Education of the republic of uzbekistan tashkent state technical university named after islam karimov

Electrical and Computer Engineering
203 
which leads to a difference in phase shifts δ (or ellipticity angles ψ) at the same magnitude of 
deformation. 
It is quite obvious that the maximum slope of the dependence ψ (F) is carried out when the 
direction of action of the deformation and the axes of the ellipse of the fiber core coincide. 
According to the measurements, the value of dδ(F) /DF = 0.57 rad / N, which is not bad (in 
order of magnitude) agrees with the data of work [3], where measurements of phase shifts δ(F) 
were carried out at significantly large values of uniaxial transverse deformations, moreover, the 
data of our measurements confirm the conclusion of work [3,4] on the correspondence of the 
measurement results δ(F) for fiber optical fibers with a protective plastic shell, the 
measurement results δ(F) in fibers, without a protective coating. 
Fig
. 1. Dependence of the ellipticity angle Ψ on the load value F at uniaxial transverse 
deformation of a fiber fiber with a length of 32 mm 
It is appropriate to note that the results shown in Fig.1 were obtained with multiple 
measurements of the value of ψ depending on the force F, both in the process of increasing the 
load and decreasing it. This figure also shows that the obtained experimental dependence ψ (F) 
is consistent with the theoretical one in the range of small loads. Note that in these 
measurements, the azimuth of the plane of polarization of the light radiation entering the fiber 
fiber with the preservation of polarization coincided with the azimuth of one of the proper axes 
of the fiber. 
Figure 2 shows the dependence of the phase shift δ on the load F [5] applied in the longitudinal 
direction, i.e. responsible for stretching the fiber. 
Fig
. 2. Dependence of the ellipticity angle Ψ on the load F in the longitudinal direction 
The measurements were carried out for two types of fibers (with different λc), moreover, 
the azimuth of the plane of polarization of light radiation in one case coincided with the 
azimuth of one of the axes of the fiber with the preservation of polarization, in the other case it 
formed an angle of 45 ° with it. It is clearly seen that these dependencies are linear in the 
specified load range (up to 1 N), but for a fiber with a "cut-off" wavelength of λc ≈ 0.6 
microns, the dependence δ(F) is more gentle than for a fiber with λc > 0.6 microns [5]. 

---