Characteristics of single-longitudinal-mode selection in short-coupled-cavity (SCC) injection lasers

Effective single-longitudinal-mode selection can be achieved in short-coupled-cavity (SCC) injection lasers consisting of a cleaved short-cavity laser (lengthL, refractive indexn) with a short external resonator (spacing d). The mode-selectivity is due to the combined advantages of large gain-rolloff for the adjacent modes in the short ( cavity, and resonator-loss-modulation in the coupled cavity. This I paper discusses the theoretical considerations and experimental studies for the SCC lasers. The results show that for good single-longitudinal-mode operation, the resonator-loss modulation period factorm, given by the effective optical length rationL/d, should be between approximately three and eight, with typical short-cavity laser lengthLin the40-100- range and external resonator spacingdalso in the40-120- range, depending on the specificL.