Jiyoon Kim

MYC translocation and an increased copy number predict poor prognosis in adult diffuse large B-cell lymphoma (DLBCL), especially in germinal centre-like B cell (GCB) type.

Aims:  Diffuse large B‐cell lymphoma (DLBCL) is a heterogeneous disease with various genetic alterations. The aim was to investigate MYC, Bcl‐2 and Bcl‐6 translocations and copy number changes in adult DLBCLs to evaluate their clinicopathological features and prognostic implications.

Expression and prognostic implications of cell cycle regulatory molecules, p16, p21, p27, p14 and p53 in germinal centre and non‐germinal centre B‐like diffuse large B‐cell lymphomas

Aims : To evaluate the different expression patterns and the prognostic significance of cell cycle regulatory molecules in diffuse large B‐cell lymphomas (DLBCLs) of germinal centre (GC) and non‐GC phenotypes.

Liquid crystal-based square lens array with tunable focal length

We demonstrate a liquid crystal (LC)-based square lens array with two focusing modes according to the polarization state of the input light. The homogeneously aligned LC layer is placed on an array of static square lenses fabricated using a photo-curable polymer whose refractive index is matched with the refractive index of the LC. For the input beam polarized parallel to the easy axis of the LC, the focal length is varied with the applied voltage from a few meters to 21 mm which corresponds to the focal length of the static lens. For the perpendicularly polarized input beam, the focal length is independent of the applied voltage and remains constant. The two focusing effects with high optical performance over fully activated areas are useful for polarization-dependent imaging systems and three-dimensional displays in projection and integral imaging.

Lenticular lens array based on liquid crystal with a polarization-dependent focusing effect for 2D–3D image applications

Demonstrated herein is a liquid-crystal-(LC)-based lenticular lens array with a polarization-dependent focusing effect, fabricated through a simple imprinting process. The input polarization dependence of the proposed LC lenticular lens array arises mainly from the index matching scheme between the polymer lenticular lens and the LC on it. For the input polarization perpendicular to the LC director, the focal length of the lenticular lens is about 3.1 mm. The focusing and non-focusing properties depending on the input polarization are useful for realizing autostereoscopic 2D/3D convertible displays combined with polarization selection elements.

Fully continuous liquid crystal diffraction grating with alternating semi-circular alignment by imprinting

We demonstrate a fully continuous liquid crystal (LC) grating device with the alternating semi-circular alignment which exhibits the switching effect between the diffraction orders independent of the thickness of the LC cell. The continuous phase modulation in the LC grating with the rotational symmetry was achieved on a micro-imprinted surface where the semi-circular alignment of the LC was spontaneously produced. Our LC grating device in the hybrid geometry exhibited the perfect continuity of the phase retardation and the switchable diffraction with the diffraction efficiency of 44% at ±1st orders as a function of an applied voltage. It was found that the symmetry of the input polarization direction with respect to the grating patterns results in the interchange between two symmetric grating configurations.

Optically switchable grating based on dye-doped ferroelectric liquid crystal with high efficiency

We demonstrate an all-optically switchable ferroelectric liquid crystal (FLC) grating constructed in an alternating binary configuration with different optical properties from domain to domain. A dye-doped FLC is uniformly aligned in one type of domains whereas it is infiltrated into the photo-polymerized networks of reactive mesogens in the other. Compared to conventional nematic LC cases, our FLC grating allows more efficient all-optical modulation and faster diffraction switching between the 0th and the 1st orders in subsecond since the optical response associated with the dye molecules in the layered state is less hindered than in the orientationally ordered state. Our dye-doped FLC grating with periodically infiltrated structures will be useful for designing a new class of all-optically switching systems.

Concept of active parallax barrier on polarizing interlayer for near-viewing autostereoscopic displays

We proposed a concept of an active parallax barrier using a liquid crystal-on-polarizing interlayer (LPI) for near-viewing autostereoscopic displays. In contrast to a conventional two-panel configuration where two independent panels are stacked together for displaying and parallaxing purposes, a monolithic one-panel architecture was demonstrated with the help of the LPI. The LPI was constructed using a polarizer sheet, one side of which provided the support for the active parallax barrier and the other served as the substrate for the image panel. For the active parallax barrier, an array of periodically patterned indium-tin-oxide electrodes was first prepared on the LPI and bi-level structures were subsequently fabricated for the cell gap and the liquid crystal alignment. Our monolithic one-panel architecture allows the near-viewing distance property which is essential for mobile applications.

Control of surface anchoring properties of liquid crystal by thermo-transfer printing of siloxane oligomers

We presented the results for the surface anchoring properties of a nematic liquid crystal (LC) in a wide range of the substrate wettability through thermo-transfer printing of siloxane oligomers. For the modification of the surface energy, poly(dimethylsiloxane) (PDMS) oligomers were directly transferred onto a glass substrate from a bulk PDMS plate by contact printing at elevated temperatures. The hydrophobicity of the PDMS-modified surface was found to increase with the temperature of the substrate during transfer printing. The LC alignment on the PDMS-modified substrate exhibited continuous variations of the pretilt angle from nearly 0° to 90° and the polar anchoring strength according to the surface energy.

Tunable binary retarder using self-aligned liquid crystal on anisotropic polymer film by photo-assisted imprinting

We demonstrate an electrically tunable binary retarder (ETBR) with a self-aligned liquid crystal (LC) on an anisotropic polymer film produced by photo-assisted imprinting. The ETBR has two parts: a tunable optical layer of an LC and a static optical layer of an imprinted anisotropic polymer film possessing two different in-plane optic axes. The anisotropic polymer film was produced using reactive mesogens spontaneously aligned along the topographic microgrooves by imprinting under the exposure of ultraviolet light. An electrically tunable hybrid wave plate, whose phase retardation varies from a quarter to a half-wave, is constructed using the self-aligned LC layer on the imprinted polymer film that behaves as a quarter wave plate with two alternating optic axes. This approach can be used to design a new class of tunable optical devices with multiple in-plane optic axes.

Dynamic polarization grating based on a dye-doped liquid crystal controllable by a single beam in a homeotropic-planar geometry

We present a dynamic polarization grating based on a dye-doped liquid crystal cell that is controllable by a single pump beam in a binary homeotropic-planar configuration produced through selective rubbing. Upon single pump beam irradiation, the azo dyes in the liquid-crystal (LC) layer diffuse and adsorb onto the planar LC-anchoring surface due to trans-cis photo-isomerization. It is found that the dynamic polarization grating effect results mainly from the photo-induced easy axis reorientation by the amount of dye molecules adsorbed on the planar LC-alignment surface in a single-beam control scheme. The initial LC-anchoring conditions and the dynamic behavior of the dye adsorption strongly influence the repetitive writing-erasing processes by the single pump beam.