The photonic spin Hall effect (PSHE) refers to the splitting of photons with opposite spin angular momentum perpendicular to the plane of incidence when a linear polarization beam passes through a nonhomogeneous medium, which originates from effective spin–orbit interaction of light [1], [2], [3], [4]. The PSHE was theoretically proposed by Onoda et al. in 2004 and then experimentally observed by Hosten et al. in 2008 [5], [6]. Soon after, the PSHE has attracted wide attention and shown potential applications in different research realms, such as precision metrology [7], [8], spin nanophotonic devices [9], [10], optical spatial differentiation [11], biochemical sensing [12], [13], [14], [15], and temperature sensor [16], [17]. Recently, researchers investigated the effect of temperature on the modulation of the PSHE in liquid crystal materials and proposed a highly sensitive temperature sensor. So far, the temperature characteristics of the PSHE have mainly been manipulated by changing the parameters of the structure or material and cannot be actively controlled. Therefore, actively manipulating the PSHE with the help of external means is of great importance in the field of sensing.

Parity-time (PT) symmetry has attracted wide attention as a powerful tool for manipulating light–matter interaction [18], [19], [20]. Exceptional point (EP) is the most interesting aspect of PT symmetric systems [21], [22], [23], [24], which refers to the critical point between the PT-symmetric state and the broken PT-symmetric state. Recently, it has been shown that a large PSHE can occur near the EP in PT-symmetric structures, and the PSHE can be modulated widely by controlling the EP [25], [26]. These methods of manipulating the PSHE via EP require changing the structure’s parameters, which is very complex and inflexible. Fortunately, the presence of graphene is expected to overcome this shortcoming and make the manipulation more flexible. Graphene is a monolayer sheet structure consisting of carbon atoms arranged in a hexagonal honeycomb lattice, which has unique electronic and optical properties in the infrared and terahertz regions [27], [28], and the electronic and optical properties can be flexibly tuned by external temperature and optical pumping [29], [30]. It has shown that the PSHE can be controlled by modulating the optical conductivity of graphene in the graphene-substrate structure, as reported in Ref. [31]. However, the structure leads to the limitation that the PSHE shift is not large enough. Thus, combining PT symmetric structure and graphene is promising to actively manipulate the large PSHE without altering the structure itself

In this paper, we actively manipulate the temperature characteristics of the PSHE in a quasi-PT symmetric structure containing graphene and propose a temperature sensor with tunable sensitivity. First, we discuss the influence of temperature on the PSHE shift with and without optical pumping. Then, we explain the physical mechanism of the giant temperature-dependent PSHE shift by studying the reflection coefficients and eigenvalues. Further, we study the effect of optical pumping power on the temperature characteristics of the PSHE. Finally, we combine weak measurement techniques to amplify the temperature-dependent PSHE shift and propose a temperature sensor with tunable sensitivity.