Photodoping phenomenon is observed when a double-layer consisting of an amorphous chalcogenide film (As2S3, GeS2, GeSe2 etc.) and a metal (Ag, Cu etc.) film is illuminated by light. The metal diffuses abnormally into the amorphous chalcogenide layer. Amorphous chalcogenide films of GeS2 with an Ag over layer exhibited large increase of refractive index through the abnormal doping of Ag by irradiating the light around the absorption edge of the GeS2 chalcogenide. In this study, we aimed the application of this effect for the fabrication of optical devices and fabricated various micro doped patterns by using a laser beam. Mask less pattering with refractive index modified films are possible by manipulating the scanning of the laser beam. Micro gratings were fabricated using a confocal laser microscope to work as both fabrication and observation system. Waveguides were also fabricated by scanning the laser beam for photodoping. Holographic gratings were fabricated by utilizing the photodoping of the two beam interference pattern, which showed the possibility to produce large scale optical devices or mass production.
Porous MgF2 films synthesized by a sol-gel method exhibit the lowest refractive index among the dielectric optical materials and are the most useful materials for the anti-reflection coatings. On the other hand, surface plasmon resonance (SPR) absorptions of noble metal nanoparticles in various solid matrices have been extensively studied. New functional materials like a SERS (Surface Enhanced Raman Spectroscopy) tips are expected by synthesizing composite materials between porous MgF2 films featured by the network of MgF2 nanoparticles and noble metal nanoparticles introduced within the network. In this study, fundamental physical properties including morphology and optical properties are characterized for these materials to make clear the potential of the composite system. Composite materials of MgF2 films dispersed with noble metal (Ag, Au) nanoparticles were prepared using the sol-gel technique with various annealing temperatures and densities of noble metal nanoparticles. The structural morphology was analyzed by an X-ray diffractometer (XRD) and a scanning electron microscope (SEM). The size and shape distributions of the metal nanoparticles were observed using a transmission electron microscope (TEM). The optical properties of fabricated composite films were characterized by UV-Vis-NIR and FT-IR spectrophotometers. The absorption spectra due to the surface plasmon resonance (SPR) of the metal nanoparticles were analyzed using the dielectric function considering the effective medium approximation, typically Maxwell-Garnett model. The Raman scattering spectra were also studied to check the enhancement effect of specimen dropped on the MgF2: Ag nano-composite films deposited on Si substrate. Enhancement of the Raman intensity of pyridine solution specimen was observed.
LEDs have been prevailing rapidly in the field of general lighting owing to the enhancement of output power and
emission efficiency. We developed luminaires for general lighting using color LEDs. We also fabricated the lighting
system for large size holograms by controlling the luminous flux of the arrayed LEDs. Multiple number of high
brightness LEDs with honeycomb arrangement were used as a light source with red, green, and blue LEDs. The
resolution and color of the reconstructed image from the color hologram were characterized quantitatively by using the
luminaire.
In the field of optical communication, either fusion splicing of optical fibers or physical contact between optical-fibers
using a fiber connector has been utilized as the typical method of optical fiber connection. Optical fiber connectors have
been widely employed in optical transmission systems according to their features of easy and quick connection without
special apparatus to connect fibers. The power of laser diodes for light sources became more intense and the
multiplexing of wavelength (WDM) of a light source was enhanced with increasing traffic data. As a result, intense light
transmits through the optical fiber. The high power transmission characteristics of the optical fiber connector are
important factors to realize dense wavelength division multiplexing systems (DWDM).
In this paper, we present an experimental investigation about the degradation of the transmission properties through the
optical fiber connector by introducing the contamination between the end faces of a connector. The metal foils to
simulate the contamination at the end of the core were inserted between the optical fibers to cover the core of an optical
fiber partially. As metal foils, Nickel, SUS304, and Phosphor Bronze which were typically used as the components of
the ferrule and sleeve were selected. The Nd: YAG laser with the wavelength of 1064 nm was used as a high power light
source at various output powers. The transmission loss was set by adjusting the insertion of a metal foil into the core
region of the fiber and the temperature rising of the connector induced by the absorption of incident light was measured
at a sleeve portion. The damage at the end face of the physical contact region was observed using an optical microscope.
The temperatures increase of the core of the fiber was estimated for the fiber connector with a zirconia ferrule through
the thermal simulation using the MSC Visual Nastran.
The damage of the fiber end face was recognized depending on the species of the metal foil and the covering ratio for
the core in the case of a high power light transmission, typically, with the average power of 1W. It was estimated that
the damage threshold of the fiber end becomes low for the ferrule with lower melting point. The correlation between the
damage threshold and various parameters was discussed.
