Quantum well structures for THz bandwidth near-infrared unipolar semiconductor lasers

Intersubband semiconductor lasers provide possibilities for obtaining compact laser sources in the mid-infrared (MIR) spectral region. The dynamical behaviour of such lasers is governed by electron lifetimes, which are typically of order 1 ps in coupled quantum well structures. In the present paper, attention is given to the design of a near-infrared unipolar semiconductor laser with a lasing wavelength of 1.55 μm. Calculations have been undertaken of the optical gain spectra of this structure and compared to that of a similiar MIR structure. In addition, it has been found that very high direct-current modulation bandwidths would be achievable in these lasers