## 1 Introduction  
One of the interesting features of the interaction of polarized light [1; 2; 3] with semiconductors and metals is the generation of a polarization-sensitive photocurrent (PSPC) that depends on the polarization of the incident radiation according to harmonic laws [4; 5; 6; 7; 8; 9]. There are longitudinal and transverse PSPCs at the oblique incidence of light on the surface of a material in which the currents flow along and perpendicular to the plane of incidence, respectively [10]. The transverse PSPC can be a combination of circular photocurrents (CPC) and linear photocurrents (LPC). The CPC depends on the direction of rotation of the electric field vector (the sign of circular polarization) of the incident radiation, while the LPC does not [11; 12; 13; 14]. It is of interest to study the laws governing the PSPC in various media in terms of excitation of spin-polarized electrons [15; 16], for the creation and development of optospintronic devices [17], laser polarization analyzers [18; 19; 20], photodiodes with high spatial resolution [21], as well as for photosensors intended for the direct recording of the polarization state of circularly polarized light [22; 23; 24; 25]. The mechanisms of the PSPC generation include the photogalvanic effect (PGE) [26; 27; 28], the circular photogalvanic effect (CPGE) [11; 29; 30; 31; 32; 33; 34], the photon drag effect (PDE) [5; 10; 35; 36; 37; 38], and the surface photogalvanic effect (SFGE) [5; 39; 40]. All of the aforementioned effects are nonlinear optical phenomena. It should be noted that the PDE and SPGE, as well as some other nonlinear optical phenomena [41; 42] can be observed in any media, regardless of the type of symmetry of the medium [35]. The PDE and SPGE photocurrent pulses excited by pulsed laser pumping are usually unipolar (see, for example, [43; 44; 14; 45; 46]). The dependence of CPC and LPC excited in film and 2D structures due to the PDE and SPGE on the beam incidence angle \(\alpha\) is described by an odd function [36; 37; 39; 46; 47; 48]. Therefore, under pulsed laser pumping, the LPC and CPC unipolar pulses change their polarity when the sign of the incidence angle changes. With the simultaneous occurrence of longitudinal PDE and SPGE, due to their interplay, it is possible to generate bipolar PSPC pulses consisting of front and tail parts of opposite polarity, which change their polarities when the sign of the angle of incidence changes [40]. It was shown in our most recent work [48] that, at a given angle of incidence, the interference of the CPC and LPC generated due to the SPGE in a CuSe/Se nanocomposite film also leads to the generation of bipolar photocurrent pulses. The temporal profiles of those pulses strongly depend on the polarization ellipse of the incident femtosecond laser beam. However, despite the large number of articles on the topic of PSPC generation in various film materials (see, for example, [33; 38; 49; 50; 51; 52]), studies of the influence of the incidence angle on the waveforms of photocurrent pulses arising due to the PDE and SPGE (and also CPGE) under pulsed laser pumping have not been carried out yet.  
In this work, using the study of the SPGE in a CuSe/Se semitransparent thin film under femtosecond laser excitation as an example, it is shown for the first time that the waveforms of the PSPC pulses can strongly depend on the angle of incidence. In particular, it has been shown that with circularly polarized pulsed pumping and a fixed sign of the incidence angle, unipolar transverse photocurrent pulses of opposite polarity are generated at small and large angles of incidence, and bipolar pulses are excited in the intermediate range of incident angles, smoothly transforming into unipolar pulses of opposite polarity at the boundaries of this interval. The results obtained are explained by the change in the state of polarization in the refracted beam and by the interference of the LPC and CPC that arises in the subsurface layer of the semiconducting medium under study.