| 摘要 |
PROBLEM TO BE SOLVED: To control an adjustable optical transmitter to operate without causing mode hoppings and at the same time, to maintain the side mode suppression ratio of the transmitter as high as possible, by supplying a tuned current of a level at which the side mode suppression ratio becomes the maximum to a laser with respect to each channel wavelength by means of a controller. SOLUTION: An analog approach is constituted of a combination of a phase sensitive detector(PSD) 20 and a dither source 28, and the primary derivative with respect to the tuned current of the output current of a distributed Bragg reflector(DBR) semiconductor laser 12 is generated. When a lock-in amplifier is used as the PSD 20, an in-phase lock-in signal generated by the amplifier becomes proportional to the primary differential coefficient. The derivative is used for controlling the operation of the laser 12. Namely, the laser 12 is constituted to operate at the maximum side mode suppression ratio(SMSR), regardless of to which channel the laser 12 is designated for providing a carrier signal. |
