  As the demand for higher data throughput in coherent optical communication
systems increases, we need to find ways to increase capacity in existing and
future optical communication links. To address the demand for higher spectral
efficiencies, we apply end-to-end optimization for joint geometric and
probabilistic constellation shaping in the presence of Wiener phase noise and
carrier phase estimation. Our approach follows state-of-the-art bitwise
auto-encoders, which require a differentiable implementation of all operations
between transmitter and receiver, including the DSP algorithms. In this work,
we show how to modify the ubiquitous blind phase search (BPS) algorithm, a
popular carrier phase estimation algorithm, to make it differentiable and
include it in the end-to-end constellation shaping. By leveraging joint
geometric and probabilistic constellation shaping, we are able to obtain a
robust and pilot-free modulation scheme improving the performance of 64-ary
communication systems by at least 0.1bit/symbol compared to square QAM
constellations with neural demappers and by 0.05 bit/symbol compared to
previously presented approaches applying only geometric constellation shaping.
