DFB+R laser structure for directly modulated laser

A system, comprising:

• a distributed feedback plus reflection (DFB+R) laser having a back facet, a DFB section, a passive section, and a front facet, wherein the passive section, a portion of the DFB section, and the front facet form an etalon filter;
• a first photodiode being arranged to monitor first output power emitted from the front facet of the DFB+R laser;
• a second photodiode being arranged to monitor second output power emitted from the back facet of the DFB+R laser;
• and
• control circuitry in electrical communication with the first and second photodiodes and the DFB+R laser, the control circuitry being configured to:
• directly modulate the DFB section;
• bias the passive section;
• monitor a ratio of the first output power relative to the second output power;
• and
• adjust the bias based on the monitored ratio.

A method comprising:

• directly modulating a distributed feedback plus reflection (DFB+R) laser, the DFB+R laser having a back facet, a DFB section, a passive section, and a front facet, wherein the passive section, a portion of the DFB section, and the front facet form an etalon filter;
• measuring first output power emitted from a front facet of the DFB+R laser;
• measuring second output power emitted from a back facet of the DFB+R laser;
• monitoring a ratio of the first output power relative to the second output power;
• and
• adjusting bias to the DFB+R laser based on the monitored ratio.