A long time ago I wanted to implement usb communication with
optocouplers for my uC's projects.
I upload two different designs in eagle files.
One uses H11L1 optocouplers but the design can achieve only up to 83.3 kbps transfer rates.
The second one uses 6N137 optocouplers and I have achieved 1Mbps transfer rates.
The latter was realized using oshpark and you can find it on the following link
I hope it shall be helpful.