Introduction
to Waveguides
You can
manufacture single mode waveguides in materials with femtosecond
lasers. At 775 nm, glass is transparent to incident light.
Our micromachining technology uses ultrafast laser pulses
to locally melt the glass via confined multiphoton absorption
and avalanche ionization inside the bulk material. The glass
then resolidifies, changing its physical properties. The result
is an index gradient that acts like a waveguide. A beam of
light propagating along the same path in the glass will be
guided in the same manner as an index-guided fiber guides
light inside it.
Only
ultrafast lasers are capable of producing this effect in transparent
materials. With longer pulse lasers (nanoseconds), the sample
damages before the intensity reaches the threshold at which
guides are formed. The picture below shows the output of a
waveguide made in glass on a far-field screen using a HeNe
laser. The waveguide can be made either single mode or multimode.
The image below is an artist's rendering of the waveguide
concepts described above.
Note:
Color was added to the waveguide for illustrative purposes
only. In reality, scattering losses are extremely low and
the beam is NOT visible while propagating inside the waveguide.
Photo
Gallery
Explore
the possibilities of using ultrafast lasers to manufacture
3D features in the bulk of transparent materials.
All the
images below show samples of linear and 3D features that were
written in our micromachining job shop using the Clark-MXR,
Inc. femtosecond direct write source.
Click
on the individual thumbnails to see larger, higher-resolution
views of the photographs below. Use your browser's "Back"
button to return to this page after viewing the larger images.
Note:
All images were taken with a digital camera and have not been
re-touched.
A small diameter helix and several straight waveguides
|
|
|
Top
view of a small diameter helix written in glass. |
This
is the same sample as the image to the left, taken at
a different angle. At this angle, you can see the straight
waveguides. |
Click
on the images to view them in detail.
Click
on the images to view them in detail.
