## 3 Results and Discussion
According to [48] and taking into account [29], for positive angles of incidence, the transverse photocurrent amplitude in the CuSe/Se film structure for elliptical beam polarization can be represented as follows:  
Figure 1:3  
where \(A_{\rm cir}\) and \(A_{\rm lin}\) are the positive coefficients of the circular and linear photocurrents at a given \(\alpha\), respectively. Taking into account Equation (18) and in accordance with the results of [37], the waveforms of the transverse photovoltaic pulses \(U_{y}(t,\alpha)\) can be written as follows:  
Figure 1:4  
Figure 1:5 The angle \(\psi\) of the semi-major axis \(a\) of the refracted beam polarization ellipse relative to the plane of incidence \(\alpha\), as well as the degrees of circular \(P_{\rm cir}\) and linear \(P_{\rm lin}\) polarizations of the refracted beam (insets) as a function of the angle of incidence \(\alpha\) for (**a**) circularly and (**b**) linearly polarized (\(\Phi=-45^{\circ}\)) radiation incident on a thin CuSe/\(t\)-Se film (points are calculated values of \(\psi\), \(P_{\rm cir}\) and \(P_{\rm lin}\) for angles \(\alpha\), for which photovoltage pulses were recorded, curves denote smoothing functions). The graphical insets show the corresponding calculated polarization ellipses of the refracted beam at \(\alpha=64.5^{\circ}\) in the \(x^{\prime\prime}y\) coordinate system, where the \(x^{\prime\prime}\) axis lies in the refraction plane coinciding with the plane of incidence \(\alpha\) and is perpendicular to the wave vector of the refracted beam. where \(B_{\rm{Gir}}(\alpha)\), \(B_{\rm{lin}}(\alpha)\) are positive coefficients (for positive \(\alpha\)) depending on \(\alpha\) and characterizing the circular and linear contributions, respectively, and \(f_{\rm{Gir}}(t)\) and \(f_{\rm{lin}}(t)\) are the transverse photovoltage waveforms normalized to the maximum values, recorded at angles \(\alpha\) close to zero for circular and linear polarizations, respectively. Equation (19) allows one to approximate the waveforms of the photovoltage pulses, recorded at different \(\alpha\), with two unknown parameters \(B_{\rm{Gir}}(\alpha)\) and \(B_{\rm{lin}}(\alpha)\). For example, Figure 7 shows the approximations of the waveforms for four of the recorded pulses at different \(\alpha\). It can be seen that the obtained approximating curves satisfactorily describe the experiment. It should be noted that if the waveforms \(f_{\rm{Gir}}(t)\) and \(f_{\rm{lin}}(t)\) coincide with each other, the generation of bipolar pulses is impossible, and the duration of unipolar pulses of the resulting photocurrent, defined by Equation (19), does not depend on the angle of incidence. Figure 8 shows the dependences of the calculated coefficients \(B_{\rm{Gir}}\) and \(B_{\rm{lin}}\) on \(\alpha\). It follows from the figure that both coefficients \(B_{\rm{Gir}}\) and \(B_{\rm{lin}}\) approach zero at small and also at grazing angles of incidence. However, the dependences of \(B_{\rm{Gir}}\) and \(B_{\rm{lin}}\) on \(\alpha\) differ significantly from each other. It can be seen that the dependences of \(B_{\rm{Gir}}\) and \(B_{\rm{lin}}\) acquire their extreme values at \(\alpha=54^{\circ}\) and \(\alpha=62^{\circ}\), respectively. The coefficient \(B_{\rm{lin}}\) prevails over \(B_{\rm{Gir}}\) for the entire range of the incident angle change and the ratio \(B_{\rm{lin}}/B_{\rm{Gir}}\) increases monotonically with increasing \(\alpha\). It follows from Figure 6b that with linear polarization (\(\Phi=-45^{\circ}\)) of the incident beam, the refracted beam becomes elliptically polarized at a negative polarization sign (\(\gamma=-1\)). This means that both terms on the right side of Equation (19) remain negative for any positive angle of incidence. In addition, when changing \(\alpha\) in the range of \(0-85^{\circ}\), the parameters \(P_{\rm{Gir}}\) and \(P_{\rm{lin}}\) of the refracted beam do not change significantly.