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We have deposited amorphous silicon (a-Si) and nanocrystalline silicon (nc-Si) materials and the total p-i-n configurations for solar cells in a high vacuum multichamber system ASTER using very high frequency plasma enhanced chemical vapour deposition (VHF PECVD) process. The deposition process is monitored and controlled by in-situ diagnostic tools to maintain reproducibility of the material quality. In this paper we show our recent results on single junction (amorphous silicon) and tandem (a-Si/nc-Si) cells on plastic foil using the Helianthos concept. The tandem cell efficiency on Asahi U-type SnO 2 :F coated glass is ∼ 12% and this is achieved by employing nc-Si deposited at high pressure (p) conditions of 5 mbar and a small inter-electrode distance (d) of 5 mm. The deposition scheme of this cell on glass was adapted for the SnO 2 :F coated Al foil substrates from Helianthos b.v., especially taking into account the expansion of the foil during deposition. The inter-electrode distance d was one of the variables for this optimisation process. Depositions at four inter-electrode distances of 6 mm, 8 mm, 10 mm and 12 mm (keeping the pressure-distance product constant) revealed that the deposition rate increases at higher distances, reaching 0.6 nm/s at a d of 10 mm and pressure p of 3.0 mbar. The Raman crystalline ratio showed a monotonic increase with the combination of higher d and lower p. Tandem cells with an area of 2.5 cm 2 on plastic foil fabricated by the Helianthos concept and employing the above mentioned nc-Si made at 0.6 nm/s in the bottom cell and a-Si in the top cell, showed an efficiency of 8.12%, with a short circuit current density of 10 mA/cm 2 , The combined deposition time of the photoactive silicon layers of the top and bottom cells amounted to only 85 min.

Objective : To evaluate the frequency and risk of postoperative complications and mortality in patients with IIIa-N2 non small cell lung cancer after induction chemotherapy and surgery. Methods : In a surgical database records from ninety two patients, operated between January 1, 2000 and December 31, 2006 were reviewed. Univariate analysis was used to identify predictors of postoperative complications and in-hospital mortality. Results : All cases were histologically confirmed stage IIIa-N2. All patients received preoperative platinum based chemotherapy without radiotherapy. Pneumonectomy was performed in 20 cases (23.5%), from which 9 right sided. (Bi)lobectomy was performed in 53 cases (62.4%) and sleeve lobectomy in 11 cases (17.2%). One wedge resection was performed (1.2%). In 7 cases (7.6%) only an exploration was done. Complications developed in 35 patients (38%). Major complications in 15 patients (16%). No bronchopleural fistulae were observed. Analysis identified increased age and high physiological and operative severity score for the enumeration of mortality and morbidity (POSSUM) as a risk factor to develop complications, and a high simplified comorbidity score as a risk factor to develop a major complica - tion. Higher age, Charlson comorbidity index , simplified comorbidity score and POSSUM were a risk factor for devel- oping pneumonia. Conclusion : Although surgery after induction therapy for IIIa-N2 NSCLC can be done with a morbidity and mortality comparable to surgery alone, it remains a high risk operation. It should therefore be performed in a center with experience. Bronchial stump protection should be used whenever there is an increased risk for developing a broncho - pleural fistula. In deciding whether to do surgery or radiotherapy one should keep in mind the feasibility of performing a complete resection together with a preoperative assessment to predict complications and mortality. For the pre - operative assessment several scoring systems can be used from which we find the simplified comorbidity score most useful .

The aim of this research is to fabricate high efficiency a-Si/μc-Si tandem solar cell modules on flexible (polymer) superstrates using the Helianthos concept. As a first step we began by depositing the top cell which contains an amorphous silicon (a-Si:H) i-layer of ∼350 nm made by VHF PECVD at 50 MHz in a high vacuum multichamber system called ASTER, with hydrogen to silane gas flow ratio of 1:1. Such amorphous cells on-foil showed an initial active area (0.912 cm2) efficiency of 7.69% (Voc = 0.834 V, FF = 0.71). These cells were light soaked with white light at a controlled temperature of 50 °C. The efficiency degradation was predominantly due to degradation of FF that amounted to only 11% after 1000 h of light soaking. The cell-on-foil data prove that thin film silicon modules of high stability on cheap plastics can be made at a reasonable efficiency within 30 min of deposition time. A minimodule of 8 × 7.5 cm2 area (consisting of 8 cells interconnected in series) with the same single junction a-Si:H p–i–n structure had an initial efficiency of 6.7% (Voc = 6.32 V, FF = 0.65).

