| 摘要 |
PURPOSE:To obtain a semiconductor laser device having a large resistance to the reflective return light by providing a current injection region having an opposite phase to the modulation current at least on one end face side in the resonator axis direction, and causing this injection region to act as a light absorbing region. CONSTITUTION:A current injection region having an opposite phase to the modulation current on at least one end face side in the resonator axis direction, and this injection region is made to act as a light absorbing region. For instance, the p-side electrode of a lambda/4 shift system DFB LD applied with non-reflecting coatings 31, 32 on both end faces thereof is divided into three electrode sections, that is, a modulated signal injection electrode 21, and opposite-phase current injection electrodes 22, 23. And, a pulse signal current Is of a 100% modulation degree is injected by a modulated signal generator 51 with a bias current Ib1-1.0 Ith, and an opposite-phase current Ip is injected from an opposite-phase current generator 52 with Ib2=0.9Ith and Ib2'=0.4Ith. since by providing an opposite-phase current injection region in this way, a return light of any phase receives absorption in this region, the noise of the output light can be reduced. |
