Waveguides, bends and Y-junctions with improved transmission and bandwidth in hexagon-type SOI photonic crystal slabs

This paper presents novel ways of implementing waveguide components in photonic crystal slabs based on silicon-on-insulator (SOI). The integration platform we consider consists of hexa¬gonal holes arranged in a triangular lattice (‘hexagon-type’ photonic crystal). The waveguides are made of one missing row of holes (W1) with triangular air inclusions symmetrically added on each side of the waveguide. \ud Size and position of these inclusions are tuning parameters for the band diagram and can be used for minimizing the distributed Bragg reflection (DBR) effect. The waveguides show single-mode behavior with reasonably high group velocity and large transmission window, inside the gap between H-like modes**. These waveguides, closely resembling conventional ridge waveguides, can be combined to form efficient bends and Y-junctions. The bends and Y-junctions include intermediate short waveguide sections at half the bend angle playing the role of corner ‘mirrors’. Qualitative design rules were obtained from 2D calculations based on effective index approximation.\u

Reconfigurable optical add-drop multiplexer using microring resonators

We report a reconfigurable four-channel optical add-drop multiplexer for use in access networks. The optical add-drop multiplexer (OADM) is based on vertically coupled thermally tunable Si/sub 3/N/sub 4/--SiO/sub 2/ microring resonators (MRs) and has been realized on a footprint of 0.25 mm/sup 2/. Individual MRs in the OADM can be tuned across the full free-spectral range of 4.18 nm and have a 3-dB bandwidth of 50 GHz

Fast prototyping of planar photonic crystal components using a combination of optical lithography and focused ion beam etching

A combination of conventional optical lithography and focused ion beam etching provides a novel method for fast and precise (10 nm accuracy) prototyping of planar photonic crystal structures having submicron features, in silicon on insulator wafers

Ultra compact spectral slicer devices based on microring resonators

In Wavelength Division Multiplexing (WDM), access network spectral slicer devices in connection with a broadband light source are attracting low-cost alternatives for the laser diodes that are required for transmission in the desired wavelength channels. The proposed ultra-compact spectral slicer devices consist of microring resonators with slightly different radius and consequently slightly different resonant wavelength. Single and cascaded multiple microring devices have been fabricated and characterized to demonstrate the desired functionality. Cascaded devices show better performance in term of lower crosstalk, higher rejection ratio and faster roll-off. Moreover, they open the possibility to improve the spectral efficiency of the individual channels without introducing additional channel crosstalk

Wavelength-selective switch using thermally tunable microring resonators

A novel wavelength-selective switch based on thermally tunable Si3N4 microring resonators has been designed, realized and characterized. The switch has an ON/OFF ratio of 7.5 dB and is made out of two thermally tunable microrings which can be tuned over 5 nm

Design and fabrication of line-defect waveguides in hexagon-type SOI photonic crystal slabs

We present a novel design approach for line-defect waveguides integrated in a photonic crystal slab (PCS) with hexagonal holes in a triangular lattice (aka 'hexagon-type'). Triangular air inclusions are symmetrically added on each side of the waveguide. Size and position of these inclusions are tuning parameters for the band diagram and can be used for minimizing the distributed Bragg reflection (DBR) effect. The waveguides show single-mode behavior with reasonably high group velocity and large transmission window, inside the gap between even-like modes. Qualitative design rules were obtained from 2D calculations based on effective index approximation and full 3D calculations of the band structure were applied for fine-tuning of structural parameters of these high-index contrast systems. Transmission spectra and losses of finite-sized structures were estimated by means of 3D finite-difference time domain (FDTD) calculations. We present a pattern definition technique, which is an integration of optical lithography with focused ion beam (FIB) high-resolution etching. The mask pattern is transferred into the SOI stack by a subsequent reactive ion etching (RIE) process. The combination of moderate resolution optical lithography and FIB etching provides an excellent tool for fast prototyping of PCS-based devices