Nonfrequency-shifted self-pumped phase-conjugate mirror using sodium vapor

An incident cw laser beam polarized along the y direction induces a four-wave mixing oscillation polarized along the x direction in a linear cavity containing a sodium cell. The interaction of the incident field with the standing wave induces the generation of a reflected field. Reflectivities of as much as 20% inside the cell and response times shorter than 100 ns have been observed.