Junya Kobayashi

PMT connectors for multi-channel film waveguides

Intensive research on optical interconnections has attracted considerable attention for high-end router and server applications. A polymer film waveguide is expected to be applied to an optical circuit board in an optical interconnection. The film waveguide requires a conventional connector if it is to be employed as a practical optical circuit board. This paper describes the MT connector used with polymer film waveguide (PMT connector), which is compatible with the MT connector used with optical fiber. This connector can be attached to a film waveguide by passive alignment, and is used to connect waveguides. When the connector was equipped with an epoxy resin film waveguide, the insertion and connection losses were less than 1.4 and 0.5 dB, respectively. These losses are sufficiently small to meet the basic requirement for optical circuit boards, so we were able to fabricate a flexible optical circuit board with PMT connectors. This paper also describes the application of a film waveguide with PMT connectors to an optical front plane system.

The IR modulator utilizing light scattering effect with ferroelectric liquid crystal for gas analysis

abstractExperimental infrared modulator elements have been fabricated utilizing the transient light scattering effect of ferroelectric liquid crystal with asymmetric waveform voltage drive. The new elements perform 80% modulation degrees at the 632.8nm. We have also achieved 30% modulation degrees in the 4 to 5µ m region where the strongest CO2 absorption bands exist. A new type of analyzer which monitors ambient air quality has been developed. This analyzer uses non-dispersive infrared absorption method and composes of a double-beam, a single detector and a pair of liquid crystal light modulator as the IR chopper. The detection has achieved 10ppm noise equivalent concentration.

Organic electroluminescent diodes as a light source for polymeric integrated devices

Organic electroluminescent diodes (OLED) were fabricated on a polymeric optical waveguide for use as an optical interconnector in data communication systems. The OLED were fabricated on an ITO sputtered polymer waveguide with a 45 degree mirror by vacuum deposition. The OLEDs, with an emission peak center at 520 nm consist of diamine derivative as a hole transporting layer and tris(8-hydroxyquinoline) aluminum (Alq3) as an emissive layer. We estimated the propagation losses of the waveguide to be 1.35 dB/cm at 520 nm. However, it decreases as increasing the wavelength of the light source and is estimated as 0.37 dB/cm at the wavelength of 614 nm. The optical pulse of more than 5 Mb/s has been obtained from the OLED with Alq3 and diamine derivative. We discuss the properties of the OLED for the light source for polymeric integrated devices.

Advanced in Development IR Modulators of Ferroelectric Liquid Crystals Utilizing Transient Light Scattering Effects

Abstract The highly efficient IR-modulation has been achieved using LC electro-optic elements. Experimental infrared modulator elements have been fabricated and demonstrated utilizing the transient light scattering effect of ferroelectric liquid crystal with asymmetric waveform voltage drive. The new elements performed 80%, 50%, 40% and 25% modulation degree in the 632.8nm, 2, 3-5 and 8-12 μm region. And we observed micro domain structure under the scattering state by a polarizing microscope to understand the mechanism of the domain switching. In addition, we evaluated properties of the scattering angular and temperature dependence quite important for the design of optics for the application in the infrared range.

A light chopper for infrared detection utilizing ferroelectric liquid crystal

The transient light scattering mode effect due to polarization inversion of ferroelectric liquid crystal was used in the experimental design of a light chopper for infrared detection. In order to understand the light scattering effect, the relationship between the driving conditions and pulse response speed of domain switching was analyzed. Light modulation was optimized by adjusting the duty cycle in rectangular wave driving. This method made it possible to improve the light scattering response due to electric field inversion, resulting in high-efficiency light modulation. It was found that the improvement of light scattering response occurred because the recovery speed from the scattering state to the nonscattering state was accelerated by the electric field inversion. By observing the generation-growth-extinction process of scattering objects, the relationship between the change in the liquid crystal structure and light scattering was obtained. The wavelength dependence of the light modulation-voltage characteristic and the temperature dependence of the field of view and the degree of modulation were elucidated.