Kwon Yeon Lee

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-beam Apodization in Photopolymer

In this paper, we present a novel apodization technique using three beams to fabricate an apodized grating in photopolymer. An orthogonal-polarization beam used to control the saturated modulation amplitude of the grating is added during recording time. As a result of the experiment, holographic apodized gratings with uniform, inverse Gaussian, and triangular profiles are fabricated successfully in DuPonts HRF-150-38 photopolymer.

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.

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.

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.

Double-layer gratings for optical demultiplexer in DWDM

In this paper, the double-layer gratings recorded in photopolymer films for the optical demultiplexer is presented. The channel spacing of 0.4nm, the channel uniformity of 3.5 dB, the 3dB-bandwidth of 0.12 nm, and the channel crosstalk of -20dB is experimentally obtained.

Laser diode beam shaping using holographic grating recorded by an additional orthogonally-polarizing beam

In this paper, we propose a method to fabricate the grating for a laser diode shaper. During the grating recording, a beam that has polarization mode orthogonal to those of two recording beams is added. The intensity of the additional beam is controlled by a spatial light modulator to provide the spatial variation of intensity modulation, which leads to the difference of the saturation diffraction efficiency. As the results of the experiment, the laser beam shaped by the obtained grating has Gaussian desired profile intensity and is not aberration along the propagation.