  We define a unitary phase operator for photons in a single momentum mode. The
operator acts on a Hilbert space with basis consisting of all number states in
both polarizations. The Susskind Glogower operator, ${\hat{E}} = e^{i
\hat{\phi}}$, thus defined is unitary and acts as a true ladder operator over
all the states. It satisfies the commutation relation $[{\hat{E}}, {\hat{n}}] =
{\hat{E}}$; consequently, the phase $\hat{\phi}$ satisfies the canonical
commutation relation $[{\hat{n}}, {\hat{\phi}}] = i$. The eigenstates of the
Susskind Glogower operator are found. Our model is able to directly account for
phase measurements when polarization changes cannot be neglected and at the
same time gives a well defined phase operator.
