Will something like this do
If so
First I created a new layer and then setup the guides as shown and used the Pen Tool to draw the shape
Then right click and select make selection
CTRL J to copy this to a new layer, go to the Gradient Tool and setup the Gradient
With the Gradient setup, CTRL click on the new layer thumbnail to activate the selection, select the Gradient Tool and draw a gradient from the just outside the middle point left to the right holding down the shift key as you do
You may have to play around with this to get the desired effect, once you're happy you can then CTRL J the new layer and select the move tool and move it to the right and then just CTRL J again and do the same again