In order to make the GaAs FET having the required negative resonator to oscillator, we use the common source configuration and add the appropriate drain open stub microwave line.

Using the periodic orbit theory, we computed the quantum level density of a particle in the two-dimensional harmonic oscillator potential with and without the magnetic flux line for different cases.

Based on the character of off-axis and multi-pass amplification systems, the possibilities are analyzed that some part of the line could form optical oscillator and occur self-excitation oscillation.