基于高频CO2激光脉冲写入的新型超长周期光纤光栅(ULPFG)，提出了一种可实现温度自补偿的新型高灵敏度折射率计。理论与实验表明，新型超长周期光纤光栅不同闪耀阶次谐振峰对外界折射率与温度变化的灵敏度各自不同，特别的是，该光栅存在对外界折变不敏感的谐振峰，测量中除了可以利用该峰实现温度同时测量外，还可以补偿另一个测量折变的谐振峰因温度变化带来的测量误差。该折射率计具有制作简单、成本低、强度好，灵敏度高等优点，当外界折射率在1.43～1.45范围内变化时，其折射率测量灵敏度可达每单位折射率240 nm，在实际工业应用中具有较大的潜在实用价值。

Based on the novel ultra-long-period fiber grating (ULPFG) written by the high-frequency CO2 laser pulses, a new high-sensitivity refractive index sensor with temperature self-compensating is proposed. The theoretical and experimental results show that different shining order resonant peaks of the ULPFG have different temperature and refractive index sensitivities. Especially, it is found that there appears one resonant peak of ULPFG insensitive to the refractive index, which offers the potential application for simultaneous temperature measurement and can compensate the measurement errors induced by temperature change when other resonant peaks are measured. This refractive index sensor is simple, with a low cost, good strength and high sensitivity, when the surrounding refractive index varies in the range of 1.43～1.45, the refractive index measurement has a sensitivity of 240 nm/per unit refractive index, which has great potentials in industry applications.