Properties of phase conjugate adaptive optical systems

The phase conjugate coherent optical adaptive technique (COAT) aims at compensating for atmospherically induced phase distortions of a laser beam. The paper investigates the convergence properties of an idealized phase conjugate COAT system by inserting thin nonlinear lenses (simulating thermal blooming) between the transmitter and the focus. The phase conjugate correction is performed using an appropriate scheme. The calculations are performed in the geometric optics limit as well as with Gaussian beams, the convergence properties of these two cases being qualitatively the same. It is shown that the phase conjugate COAT technique leads to nearly complete compensation of atmospheric turbulence and partial compensation for cases with moderate thermal blooming, with and without turbulence, so long as the effective thermal lens is thin and near the transmitter. For cases where refocusing is not possible, the phase conjugate COAT iteration diverges.