Optical absorptions due to intraband transition in a QD are studied theoretically. The conduction band energy levels were
calculated for a cylinder quantum dot with finite confining potential in the framework of the effective-mass
envelope-function theory. Numerical calculations on a typical GaAs/AlAs QD are performed for different incident laser
energies. It is found that the optical absorptions are very sensitive to the incident radiation wave vector. The effect could
be utilized for the realization of polarization-sensitive detectors.