We propose a novel temperature compensation method that HBF is mounted on a piece of organic glass. It can lessen its temperature sensitivity to 0.059 nm/K, which are two orders of magnitude lower than that of an uncompensated HBF loop mirror. It is feasible that HBF loop mirror packaged with a large thermal-expansion material is insensitive to ambient temperature perturbation. This technique is beneficial to the practicality of loop mirror filter based fiber sensors.
In this paper, an all-fiber electric voltage sensor based on high birefringence fiber loop mirror is presented. This voltage sensor is composed of a 3dB coupler and ~8m high birefringence (HiBi) fiber, part of which is affixed to a piezoelectric translator (PZT). When the voltage applied on the PZT changes, the transmission spectrum of this HiBi fiber loop mirror will shift accordingly. As the direct current voltage increases to 75.2V, the phase shift of this HiBi fiber loop mirror is nearly π rad and the transmission peak changes by about half of a period. This voltage sensor has a sensitivity of 0.004nm/V and its linearity reaches 0.99878. Moreover, we have theoretically studied transmission spectrum shift of this HiBi fiber loop mirror when the length and refractive index difference of HiBi fiber are altered.
In the paper, a simple and effective FBG sensor able to discriminate temperature from strain at a single point had been worked out, by sticking half of it on the fixed end of the polymer equivalent beam, leaving the other half free. The FBG was then separated into two segments with different temperature and strain coefficients, which composed the measuring matrix. The measuring sensitivities of temperature and strain of our setup are 9.58×10-6(1/°C) and 6.72×10-7(1/με) respectively. This device will have wide applications to discriminate between strain and temperature of sensing networks.