Light emitting diode (LED) became popular rapidly by the appearance of blue LED. Three color (R, G, B) emitting
LEDs are utilized for the image display system by the development of multi color emitting LED. White LEDs became to
commercial base by combining blue or UV light sources for excitation and materials for fluorescence. White LEDs are
prevailing for general lighting applications. A single tip with the power of 5W became line up for commercial market
owing to the research for high intensity LEDs. As a result, LEDs are replacing the market of conventional incandescent
lighting and even head lights of the automobile. In this study, we aim to fabricate the white and R, G, B lighting system
using high brightness LEDs for the lighting of holograms instead of a conventional halogen lamp.
Fundamental experiments of multiple image recording were carried out for university students to understand the basic
concept of the 3D image storage. We performed holographic image recording experiments using simple two beam
interference. Multiple image recording of 2D and 3D was successfully performed.
Fundamental experiment of holographic memory was carried out for university students to understand thebasic concept of the memory as a large format storge method of next generation. We performed holographic data recording experiment using simple two beam optical systems. Multiple recording to enhance storage capacity was also successfully performed.
We have constructed the four detectors polarimeter of transmission type (T-FDP) whose principle was originally invented by Azzam et. al. Some of the distinct features of our instrument are the liner optical axis and high speed data acquisition of msec order. It can determine the polarization state of the light that passed through the anisotropic materials such as liquid crystals in a very short time. We observed the dynamic change of the polarization state of the transmitted light through the liquid crystals (smectic and super twisted nematic) that are driven by alternating voltage. The behaviors of the both liquid crystals showed hysteresis. We also showed the trajectory of the polarization state observed through the super twisted nematic liquid crystal on the Poincare sphere.
This paper introduced one method of physics education in universities and colleges to make use of making holograms in classroom. The procedures, we proposed in this paper, are so simple that it is realized easily to make holograms. To construct holography accessible to universities and colleges, cost, safety, simplicity, scientific content, and usefulness are primary requirements.
We introduced the following system and applied it to process of making holograms for science education. The procedures we proposed in this report are so simple that it is realized easily. By using this method, a hologram is produced simply and the process is safe and less expensive. Therefore, holography can be easily demonstrated to younger generation.
Patterning of vanadium pentoxide (V2O5) visible light absorbing amorphous films was attempted using a SHG beam (? =532nm) of Q-switched Nd:YAG laser. Amorphous V205 films (350nm thick) were deposited on an optical glass slide substrate 1.4mm thick by normal resistance-heating vacuum evaporation. A sheet beam ofthe pulse laser with an output power of 1 .4J/pulse was used, having a pulse width of iOns, and a calculated laser fluence of 46. 1J/cm2. The beam with pulse repetition of 10Hz was irradiated in air at room-temperature on the film sample that moved to the direction normal to that of the sheet beam with a speed of 5mm/s. Both direct and indirect beam irradiation through the glass substrate produced a regular stripe pattern due to film removal. Characterization of removed and non-removed film portions in a laser track reveals a molecular and/or nanocluster sublimation of amorphous V2o5 caused by laser irradiation. This patterning has an advantage of short-time film processing.
Silver halide photographic plates and photo-polymers have been utilized for the holographic recording. These materials are available only for recording of still pictures, and require complex developing process and relatively long time for recording and reproduction of the image. As an alterative, image recording using bismuth sillenite compound has been researched. The BGO and BSO single crystal bulk samples have been sued for these studies. On such background, we aimed to fabricate BGO and BSO films for image recording. Thin films have merits in device integration and mass production. We have already found out the process condition to obtain good crystalline BGO films on glass substrates. The film with crystalline phase only was obtained at the substrate temperatures above 200 degrees C. In this paper, BGO and BSO films were deposited on glass substrates and the ITO conducting films on the glass substrates using RF magnetron sputtering method. Preliminary image recording experiments were carried out for a BSO single crystal and its film. Image recording properties were characterized for the polycrystalline films with different film thickness by recording interference fringes using the Ar ion laser.
Silver halide photographic plates and photosensitive polymers have been utilized for the holographic recording. These materials are available only for recording of still pictures and require complex developing processes and a relatively long time for recording and reproduction of the image. As an alternative, image recording using bismuth silenite compounds has been researched. The BSO and BGO single crystal bulk samples have been used for these studies. We aimed to fabricate BGO and BSO films appropriate for image recording. Films have merits in device integration and mass production. The process condition to obtain a good crystalline film was studied. The film with crystalline phase only was obtained at the substrate temperatures above 200C.
We have equipped an ion assisted deposition system with a rotating-analyzer ellipsometer (RAE) for in-situ monitoring of the deposition process. We propose the optimum conditions for the SiO2/Si substrate system for observation of growth processes of Au film deposition. The deposition of Au films on optimized silicon oxide substrates was observed in- situ using the RAE. The growth curves for Au films were different from those for continuous layer growth in the initial stage. The critical thickness at which the growth became continuous layer growth varied with the irradiated current density of Ar ions. The ion-current density for the minimum critical thickness of Au films has an optimum value of around 100 (mu) A/cm2. The initial stage of Au growth before continuous layer growth occurred was analyzed using the Maxwell-Garnett theory and semi-quantitative agreement was obtained between the experimental and calculated results.
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