(wave plate, retardation plate or phase shifter) is made
from material which exhibit birefringence, the most common
waveplate material is crystal quartz. The velocities of
the extraordinary and ordinary rays through the birefringent
materials vary inversely with their refractive indices.
The difference in velocities gives rise to a phase difference
when the two beams recombine. In the case of an incident
linearly polarized beam this is given by a=2 *d(ne-no)/
(a-phase difference; d-thickness of waveplate; ne,no-refractive
indices of extraordinary and ordinary rays respectively;
-wavelength). At any specific wavelength the phase difference
is governed by the thickness of the retarder.
The thickness of a half waveplate is such that the
phase difference is 1/2-wavelength (true-zero order)
or some multiple of 1/2-wavelength [(2n+1)l/2multiple
A linearly polarized beam incident on a half waveplate
emerges as a linearly polarized beam but rotates
such that its angle to the optical axis is twice
that of the incident beam. Therefore, half waveplates
can be used as continuously adjustable polarization
rotators. Half waveplates are used in rotating the
plane of polarization, electro-optic modulation
and as a variable ratio beamsplitter when used in
conjunction with a polarization cube.
The thickness of the quarter waveplate is such that
the phase difference is 1/4 wavelength (l/4,true-zero
order) or some multiple of 1/4 wavelength [(2n+1)l/2,multiple
If the angle q (between the electric field vector
of the incident linearly polarized beam and the
retarder principal plane) of the quarter waveplate
is 45, the emergent beam is circularly polarized.
When a quarter waveplate is double passed, i.e.
by mirror reflection, it acts as a half waveplate
and rotates the plane of polarization to a certain
angle. Quarter waveplates are used in creating circular
polarization from linear or linear polarization
from circular, ellipsometry, optical pumping, suppressing
unwanted reflection and optical isolation.
are much better than the multi-order waveplate because
of its thinner thickness (less than 0.5mm). Better
temperature (380C), wavelength (1.5nm) and incident
angle (4.50) bandwidth and high damage threshold
make it widely used in common application. Also,
it is economical.
|Zero order waveplate
||It is constructed
of two multi-order waveplates with their axis crossed.
Thus, it performs as a zero-order waveplate because
of the effect of two plates counteracting each other.
It has wide temperature bandwidth and wavelength
bandwidth properties. Because it is cemented, the
damage threshold must be considered (about 10MW/cm2)
is as good as cemented zero order waveplate. Additionally,
the air spaced construction enables it is suitable
for the high power laser application. The damage
threshold is more than 500MW/cm2.
|True Zero order Waveplate
||The true zero
order waveplate means that the thickness of waveplate
is very thin (less than 0.1mm) which make the true
zero-order waveplate excellent in temperature, wavelength
and incident angle (about 20deg.) bandwidth. Therefore,
it is excellent choice for the highly accurate application.
It is cemented with a block of glass which is limited
to low and medium power application.
||In order to enable
the waveplate suitible for high damage threshold
(more than 1GW/cm2) application: Simphoton provides
a single plate of true zero-order waveplate
*The thickness of this waveplate
means handling can be difficult, we can provide
mounts upon request.
is similar to Zero-order waveplate except that the
two plates are made from different materials, such
as crystal quartz and magnesium fluoride. Since
the dispersion of the birefringence can be different
for the two materials, it is possible to specify
the retardation values at a wavelength range. Hence,
the retardation of the resulting waveplate can be
made to low sensitivity to wavelength change.
||In fact, it is
a low order or multi-order waveplate, but which
is suitable for two different wavelengths with different
retardation. The dual-wavelength waveplate is often
applied in laser harmonic generation.
plane of linearly polarized light will be rotated
by crystal quartz.
waveplate is available.
Metal ring mount
and AR coating is available upon request.
Contact us now for a quotation!