Abstract

We report on the observation of phase conjugation at 10.6 μm via intersubband third order nonlinearities in a multiple quantum well structure, in a phase matched configuration, yielding reflection efficiency of 0.2%. Our sample consists of 50 periods of heavily Si-doped, GaAs quantum wells, clad by AlGaAs barriers. The input facets were lapped to 45°. In our experiment, the light from a CO₂ laser was split into two beams: the first, acting as the pump beam, was focussed onto the sample edge at normal incidence; the second (probe) beam was focussed at an angle of 15° from the normal. The (nor mal) reflection of the first pump beam from the back facet inside the sample provided the second counterpropagating pump beam, and the phase conjugate beam was obtained, retracing the path of the incident probe beam.

© 1992 Optical Society of America