  Due to its exceptional dimensional stability in harsh thermal conditions and
excellent mechanical and optical properties, Corning ultra-low expansion (ULE)
glass is the material of choice in many high-demanding fields such as
aerospace, astronomy, and advanced optics. This material has recently attracted
renewed attention with the advent of femtosecond laser technology, with a
particular focus on the interaction of ultrafast pulses and the material
itself. Phenomena like the formation of self-assembled nanogratings and their
thermal stability as well as the darkening of laser-affected zones have then
been characterized. This paper presents how to exploit femtosecond selective
laser etching (SLE) techniques to manufacture truly three-dimensional (3D)
components. To demonstrate the micron-scale accuracy and repeatability of this
process from the mm- to the cm-size range, various devices are designed and
fabricated: fiber hole arrays with different hole densities, sizes,
orientations, and shapes; and fiber V-groove arrays. Additionally, a mechanical
flexural fiber mount is presented as an example of how multiple functionalities
can be monolithically integrated into a single piece of glass through SLE
technology. An example of a passive alignment substrate for optical components
is also shown. SLE technique represents a new advancement in the field of
microscale manufacturing, enabling the scalable production of custom-designed
ULE glass structures with unprecedented precision and complexity, paving the
way for the miniaturized integration of highly stable components.
