Edit: A video dropped on Youtube confirmed my theory. There's no more doubt now !
The Flash became more ambitious for his sophomore year, introducing Earth-Two and the notion of Multiverse. This opened up a bunch of opportunities for the show to toy with.
Thus, the producers teased the possibility of doppelgangers, that confirmed itself with the arrival of Earth-Two Harrison Wells in Central City.
And among the new characters of this second season, one in particular stayed very mysterious now less than one week from his appearance: Dr. Light.
In the comics, Arthur Light was a super villain, a criminal physicist foe of the Justice League. However, The Flash will deal with the most recent version of the character, Kimiyo Hoshi a supervising astronomer in an observatory in Japan. She was during Crisis on Infinite Earths affected by a beam of energy send by the Monitor, granting her photonics powers. She later became a member of the Justice League unlike her predecessor.
So, Dr. Light didn't get a cast announcement until now and after seeing the official photos of next week episode we may now why.
Could Dr. Light be Earth-Two Linda Park ?
All the mystery surrounding Dr. Light really bugged me and I wondered: what if she was an already known character ? That would explains why no announcement has been made about her character. Plus, as I said the release of pictures from the episode is also unequivocal.
In this picture, we can see a Linda Park shocked about something while facing Dr. Light, who is in the left corner. For what reason would she make such a face ? I'm guessing that Kimiyo Hoshi - if that's her name here - is in fact the Earth-Two version of Linda Park. Also, why Dr. Light would have come to the Central City Picture News otherwise ? I don't see another reason for her presence here.
The Flash producers accustomed us to toy with the DC lore in the past and it would provide a good twist on the show. The difference of nationalities between the two characters (Linda is half Korean, Kimiyo is Japanese) is not a big obstacle and they could change her origins a bit.
The Flash season 2 airs Tuesdays on The CW.