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A portion of the conduction band structure along with the moduli squared of the relevant wave functions. Wave functions in bold illustrate the upper and lower laser levels of each active period. The optical transition, with a design energy of 298 meV, is depicted by vertical arrows. A very low voltage defect of is identified by , for an applied electric field of 91 kV/cm. One can see the shortened injector regions, consisting of four quantum wells between each set of active regions. The calculation takes the free carrier density into account through a self-consistent solution of the Schrödinger and Poisson equations.
Pulsed measurements for a 3 mm long and wide laser ridge at the indicated heat-sink temperatures. The light, showing output from both facets, is corrected for a collection efficiency of 75%.
Peak WPE (squares), voltage efficiency at lasing threshold (circles), and voltage efficiency at peak WPE (triangles) vs heat-sink temperature for a 3 mm long and wide laser ridge under pulsed operation.
Threshold current density (black squares) and voltage defect at laser threshold (red circles) vs heat-sink temperature for a 3 mm long and wide laser ridge under pulsed operation. The threshold current density values are fit with exponential curves, , resulting in two regions of differing characteristic temperature . A of 118 K exists at lower temperatures, while a of 174 K is obtained at higher temperatures. The discontinuity in the temperature performance occurs where the voltage defect at threshold corresponds to one LO phonon . The inset shows pulsed laser spectra for the device at 1.1 times threshold current for various heat-sink temperatures.
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