Chirping effects in phase-coupled laser arrays

An improved coupled-mode theory is used to analyse various phase-coupled, index-guided diode laser arrays. Different designs of 10-guide arrays are considered, including uniform, linearly chirped, A-chirped, V-chirped, and saw tooth arrays. Lower-order supermodes are favoured when there is excess gain between the guides. However, a common problem with large arrays is the relatively poor mode discrimination. This can be remedied by proper gain tailoring, which results in significantly higher gain for the lowest-order supermode. Further improvement can be achieved with moderately strong coupling, when the highest-order supermodes can be made cut-off, thus reducing mode competition due to spatial hole burning effects above threshold.