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This article presents a bonded dual-component microstructured planar device made of acrylic glass for vertical light emission. It features optical, cone-like undercut microstructures for efficient illumination from a light guiding plate. This microstructured light guide is designed with the help of numerical raytracing simulations for the use as an innovative luminaire for room lighting. It can also find application in display technology for efficient backlight units. To realize such undercut microstructures in acrylic glass, a variothermal injection molding process, complemented by an ultraviolet radiation assisted thermal bonding procedure is introduced. By modifying the glass transition temperature of a thin surface layer of the microstructures the undercut microstructures can be bonded thermally to a light guiding plate without any glue or solvent, while the shape of the microstructures is perfectly preserved. Measurements verify the high bonding quality and confirm the good correspondence between measured light emission and ideal optical simulations.

The temperature increase due to incident solar radiation has an adverse impact on the electrical output of photovoltaic (PV) modules. A theoretical model of the fabricated and tested bionic evapora...

In the course of claiming more energy efficient buildings it is necessary to reduce the amount of artificial lighting. With the aim of realizing a very thin system integrated into building facades microstructures for the redirection of daylight are developed. In order to achieve sufficient room lighting at night or other situations of less sunshine, this daylighting system is coupled to a system for artificial lighting consisting of a microstructured light guide plate. This system transforms LED point light sources to a planar light source, which lights the room ceiling. The micro structures, its functionality and application are explained.

This paper describes a novel technique to derive a pure-spectral system clock with a common multi-modulus divider from a frequency modulated signal. Therefore, the dividing factor is inverse frequency modulated to compensate the frequency modulation component on the divider input signal. Additionally, $$\Upsigma\Updelta$$ dithering is applied to the frequency divider. The technique is used for a FM-radio transmitter based on an all-digital phase-locked loop (PLL) to generate a higher-frequency clock for baseband signal processing. It can also be applied to other PLL based transmitters or receivers, especially, if only a slow PLL reference clock is available and a faster system or baseband clock is required. The main factor determining the quality of the generated clock signal is the PLL’s reference quartz oscillator as it determines the accuracy of the PLL’s RF oscillator, which limits then the accuracy of the newly generated clock. In the FM-radio transmitter, a generated ≈1 MHz clock signal with 30.58 ppm frequency offset and 515 ps root mean square jitter is generated. The phase noise is determined to −83.5 dBc/Hz at 10 kHz offset and −70.5 dBc/Hz at 1 kHz, respectively. The signal can also be used in co-integrated or external circuits.

Polydimethylsiloxane (PDMS)-based large-scale electrical-optical circuit boards (EOCBs) have been developed based on a combination of a large-scale PDMS waveguide fabrication technique and a process for efficient interfacial bonding between PDMS optical layers and standard FR4 (fiberglass-reinforced epoxy and grade 4 on flame retardance) printed circuit board materials using a specially developed surface adhesion promoter (SAP). The main mechanism of forming a good bonding between PDMS and FR4 has been identified. The optical properties of the PDMS waveguide layer remained unchanged by the addition of the SAP. According to the defined test procedures from the Institute of Printed Circuits, the International Electro Technical Commission, and Telcordia, the environmental stability of packaged EOCBs has been tested with the result that they exhibited excellent mechanical, optical, and thermal stabilities. The mechanical stability limit of the tested EOCBs is determined only by the intrinsic mechanical stability of the used PDMS materials. The optical waveguide propagation loss at 850 nm is less than 0.1 dB/cm after surviving from the defined environmental test procedures.

