SELECTING METHOD OF TEMPERATURE COEFFICIENT FOR WAVELENGTH SHIFT OF MULTILAYER FILM FILTER AND MULTILAYER FILM FILTER HAVING ALMOST ZERO TEMPERATURE COEFFICIENT OF WAVELENGTH SHIFT

摘要

PURPOSE: To decide the temp. coefft. of wavelength shift of a multilayered film filter according to decision of the coefft. of linear expansion of a substrate and to obtain a multilayered film filter having almost zero temp. coefft. of wavelength shift. ;CONSTITUTION: Dense multilayer films are formed on different substrates by vapor deposition by an ion or plasma process. The temp. coefft. of wavelength shift of each multilayer film is plotted on the coordinate of linear expansion coefft.-temp. coefft. of wavelength shift. Based on the obtd. plot, the temp. coefft. shift line intrinsic to each multilayer film is obtd. The substrate for a multilayer film having a specified temp. coefft. of wavelength shift is selected according to this temp. coefft. shift line. Further, by using a substrate having coefft. of linear expansion of 75-150(1/10⁷), a multilayered filter having almost zero temp. coefft. of wavelength shift is obtd. Thereby, the temp. coefft. of wavelength shift can be determined from the temp. coefft. shift line. A multilayered filter having almost zero temp. coefft. of wavelength shift can be obtd. by using a substrate having the coefft. of linear expansion in a specified range.;COPYRIGHT: (C)1995,JPO