Paul-Émile Bécat (1885 - 1960) was a French illustrator and painter who studied with Gabriel Ferrier and Francois Flameng and was awarded the prestigious Prix de Rome in 1920. He is most famous for his erotic illustrations for many books between 1934 and 1959, as well as his portraits.
Becat began specializing in erotic art quite late in his career. Before then his focus was mostly on portraits and not-so-erotic literature. The earliest example I can find of one of Becat's erotic prints is from the book Fortuna by Theophile Gautier that was published in 1934 and had several nude engravings by Paul-Émile Bécat. Becat would have been 49 at the time. He had done illustrations for books before but nothing especially erotic as far as I can tell.
A technique often used by Becat was drypoint. Drypoint is a printmaking technique that can produce very soft lines due to the burring it leaves on the copper plates. This combined with the pastel shades are what gives many of Becat's illustrations their gentle feel.
We have a few of examples by Paul-Emile Becat including La Vie des Dames Galantes, a limited edition two volume erotic novel written by Brantôme that was republished in 1948 including a series of 26 hand colored erotic drypoints by Becat. Also, there is Le Florentin, a set of erotic playing cards that was designed by Becat. The eroticism is only present on the royals, aces, and jokers of this set. Le Florentin is a particularly interesting series because, as is traditional with playing cards, the images are reversible so every card in the royal suite has two interpretations depending on which way up you hold them that seamlessly flow into one another.