Confined band gap in an air-bridge type of two-dimensional AlGaAs photoniccrystal

The transmittance spectrum for an air-bridge type of AlGaAs photonic crysta l (PC) slabs successfully fabricated was measured. It is found that the obs erved spectrum is consistent with both the theoretical band structure and t he calculated one. Moreover, the transmittance due to the modes below the l ight line is found to be almost 100%, indicating that the guided modes shou ld exist. The respective stop bands are observed in the Gamma -M direction for TM-like and TE-like modes, implying that a photonic band gap should exi st for the TE-like guided modes. The present PC is very suited for controll ing the radiation field.