| 摘要 |
Methods and apparatus for stabilizing or otherwise controlling wavelength in tunable semiconductor lasers and other optical sources. A tunable semiconductor laser includes a gain section and at least one tuning section. Spontaneous emission (SE) from the tuning section is detected and used in a feedback control loop to control the amount of current applied to the tuning section. The SE may be detected using an integrated detector on the semiconductor laser chip, an external detector arranged adjacent the chip to detect SE emitted from a side of the tuning section, or an external detector arranged to detect SE coupled from an optical fiber or other signal line connected to an optical signal output of the laser. The feedback control loop may operate to maintain the detected SE at a constant level, such that the current applied to the tuning section is adjusted to compensate for the effects of aging and the laser output wavelength is thereby stabilized. The invention may also be implemented using multiple feedback control loops to control the current supplied to corresponding multiple tuning sections of a given optical source. Each of the multiple feedback control loops may operate to maintain the SE detected from a corresponding one of the tuning sections at a constant level, such that the output wavelength is stabilized.
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