OPT101: operation of opt101 in single or dual supply- which one is better for small signal?

i am currently using a setup for opt using both single and dual power supply. but when i use it in single power supply i am getting my signal with positive and negative peaks which is unwanted, i only need positive peaks.  but when i use it in dual power supply it removes the negative peaks but it induces ore noise.

so , here i would like to ask which power supply is better for small signal in OPT101???