A study is performed of features of surface-emitting quantum-cascade lasers with a ring resonator and second-order diffraction grating. The coefficient of coupling can be raised to 12 cm−1 by selecting the modes for direct ion lithography etching. Lasing is done near 7.6 μm with a threshold current density of only 0.3 kA/cm2.
Optical absorption of s- and p-polarized light was studied in GaN/AlN quantum wells in the near-infrared spectral range. An absorption peak associated with intersubband electron transitions in quantum wells was observed near a wavelength of 1.55 μm. Optoelectronic devices based on these structures can be used in fiber-optic telecommunication technologies.
Photoconductivity in GaAs/AlGaAs quantum well nanostructures doped with acceptors was studied at low lattice temperatures in the infrared and terahertz spectral ranges. The photocurrent spectra revealed features that can be attributed to the hole transitions from the ground acceptor state to the excited acceptor states and size-quantized subbands.
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