To simplify this expression, we can use trigonometric identities.

Let's start by using the Pythagorean identity: sin^2 L + cos^2 L = 1

Rearrange the Pythagorean identity to solve for cos^2 L: cos^2 L = 1 - sin^2 L

Now, we can substitute cos^2 L = 1 - sin^2 L into the expression:

= (2sin^2 L - 1) / (1 - 2(1 - sin^2 L))
= (2sin^2 L - 1) / (1 - 2 + 2sin^2 L)
= (2sin^2 L - 1) / (-1 + 2sin^2 L)
= (1 - 2sin^2 L) / (1 - 2sin^2 L)

Therefore, the simplified expression is (1 - 2sin^2 L) / (1 - 2sin^2 L) or simply 1.