This Sunday is celebrated that Lent is halfway through and Easter is approaching. From the ninth century this Sunday had a festive character. On this day the Pope also gives the Golden Rose. Laetare is named after the first word from the Introit of the proprium of the mass.
Just like on Sunday Gaudete in Advent, old-pink (= a mixture of purple and white) may be used as a liturgical color instead of purple on this Sunday. Father Henri therefore wears an old-pink chasuble.