. The morphine doses used in this study decrease clinical signs of pain but can cause significant adverse effects in ventilated preterm neonates.
|
|
