Tatsuya Kimoto, Tatsushi Shinagawa, Toshikazu Mukaihara, Hideyuki Nasu, Shuichi Tamura, Takehiko Numura and Akihiko Kasukawa
To suppress crosstalk between adjacent channels in communications systems based on dense wavelength-division multiplexing (DWDM) requires a laser module that incorporates a wavelength monitor capable of high-precision locking on the channel of the desired wavelength. We have developed a distributed feedback (DFB) laser module with a PMF output of 40 mW, integrated with a wavelength monitor for DWDM with 25-GHz spacing. By means of a highly efficient and highly reliable DFB laser diode and an optimized thermal design, it has been possible to realize thermally tunable operation, and, under variations in laser diode temperature of approximately 40°C, a tunable range of 4 nm or more and a maximum power consumption of 4 W or less. High-temperature storage tests and aging tests showed that despite a structure that is more complex than conventional DFB laser modules, these modules exhibit higher reliability, making them applicable to DWDM systems.