A novel class of optical waveguides with a box-shaped cross section consisting of a low-index inner material surrounded by a thin high-index coating layer is presented. This original multilayered structure widens the traditional concept of index contrast for dielectric waveguides toward a more general concept of effective index contrast, which can be artificially tailored over a continuous range by properly choosing the thickness of the outer high-index layers. An electromagnetic analysis is reported, which shows that the transverse electric and transverse magnetic modes are spatially confined in different regions of the cross section and exhibit an almost 90degC rotational symmetry. Such unusual field distribution is demonstrated to open the way to new intriguing properties with respect to conventional waveguides. Design criteria are provided into details, which mainly focus on the polarization dependence of the waveguide on geometrical parameters. The possibility of achieving single-mode waveguides with either zero or high birefringence is discussed, and the bending capabilities are compared to conventional waveguides. The feasibility of the proposed waveguide is demonstrated by the realization of prototypal samples that are fabricated by using the emerging CMOS- compatible Si3N4-SiO2 TriPleX technology. An exhaustive experimental characterization is reported, which shows propagation loss as low as state-of-the-art low-index-contrast waveguides (< 0.1 dB/cm) together with enhanced flexibility in the optimization of polarization sensitivity and confirms the high potentialities of the proposed waveguides for large-scale integrated optics.

(2015). Severe Acute Postoperative Gastric Dilatation. Acta Chirurgica Belgica: Vol. 115, No. 3, pp. 232-233.

To evaluate the results of a combination of fistulectomy with a rectal advancement flap and an anal fistula plug in the treatment of transsphincteric anal fistulas.All patients with a transsphincteric fistula and a limited number of anterior intersphincteric fistulas in female patients were registered from July 1(st), 2010 until November 30(th), 2012. All operations were performed by one surgeon (CdG). Patient data and results (healing, continence) were collected in a prospective database.28 patients were treated with a healing rate of 75% after one procedure. Four out of seven patients who failed to heal underwent a redo anal fistula plug and rectal advancement flap. Three of them were cured. Cumulative healing rate was 86% after two procedures. There were four minor complications. Mean postoperative Wexner score was 0.62.Combination of anal fistula plug and rectal advancement flap in treating transsphincteric anal fistulas can result in good healing rates with minimal incontinence.

Optical ring resonators (ORRs) are good candidates to provide continuously tunable delay in optical beam forming networks (OBFNs) for phased array antenna systems. Delay and splitting/combining elements can be integrated on a single optical chip to form an OBFN. A state-of-the-art ring resonator-based 1times 8 OBFN chip has been fabricated in complementary metal-oxide-semiconductor-compatible waveguide technology. A binary tree topology is used for the network such that a different number of ORRs is cascaded for delay generation at each output. In this letter, the principle of operation is explained and demonstrated by presenting some measurement results on the 1times 8 OBFN chip.

The SYDDARTA project is an on-going European Commission funded initiative under the 7th Framework Programme. Its main objective is the development of a pre-industrial prototype for diagnosing the deterioration of movable art assets. The device combines two different optical techniques for the acquisition of data. On one hand, hyperspectral imaging is implemented by means of electronically tunable filters. On the other, 3D scanning, using structured light projection and capturing is developed. These techniques are integrated in a single piece of equipment, allowing the recording of two optical information streams. Together with multi-sensor data merging and information processing, estimates of artwork deterioration and degradation can be made. In particular, the resulting system will implement two optical channels (3D scanning and short wave infrared (SWIR) hyperspectral imaging) featuring a structured light projector and electronically tunable spectral separators. The system will work in the VIS-NIR range (400-1000nm), and SWIR range (900-2500nm). It will be also portable and user-friendly. Among all possible art work under consideration, Baroque paintings on canvas and wooden panels were selected as the project case studies.

Deterioration of artwork, in particular paintings, can be produced by environmental factors such as temperature fluctuations, relative humidity variations, ultraviolet radiation and biological factors among others. The effects of these parameters produce changes in both the painting structure and chemical composition. While well established analytical methodologies, such as those based in Raman Spectroscopy and FTIR Spectroscopy require the extraction of a sample for its inspection, other approaches such as hyperspectral imaging and 3D scanning present advantages for in-situ, noninvasive analysis of artwork. In this paper we introduce a novel system and the related methodology to acquire process, generate and analyze 4D data of paintings. Our system is based on non-contact techniques and is used to develop analytical tools which extract rich 3D and hyperspectral maps of the objects, which are processed to obtain accurate quantitative estimations of the deterioration and degradation present in the piece of art. In particular, the construction of 4D data allows the identification of risk maps on the painting representation, which can allow the curators and restorers in the task of painting state evaluation and prioritize intervention actions.

