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A laser which directly emits Airy beams is demonstrated
experimentally
for the first time. In fact, a method to realize lasers emitting
arbitrary beam
profiles is developed. The demonstrated Airy beam laser is a proof of
principle
of the general method. The basic idea is the use of a reflection
diffraction
grating as the laser output mirror. The grating reflects most of the
light back
into the cavity, as an ordinary mirror, while the remainder is
reflected out of
the cavity via the various diffraction orders. Furthermore, this
grating is
modulated to impose a phase and amplitude onto the diffracted light,
thus
providing it with the same functionality as a phase and amplitude mask,
only
that here the modulating element is the output coupling mirror of the
laser. In
the case of the Airy beam laser, the phase modulation is cubic, thus an
Airy
beam is obtained by performing optical Fourier transform of the
out-coupled
light. This scheme is more compact then the conventional method, which
requires
a phase modulating element outside the laser cavity in addition to a
laser.
Reference
- Gil Porat, Ido Dolev, Omri Barlev, and Ady Arie, Optics Letters 36, 4119-4121 (2011) pdf.
- News and Views, Nature Photonics 5, 715
(2011) pdf.
Written by: Gil Porat
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