封装对长周期光纤光栅的影响

Effect of Package on Properties of Long-period Gratings

对于长周期光栅 ,谐振波长阶数越高 ,封装材料折射率对其特性的影响越大 ;封装材料折射率小于包层时 ,随封装材料折射率增大 ,波长减小 ;封装材料折射率大于包层时 ,波长向长波长移动 1.5nm。研制了一种负热胀系数的材料用于封装光栅 ,使光栅波长的温度系数不大于 5 .1× 10 - 3nm/K。

Theoretical and experimental study on how to pack long period gratings has been made. It is found that index of package material affects the grating resonance peak. Displacement of resonance wavelength decreases when the index is 1< n pk < n cl ; resonance peak completely disappeared when n pk = n cl ; displacement keeps constant at 1.5 nm when n cl < n pk < 1.65 . A novel package material with negative thermal expansion coefficient has been developed, with which the displacement of resonant peak is less than 5.1×10 -3 nm/K between 265 K and 334 K. Different package structures are demonstrated as well.