Determination of subband energy levels from self-excited Raman scattering in compressively strained InGaAs/GaAs quantum well lasers

Determining the electron and hole subband energy levels in a quantum-well (QW) laser itself is a key issue for the device design to improve laser characteristics such as temperature insensitive performance and so on. The resonant electron Raman scattering (ERS) spectra has been observed at room temperature above threshold by self-photo-excitation in InGaAs/GaAsP single 7nm QW lasers and InGaAs double 8nm QW lasers both grown on GaAs with different Indium contents. The first and the second subband energies of the electrons and holes in the QW are determined from the ERS spectra. The efficiencies of some ERS peaks exceed ~10 -3 . The confined self-photo-excitation occurs along the laser active waveguide and induces the efficient intersubband transitions in the QW. These indicate that the efficiency of the ERS is possible to increase by lengthening laser photon lifetime in the cavity with a high reflective coating for the laser light, and by enhancing the TM polarized intersubband transitions with TM polarized laser light, which is generated between electron and light hole transition by introducing tensile strained QW. We propose a new type semiconductor with coherent wave generation and amplification by the self-induced ERS in Qws and quantum wires and quantum dots.