We report experiments which show evidence that stimulated emission at 863 nm takes place in hybrid monomode Si3N4 waveguides where LaF3 :Nd nanoparticle-doped polymethylmethacrylate (PMMA) was used as a top cladding material. Furthermore, optical gain at 1319 nm in LaF3:Nd nanoparticle dispersed PMMA s0.1 dB/cmd and photodefinable epoxy (Microchem SU-8) multimode waveguides has been observed at pump powers below 10 mW. This class of composite materials based on polymers with dispersed nanoparticles shows promising properties for planar optical amplifiers. Simulation showed that optical gain in the order of 10 dB can be achieved at 100 mW pump power in a 20 cm long monomode waveguide.

For enhanced communication on board of aircraft, novel antenna systems with broadband satellite-based capabilities are required. So far existing L-band satellite based systems for communications are used primarily for passenger application (APC) or administrative communications (AAC); initially analogue voice and now data are tending to evolve towards broadband digital applications. Many studies are going on worldwide to employ Ku-band TV geostationary satellites for communication with mobile terminals on aircraft. For a short period broadband internet was available on aircraft via Connexion by Boeing (CBB) services. Lufthansa installed the CBB system on some of their long-haul aircraft. In the EC Sixth Framework Programme ANASTASIA (Airborne New and Advanced Satellite techniques and Technologies in A System Integrated Approach) existing and planned aeronautical SATCOM services, systems and technology have been analysed. It has been concluded that for cockpit services, L-band systems (namely Inmarsat, MTSAT, Iridium and Globalstar) are clearly most suitable, whilst Ku-band systems have appeal for passenger services

In this contribution we report the result of an a-Si/μc-Si tandem thin film silicon solar mini-module deposited on plastic foil containing intrinsic layers made by hot-wire CVD (eff. ≫ 7%, series-connected with aperture area 25 cm2). We used the Helianthos cell transfer process. The cells were first deposited on a temporary aluminum foil carrier, which allows using optimal process temperatures, and then transferred to a plastic foil. The paper reports the characteristics of the flexible solar cells obtained in this manner, and compares the results with those obtained on reference glass substrates. The issues for implementation of the hot-wire CVD technique for the R2R process are also discussed.

For enhanced communication on board an aircraft, novel antenna systems with broadband satellite based capabilities are required. The technology will enhance airline operations by providing in-flight connectivity for flight crew information and will bring live TV and high speed Internet connectivity to passengers. The installation of such systems on board an aircraft requires for aerodynamic reasons the development a very low-profile aircraft antenna, which can point to satellites anywhere in the upper hemisphere. To this end, phased array antennas which are conformal to the aircraft fuselage are attractive. In this paper, two key aspects of conformal phased array antenna arrays are addressed: the development of a broadband Ku-band antenna and an optical beam forming network for tracking satellites. The antenna elements of the conformal array are stacked patch antennas with dual linear polarization which have sufficient bandwidth. For tracking an optical circuit is proposed that consists of a cascade of optical ring resonators.

23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 2065-2068, Nuon Helianthos has developed a proprietary process to manufacture large area flexible thin film solar cells on a temporary carrier foil. The resulting flexible light weight PV laminates are intended for large area solar power applications. Integrated in or on building materials PV laminates will serve as an electricity generating skin for buildings and other structures in the built environment. The ability to produce such laminates on kilometer long substrates will enable cost competitive solar electricity generation. While preparing for upscaling, Nuon Helianthos is operating a roll-to-roll pilot line capable of producing 6 x 0.3 m2 amorphous silicon PV laminates yielding 6.7% initial aperture area efficiency. Stabilized energy efficiency amounts to 6% on 840 cm2 scale. With a parallel lab line amorphous/microcrystalline silicon tandem cell modules with stabilized aperture area efficiency of 7.8% are fabricated. The pilot line processes for single and multi-junction thin film silicon based photovoltaic laminates are being scaled up for 1.2 m wide substrates.

