Duc Dung Do

Expansion of channel number in optical demultiplexer using cascaded photopolymer volume gratings

A method to expand the number of channels in the optical demultiplexer (DMUX) using two cascaded photopolymer volume gratings is proposed and presented. A 0.4-nm-spaced 130-channel DMUX with the channel uniformity of 3.5 dB, the 3-dB bandwidth of 0.12 nm, and the channel crosstalk of -20 dB is experimentally demonstrated.

Design of cascaded volume holographic gratings to increase the number of channels for an optical demultiplexer.

The design and demonstration of a holographic optical demultiplexer based on cascaded volume holographic gratings are presented. By serially adding a second holographic grating, which has a different grating period, slant angle, and center wavelength compared with those of the first grating, the operating wavelength range of the optical demultiplexer could be expanded, and, therefore, the number of channels of the holographic demultiplexer is doubled. As a result of the experiment, a 0.4 nm spaced 130- channel demultiplexer with a channel uniformity of 3.5 dB, a 3 dB bandwidth of 0.12 nm, and channel cross talk of -20 dB is experimentally achieved.

Three-dimensional floating image system using a two-lens system and a stereoscopic display

In this paper, we present a floating image system that consists of a stereoscopic display and a two-lens system. A 3-D image is produced inside of the stereoscopic display and that image is projected into the air by the two-lens system. From the experimental results, our proposed system successfully produces the 3-D image, without the distortion and the defects, in midair so that image is a 3-D floating image.

A Spatial-Distance-Controllable Demultiplexer Using a Chirped Volume Holographic Grating

In this letter, we introduce a demultiplexer with a function of controlling spatial distance based on a chirped volume holographic grating. The chirped grating is recorded by illuminating a photopolymer film under the interference of convergent and divergent beams. The theoretical and experimental results show that the position of the focused points of the diffracted beam at the readout stage depends on the distance between the grating and the output lens. This characteristic can be utilized to control the channel spacing and spatial distance in the dense wavelength-division-multiplexing demultiplexer.

Stereoscopic Floating Image System Using Stereoscopic Display and Two Lenses

The proposed technique uses a combination of two systems, viz. a three dimensional stereoscopic system and a two-lens system. This novel combined system successfully produces a stereoscopic floating image in mid air near the observer. The two-lens system produces a floating image from the stereoscopic image originating from the stereoscopic system, and the two lenses eliminate the defects of the floating lens and concave mirror. The experimental results show that the two lenses eliminate the defects of the lens and the concave mirror, so that the proposed system successfully produces a touchable stereoscopic floating image.

Gaussian apodized volume grating for a holographic demultiplexer

In this paper, a fabrication of Gaussian apodized volume gratings for a holographic demultiplexer is presented. The DuPont HRF-150-38 photopolymer is used because of its stability and ease of use. Based on the Gaussian apodized grating, a 42-channel demultiplexer is optically demonstrated. The interchannel spacing, the interchannel cross-talk level and the channel uniformity of 0.4 nm, -30 dB and 1.5 dB, respectively, are obtained.

High Performance Holographic Polymer Dispersed Liquid Crystals and Their Applications on Dense Wavelength Division Multiplexing Systems

Novel process for formation of holographic gratings was introduced by simultaneous photopolymerization and siloxane network. Diffraction efficiency and volume shrinkage of gratings formed with combination of liquid crystal and alkoxysilane derivatives were improved by modifying the chemical structures of alkoxysilane derivatives, and their application was characterized on dense wavelength division multiplexing systems.

Floating-image display based on the combination of two-lens system and the stereoscopic polarization-multiplexing display

Today, there are many kinds of 3D displays used to produce 3D images but these 3D images are not touchable. Therefore many researchers study how to produce a floating image from 3D image. In floating image display, a large concave mirror or a large lens is used to produce the floating image. However the lens and the concave mirror produce the defected image because magnifications of these two elements are not constant, and an image distance is not linear relationship from an object distance. In this paper we present the stereoscopic floating image system using a stereo display and two lenses. The proposed floating display system provides an impressive feel of depth, and produced image appears to be located in a free space and near the observer. The two-lens system can eliminate all defects of large convex lens because the magnifications are constant and are not related the object distance and the image distance. The experimental result shows that the proposed system successfully makes a touchable stereoscopic floating image.

Chirp volume grating recorded in photopolymer for the optical demultiplexer

In this paper, the chirp volume grating recorded in photopolymer for the optical demultiplexer is presented. By using the chirp grating, the spatial distance of fibers can be controllable. The chirp rate of the grating is investigated. As a result of the experiment, a 51-channel 0.4-nm-spaced demultiplexer with the channel uniformity of 3.5 dB, the 3dB-bandwidth of 0.12 nm, and the channel crosstalk of -20 dB is experimentally achieved.

A 130-channel demultiplexer using cascaded volume holographic gratings recorded in photopolymer films

The number of channels of an optical communication system is increasing rapidly. In this paper, the demonstration of a 130-channel demultiplexer based on the cascaded volume holographic gratings is presented. Those gratings are recorded separately in 100-μm thickness photopolymer films, which attached on both sides of a glass substrate. They have different grating periods, slant angles, and center wavelengths. By ultilizing this configuration, the operating wavelength range of the optical demultiplexer could be expanded, and therefore, the number of channels of the holographic demultiplexer is increased. As a result of the experiment, a 0.4-nm-spaced demultiplexer with the channel uniformity of 3.5 dB, the 3dB-bandwidth of 0.12 nm, and the channel crosstalk of -20 dB is experimentally achieved.