Keisuke Yoshiki

Second-harmonic-generation microscope using eight-segment polarization-mode converter to observe three-dimensional molecular orientation.

We developed a compact polarization-mode converter for microscopy to control three-dimensional polarization at the focus. The converter consisted of two homogeneously aligned liquid-crystal spatial light modulators with eight independently controllable electrodes (segments), and a quarter-waveplate. The converter converted a linearly polarized beam to three polarization modes: two orthogonal linear polarizations and a pseudo-radial polarization. We applied the converter to second-harmonic-generation microscopy and demonstrated the detection of three-dimensional molecular orientation.

Second-Harmonic-Generation Microscopy Using Excitation Beam with Controlled Polarization Pattern to Determine Three-Dimensional Molecular Orientation

We have developed a second-harmonic-generation (SHG) microscope using an excitation beam with a controlled polarization pattern in order to detect three-dimensional molecular orientation. The electric field at the focus is controlled three-dimensionally by modifying the polarization distribution with a parallel-aligned nematic-liquid-crystal spatial-light-modulator without any mechanical moving parts. We demonstrated that the SHG signal from an Achilles tendon, sliced so that collagen fibers were aligned parallel to the optical axis, excited by a radially polarized beam was higher than those excited by linearly polarized beams. The possibility of determinating three-dimensional molecular orientation was thus shown.

Enhancement of second-harmonic generation from self-assembled monolayers on gold by excitation with a radially polarized beam.

We have studied the enhancement of second-harmonic generation (SHG) from self-assembled monolayers on Au surfaces excited by radially polarized beams. The electric field at the metal surface was enhanced by constructive interference between the incident and the reflected beams due to a longitudinal field, which is the field parallel to the optical axis, generated around the focus by the radially polarized beam. Since even-order nonlinear phenomena are surface sensitive, the combination of SHG and a radially polarized beam has the potential to be a powerful new imaging tool for characterization of metal surfaces. The SHG signal excited by the radially polarized beam was about 3 times higher than that excited by a linearly polarized beam; in addition, the SHG from a 7-(dimethylamino)-4-methylcoumarin-3-isothiocyanate monolayer was about 1.3 times higher than that from a bare Au substrate.

Three dimensional polarization control and its application to SHG imaging

We have developed second harmonic generation microscopy whose electric filed at the focus is controlled three-dimensionally with a spatially light modulator without any mechanical parts. We demonstrated the detection of the three dimensional molecular orientation.

Second-harmonic-generation microscope using eight-segment polarization-mode converter to observe three-dimensional molecular orientation: publisher's note

The order of authors in Opt. Lett.32, 1680 (2007) was incorrect as published. The order has been corrected online as of August 1, 2007.

Advanced Inter-/Multi-Disciplinary Graduate-Level Programs for Education, Research, and Training in Nanoscience and Nanotechnology Offered at Osaka University

Nanoscience: an area that promises new understanding of nature with the aid of rapid progress of nanotechnology. Nanotechnology: the use of nanoscience to build new technologies that will change the world. Nanoscience and Nanotechnology have captured the attention of the public, government, and corporations. How they will influence our lives depend on how we prepare ourselves, and our successors. Here we present a brief outline of the efforts being taken at Osaka University since 2004, in order to prepare our future scientists, engineers, and leaders in the rapidly flourishing trans-/multi-disciplinary field of Nanoscience and Nanotechnology.

A compact polarization converter to observe molecular orientation

We developed a compact polarization-converter using two liquid-crystal spatial-light-modulators with eight electrodes. The converter converted a linearly polarized beam to two orthogonal linearly polarized beams and a radially polarized beam, and the direction of the electric filed at the focal point were controlled three-dimensionally. We constructed a second-harmonic-generation microscope using the polarization-converter to observe three-dimensional molecular orientation and demonstrated the detectability of molecular orientation.