The most remarkable feature of organic dye laser is that they can be tuned continuously over a range of wavelengths. High intensity tunable coherent light in the wavelength region from 330 to 1, 200nm can be obtained from dye laser. The lasing mechanism of dye laser, the spectroscopic properties of fluorescent organic molecules, the useful materials for dye laser, and the excitation sources of dye laser, are descrived. Especially, several new techniques, which developed after 1970, are reviewed; for example, CW operation, tuning and spectral narrowing techniques, and picosecond-pulse generation.
Unusually large deformation coefficients were observed by applied electric fields in conducting Mn-Zn ferrite crystals. The observed electrostrictive coefficients (X) defined by S=1/2XE2 (S: strain, E: electric field) were of the order of magnitude of 10-10(m/V)2, which were 1011 times larger than the electrostrictive coefficient of BaTiO3. The observed strains are due to a magnetostrictive effect from the magnetic field induced by the electric current through the crystal. The electric signals due to elastic strains were obtained by using a dc biasing current. A large piezoelectric effect was also observed in the same Mn-Zn ferrite crystals under magnetic fields both parallel to and perpendicular to the electric field. The induced strains were correctly given by the relation: S=d•E, The piezoelectric d-constants were dependent upon the magnetic field and crystallographic orientations and were of the order of magnitude of 10-10 C/N under a suitable magnetic field. These are, respectively, about 100 times larger than and of the same order of magnitude as the piezoelectric constant of a quartz crystal and a PZT ceramic element. The emf voltages due to elastic strains were obtained as a result of the inverse processes mentiond above.
Edge dislocations in wurtzite-type CdSe single crystals were observed by etching technique, and etch pit densities were measured along its low-angle grain boundaries, and also for crystals which were bent around the caxis at 250_??_500°C. The results indicate a good correspondence between the edge dislocations and etch pits.