The photo diode in the figure below has an active sensing area of $10 \;mm^2,$ a sensitivity of $0.5\;A/W$ and a dark current of $1\; \mu A$. The $i-to-v$ converter has a sensitivity of $100\;mV/\mu A$. For an input light intensity of $4\;W/m^2,$ the output $V_0$ in $volt$ is $\_\_\_\_\_\_\_\_\_.$
