Patent ID: 7724424

Claim:
An optical module for supplying pump light for amplifying to-be-amplified light, comprising: an pump light source; optical coupling means; and an optical guide section, wherein said optical guide section optically connects said pump light source and said optical coupling means, and propagates said pump light, which is output from said pump light source, in multi-transverse-mode, said optical coupling means comprises a first input port to which said to-be-amplified light is input, a second input port to which said pump light from said optical coupling means is input, and an output port having a fiber structure which outputs said to-be-amplified light, and said pump light is output from said first input port or said output port in multi-transverse-mode, at least one of (i) at least one of end faces, of which said optical guide section and said optical coupling means are connected, (ii) an area between said end faces of said optical guide section and said optical coupling means, and (iii) said optical guide section having a loss medium of which transmission loss is greater in a wavelength of said to-be-amplified light than in a wavelength of said pump light, said optical guide section comprises a first optical fiber for guiding and a second optical fiber for guiding, and said loss medium is formed between said first and second optical fibers for guiding, and said loss medium is a coating formed on a fiber end face of at least one of said first and second optical fibers for guiding.