Steering and splitting light with light
In this paper we give a simple method to amplify and steer a beam of
light inside a laser and to split it
into two separate copies by using light itself. The method consists in
feeding a small
fraction of the beam back into the laser at a slightly shifted position.
This type of feedback
can be easily implemented and is conceptually similar to feedback with
temporal delay
which occurs not only in different fields of physics but also in biology
and engineering. The
signal split shown in the picture is rather surprising, as it is not
produced by an external
optical element and shows more symmetry between left and right than the
device itself (in
which the feedback removes the symmetry between left and right).
Interestingly from the
standpoint of applications, we show that these properties are robust
with respect to noise.
The reported features make the spatially shifted feedback an appealing
tool for applications
such as optical beam routing and multiplexing.
***
LV11028
For Solutions, Size Doesn't Matter.
Our recent work shows that even particles in suspension, if they have
the right properties, can act like dissolved molecules. Everybody knows
that you can dissolve sugar in water, and if you cool the solution,
sugar crystals will precipitate out; heat it back up, and the sugar will
redissolve. Everybody also knows that you can shake a suspension of fine
particles in water and they will remain suspended for a while, but
regardless of temperature, they will eventually fall out. But how are
suspensions of particles different than solutions of molecules; is it
simply a matter of size? We studied a suspension of nanoparticles, 8 nm
in diameter, and showed that their suspension ability was thermally
reversible like a sugar solution; the suspension was a solution too! Our
nanoparticles are a lot bigger than molecules yet they have many of
their key attributes in that they all have nearly the same size and they
interact with each other weakly.
