46
1 Resonance Methods for Increasing Sensitivity of Interferometry …
which, according to the studies stated in the previous paragraph, is not formed under
the path difference more than 2 mm. The observed effect seems to be explained by
the rotation of the polarization plane of a weak wave in the field of a strong wave
that is provided by birefringence induced by a strong wave.
Such effects were studied by several authors [96–103]. So, in particular, induced
ellipse rotation of polarization seemed to be observed for the first time in the
work [96]. The effect of light beam self-action under distribution through resonance medium was studied by the authors of another work [102]. In one of the latest
works [97], polarization twisting of weak waves in the field of strong monochromatic
radiation was investigated.
In our case, unlike the work [97], polarization twisting of weak wave in the field of
strong wave of the same frequency was observed. This effect is referred to nonlinear
optics and can be described phenomenologically if we make an assumption about
the dependence of dielectric medium permeability ε (in the region of resonance
absorption line) on the amplitude of an electric field of light wave
E. In quadratic on
E approximation for tensor component, we have
ε ik = ε
0
ik + γ iklm E
∗
l E m ,
(1.36)
where ε
0
ik is the non-perturbed value of tensor components of dielectric constant (for
gas ε
0
ik = ε
0
δ ik , where δ ik is the Kronecker delta), and γ iklm is the tensor components
of fourth-rank tensor describing nonlinearity.
For reasons of symmetry, it is possible to show that this tensor has nonzero components of only three types γ xxxx , γ xxyy , γ xyxy , and γ xxyy = γ xxxx − γ xyxy . Then denoting
as in the work [104] γ xxyy =
1
2
B, γ xyxy = A and γ xxxx = A +
1
2
B, we will rewrite
(1.36) in the final form:
ε ik =
ε
0
+
1
2
B
E
∗
n E
δ ik + AE
∗
i E k
(1.37)
In the conducted experiment two beams, namely high-intensity and low-intensity
beams are used. For simplicity, we are going to assume that displaying nonlinear
medium properties is provided only by high-intensity beam. Also, we are going to
examine the fact how the change of ε caused by this beam influences the conditions of
passing low-intensity beam. When choosing the direction of propagation of powerful
beam along z-axis, then
E
(M)
=
E
(M)
x ,
E
(M)
y , 0
.
As the angle between the directions of low-intensity and powerful-intensity beams
is low (ϕ ≈ 10
−3 rad.), it is possible to approximately assume that weak beam also
propagates along z-axis:
E
(C)
=
E
(C)
x ,
E
(C)
y , 0
.
1 Resonance Methods for Increasing Sensitivity of Interferometry …
which, according to the studies stated in the previous paragraph, is not formed under
the path difference more than 2 mm. The observed effect seems to be explained by
the rotation of the polarization plane of a weak wave in the field of a strong wave
that is provided by birefringence induced by a strong wave.
Such effects were studied by several authors [96–103]. So, in particular, induced
ellipse rotation of polarization seemed to be observed for the first time in the
work [96]. The effect of light beam self-action under distribution through resonance medium was studied by the authors of another work [102]. In one of the latest
works [97], polarization twisting of weak waves in the field of strong monochromatic
radiation was investigated.
In our case, unlike the work [97], polarization twisting of weak wave in the field of
strong wave of the same frequency was observed. This effect is referred to nonlinear
optics and can be described phenomenologically if we make an assumption about
the dependence of dielectric medium permeability ε (in the region of resonance
absorption line) on the amplitude of an electric field of light wave
E. In quadratic on
E approximation for tensor component, we have
ε ik = ε
0
ik + γ iklm E
∗
l E m ,
(1.36)
where ε
0
ik is the non-perturbed value of tensor components of dielectric constant (for
gas ε
0
ik = ε
0
δ ik , where δ ik is the Kronecker delta), and γ iklm is the tensor components
of fourth-rank tensor describing nonlinearity.
For reasons of symmetry, it is possible to show that this tensor has nonzero components of only three types γ xxxx , γ xxyy , γ xyxy , and γ xxyy = γ xxxx − γ xyxy . Then denoting
as in the work [104] γ xxyy =
1
2
B, γ xyxy = A and γ xxxx = A +
1
2
B, we will rewrite
(1.36) in the final form:
ε ik =
ε
0
+
1
2
B
E
∗
n E
δ ik + AE
∗
i E k
(1.37)
In the conducted experiment two beams, namely high-intensity and low-intensity
beams are used. For simplicity, we are going to assume that displaying nonlinear
medium properties is provided only by high-intensity beam. Also, we are going to
examine the fact how the change of ε caused by this beam influences the conditions of
passing low-intensity beam. When choosing the direction of propagation of powerful
beam along z-axis, then
E
(M)
=
E
(M)
x ,
E
(M)
y , 0
.
As the angle between the directions of low-intensity and powerful-intensity beams
is low (ϕ ≈ 10
−3 rad.), it is possible to approximately assume that weak beam also
propagates along z-axis:
E
(C)
=
E
(C)
x ,
E
(C)
y , 0
.