Analysis of single-mode yields above threshold for complex-coupled distributed feedback lasers with asymmetric facet reflectivities

Abstract

Single-mode yields above threshold of complex-coupled (CC) distributed feedback (DFB) lasers with antireflection and high-reflection-coated facets for various values of ∣kL∣ and coupling coefficient ratio (CR) are presented and compared with the spatial hole burning- (SHB-) corrected yield at threshold. If the criterion necessary for the SHB-corrected yield is selected properly, the two yields give good agreement. We present two single-mode yields above threshold, showing the difference between in-phase (IP) and antiphase (AP) CC DFB lasers, even though the two yields are the same at threshold. Single-mode yields above threshold of IP CC DFB lasers are higher than those of AP CC DFB lasers, since the threshold gain of the next strongest mode of AP CC DFB lasers, increases rapidly compared with that of IP CC DFB lasers because of the SHB effect. As the CR increases, the single-mode yield of IP CC DFB lasers initially increases and has a nearly constant value of more than 90% for a CR greater than or equal to 0.3. As the CR and ∣kL∣ increase, the effect of the reflectivity of the antireflection facet on the single-mode yield decreases.