Temperature-dependent tuning of photonic band gaps for wavelength-selective switching applications

Abstract

Transmission characteristics of a thermally tunable optical filter system composed of two 1D silicon–air photonic crystals with different periods have been explored by transfer matrix method. The proposed structure is capable of separating and switching unique wavelength channel without interfering with others amongst 11 equally spaced wavelength channels. Each channel has full width at half maximum of 1 nm as per the wavelength-division multiplexing standards developed by the International Telecommunication Union specifying channel spacing between the adjacent channels in terms of wavelength for wavelength-selective switching applications. The refractive index of silicon is known to be dependent on both temperature and wavelength. Thus, any change in the operating temperature of both photonic crystals by same amount causes their photonic band gaps to alter simultaneously and significantly in such a way as to switch the wavelength-division multiplexing channels one by one as per requirement. The working of the proposed filter system is dependent only on tuning the photonic band gaps and is completely different from the conventional photonic crystals with defect.