Patent ID: 6588948
Filing Date: 2003-07-08
Classification: G02B,H01S

Abstract:
An optical module, having:a housing; and a junction having a light transmissive window structure which uses a sapphire plate cut so as to be perpendicular to a C axis of the sapphire, wherein the following expressions (1)-(4) are established between an angle &psgr; as viewed from the optical axis, formed by the C axis of the sapphire and the plane of polarization of light, which is linear polarization, and an angle &thgr; formed by the C axis of the sapphire and the optical axis: n=&ohgr;&egr;/{square root over ((&ohgr;2cos2&thgr;+&egr;2sin 2&thgr;))}â€ƒâ€ƒ(1) &dgr;=2&pgr;d(&ohgr;âˆ’n)/&lgr;â€ƒâ€ƒ(2) tan&it;â€ƒ&it;Î²=(sin2&it;2&it;â€ƒ&it;Ïˆ&it;â€ƒ&it;sin2&it;â€ƒ&it;Î´+1)-1sin&it;â€ƒ&it;2&it;â€ƒ&it;Ïˆ&it;â€ƒ&it;sin&it;â€ƒ&it;Î´(3)â€ƒâˆ’30&gE;+20log(tan&bgr;)â€ƒâ€ƒ(4)where,&ohgr;: Principal refractive index of the sapphire &egr;: Secondary refractive index of the sapphire &lgr;: Wavelength of a transmitted light d: The sapphire plate thickness.