Optical device

Abstract

To provide an optical device having satisfactory optical coupling efficiency with the outside.SOLUTION: An optical device 1 comprises: a first lens 10 connected to an end face of an optical waveguide of an optical element and emitting emission light from the optical element; a second lens 20 optically connected to the first lens 10 and converting the emission light from the first lens into collimated light. The optical element may be any of a laser element, an optical modulation element and an optical amplification element. The first lens 10 is an aspherical lens with a curved surface projecting to the opposite side of the optical element, a side of which connected to the end face of the optical waveguide of the optical element is formed in a flat surface intersecting an optical axis of the first lens 10. The area of the flat surface is smaller than the maximum area of a section orthogonal to the optical axis of the optical waveguide. Point O denoting a prescribed position on a surface of the first lens 10 facing the optical element, point S denoting a prescribed position on a surface of the first lens 10 excluding the surface facing the optical element, and position P of a virtual image satisfy the relation of a prescribed distance.SELECTED DRAWING: Figure 1

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