Should I have to include photocoupler in SSR application circuit?
The answer to your question is, "Go find the data sheet for the SSR you are planning on using, and find out". I would expect that the majority of SSRs would have opto-isolators built in. 

Note that some SSRs with optos have resistors in line with the LEDs, some of them don't. If they don't, you'll need to add an appropriate dropping resistor.