Optical coupler

Claim 2

An optical coupler according to claim 1, wherein said second prism is a triangular prism having an apex angle of 22.5 degrees.

Claim 3

An optical coupler according to claim 1, wherein said second prism is a quadrangular prism having opposing apex angles of 22.5 degrees and 45 degrees.

Claim 4

An optical coupler according to claim 1. wherein the first beam is a signal beam. and the second beam is a pumping beam.

Claim 5

An optical coupler according to claim 4, further comprising polarized beams coupling means for coupling a first pumping beam and a second pumping beam having perpendicular polarization directions to each other.

Claim 6

An optical coupler according to claim 4, further comprising an Er doped fiber into which a wavelength multiplexed beam is introduced, and an optical isolator interposed between said Er doped fiber and said optical coupler.

Claim 7

An optical coupler for coupling a first beam and a second beam having different wavelengths to each other, comprising: a first prism having an included angle of 45 degrees and having a total reflection film formed on a first one of a pair of faces thereof which define the included angle while an optical wavelength multiplexing film is formed on the second one of the faces of said first prism defining the included angle; a quadrangular prism having a first included angle sufficient to allow a wavelength multiplexing of the first beam and the second beam and a second included angle of 45 degrees opposing to the first included angle, said quadrangular prism being adhered to the second face of said first prism on which said optical wavelength multiplexing film is formed such that the first included angle of the former is positioned adjacent the included angle of said first prism, said quadrangular prism having a polarized beams coupling film formed on a face thereof remote from the second face of said first prism on which said optical wavelength multiplexing film is formed; and a triangular prism adhered to the face of said quadrangular prism on which said polarized beams coupling film is formed.

Claim 8

An optical coupler according to claim 7, wherein the first beam is a signal beam, and the second beam is constituted from a first pumping beam and a second pumping beam having mutually perpendicular polarization directions.

Claim 9

An optical coupler according to claim 8, wherein a filter film which reflects a signal beam component but transmits the first and/or second pumping beams therethrough is provided on an interface of said quadrangular prism and said first prism through which the first and/or second pumping beams pass.

Claim 10

An optical coupler according to claim 9, wherein a filter film which reflects a signal beam component but transmits the first and/or second pumping beams therethrough is provided on each of end faces of said quadrangular prism and said triangular prism into which the first and/or second pumping beams are introduced.

Claim 11

An optical coupler for coupling a first beam and a second beam having different wavelengths to each other, comprising: a first prism having an included angle of 45 degrees and having a total reflection film formed on a first one of a pair of faces thereof which define the included angle while an optical wavelength multiplexing film is formed on the second one of the faces of said first prism defining the included angle; a triangular prism having a first included angle between a first inclined face and a bottom face sufficient to allow a wavelength multiplexing of the first beam and the second beam and a second included angle of 45 degrees between a second inclined face and the bottom face, said triangular prism being adhered to the second face of said first prism on which said optical wavelength multiplexing film is formed such that the first included angle of the former is positioned adjacent the included angle of said first prism, said triangular prism having a polarized beams coupling film formed on the second face thereof; and a parallelogram prism adhered to the face of said triangular prism on which said polarized beams coupling film is formed.

Claim 12

An optical coupler according to claim 11, wherein the first beam is a signal beam, and the second beam is constituted from a first pumping beam and a second pumping beam having mutually perpendicular polarization directions.

Claim 13

An optical coupler according to claim 12, wherein a filter film which reflects a signal beam component but transmits the first and/or second pumping beams therethrough is provided on an interface of said triangular prism and said first prism through which the first and/or second pumping beams pass.

Claim 14

An optical coupler according to claim 13, wherein a filter film which reflects a signal beam component but transmits the first and/or second pumping beams therethrough is provided on each of end faces of said triangular prism and said parallelogram prism into which the first and/or second pumping beams are introduced.