Let \( PQ \) be a chord of the hyperbola \( \frac{x^2}{4}-\frac{y^2}{b^2}=1 \), perpendicular to the \( x \)-axis such that \( OPQ \) is an equilateral triangle, \( O \) being the centre of the hyperbola. If the eccentricity of the hyperbola is \( \sqrt{3} \), then the area of the triangle \( OPQ \) is:
