Compact, low cross-talk CWDM demultiplexer using photonic crystal superprism

This paper addresses the problem of a photonic crystal (PhC) superprism design for coarse wavelength division multiplexing (CWDM) application. The proposed solution consists in using a PhC structure that presents an efficient balance between the wavelength dispersion and the beam divergence. It is shown that a bidimensional rhombohedral lattice PhC displays both a high beam collimation and an important wavelength dependant angular dispersion. We report the design, fabrication and experimental demonstration of a 4-channel optical demultiplexer with a spectral spacing of 25 nm and a cross-talk level of better than -16 dB using a 2800 microm(2) PhC region. The minimum of insertion losses of the demultiplexer is less than 2 dB. The obtained results present an important milestone toward PhC devices for practical applications.