DOUBLE REFRACTIVE DIFFRACTION GRATING TYPE POLARIZER

Japanese Patent JP2848137

B2

PURPOSE: To obtain an extinction ratio sufficient for practicable use over a wide wavelength range of incident light.
CONSTITUTION: The diffraction gratings of proton exchange regions 18 and phase compensation films 19 are formed on a surface 16 of a lithium niobate substrate 15. The diffraction gratings of proton exchange regions 20 and phase compensation films 21 are formed on the surface 17. The phase difference between the line parts and base parts of the diffraction gratings of the surface 16 is 0 with an ordinary light component and π with an extraordinary light component in the case of a wavelength λ1 of incident light. The phase difference between the line parts and base parts of the diffraction gratings of the surface 17 is 0 with the ordinary light component and π with the extraordinary light component in the case of a wavelength λ2 (λ1<λ2) of the incident light. The high extinction ratio is obtd. by the diffraction gratings formed on the surface 16 if the wavelength of the incident light is smaller than λ1. The high extinction ratio is obtd. by the diffraction gratings formed on the surface 17 if the wavelength of the incident light is larger than λ2. The necessary extinction ratio is assured by adequately determining the values of the ' λ1, λ2 even if the wavelength of the incident light exists between the λ1 and the λ2.

KATAYAMA RYUICHI

JP18326892A

January 20, 1999

July 10, 1992

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NIPPON DENKI KK

G02B5/18; G02B5/30; (IPC1-7): G02B5/30; G02B5/18

JP331803A
JP2230203A
JP2165023A

Naoki Kyomoto (2 outside)

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