In-line mixing technologies used in paper and pulp manufacturing have been studied long and broadly by XAMK Fiberlaboratory in Savonlinna, Finland. Especially, wider introduction and diversification of technologies related to mixing of paper chemicals have created a need to determined research of the in-line mixing technologies. In Finnish research project FLASH, a ground was based for researching and developing the fast in-line mixing techniques together with companies operating in pulp and paper industry segment. Application potential, basic knowledge, measurement technologies, experiment techniques, and research facilities were surveyed for utilizing them later in practical processes. One of the tested measurement technologies was high-speed infrared imaging.
The high-speed infrared imaging tests were carried out together by VTT, XAMK and the companies in Fiberlaboratory research facility in 2013-2015. The Fiberlaboratory research facility includes medium-consistency pulp (MC) chemical mixing equipment, which is almost equal to real life paper mill chemical mixing environment. The infrared imaging was done with the help of IR transmitting sapphire window attached to suitable point in mixing tube system. Temperature differences of main flow and mixing flow enabled analyzing and calculating mixing indexes for different mixing drive parameters successfully.
VTT has also designed a new kind of infrared omnilens for example for panoramic streetview thermography. The VTT omnilens technology enables the streetview thermography with a single infrared camera. Horizontal 360 degree infrared image is achieved by novel lens solution and also vertical image portion is possible. The streetview thermography is useful when finding thermal leaks from buildings in wide area or it can be used to find thermal leaks inside buildings with wheeled small vehicles. Also, utilizing the omnilens in drones to prevent them to collide each other or other drone applications are possible in the future.
We report on the design, fabrication, and optical characteristics of arrayed waveguide grating (AWG) devices on silicon-on-insulator (SOI) platforms to act as multiplexers in a hybridly integrated wavelength division multiplexing (WDM) transmitter for telecommunications and datacom applications. In order to achieve efficient coupling to laser diodes, SOI layers with 4-µm-thick Si were used to form rib waveguides. The AWG devices comprised eight channels with a channel spacing of 200 GHz around a center wavelength at 1550 nm. AWG integration with variable optical attenuators is demonstrated to add channel equalization ability.
In this work the feasibility of the atomic layer deposition (ALD) in producing erbium-doped waveguides is studied. Two microns thick erbium-doped aluminum oxide layers were grown with ALD on silica-coated silicon wafers. The waveguides were patterned using photolithography and wet etching. Resulted single-mode ridge-type waveguides were measured to obtain absorption, emission, fluorescence lifetime, and gain characteristics. Optical pumping was done using the 980 nm wavelength. The material showed broad emission spectrum with FWHM of 52 nm and maximum absorption of 6.2 dB/cm at 1530 nm. Maximum signal enhancement of 2.6 dB/cm was measured at 1530 nm for the 20 dBm signal power.