title: Temperature-induced spectrum response of a volume grating as an effective strategy for holographic sensing in an acrylamide polymer part II: physical mechanism.
abstract: The temperature response mechanism of a diffraction spectrum in a holographic grating is characterized. Two possible major factors, changes in the refractive index and thermal expansion, are measured and analyzed to identify the sensing physical mechanism. Average refractive indices at various temperatures and relative humidity values are independently measured. Thermal optical coefficients of polymers are estimated quantitatively to evaluate the temperature response capability of the refractive index. Angle selectivity of multiplexing gratings is scanned at various temperatures to obtain magnitudes of Bragg angle detuning. The linear thermal expansion coefficients are extracted by the nonlinear fitting reading angle dependence of angle detuning. The significance of the thermal optical coefficient and the thermal expansion coefficient for holographic sensing is discussed. Finally, the primary factor for temperature-induced wavelength blueshift is analyzed theoretically.
authors.forename: Hongpeng
authors.initials: H
authors.lastname: Liu
authors.forename: Dan
authors.initials: D
authors.lastname: Yu
authors.forename: Ke
authors.initials: K
authors.lastname: Zhou
authors.forename: Dongyao
authors.initials: D
authors.lastname: Mao
authors.forename: Langbo
authors.initials: L
authors.lastname: Liu
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: Weibo
authors.initials: W
authors.lastname: Wang
authors.forename: Qinggong
authors.initials: Q
authors.lastname: Song