  When quantum fields are coupled to gravitational fields, spontaneous particle
creation may occur similarly to when they are coupled to external
electromagnetic fields. Gravitational fields can be incorporated as background
spacetime if the back-action of matter on it can be neglected, yielding
modified Dirac or Klein-Gordon equations for elementary fermions and bosons
respectively. The semi-classical description predicts particle creation in many
scenarios including expanding universe, near the event horizon of a black hole
(the Hawking effect), and an accelerating observer in flat spacetime (the Unruh
effect). In this work, we give a pedagogical introduction to the Dirac equation
in a general 2D spacetime and show examples of spinor wave packet dynamics in
some background spacetimes. In particular, we cover the phenomenon of particle
creation in a time-dependent metric. Photonic analogs of these effects are then
proposed, where classical light propagating in an array of coupled waveguides
provides a visualisation of the Dirac spinor propagating in curved 2D
spacetime. The extent to which such a single-particle description can be said
to mimic particle creation is discussed.
