Furukawa Electric Review No.49Telecommunication・EnergyA High Power Tunable Light Source for Coherent Communications Using a Distributed Reflector Laser Array Combined With an AWG Coupler

Yusuke Inaba, Maiko Ariga, Kazuaki Kiyota, Toshihito Suzuki, Kazuki Yamaoka, Shunsuke Okuyama, Masayoshi Nishita, Tatsuro Kurobe, Hajime Mori

The high power and narrow beam linewidth of a tunable light source (TLS) is essential to achieve higher speed in digital coherent communication. In order to meet such requirement, we have developed the TLS which has integrated a Distributed Reflector (DR) Laser Array and an Arrayed Waveguide Grating (AWG) coupler. Improving the coupling efficiency by adjusting the transmission wavelength of the AWG coupler and the lasing wavelength of each of the lasers, using DR lasers which have backward Distributed Bragg Reflector (DBR) for the each laser, and reducing its threshold gain, the development of the laser chip with a high power and a narrow beam linewidth can be available. And moreover, by adapting a new configuration where a Semiconductor Optical Amplifier (SOA) is placed on a different thermo-electric cooler from the one the laser array chip is on in the module, a farther higher power/narrower beam linewidth can be obtained and a 19 dBm optical output / less than 70 kHz linewidth as required characteristics to the light sources on the next generation high-speed telecommunication has been achieved.