| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for selecting noise characteristic of a semiconductor laser by which the level of the noise characteristic can be easily determined even in a semiconductor laser of an actual refractive index wave guide type structure or the like without measuring each time the noise in mounting state. SOLUTION: For example, when TE/TM is less than a certain value, noise intends to increase sharply according to a relationship between the polarization ratio of the TE/TM and noise. Therefore, the polarization ratio of a TE polarization element of a semiconductor laser output to a TM polarization element thereof is used to select the noise characteristic.
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