Optical and Thermal Properties of Nickel-Azo Dyes for Digital Versatile Disc-Recordable

We investigate the absorption spectra, optical constants and thermal decomposition as well as red-light (650 nm) static recording properties of three novel nickel-azo dye films based on 4-methylthiazole, benzothiazole and 6-methylbenzothiazole. Particularly, we obtain the nickel-azo complex film based on 4-methylthiazole, peaking at 562 nm and 613 nm, with higher refractive index (n = 2.46) and lower extinction coefficient (k = 0.18) at the wavelength 650 nm and a sharp threshold of thermal decomposition at 330°C. The results of the static optical recording test of this dye film indicate that high reflectivity contrast of 51% can be observed at a laser writing power of 5.9 mW and pulse width of 350 ns. These results imply that the nickel-azo complex based on 4-methylthiazole is a promising candidate for a recording medium of digital versatile disc-recordable.