Thermal cracking effects of CeCl3 dopant on blue electroluminescent properties in SrGa2S4:Ce thin films

Jpn.J.Appl.Phys., Vol.38, No.12A, pp.L1419-L1421 (1999)
Katsu TANAKA, Shinji OKAMOTO, Yoshitaka IZUMI, Youji INOUE and Kikuo KOBAYASHI

To realize full-color electroluminescent (EL) flat panel display, the most essential subject is to improve the pure blue emission with high luminous intensity. The authors have investigated cerium-activated strontium thiogallate (SrGa2S4:Ce) as a promising blue phosphor material. The thin films have been grown by multi-source deposition method, using molecular beam epitaxy (MBE) system.
The authors found that the activated cerium concentration could be greatly increased by thermal cracking of cerium source material without degradation of the SrGa2S4 host crystallinity. For this cracking, a new MBE cell system was developed. As the result, the maximum luminous intensity was improved to 85 cd/ at a driving frequency of 1 kHz. A saturated blue color with CIE chromaticity coordinates of x=0.14 and y=0.15 was also obtained.

Amplitude probability distribution of intermodulation distortion in multichannel digital optical cable transmission

IE I CE transactions on communication,
Vol.E82-B, p.1154-1161 and Vol.E82-C, p.1420-1427, No.8, August 1999
Tadayoshi NAKAMURA, Takuya KURAKAKE, Yasuhiro ITO*, Mikio MAEDA, Kimiyuki OYAMADA
(* Engineering Department Center of Engineering Administration Department)

The statistical behavior of the amplitude probability distribution of intermodulation distortion interference in multichannel optical-cable TV systems was experimentally investigated.
In multichannel transmission, the non-linearity of a laser diode (LD) or an electrical amplifier can cause intermodulation distortion (composite-second -order beat; CSO, composite-triple-beat; CTB, etc.). Even though it has been discussed as laser-clipping distortion, intermodulation distortion is usually distortion from AM-VSB carriers. The statistical analysis and evaluation of the distortion in a transmitted channel is controversial.
We evaluated the distortion in 20 frequency-division-multiplexed 16-QAM channels, with each carrier carrying 80Mbps for an optical cable TV system. We first enumerated the distortion components causing interference in each transmission channel so as to identify the intermodulation products. Then, in selected channels, we precisely measured the power of each kind of distortion and the amplitude distributions of the intermodulation distortion from sinusoidal and digital-modulated carriers on cable TV as a function of optical modulation depth (OMD) of LD. And we clarified how the probability distribution function (PDF) changed as the OMD increased. Also, the BER performance of a 16-QAM signal was measured and compared to the intermodulation behavior of the different distortion sources.
We found evidence that the amplitude distribution of intermodulation distortion from digital carriers differs from that of thermal noise. Experimental results showed that the PDF of the intermodulation distortion changed when the ratio of intermodulation distortion among all undesired signals varied with the OMD. The BER performance varied with intermodulation of both analogue and digital carriers even when the carrier to interference noise power ratio was the same.

Time-alternating method based on single-sideband holography with half-zone-plate processing
for the enlargement of viewing zones


Appl. Opt. 38, pp. 3703-3713 (1999)
T. MISHINA, F. OKANO, and I. YUYAMA

The single-sideband method of holography, as is well known, cuts off beams that come from conjugate images for holograms produced in the Fraunhofer region and from objects with no phase components. The single-sideband method with half-zone-plate processing is also effective in the Fresnel region for beams from an object that has phase components. However, this method restricts the viewing zone to a narrow range. We propose a method to improve this restriction by time-alternating switching of hologram patterns and a spatial filter set on the focal plane of a reconstruction lens.