| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem wherein a plurality of etalon filters are required and the number of adjustment working hours is increased, to detect a minute change in an LD output wavelength in a wide wavelength range, since characteristics in the etalon filters are periodic, even though the etalon filter is usually used to detect the minute change in the LD output wavelength in an LD module, having a built-in wavelength locker. SOLUTION: The output light of an LD element 10 is changed to two different polarization states by a polarization switching element 5, and by setting transmission characteristics in a filter 31A to be different characteristics by the polarization state, variations in the output wavelength of the LD element 10 are detected over a wide wavelength range. COPYRIGHT: (C)2005,JPO&NCIPI
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