The period of the Omer is one associated with mourning, as the period has been considered for hundreds of years, especially in connection with the death of the student of Rabbi Akiva.
However, this period of Sefirat HaOmer, the counting of the Omer, is not supposed to be sad – it is the opposite. It is supposed to be a transformation from our leaving of Egypt on Pesach to the receiving of the Torah on Shavuot.
In our generation, we have seen how the Omer has returned somewhat to its true nature with Yom HaAtzmaut and Yom Yerushalayim.