Best way to index a datetime field

i'm working on an app with the neo4jGraphQL, in its scenario we need to work a lot with datetimes, so we want to index on the fields with the datetime type which are not really unique so we coudnt use @unique ,but what is the best way of indexing a datetime field.
note : i thought that one way is to cast datetimes to integer and use @unique directive, but the problem is that our fields are not really unique and may have repeated datetimes.
is it a good idea to cast datetime to string and use @fulltextindex directive?
is there another better solution?
tnx before your helps...