Nozomi Nishizawa

We report the room-temperature electroluminescence (EL) with nearly pure circular polarization (CP) from GaAs-based spin-polarized light-emitting diodes (spin-LEDs). External magnetic fields are not used during device operation. There are two small schemes in the tested spin-LEDs: first, the stripe-laser-like structure that helps intensify the EL light at the cleaved side walls below the spin injector Fe slab, and second, the crystalline AlO _<i>x</i> spin-tunnel barrier that ensures e

Depolarization of circularly polarized light scattered from biological tissues depends on structural changes in cell nuclei, which can provide valuable information for differentiating cancer tissues concealed in healthy tissues. In this study, we experimentally verified the possibility of cancer identification using scattering of circularly polarized light. We investigated the polarization of light scattered from a sliced biological tissue with various optical configurations. A significant diffe

Abstract The circular polarization of light scattered by biological tissues provides valuable information and has been considered as a powerful tool for the diagnosis of tumor tissue. We propose a non-staining, non-invasive and in vivo cancer diagnosis technique using an endoscope equipped with circularly polarized LEDs (spin-LEDs). We studied the scattering process of the circularly polarized light against cell nuclei in pseudo-healthy and cancerous tissues using the existing Monte Carlo method

Fabrication and optical characteristics of a spin light-emitting-diode (spin-LED) having dual spin-injection electrodes with anti-parallel magnetization configuration are reported. Alternating a current between the two electrodes using a computer-driven current source has led us to the observation of helicity switching of circular polarization at the frequency of 1 kHz. Neither external magnetic fields nor optical delay modulators were used. Sending dc-currents to both electrodes with appropriat

We report that an ultra-thin, post-oxidized aluminum epilayer grown on the AlGaAs surface works as a high-quality tunnel barrier for spin injection from a ferromagnetic metal to a semiconductor. One of the key points of the present oxidation method is the formation of the crystalline AlOx template layer without oxidizing the AlGaAs region near the Al/AlGaAs interface. The oxidized Al layer is not amorphous but show well-defined single crystalline feature reminiscent of the spinel γ-AlOx phase. A

Spin-photonic devices, represented by spin-polarized light emitting diodes and spin-polarized photodiodes, have great potential for practical use in circularly polarized light (CPL) applications. Focusing on the lateral-type spin-photonic devices that can exchange CPL through their side facets, this review describes their functions in practical CPL applications in terms of: (1) Compactness and integrability, (2) stand-alone (monolithic) nature, (3) room temperature operation, (4) emission with h

Quantitative depth estimation of tumor invasion in early gastric cancer by scattering of circularly polarized light is computationally investigated using the Monte Carlo method. Using the optical parameters of the human stomach wall and its carcinoma, the intensity and circular polarization of light scattered from pseudo-healthy and cancerous tissues were calculated over a wide spectral range. Large differences in the circular polarization with opposite signs, together with the large intensity,

The depolarization diagrams with particle size and wavelength as independent variables were obtained, which are particularly helpful for investigating the feasibility of various particle-monitoring methods. Based on the obtained diagrams, several applications have been proposed, including blood cell monitoring, early embryogenesis, and antigen-antibody interactions.

Magneto-optical properties of a ferromagnetic semiconductor (Zn,Cr)Te were investigated through magnetic circular dichroism (MCD) measurements in the visible spectral range. (Zn,Cr)Te films without and with an additional nitrogen (N) doping as an acceptor exhibited different MCD spectra around the Γ point; a broad MCD band extending over a few hundred meV was observed in the undoped (Zn,Cr)Te while a relatively sharp peak appeared in the heavily N-doped (Zn,Cr)Te. The different MCD spectra are c

We report that an ultra-thin, post-oxidized aluminum epilayer grown on the AlGaAs surface works as a high-quality tunnel barrier for spin injection from a ferromagnetic metal to a semiconductor. One of the key points of the present oxidation method is the formation of the crystalline AlOx template layer without oxidizing the AlGaAs region near the Al/AlGaAs interface. The oxidized Al layer is not amorphous but show well-defined single crystalline feature reminiscent of the spinel gamma-AlOx phas

The circular polarization (CP) of light scattered by biological tissues provides valuable information about the structural changes in tissues. We investigate the spatial discrimination of cancer using CP light scattering within the in-plane and along the depth direction. In-plane spatial resolution was investigated using experiments on sliced biological tissues, which show a noticeable difference in polarization values between healthy and cancerous parts in a wide angular range. The resolution i

Significance: The depolarization of circularly polarized light caused by scattering in turbid media reveals structural information about the dispersed particles, such as their size, density, and distribution, which is useful for investigating the state of biological tissue. However, the correlation between depolarization strength and tissue parameters is unclear. Aim: We aimed to examine the generalized correlations of depolarization strength with the particle size and wavelength, yielding depol

Abstract Cancer identification in vivo using circularly polarized light scattering with spin‐polarized light‐emitting diodes (spin‐LEDs) integrated at the tip of an endoscopic biopsy apparatus. Circularly polarized light emitted from a spin‐LED device impinges on a biological tissue, and the scattered light is detected at some spin‐LEDs on the apparatus. Polarization states of the scattered light provide valuable information for differentiating cancer tissues concealed in healthy tissues. Furthe