A high-sensitivity temperature sensor based on photonic crystal fiber Sagnac interferometer is proposed and studied. All holes of the PCF are filled with ethanol with capillarity. The cladding air holes are uniform arrangements. The two air holes around the core are removed to form new core modes with high birefringence. The sensitivities of the temperature can be up to −8.7657 and 16.8142 nm/
 $$^{\circ }$$
 C when temperature rises from 45 to 75 
 $$^{\circ }$$
 C and the fiber length is 5.05 cm. And when temperature rises from 10 to 45 
 $$^{\circ }$$
 C, the sensitivity can reach −7.848 and 16.655 nm/
 $$^{\circ }$$
 C with fiber length 2.11 cm. The performance of the selective-filled and the fully-filled PCF with temperature from 45 to 75 
 $$^{\circ }$$
 C and fiber length 5.05 cm are analyzed and compared. The fully filling can better achieve PCF’s sensing performance. The simple structure and high sensitivities make the temperature sensor easy to achieve. The temperature sensor with high sensitivities and good linearity has great application value for environmental temperature detecting.

A high-sensitivity temperature sensor based on Sagnac interferometer employing photonic crystal fiber fully filled with ethanol

We propose a highly-sensitive temperature sensor employing a Mach-Zehnder interferometer (MZI) based on silicon-on-insulator (SOI) platform The waveguide widths in the two MZI arms are tailored to have different temperature sensitivities but nearly the same group refractive indices A temperature sensor with an enhanced sensitivity of larger than 438pm/°C is experimentally demonstrated, which is over seven times larger than that of conventional silicon optical temperature sensor (about 60pm/°C for quasi-TM mode) Moreover, the sensor is easy to fabricate, only by a single mask, and no need of any polymer cladding, which makes it more robust, and can be used in lab-on-chip systems as a temperature monitor

Temperature sensor with enhanced sensitivity based on silicon Mach-Zehnder interferometer with waveguide group index engineering.

A temperature sensor based on a fiber ring laser embedded with liquid-filled photonic crystal fiber (PCF) is proposed and experimentally demonstrated High refractive index liquid is infiltrated into an index-guiding PCF to generate band gap-like effect then used as the laser filter and the sensing head simultaneously With the temperature increasing, the emission wavelength of the fiber laser shifts to the shorter wavelength and the output intensity increases due to the band gaps’ movement The temperature sensitivity −1747 nm/°C and 0137 dB/°C are obtained utilizing the wavelength modulation and the intensity modulation, respectively, with high signal-to-noise ratio (~55 dB), narrow 3-dB bandwidth (less than 008 nm) and good stability

Fiber Ring Laser Temperature Sensor Based on Liquid-Filled Photonic Crystal Fiber

A humidity sensor based on Fabry–Perot interferometer (FPI) and intracavity sensing of a fiber ring laser is proposed and experimentally demonstrated. A compact humidity-sensitive fiber-optic FPI is developed and inserted in a fiber ring laser. Because the output power of the fiber laser is modulated by the reflection loss of the FPI at different ambient humidity, intracavity humidity sensing is induced. The experiment shows that the relative output power of the fiber laser has a good linear response to ambient humidity from 25%RH to 95%RH and the humidity sensitivity of 0.202 dB/%RH is obtained with a narrow 3-dB bandwidth and high signal-to-noise ratio. Furthermore, the excellent performance of the sensor for remote humidity detection is demonstrated. The sensor also shows a low temperature cross-sensitivity, fast time response, and good stability. The proposed sensor has a great potential in high-capacity sensor network and remote detections.

Humidity Sensor Based on Fabry–Perot Interferometer and Intracavity Sensing of Fiber Laser

A cost-efficient all fiber temperature sensor based on a Sagnac interferometer is proposed and experimentally demonstrated. The sensor proposed comprises a section of thin core fiber (TCF) in combination with Panda type polarization maintaining fiber (PMF). The key point is that the core of TCF is intentionally aligned to one of two stress areas of Panda type PMF in order to change the mode transmission. Then the prepared TCF-PMF fiber structure is built into a Sagnac loop. A well-defined spectrum is obtained and the fringe contrast reaches up to 28 dB. The dip wavelengths are employed to demonstrate the temperature characteristics. The experimental results show the transmission spectrum blue-shift with the temperature and sensitivity of -1.54 nm/°C is obtained. The proposed sensor has potential application in temperature measurement.

Temperature Sensor Employed TCF-PMF Fiber Structure-Based Sagnac Interferometer

In this letter, a temperature sensor based on a fiber ring laser with a reflective Sagnac loop is proposed. The reflective Sagnac loop inserted into the fiber ring laser through a downlead optical fiber is used as the filter and sensing head to supply high temperature sensitivity. As the temperature varies, the transmission spectrum of Sagnac loop changes, leading to the shift of emission wavelength of a fiber ring laser. We obtain a temperature sensor system with a high temperature sensitivity of 1.739 nm/°C, a narrow 3-dB bandwidth less than 0.05 nm, and a high signal-to-noise ratio $\sim 50$ dB. Moreover, it is convenient to achieve the remote sensing by changing the length of the downlead optical fiber.

Liangcheng Duan

Papers

Temperature Sensor Based on Fiber Ring Laser With Sagnac Loop