HR-COATED FACET EFFECT ON THE SPECTRAL CHARACTERISTICS OF A 3-SECTIONDBR TUNABLE LASER

High-reflection (HR)-coated facet effects on the spectral characterist ics of a three-section distributed Bragg reflector (DBR) tunable laser are investigated theoretically, in which the output power emits to th e DBR section. It is found that the output power to the DBR section P( DBR) compared to the cleaved facet output power P0 is nearly constant to some degree with increasing tuning current. Owing to the high-Q res onator, the HR-coated DBR laser showed a decrease in spectral linewidt h. However, there is still linewidth broadening of the HR-coated DBR l aser even though the rate of increase is smaller than that of the clea ved-facet DBR laser. In the case of output power emission to the DBR s ection, it is thought that the HR-coated effect can overcome the decre ase in output power under frequency tuning, which is one of the most i mportant drawbacks of DBR laser performance.