The concept of a photon as a wave can be understood in two different ways: the oscillation of its electromagnetic field and the wave function that describes its overall state.
From the perspective of classical electrodynamics, a photon is an oscillation or disturbance in the electromagnetic field. It can be described as a wave of oscillating electric and magnetic fields that propagate through space. In this interpretation, the wave nature of the photon refers to the oscillations of the electric and magnetic fields, which are fundamental components of the electromagnetic wave.
On the other hand, in quantum mechanics, particles like photons are described by wave functions. The wave function is a mathematical function that encodes the probability distribution of finding the particle in different states or locations. The wave function of a photon describes its overall quantum state, including properties such as its energy, momentum, and polarization.
In quantum mechanics, the wave-particle duality suggests that particles, including photons, can exhibit both wave-like and particle-like behavior. The wave function of a photon describes the probabilistic nature of its behavior, allowing predictions to be made about the outcomes of measurements.
So, to summarize, the wave concept of a photon can refer to the oscillating electromagnetic field associated with it in classical electrodynamics, or it can refer to the wave function that describes its quantum state in the framework of quantum mechanics. Both interpretations capture different aspects of the behavior and nature of photons.