Beam splitter and optical coupler using the same

US5621832A · kind A · utility

Assignees

• NEC CORPORATION · JP
• Vacuum Optics Corporation · JP

Inventors

• Jun Yokoyama · Niihama, JP
• Masaaki Miyake · Shizuoka, JP

Key dates

• Filing date: Dec 14, 1994
• Grant date: Apr 15, 1997
• Expiry date: Dec 14, 2014

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B2006/12038
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A beam splitter is an optical multilayer film obtained by sequentially stacking first to fifth layers respectively having refractive indexes of n.sub.1 to n.sub.5 and geometrical thicknesses d.sub.1 and d .sub.5 on a substrate having a refractive index n.sub.G. The refractive indexes of the substrate and the first to fifth layers satisfy any one of a relationship of n.sub.G =1.45 to 1.60, n.sub.1 =2.02 to 2.20, n.sub.2 =2.25 to 2.38, n.sub.3 =1.44 to 1.47, n.sub.4 =2.25 to 2.38, and n.sub.5 =1.44 to 1.47, a relationship of n.sub.G =1.45 to 1.60, n.sub.1 =1.44 to 1.47, n.sub.2 =2.25 to 2.38, n.sub.3 =1.44 to 1.47, n.sub.4 =2.25 to 2.38, and n.sub.5 =2.02 to 2.20, and a relationship of n.sub.G =1.45 to 1.60, n.sub.1 =1.44 to 1.47, n.sub.2 =2.25 to 2.38, n.sub.3 =2.02 to 2.20, n.sub.4 =2.25 to 2.38, and n.sub.5 =1.44 to 1.47, and a geometrical thickness d.sub.i of an ith layer of the first to fifth layers satisfies relation n.sub.i d.sub.i cos (.theta..sub.i)=.lambda./4, where n.sub.i is a refractive index of the ith layer, .theta..sub.i is an angle of refraction in the ith layer, and .lambda. is a center wavelength of an incident light beam to the multilayer film with an angle of inc…