Gain saturation and propagation characteristics of index-guided tapered-waveguide traveling-wave semiconductor laser amplifiers (TTW-SLAs)

A model is developed to investigate the propagation characteristics and gain saturation performances of tapered-waveguide traveling-wave semiconductor laser amplifiers (TTW-SLAs). The influences of several physical mechanisms are analyzed. Two taper geometries are studied in detail: the exponential TTW-SLA and the linear TTW-SLA. The first is shown to be more efficient for narrow tapers (output width <14 mu m), whereas the linear TTW-SLA becomes superior for wide-taper geometries because of its better adiabatic propagation characteristics. Both tapered structures can provide a consistent improvement in the saturation output power compared to the conventional TTW-SLA, reaching absolute values on the order of approximately 18 dBm and approximately 23 dBm for the exponential and linear TTW-SLAs, respectively.<
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