Internal Spatial Modes of One Dimensional Photonic Band Gap Devices Imaged with Near- eld Scanning Optical Microscopy

Scotland, United Kingdom Photonic band gap (PBG) devices have been used to improve optoelectronic device performance through modi cation of spontaneous emission, and are currently of much interest due to the control of the photonic state which incorporated defects can provide. The concept of defect localized photon states has led to the design of structures that guide light on the nanometer scale. Neareld scanning optical microscopy (NSOM) can image the optical emission and absorption properties of materials and devices at resolutions typically < =10. Neareld imaging relies on maintaining near-surface scanning and is thus ideally suited to collect evanescent optical elds which do not propagate into the fareld, and cannot be measured by conventional microscopy. The devices studied were Al x Ga1 xAs waveguides with microcavities de ned by air gaps patterned using e-beam lithography. A slightly tapered single mode ber was used to launch a tunable Ti:Sapphire laser into the waveguide as shown in gure 1. Optical elds present at the surface of the device were detected in collection mode NSOM with an Al-coated single mode ber tapered to an aperture of 0:1 m. During scanning, the NSOM probe