| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to lower tie coupling efficiency of reflected return light to a laser diode chip and to lessen the influence exerted on the characteristics of a laser diode module by providing the central axis of the output light of the laser diode chip with a specific angle. SOLUTION: The reflected return light from an optical fiber 3 is reflected by the photodetecting surface of the optical fiber 3 at the same angle as an angleθ1 at which the light is made incident on the optical fiber 3. Thus reflected light is coupled to the laser diode chip 1. The central axis of the reflected return light coupled to the laser diode chip 1 has the angle 2θtwice the angleθof the axis at which the center of the light emitting part of the chip 1, the central axis of a header 4, the central oxide of a lens 2 and the central axis of the optical fiber 3 are arranged and the central axis of the output light of the laser diode chip 1 with respect to the central axis of the laser diode chip 1. The coupling efficiency is, therefore, lowered by this angle 2θand the coupling efficiency of the reflected return light to the chip 1 is made lower than the case where the central axis of the light output of the laser diode ship 1 is not provided with the angle.
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