Bragg gratings with ultrastrong cladding modes are inscribed in a standard telecom optical fiber (i.e., SMF-28) using the phase mask technique and an infrared femtosecond laser. 1000°C-resistant fiber Bragg gratings (FBGs) whose cladding modes exceed 30 dB in transmission and spectrally span more than 250 nm can be produced with only a few (i.e., less than five) laser pulses, provided that the light intensity in the fiber core is kept at the level of ${\sim}{6} \times {{10}^{13}}\;{\rm W}/{{\rm cm}^2}$. The use of FBGs fabricated under the above conditions for refractometry is demonstrated.

中文翻译：

---

使用相位掩膜技术和红外飞秒激光写入的具有超强包层模式的高温稳定光纤布拉格光栅

使用相位掩膜技术和红外飞秒激光，将具有超强包层模式的布拉格光栅刻在标准电信光纤（即SMF-28）中。如果包层中的光强度只有几个（即少于五个）激光脉冲，则可以产生包层模式在传输中超过30 dB且光谱跨度超过250 nm的耐1000°C光纤布拉格光栅（FBG）。光纤纤芯保持在$ {\ sim} {6} \ times {{10} ^ {13}} \; {{rm W} / {{\ rm cm} ^ 2} $的级别。证明了在上述条件下制造的FBG在折射仪中的使用。