This paper presents 3D Fabry–Prot (FP) cavities fabricated directly onto cleaved ends of low-loss optical fibers by a two-photon polymerization (2PP) process. This fabrication technique is quick, simple, and inexpensive compared to planar microfabrication processes, which enables rapid prototyping and the ability to adapt to new requirements. These devices also utilize true 3D design freedom, facilitating the realization of microscale optical elements with challenging geometries. Three different device types were fabricated and evaluated: an unreleased single-cavity device, a released dual-cavity device, and a released hemispherical mirror dual-cavity device. Each iteration improved the quality of the FP cavity’s reflection spectrum. The unreleased device demonstrated an extinction ratio around 1.90, the released device achieved 61, and the hemispherical device achieved 253, providing a strong signal to observe changes in the free spectral range of the device’s reflection response. The reflectance of the photopolymer was also estimated to be between 0.2 and 0.3 over the spectrum of interest. The dual-cavity devices include both an open cavity, which can interact with an interstitial medium, and a second solid cavity, which provides a static reference reflection. The hemispherical dual-cavity device further improves the quality of the reflection signal with a more consistent resonance, and reduced sensitivity to misalignment. These advanced features, which are very challenging to realize with traditional planar microfabrication techniques, are fabricated in a single patterning step. The usability of these FP cavities as thermal radiation sensors with excellent linear response and sensitivity over a broad range of temperature is reported. The 3D structuring capability the 2PP process has enabled the creation of a suspended FP heat sensor that exhibited linear response over the temperature range of 20 C –120 C; temperature sensitivity of ∼50 pm C⁻¹ at around 1550 nm wavelength; and sensitivity improvement of better than 9x of the solidly-mounted sensors.

本文介绍了通过双光子聚合（2PP）工艺直接在低损耗光纤的切割端上制造的3D Fabry-Prot（FP）腔。与平面微制造工艺相比，该制造技术快速，简单且便宜，从而能够快速制作原型并具有适应新要求的能力。这些设备还利用了真正的3D设计自由度，有助于实现具有挑战性几何形状的微型光学元件。制作并评估了三种不同的设备类型：未发布的单腔设备，已发布的双腔设备和已发布的半球镜双腔设备。每次迭代都提高了FP腔反射光谱的质量。未发布的设备显示出约1.90的消光比，发布的设备达到了61，半球形设备达到了253，提供了一个强大的信号来观察设备反射响应的自由光谱范围内的变化。在感兴趣的光谱上，光敏聚合物的反射率也估计在0.2和0.3之间。双腔装置既包括可与间隙介质相互作用的开放腔，又包括提供静态参考反射的第二固态腔。半球形双腔器件进一步改善了反射信号的质量，具有更一致的谐振，并降低了对未对准的敏感度。这些先进的特征是用传统的平面微细加工技术来实现的，这是非常具有挑战性的，它们是在单个图案化步骤中制造的。据报道，这些FP腔可用作热辐射传感器，在广泛的温度范围内具有出色的线性响应和灵敏度。2PP工艺的3D结构能力使得能够创建悬浮式FP热传感器，该传感器在20 C – 120 C的温度范围内表现出线性响应；温度敏感度约为50 pm C在大约1550 nm波长处为^-1 ; 灵敏度提高了超过固定式传感器的9倍。