The degeneration of performance of an optical thin-film interference filter associated with the change of temperature is not acceptable. In this letter, we report a new progress in improving low-temperature performance of infrared narrow-band filters by using Pb1-xGexTe initial bulk alloy with appropriate Ge concentration x. It can be found that there exists a critical temperature for the investigated narrowband filter, at which the temperature coefficient of filter is exactly zero. Therefore, by means of controlling the composition in (Pb1-xGex)1-yTey layers, the temperature coefficient of filter can be tunable at the designated low-temperature. In our present investigation, when temperature varies from 300 to 85 K, a shift of peak wavelength of 0.05935 nm.K-1 has been achieved.
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