Phase‐matched optical second‐harmonic generation in Langmuir–Blodgett film waveguides by mode conversion

Phase‐matched second‐harmonk light generation by guided mode conversion has been observed for the first time in nonlinear optically active Langmuir‐Blodgett films. The sketch of the experimental setup (Figure) shows how the infrared fundamental beam is coupled via a grating into SiO 2 /TiO 2 ‐DCNAP waveguides with various thicknesses of DCNAP film. The film with the correct thickness for phase matching guides a second‐harmonic mode, which is observed as a blue beam, as illustrated in a photograph in the article. magnified image