This study proposes an optical sensor based on a refractometer integrating a bend waveguide and a trench structure. The optical sensor is a planar lightwave circuit device involving a bend waveguide with maximum optical loss. A trench structure was aligned with the partially exposed core layer’s sidewall of the bend waveguide, providing a quantitative measurement condition. The insertion losses of the proposed 1×2 single-mode optical splitter-type sensor were 4.38 and 8.67 dB for the reference waveguide and sensing waveguide, respectively, at a wavelength of 1550 nm. The optical loss of the sensing waveguide depends on the change in the refractive index of the material in contact with the trench, but the reference waveguide had stable optical propagating characteristics regardless of the variations of the refractive index.
This study proposed a novel optical sensor based on a refractometer integrating a bend waveguide and a trench structure. The optical sensor is a planar lightwave circuit (PLC) device involving a bend waveguide with maximum optical loss. A trench structure was aligned with the partially exposed core layer’s sidewall of the bend waveguide, providing a quantitative measurement condition. The insertion losses of the proposed 1 x 2 single-mode optical splitter-type sensor were 4.38 dB and 8.67 dB for the reference waveguide and sensing waveguide, respectively, at a wavelength of 1,550 nm. The optical loss of the sensing waveguide depends on the change in the refractive index of the material in contact with the trench, but the reference waveguide had stable optical propagating characteristic regardless of the variations of the refractive index.
Selective energy transfer from triplet states of the fluorescent blue emission layer to a red phosphorescent dye in a
neighbored triplet harvesting layer has been achieved, which has provided improved efficiency with emissions from
fluorescent and phosphorescent dyes. First of all, it is crucial to find a wide band gap host for a fluorescent blue emission
layer which has larger triplet state band gap than green or red phosphorescent dye. It was found that TcTa is a good wide
band gap host for fluorescent blue dopant(BD) and a efficient blue device was obtained. A phosphorescent red dopant
(RD) was introduced into a neighboring electron transporting layer to harvest triplet states in the fluorescent blue
emission layer and by optimizing the distance between the blue emission layer and the red triplet harvesting layer, we
have succeeded in obtaining the balanced emission of the blue and the red emissions with high efficiency from the
device structure of NPB/TcTa:BD/BAlq/BAlq:RD/BAlq/LiF/Al. The device showed maximum external quantum
efficiency of 16 % at 0.1 mA/cm2 and 13 % of external quantum efficiency, (0.29, 0.23) of CIE coordinates and 920
cd/m2 at 10 mA/cm2. To realize RGB WOLED, a fluorescent green dopant was introduced into the blue emission layer.
The RGB WOLED was successfully obtained through optimization of doping concentration for green dopant and it
showed 10 % of external quantum efficiency, (0.36, 0.36) of CIE coordinates and 1400 cd/m2 at 10 mA/cm2.
Organic thin-film transistors (TFTs) using the pentacene as an active electronic material have shown the mobility of 0.8 cm2Vs and the grains larger than 1 micrometers . Deep level transient spectroscopy (DLTS) measurements have been carried out on metal/insulator/organic-semiconductor (MIS) structure devices that have a depletion region at the insulator/organic-semiconductor interface. The very long capacitance transients were measured by the trapping of electronic charge carriers distributed in energy. Based on the DLTS characteristics, the energy levels of hole and electron traps in the obtained pentacene films were approximately Ev+0.24eV, Ev+0.31eV, and Ec- 0.69eV.
Multicolored electroluminescent (EL) devices has been realized utilizing poly((1-dodecyloxy-4-methyl-1,3- phenylene)(2,5"-terthienylene)) (mPTTh) as an emitting layer and tris(8-hydroxyquinoline) aluminum (Alq3) as an electron transport layer. A single layer EL device of mPTTh polymer emits orange-colored light. EL intensity increase as the thickness of Alq3 layer increases up to 30 nm, but the emission color becomes diversified when the Alq3 layer thickness is greater than 30 nm since the relative peak intensity of green EL from Alq3 layer grows. EL color is changed form orange to greenish orange depending on the thickness of Alq3 layer. EL efficiency of the double layer device was greatly enhanced by 3000 times in compared to that of single layer device. Alq3 layer in device acts as a hole blocking electron transporting layer and an emitting layer as a function of the thickness of Alq3 layer.
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