Photonic Crystal Cavity Lasers Patterned by a Combination of Holography and Photolithography

Air-bridge-type InGaAsP photonic crystal cavity lasers (PCCLs) have been fabricated by employing a combined lithographic technique of laser holography (LH) and photolithography. Cavities of 4-5 mum in diameter were formed photolithographically on a square-lattice photonic crystal background pattern which was predefined by the LH process. Despite structural imperfections originated from the inevitable pattern misalignment during the combination lithography, 40% or higher of the PCCLs lased. Removal of modal degeneracy due to symmetry breaking, which was confirmed by computer simulations, provided a rationale on this rather unexpected result: the structurally imperfect PCCLs (as defined by our combination lithography) might compete with the so-called perfect PCCLs (as defined by, say, the electron-beam lithography) in terms of cavity Q-factor