Photonics and Optoelectronics

1-7

Authors: Masatoshi Tsuji, Wataru Inami, Yoshimasa Kawata

We developed a compact and high-power mode-locked fiber laser for multilayered optical memories. The average power and pulse width of the output pulse from the fiber laser that we developed were 109 mW and 2.1 ps, respectively. The dispersion of the output pulse was compensated with an external single-mode fiber of 2.5 m length. The pulse was compressed from 2.1 ps to 93 fs by dispersion compensation. We proposed a fiber confocal microscope as an alignment-free readout system of multilayered optical memories. The fiber confocal microscope does not require fine pinhole position alignment because the fiber core is used as the point light source and the pinhole, and both of which are always located at the conjugated point. The configuration reduces the required accuracy of pinhole position alignment. The fiber confocal microscope can also achieve a compact pickup head. Recording layers in a multilayered medium could be detected with an axial resolution of approximately 900 nm. We demonstrated eight-layer readout with the fiber confocal microscope.

17-23

Authors: Vipin Kumar, B. Suthar, J. V. Malik, Arun Kumar, Kh. S. Singh, T.P. Singh, A. Bhargva

The properties and origin of defect modes in the one dimensional photonic crystal (PC) with a central defect has been studied. Two types of photonic crystals, each having single defect, namely, symmetric and asymmetric PCs are considered. It is found that a defect mode arise at central wavelength for asymmetric PC, whereas two defect modes arise in the vicinity of central wavelength for symmetric PC. These two defect modes can be fixed to a single central defect by increasing the width of the defect layer. But the intensities of these defect modes are found to be different from the intensities of defect modes for asymmetric case. The origin of these defect modes can be explained using impedance matching condition. The propagation characteristics of the proposed structure are analyzed by using the transfer matrix method.