Patent ID: 7309172

Claim:
An optical transmitter-receiver module, comprising: (a) a wavelength-selecting filter; (b) an optical fiber for transmitting an optical signal bidirectionally; (c) a light-emitting device; (d) a light-receiving device into which a lightwave having travelled the optical fiber is introduced after it is reflected from the wavelength-selecting filter; and (e) a filter-holding sleeve that: (e1) holds the wavelength-selecting filter obliquely; (e2) holds the optical fiber attached at its one end wall; (e3) holds the light-emitting device at the end wall opposite to the end wall at which the optical fiber is attached; and (e4) has an inverted conical hole that: (e4a) is bored in a side wall at the position at which a lightwave of the light-emitting device arrives after it is reflected from the wavelength-selecting filter; (e4b) has a size larger than the spread of the lightwave of the light-emitting device having arrived at the inverted conical hole after it is reflected from the wavelength-selecting filter; (e4c) has a vertical angle, α, of a value selected from the two ranges consisting of a range of 100 to 160 degrees and a range of 72 to 80 degrees; and (e4d) the inverted conical hole has a slanted face having a surface roughness, Ra, of 0.6 μm or less.