The aim of this research is to fabricate high efficiency a-Si/μc-Si tandem solar cell modules on flexible (polymer) superstrates using the Helianthos concept. As a first step we began by depositing the top cell which contains an amorphous silicon (a-Si:H) i-layer of 350 nm made by VHF PECVD at 50 MHz in a high vacuum multichamber system called ASTER, with hydrogen to silane gas flow ratio of 1:1. Such amorphous cells on-foil showed an initial active area (0.912 cm2) efficiency of 7.69% (Voc = 0.834 V, FF = 0.71). These cells were light soaked with white light at a controlled temperature of 50 °C. The efficiency degradation was predominantly due to degradation of FF that amounted to only 11% after 1000 h of light soaking. The cell-on-foil data prove that thin film silicon modules of high stability on cheap plastics can be made at a reasonable efficiency within 30 min of deposition time. A minimodule of 8 × 7.5 cm2 area (consisting of 8 cells interconnected in series) with the same single junction a-Si:H p–i–n structure had an initial efficiency of 6.7% (Voc = 6.32 V, FF = 0.65).

23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 2422-2427, In this paper we present the development and implementation of protocrystalline silicon for use as an absorber layer in single junction a-Si:H photovoltaic modules on plastic foil. The development process included three steps. The first step was the investigation of the opto-electronic properties of protocrystalline silicon films deposited in a temperature range of 75°C to 200°C. In the second step the characterization of solar cells on glass with the protocrystalline silicon absorber layer was carried out during light soaking. The last step involved the characterization of photovoltaic mini-modules on plastic foil with the protocrystalline silicon absorber layer. The absorber layers were deposited in the temperature range of 150°C to 200°C. The results show that the protocrystalline silicon films have a low defect density (

23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 2309-2312, Thin film silicon technology is one of the most promising branches of the growing photovoltaic industry. For its lower cost, roll-to-roll deposition process on sacrificial Al superstrate is being tested for use in large industrial production at Helianthos bv. Fourier Transform Photocurrent Spectroscopy (FTPS) is a modern method widely used for thin film silicon solar cell diagnostics. At the same time the optical modeling of light management in thin film solar cells is a key tool for structure optimization. Here we refer to a comprehensive study of a single a-Si:H or tandem a-Si:H/μc-Si:H solar cell comprising material quality assessment by FTPS, optical constants evaluation by PDS (Photothermal Deflection Spectroscopy) and T/R spectroscopy, quantum efficiency measurements by FTPS and optical simulations by our numerical model Cell.. This is not an easy task because the aluminum foil, that is later in the process etched off, complicates the FTPS and optical measurement. The result of our study is the assessment of optical parameters of all layers forming the cell and the calculation of limiting efficiencies for several proposed cell structures. For absorbers we can evaluate the electronic quality by the measurement of sub-bandgap absorption in a single solar cell and newly also in a tandem solar cell. We also refer to the possibility and to our experimental experience with such measurement performed on completed modules.

A novel squint-free, continuously tunable beamformer mechanism for a phased array antenna system is proposed. It consists of filter-based optical single-sideband suppressed-carrier modulation, a fully integrated optical beam forming network using cascades of optical ring resonators as tunable delay elements, and balanced coherent optical detection. The proposed system brings advantages in optical bandwidth requirement, system complexity, and dynamic range, without introducing the problem of beam squint or limited tuning resolution. Some experimental results are presented in order to demonstrate the feasibility of the proposed concept.

A novel optical beamformer system for phased array transmit antennas is proposed and experimentally demonstrated. It is based on an optical IM/DD link through a ring resonator-based optical beam forming network chip.

The activities of the Telecommunication Engineering (TE) group span the communications spectrum from copper cables, optical fibres, microwaves, radio and electromagnetic compatibility. Our research concentrates on optical signal processing and networks, mobile communications, microwave techniques and radiation from ICs and PCBs [1]. A considerable (and particularly interesting) part of it is related to optical beam forming for phased array antennas, using optical ring resonators. In this article the theoretical basics and practical challenges of this interesting research topic will be summarized.

Optical ring resonators (ORRs) are good candidates to provide continuously tunable delay in beam forming networks (BFNs) for phased array antenna systems. Delay and splitting/combining elements can be integrated on a single optical chip to form an OBFN. A state-of-the-art 1×8 OBFN chip has been fabricated in LPCVD waveguide technology. It is designed with 1 input and 8 outputs, between which a binary-tree topology is used. A different number of ORRs (up to 7) are cascaded for each output. In this paper, the principle of operation is explained and demonstrated by presenting measurements on the 1×8 OBFN chip.