The copolymers of tetrachloroethylacrylate (TeCEA) and pentafluorophenylacrylate (PFPA) and of TeCEA and pentafluorophenylmethacrylate (PFPMA) have been examined with regard to their applicability as core materials for optical waveguides. In particular, their thermal properties as function of polymerisation conditions have been investigated and optimized by addition of crosslinkers. The polymerisation reactions were followed by FT-Raman and FT-IR spectroscopy. Also the optical characteristics like material dispersion and attenuation of the polymers have been studied. The fundamental demands of waveguide polymers are high optical transmission at the near-IR wavelengths windows around 1300 and 1550 nm, respectively, the adjustability of the refractive index of the core polymer versus the cladding polymer, and sufficient thermal stability of at least 70°C. Both the examined copolymers show low absorption at 1300 and 1550 nm of 0.2 and 0.7 dB/cm (best values), respectively. The refractive index (RI) of TeCEA/PFPA copolymer is tunable between 1.464 and 1.518 (1300 nm). TeCEA/PFPMA copolymers are tunable between RI values of 1.469 and 1.518 (1300 nm). Thermal stability as indicated by the glass transition temperature (Tg), which reaches about 81°C for the TeCEA/PFPA copolymer with 5 weight% (wt%) of ethyleneglycoldimethacrylate (EGDMA) crosslinker, whereas for TeCEA/PFPMA copolymer with the same amount of EGDMA a Tg of 105°C is obtained. As determined by quantitative vibrational spectroscopy the conversion in the all-acrylate based copolymer is in the order of 98%. Using also EGDMA as crosslinker and with an additional thermal treatment the unsaturation in photocured TeCEA/PFPMA copolymer can be decreased to values of 4%.

Ray-tracing calculations are employed to identify basic design rules for the configuration of microstructured daylighting systems. The results show the advantage of combinations of lenslike geometries in comparison to conventional microprism arrays regarding the overall light redirection efficiency as well as the producibility and cost efficiency. Measurements at silicone prototypes and large scale industrially produced acrylic panels confirmed the simulation results. Optimization leads to free-form geometries which can further be improved by selective roughening of specific microsurfaces.

Based on KMnO 4 wet etching technology, a low-cost waveguide integration technique of polydimethysiloxane (PDMS) based electrical-optical-circuit-board (EOCB) with FR4 substrates was developed, which is quite suitable for large-scale EOCB production. The optical and mechanical properties of the PDMS waveguide layer remained unchanged before and after waveguide integration. The mechanical stability limit of the tested EOCBs is determined only by the intrinsic mechanical stability of the used PDMS materials. The optical waveguide propagation loss at 850 nm is less than 0.1 dB/cm after surviving the defined environmental test procedures.

A large area (390/spl times/150 mm) flexible polymer optical waveguide foil and its production process is presented. The waveguide materials are highly transparent, refractive index tuned polysiloxanes. The waveguide layer is embedded between two flexible PCB laminates. The optical loss at 850 nm is

A hybrid electrical-optical circuit board is demonstrated using polysiloxane as low-loss and high-temperature stable waveguide material system. After board lamination at 180°C for two hours and a subsequent annealing at 230°C for 5 minutes the waveguide insertion loss is 0.05 dB/cm at 850 nm wavelength.

Temperature stable polymer optical waveguides have been realised and integrated into printed circuit boards (PCBs). A special waveguide fabrication process has been developed which is compatible with standard PCB processing technologies. Multimode waveguides with a 100/spl times/100 /spl mu/m/sup 2/ cross-section have been produced by hot embossing thin polymer foils. Embedding of the waveguide foils into multilayer PCBs has led to a hybrid electrical-optical circuit board solution.

Fabrication of integrated optic polymeric components by moulding waveguide and fibre alignment grooves to a substrate in a one-step process, and subsequently filling the waveguide grooves by means of a microstructured strip-off cover which is later removed, is presented. The latest measurement results on waveguide attenuation, coupling losses owing to passive fibre-waveguide coupling and excess loss values are given.

2×4 optical interconnects are realised by plastic optical fibres which are precisely aligned by means of 2D arrays of holes. Coupling to the emitters and detectors is accomplished by low loss 90° fibre bends. The total insertion loss of a 20 cm long 2×4 interconnect is 2 dB ±0.2 dB at 633 nm, including two 90°-bends.

Singlemode polymer waveguides with integrated mirrors for applications in optical bus systems are realised. The waveguide and mirror structures are fabricated in PMMA substrates by injection moulding. The microstructured metal mould inserts are prepared by silicon micromachining and electroplating. PFPMA/TeCEA is used as a UV-curing waveguide core copolymer. Devices with a waveguide attenuation of 0.21 dB/cm at 1300 nm and minor losses of /spl sim/1 dB have been demonstrated.