In this work, the design, fabrication and characterization are reported for a distributed Bragg reflector (DBR) filter with a specific wavelength and angular dependency, which aims to improve the light collection from a wavelength-converter-based light source into a smaller angle than the full angle Lambertian emission. The desired design is obtained by optimizing the transmission characteristics of a multi-layer structure. Titania (TiO 2 ) and silica (SiO 2 ) are used as high and low refractive index materials, respectively. The deposition is made by electron beam evaporation without substrate heating, followed by a post-annealing procedure. The optical properties of the evaporated layers are analyzed by ellipsometer and spectrometer measurements. The angular and wavelength dependency of the fabricated DBR is in good agreement with simulations for the designed structure.

We demonstrate a laser beam combiner based on four photo-patterned Pancharatnam–Berry (PB) phase gratings, which is compact and has high diffraction efficiency for incident circularly polarized light. The nematic liquid crystal mixture E7 is used as anisotropic material, and the thickness of the layer is controlled by spacers. The beam combiner can bring two parallel laser beams closer to each other while remaining parallel. This work shows the potential to realize components based on flat optical LC devices.

The surface area of liquid crystal (LC) devices in different applications, such as displays, signage devices and smart windows is becoming larger and larger. The electrical driving of such devices does not pose many problems when working on centimetre sized devices. Different types of driving issues arise when up-scaling such devices to areas of several square meter, due to the fact that the thin-film transparent conductors used in these device exhibit a finite sheet conductivity. One of the resulting issues is the non-uniformity of the electric field across the area of the device and the resulting non-uniform optical behaviour. In this work we present a simulation model that is able to predict the optical and electrical behaviour of large-sized liquid crystal devices with different applied voltage signals, including the power consumption. The simulation results are compared with optical and electrical measurements on a liquid crystal device of 1.5 m by 1.2 m.

This paper describes a method for forward-coupling microstrip filter. It is tuning an HTS filter at the cryogenic temperature. necessary to tune the filter when its response is Sonnet software was used for simulating the deviates from the design. distribution of current density. Dielectric tuning Several tuning methods in the cryogenic screws were used toregulite the redistribution of temperatures have been reported, such as electromagnetic field, so that the response . -. .^~~~~~~~e lectrically tuning the base on the ferroelectric characteristics of the filter can be improved. For matching the designed result, this technique tunablecomponents[1,2],magnetictuning[31, allows correcting the deviation caused by laser trimming [4] and so on. But the former fabrication processing and non uniformity of reports mostly show the frequency shift aflter substrate thickness and dielectric constant. 9-pole tuning. For meeting the design requirements and forward-coupling microstrip filter as a sample correcting the deviation caused by fabrication shows its response characteristics before and after processing and non-uniformity of substrate tuning. The tuning result showed better thickness and dielectric c-onstant, a tuning step is performance than simulation. The insertion loss necessary to keep the HTS filter within the and return loss were improved and the center desired performance parameters. We present a frequency shift towards the low end after tuning. -~~~~~~~~~~t uning method with dielectric ttmnmg screws. The insertion loss and return loss can be Keywords: HTS filter; tuning in cryogenic improved with the center frequency shift temperature; return loss twrstelwed towards the low end. This paper investigates electro-magneticallv I . Introduction tunable HTS half-wavelength 9-pole forward-coupling microstrip filter. Each High temperature superconductor filters (HTS resonator can be tuned by dielectric tuning filter) have many unique characteristics for screw in the cryogenic temperature. Thle enhancing the performance of mobile dispersion relation of electromagnetic field communication systems, such as their low distribution is simulated by EM Sonnet Software insertion loss and very steep skirt. But the filter and experimental results are presented. characteristics are sensitive to the variance of the material characteristics and the temperature fluctuation. Computer simulation shows that if II. Design and Simulation the -dielectric constanlt of the substrate has a 0.1 offset, the center frequency will have a 3MHzA hal-f-wavelength 9-pole forward-coupling offset in our sample of a 9-pole microstrip filter was designed by the EM Sonnet 0-7803-9128