Asahi Glass Company, Limited

Ryuichiro Goto

Yoshiharu Ooi

Hiroki Hotaka

Noriaki Shimodaira

Ryota Murakami

Reiko Nozawa

Noriaki c/o Asahi Glass Company Ltd Shimodaira

Ryota Asahi Glas Koriyamadenzai CoLtd Murakami

Hiroki c/o Asahi Glass Company Limited Hotaka

Yoshiharu Asahi Glass Koriyamadenzai CoLtd Ooi

An optical head device having an optical element capable of transmitting without diffracting light having a wavelength emitted from a two-wavelength semiconductor laser and capable of diffracting light having another wavelength, to provide high utilization efficiency of light in a stable manner. For this purpose, a wavelength-selective diffraction elementA comprising a transparent substrate having a front surface on which a grating having a periodically recessed and projected shape in cross section is formed and a filling memberA filled in the concavo-convex portionA of the grating wherein the concavo-convex portion of the grating is provided with an organic pigment having the absorption edge of light in a region having a shorter wavelength than the wavelength &#x3bb;, and the concavo-convex member and the filling member have the same refractive index with respect to either one of light having a wavelength &#x3bb;and light having a wavelength &#x3bb;, and they have different refractive indices with respect to the other light having a wavelength, is disposed between the light source and the objective lens of the optical head device.

Wavelength-selective diffraction element and an optical head device

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Yokohama, Japan

Ryuichiro Goto