THE 7 LAYERS OF PHOTONICS 1. Materials & Wafers (substrate layer) $AXT Inc(AXTI)$, $IQE(IQE.UK)$ $Wolfspeed Inc.(WOLF)$, $COHERENT(COHR)$, $Lightwave Logic, Inc.(LWLG)$ 2. Tools (fabrication layer) $ASML Holding NV(ASML)$, $Applied Materials(AMAT)$, $Lam Research(LRCX)$ 3. Lasers (light generation layer)