辐照环境下掺铒光纤性能下降严重影响了其在空间环境中的应用，而Ce可以凭借其变价能力抑制光纤的辐致损伤效应。利用螯合物气相沉积法制备了不同Ce掺杂量的掺铒光纤，在常温下使用⁶⁰Co辐照源对光纤进行了累积剂量100 krad、剂量率6.17 rad/s的辐照实验。通过吸收损耗谱的测试发现Ce掺杂含量高的光纤在辐照后损耗为419.185 dB/km@1200 nm，且荧光寿命变化量减小了0.578 ms。通过切片芯层透过率及电子顺磁共振测试发现Ce掺杂可以有效降低光纤中Al和Ge相关的色心缺陷数量。最后通过增益测试验证了Ce掺杂对掺铒光纤抗辐照能力的改善，辐照后高Ce掺杂的光纤比未掺杂Ce光纤的增益高出4.15 dB。实验结果表明，Ce掺杂可以有效增强掺铒光纤抗辐照性能，这一结论对掺铒光纤在太空中的应用具有重要意义，该研究结果能够为后续掺铒光纤的耐辐照加固及其在空间中的应用提供参考。

为验证La掺杂对于掺铒光纤抗辐照性能的影响，采用La掺杂光纤与无La掺杂光纤进行光纤辐照实验。使用⁶⁰Co辐照源在常温下对光纤进行累积剂量100 krad，剂量率6.17 rad/s的辐照实验。结果发现，La掺杂光纤在1 200 nm处损耗为0.030 67 dB（km·krad），相比于无La掺杂光纤0.039 53 dB（km·krad）更低，且La掺杂光纤在辐照环境下的增益变化更小。通过光纤吸收谱和EPR谱辐照前后的对比，确定了Al-OHC缺陷为影响光纤辐致损耗的关键因素。La掺杂可以在一定程度上代替Al作为Er离子的分散剂从而增强光纤的抗辐照能力，且La掺杂对光纤的增益性能不会产生负面影响。该研究可为后续特种光纤在空间应用中的抗辐射加固设计提供参考。

We propose and demonstrate an ultrasensitive integrated photonic current sensor that incorporates a silicon-based single-mode-multimode-single-mode waveguide (SMSW) structure. This kind of SMSW structure is placed over a direct current carrying power resistor, which produces Joule’s heat to change the temperature of the SMSW and further results in the change of the effective refractive index between different propagating modes. Interference occurs when the modes recombine at the second single mode waveguide. Finally, the current variation is measured by monitoring the shift in the output spectrum of the multimode interferometer. In low current, the wavelength shift has almost linear dependence: Δλ∝Ic. This effect can be used as a current sensor with a slope efficiency of 4.24 nm/A in the range of 0–200 mA.

In this Letter, we study the characteristics of a selectively buried glass waveguide that is fabricated by the backside masking method. The results show that the surface region appears when the width of the backside mask is larger than 7 mm. Here, the glass substrate is 1.5 mm thick. It is also found that the buried depth evolution of the transition region remains almost unchanged and is independent of the width of the backside mask. The loss of the transition region is only 0.28 dB at the wavelength of 1.55 μm if the surface condition is good enough.