Giuliana BORSA,¹ Stefania CASTELLETTO,^2,* Aldo GODONE,¹ Carlo NOVERO¹ and Maria Luisa RASTELLO¹

¹Istituto Elettrotecnico Nazionale Galileo Ferraris, Strada delle Cacce 91, 10135 Torino, Italy, ²Politecnico di Torino, Dipartimento di Ingegneria Elettronica, Corso Duca degli Abruzzi 24, 10129 Torino, Italy

(Received April 28, 1997; Accepted May 6, 1997)

This work presents a new technique for the measurement of second-order optical nonlinear coefficients from the absolute radiant power of the parametric fluorescence emission. It is based on calibrated detectors regarded as secondary radiometric standards. This technique makes it possible to skip a number of problems usually encountered with standard techniques based on calibrated neutral density filters and reference sources of light at much higher power levels. We infer a value for the d₃₁ nonlinear coefficient of LiIO₃ from spectral measurements of the fluorescence power integrated over all solid angles, by defining the wavelength bandwidths with interference filters. Moreover, by performing the measurements on the ultraviolet and visible emission lines of an argon ion laser in the range from 351 to 488 nm, the wavelength dependence of d₃₁ is compared with the expected one obtained by Miller's dispersion law.

Key words : absolute measurements, second-order nonlinear optical coefficient, parametric fluorescence

*castelle@tf.ien.it