We have studied the intrinsic frequency tuning of several terahertz (THz) quantum-cascade lasers (QCLs) based on a hybrid design. With increasing driving current, most QCLs exhibit either a redshift or… Click to show full abstract
We have studied the intrinsic frequency tuning of several terahertz (THz) quantum-cascade lasers (QCLs) based on a hybrid design. With increasing driving current, most QCLs exhibit either a redshift or a blueshift, while some QCLs show both. An oscillator model describes the observed behavior. The accuracy of the model is affected by the complexity of the current-dependent gain spectra of the THz QCLs. Numerical simulations demonstrate a cavity pulling effect insofar as the tuning behavior depends on the resonator losses and on the width of the gain spectra.
               
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