Pure photonic crystal waveguiding for signal processing at optical junctions

This paper describes a photonic crystal (PhC) waveguide of two-dimensional (2D) photonic bandgap lattice structure. Typically, PhC waveguides demonstrated have line defects of high index material placed in an otherwise periodic lattice structure, which serves to prohibit the propagation of light radiation within; such technique makes use of PhC waveguiding in the lateral axis and index confinement in the vertical axis. Here, pure 2D PhC waveguiding at 1550 nm without index guiding assistance was achieved instead, through successful fabrication of high aspect ratio pillar-type PhC lattices with intersecting orthogonal line defects and tunneling cavities. The experiment results were found to coincide with first principle simulation results of different tunneling cavity dimensions. These optical junctions therefore can be used for effective control of optical signal levels (via the phenomenon of drude absorption) to achieve ultrafast optical switching by means of high power 200 fs laser pulses as control signals.