A novel beam steering mechanism for a phased array antenna receiver system is introduced. The core of the system is a ring resonator-based integrated optical beam forming network chip. Its principles are explained and demonstrated by presenting some measurement results. The system architecture around the chip is based on a combination of frequency down conversion, filter-based optical single sideband modulation and balanced coherent detection. It is proven that such an architecture has significant advantages with respect to a straightforward architecture using double sideband modulation and direct detection, namely relaxed bandwidth requirements on the optical modulators and detectors, reduced complexity and optical losses of the beam forming chip, and enhanced dynamic range.

— Optical ring resonators (ORRs) can be used as continuously tunable delay elements in a beam forming network for a phased-array antenna system. The bandwidth of such delay elements can be enhanced by cascading multiple ORRs. When delays and splitting/combining circuitry are integrated in one optical circuit, an optical beam forming network (OBFN) is obtained. In this paper, the principles of optical beam forming using ORRs are explained and demonstrated, by presenting measurements on a 1×4 OBFN chip, realized in LPCVD waveguide technology. To our knowledge, this is the first single-chip demonstration of continuous optical beam forming.

A new class of integrated optical waveguide structures is presented, based on low cost CMOS compatible LPCVD processing. This technology allows for medium and high index contrast waveguides with very low channel attenuation. The geometry is basically formed by a rectangular cross-section silicon nitride (Si3N4) filled with and encapsulated by silicon dioxide (SiO2). The birefringence and minimal bend radius of the waveguide is completely controlled by the geometry of the waveguide layer structures. Experiments on typical geometries will be presented, showing excellent characteristics (channel attenuation ≤ 0.1 dB/cm, IL ≤ 1.5 dB, PDL ≤ 0.2 dB, Bg ≤ 1×10-4, bend radius « 1 mm).

Optical circuits providing a time delay to signals modulated on optical carriers are considered important for optical communication systems and phased array antennas. A continuously tunable optical delay line is demonstrated in low-cost CMOS compatible LPCVD planar waveguide technology. The device consists of three cascaded ringresonator all-pass filters with fixed circumference of 2 cm (delay of 0.12 ns and FSR of 8.4 GHz). The measured group delay ranges from 0 ns up to 1.2 ns with a bandwidth of 500 MHz and delay ripple smaller than 1 ps, which is in accordance with the calculations.

Polymers with optically active nonlinear chromophores have been shown to have a promising future in low cost and high speed electro–optic device applications. However, a main question of concern is the photochemical stability of the chromophores for long term application. The chromophore TCVDPA with a benzene bridge between a tricyanovinyl acceptor and an amino donor has been reported to have high photochemical stability combined with high electro-optic activity. In the current work direct waveguide definition of the host polymer SU-8, a negative photoresist, containing this chromophore by masked UV exposure followed by development, has been demonstrated. This was possible by utilizing the chromophore low absorption window in the UV region that allows crosslinking of the host polymer by exposing to UV light followed by thermal curing.

We report on rare earth doped LaF3 nanoparticles dispersed in PMMA and SU-8 photosensitive polymers. We observed optical gain after we applied these materials for waveguides. Experimental results on various samples will be discussed. We theoretically discuss the improvements that can be obtained and the possibilities of this new class of materials when applied to microring resonators.

A multimode fiber-matched arrayed waveguide grating-based demultiplexer has been demonstrated. In this design, multimode waveguides have been used as array elements. The device, which can be used in short-distance communications, has been realized using low-cost polymer planar waveguide technology. Three wavelength channels were successfully separated. The average fiber-to-fiber insertion loss was 14 dB and the worst-case cross talk was < -12.5 dB.

Large cross section multimode waveguides have been realized in SU-8 using selective polymerization. SU-8 is a negative photoresist, which has shown good optical properties and it is mechanically and chemically stable. The fabricated waveguides have very smooth sidewalls and exhibit low optical losses. The fabrication method is simple and potentially very cost effective. N x N and 1 x N multimode power splitters have been realized using this fabrication technology.

The development of polymer based waveguide devices for optical add/drop multiplex and optical cross-connect applications is summarized. Polymeric integrated optics can provide the basic building blocks to rapidly build complex devices with predictable performance.