1. Raghu asked for using the optocoupler as a noise suppression, i.e. low pass. (It is amusing, that many people don't read the question and they answer a related but different, albeit more common question).
2. Raghu's useful bandwidth is 6kHz - at 18us worst case rise/fall time this is safely met (at load and V_CE given in datasheet).
3. PC817 has a floating base phototransistor. It has no way to find out, if the load resistor is in its collector or emitter.
4. If posting urls, insert one space after it (test it in preview before posting) befor any closing bracket, fullstop, comma etc. Makes life easier.
5. Get the original PC817 datasheet at http://sharp-world.com/products/...817x_e.pdf . There are nice frequency response graphs in it (read also the comment below them - they are "typical" not "guaranteed"). Beware, this is the original; copies (although
brands) might not meet this datasheet exactly in all parameters. I found out the hard way :-(
7. Repeating myself, optocouplers should not be used for noise supression/filtering.

Jan Waclawek