New scheme of phase matching for four wave mixing laser spectroscopy of C/sub 2/ molecules in acetylene-oxygen flame

A weak resonant probe and two strong off-resonant pump beams are aligned in a new scheme of phase matching to generate third order nonlinear optical signal for application in laser spectroscopy. The electronic swan band spectrum of C/sub 2/ molecules is obtained in acetylene-oxygen flame, and the signal behavior is investigated as a function of input pump intensity.