Research On Optical Fiber Temperature And Humidity Sensor Based On Mach - Zehnder And Fabry - Perot Interference Structures

As is known to all, China is a cultural power, in the development of thousands of years, a large number of painted cultural relics is retained, which recorded a lot of production and living information of the ancient people. It is the precious wealth of modern scientists to study ancient Chinese culture,however,due to these cultural relics are mostly made in hundreds or even thousands of years ago,and the vast majority of pre-modern cultural relics are in the open field environment, the surface of colored layer has been severely damaged, so it is necessary to provide a suitable preservation environment for the artifacts and to monitor the environment temperature and humidity and other factors that affect the durability of the painted pigment layer.Optical fiber sensing technique developed in recent years, which overcome the shortcoming of traditional temperature and humidity sensor, such as easy to corrode for using a long time,poor stability and so on. With the characteristic of high measurement precision,resistance to electromagnetic interference, miniaturization to facilitate integration and multiplexing, it is able to meet the needs of the painted cultural relics environmental monitoring, which application in the field of painted cultural relics protection has important scientific value and research significance.In this paper, to protect painted cultural relics, we research temperature and humidity fiber-optical sensors used in the monitoring of cultural relics preservation environment,based on interference principle, two kinds of fiber optic temperature and humidity sensors are designed: 1) based on fiber optic M-Z interference principle, a optical fiber temperature and humidity sensor,with simple structure,is designed and construct,this interferometer presented high sensitivity to RI change,the experimental results showed the RI sensitivity was 155.6 nm/RIU and 163.1 dB/RIU, the relative humidity sensitivity was 1.29 pm%-1 and 0.00542 dB%-1, considering that temperature is also important in cultural relic's conservation environment,the temperature was measured,the temperature sensitivity was 0.0055 nm/?, in order to eliminate the cross sensitivity of the temperature, the decoupling method was used, and realizes the temperature and humidity measurement at the same time.2) based on the optical fiber F-P interference principle in the second chapter the paper, the humidity-sensitive material PI was combined with optical fiber, a new high sensitivity F-P interferometer was designed, this interferometer presented high sensitivity to temperature and humidity change. In order to eliminate the cross sensitivity of the temperature,a fiber Bragg grating (FBG) was cascaded, the temperature and humidity measurement at the same time realized. The experimental results showed the RI sensitivity was 986.25 pm%-1 within the scope of the humidity of 35% to 65%, temperature sensitivity was 190.7 pm/C at 0? to 50? temperature range. FBG have no response for the humidity, temperature sensitivity was 10.21 pm/?.