**2. Fabrication processes**

Here, the fabrication processes are composed of two parts. One is the epitaxial growth on sapphire substrates by metal organic chemical vapour deposition (MOCVD), including a 29 pair distributed Bragg reflectors (DBR), a p-GaN layer, multi-quantum wells, a n-GaN, and a un-doped GaN layer, etc. Another one is to fabricate the PhC nanostructure on the epitaxial wafers by the E-beam lithography system and inductive coupled plasma reactive ion etching (ICP-RIE) system. Finally, the GaN-based photonic crystal surface emitting laser (PCSEL) devices with AlN/GaN DBR are performed.
