Researchers develop glass-in-glass fabrication approach for making
miniature IR optics
New technique can create complex 3D optics for infrared spectroscopy,
sensing and more
Date:
April 7, 2022
Source:
Optica
Summary:
Researchers have developed a new fabrication process that allows
infrared (IR) glass to be combined with another glass and formed
into complex miniature shapes. The new technique can be used
to create virtually any interconnected 3D shape with features
measuring a micron or less. The technique can be used to create
complex infrared optics that could make IR imaging and sensing
more broadly accessible.
FULL STORY ========================================================================== Researchers have developed a new fabrication process that allows infrared
(IR) glass to be combined with another glass and formed into complex
miniature shapes. The technique can be used to create complex infrared
optics that could make IR imaging and sensing more broadly accessible.
========================================================================== "Glass that transmits IR wavelengths is essential for many applications, including spectroscopy techniques used to identify various materials
and substances," said research team leader Yves Bellouard from Ecole Polytechnique Fe'de'rale de Lausanne (EPFL) in Switzerland. "However,
infrared glasses are difficult to manufacture, fragile and degrade
easily in the presence of moisture." In the Optica Publishing Group
journal Optics Express, the researchers describe their new technique,
which can be used to embed fragile IR glasses inside a durable silica
matrix. The process can be used to create virtually any interconnected
3D shape with features measuring a micron or less. It works with a wide
variety of glasses, offering a new way to fine-tune the properties of
3D optics with subtle combinations of glass.
"Our technique could open the door to a whole new range of new optical
devices because it can be used to make infrared optical circuits and arbitrarily shaped IR micro-optics that were not previously possible
because of the poor manufacturability of IR glass," said Enrico Casamenti, first author of the paper. "These optics could be used, for example,
for spectroscopy and sensing applications or to create an IR camera
small enough to integrate into a smartphone." Merging materials The
new fabrication process grew out of previous work in which Bellouard's
research team collaborated with the team of Andreas Mortensen, also at
EPFL, to develop a method for forming highly conductive metals inside
an insulating 3D silica substrate.
==========================================================================
"Our team began seeking innovative ways to achieve broadband
light confinement in arbitrarily shaped 3D optical circuits," said
Bellouard. "That's when we decided to explore the possibility of modifying
a process that we first demonstrated using metal so that it could be
used to produce structures that combine two types of glass." For the
new approach, the researchers start by creating an arbitrarily shaped 3D
cavity inside a fused silica glass substrate using femtosecond laser-
assisted chemical etching. This uses the pulsed beam of a femtosecond
laser - - which can be focused to a spot roughly one micrometer wide --
to alter the glass structure in a way that allows the exposed areas to
be removed with a chemical such as hydrofluoric acid.
Once this is done, the tiny cavity must be filled with another material to create a composite structure. The researchers accomplished this by using
a miniaturized version of pressure-assisted casting, in which a second
material is melted and pressurizing so that it can flow and solidify
within the network of carved silica cavities. The second material can
be a metal, glass or any material with a melting point below that of
the carved silica substrate and that does not react with silica glass.
Creating complex optics "Our fabrication method can be used to protect IR glass, opening new avenues for micro-scale infrared optical circuits that
are fully integrated in another glass substrate," said Bellouard. "Also, because fused silica and chalcogenide offer high refractive-index
contrast, we can form these materials into IR waveguides that can transmit light much like optical fibers." The researchers demonstrated the new
method by creating various complex shapes, including an EPFL logo, using chalcogenide IR glass and a silica glass substrate. They also showed,
with the help of colleagues at ETH Zurich, that some of the structures
they created could effectively be used for guiding mid- IR light emitted
from a quantum cascade laser at 8 microns. Few optical components are
available for this spectral range because of manufacturing challenges.
They are continuing to explore the capabilities of the new process in
terms of combining different glasses and plan to test the composite
parts in spectroscopy and other applications.
========================================================================== Story Source: Materials provided by Optica. Note: Content may be edited
for style and length.
========================================================================== Journal Reference:
1. Enrico Casamenti, Go"zden Torun, Luciano Borasi, Maxime
Lautenbacher,
Mathieu Bertrand, Je'ro^me Faist, Andreas Mortensen, Yves Bellouard.
Glass-in-glass infiltration for 3D micro-optical composite
components.
Optics Express, 2022; 30 (8): 13603 DOI: 10.1364/OE.451026 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/04/220407121559.htm
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