Use a design that prevents reflected photons from entrying back into laser.
Also to prevent PSCN and NSCN from melting do not allow these elements to be in contact with the dmnd body.The PCLN can also be toggled from a gap of 1 pixel of empty space i.e It is not necessary for PSCN and NSCN to actually touch pcln in order to activate/deactivate it respectively.